US20020003123A1 - Cleaning solution for removing damaged portion of ferroelectric layer and cleaning method using the same - Google Patents
Cleaning solution for removing damaged portion of ferroelectric layer and cleaning method using the same Download PDFInfo
- Publication number
- US20020003123A1 US20020003123A1 US09/797,454 US79745401A US2002003123A1 US 20020003123 A1 US20020003123 A1 US 20020003123A1 US 79745401 A US79745401 A US 79745401A US 2002003123 A1 US2002003123 A1 US 2002003123A1
- Authority
- US
- United States
- Prior art keywords
- cleaning solution
- ferroelectric layer
- fluoride
- layer
- cleaning
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000004140 cleaning Methods 0.000 title claims abstract description 107
- 238000000034 method Methods 0.000 title claims abstract description 38
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims abstract description 22
- 150000007524 organic acids Chemical class 0.000 claims abstract description 22
- 239000003002 pH adjusting agent Substances 0.000 claims abstract description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims abstract description 13
- 239000000758 substrate Substances 0.000 claims description 33
- 239000003990 capacitor Substances 0.000 claims description 32
- 238000005530 etching Methods 0.000 claims description 23
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical group F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 16
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 12
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 12
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims description 12
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 10
- 238000000137 annealing Methods 0.000 claims description 9
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 9
- 230000008021 deposition Effects 0.000 claims description 8
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 claims description 8
- 238000000059 patterning Methods 0.000 claims description 6
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical group [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 5
- 235000019253 formic acid Nutrition 0.000 claims description 5
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 4
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 claims description 4
- 239000000908 ammonium hydroxide Substances 0.000 claims description 4
- 229940073455 tetraethylammonium hydroxide Drugs 0.000 claims description 4
- LRGJRHZIDJQFCL-UHFFFAOYSA-M tetraethylazanium;hydroxide Chemical compound [OH-].CC[N+](CC)(CC)CC LRGJRHZIDJQFCL-UHFFFAOYSA-M 0.000 claims description 4
- 239000003513 alkali Substances 0.000 claims description 3
- 239000000243 solution Substances 0.000 description 47
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 21
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 12
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 11
- 239000007789 gas Substances 0.000 description 9
- 238000000151 deposition Methods 0.000 description 7
- 239000002904 solvent Substances 0.000 description 7
- 238000003860 storage Methods 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 6
- 230000001476 alcoholic effect Effects 0.000 description 6
- 239000008367 deionised water Substances 0.000 description 6
- 229910021641 deionized water Inorganic materials 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 6
- 229910044991 metal oxide Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 239000000460 chlorine Substances 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- 239000006227 byproduct Substances 0.000 description 3
- 239000003638 chemical reducing agent Substances 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- -1 hydroxy ions Chemical class 0.000 description 3
- 229910052741 iridium Inorganic materials 0.000 description 3
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 3
- YADSGOSSYOOKMP-UHFFFAOYSA-N lead dioxide Inorganic materials O=[Pb]=O YADSGOSSYOOKMP-UHFFFAOYSA-N 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910020289 Pb(ZrxTi1-x)O3 Inorganic materials 0.000 description 2
- 229910020273 Pb(ZrxTi1−x)O3 Inorganic materials 0.000 description 2
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 2
- 150000004697 chelate complex Chemical class 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- HTXDPTMKBJXEOW-UHFFFAOYSA-N dioxoiridium Chemical compound O=[Ir]=O HTXDPTMKBJXEOW-UHFFFAOYSA-N 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 229910052736 halogen Inorganic materials 0.000 description 2
- 150000002367 halogens Chemical class 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 239000010948 rhodium Substances 0.000 description 2
- 229910052707 ruthenium Inorganic materials 0.000 description 2
- WOCIAKWEIIZHES-UHFFFAOYSA-N ruthenium(iv) oxide Chemical compound O=[Ru]=O WOCIAKWEIIZHES-UHFFFAOYSA-N 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 229910002938 (Ba,Sr)TiO3 Inorganic materials 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 229910018276 LaSrCoO3 Inorganic materials 0.000 description 1
- 229910019834 RhO2 Inorganic materials 0.000 description 1
- 229910002370 SrTiO3 Inorganic materials 0.000 description 1
- LDDQLRUQCUTJBB-UHFFFAOYSA-N ammonium fluoride Chemical compound [NH4+].[F-] LDDQLRUQCUTJBB-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Inorganic materials [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000009920 chelation Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000013068 control sample Substances 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- KZYDBKYFEURFNC-UHFFFAOYSA-N dioxorhodium Chemical compound O=[Rh]=O KZYDBKYFEURFNC-UHFFFAOYSA-N 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 229910000457 iridium oxide Inorganic materials 0.000 description 1
- 238000001020 plasma etching Methods 0.000 description 1
- 239000002798 polar solvent Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910001925 ruthenium oxide Inorganic materials 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- IATRAKWUXMZMIY-UHFFFAOYSA-N strontium oxide Inorganic materials [O-2].[Sr+2] IATRAKWUXMZMIY-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
- C11D7/22—Organic compounds
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/53—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone involving the removal of at least part of the materials of the treated article, e.g. etching, drying of hardened concrete
- C04B41/5315—Cleaning compositions, e.g. for removing hardened cement from ceramic tiles
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/91—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics involving the removal of part of the materials of the treated articles, e.g. etching
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
- C11D7/02—Inorganic compounds
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
- C11D7/22—Organic compounds
- C11D7/26—Organic compounds containing oxygen
- C11D7/265—Carboxylic acids or salts thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31105—Etching inorganic layers
- H01L21/31111—Etching inorganic layers by chemical means
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00844—Uses not provided for elsewhere in C04B2111/00 for electronic applications
-
- C11D2111/22—
Definitions
- the present invention relates to a cleaning solution for use in removing a damaged portion of a ferroelectric layer, and a method for removing a damaged portion of a ferroelectric layer using the cleaning solution.
- a ferroelectric random access memory can retain its contents without power for years.
- FRAM capacitors are kept in a charged state while the supply of power is suspended.
- active components of etching gases used for the patterning such as argon (Ar), fluorine (F) or chlorine (Cl)
- etching gases such as argon (Ar), fluorine (F) or chlorine (Cl)
- electrode materials or ferroelectric materials react with electrode materials or ferroelectric materials, thereby resulting in byproducts such as PbO 2 , ZrO 2 , TiO 2 or TiO 3 , on the surface of a ferroelectric layer.
- the ferroelectric layer is damaged by the byproducts.
- the damaged ferroelectric layer serves as a leakage current path between upper and lower electrodes, thereby degrading the electrical properties of the FRAM capacitor.
- annealing is carried out so as to provide the FRAM capacitor with a stable perovskite structure.
- a pyrochlore structure which is a semi-stable phase, appears from the top of the ferroelectric layer to a predetermined depth. If an upper electrode layer is deposited over the ferroelectric layer having the pyrochlore structure, a desirable FRAM capacitor having superior performance cannot be obtained.
- the ferroelectric layer having the pyrochlore structure is regarded as a kind of damaged layer, relative to the whole ferroelectric layer with the perovskite structure.
- a conventional cleaning solution used in the cleaning step includes hydrogen fluoride (HF) diluted with an alcoholic solvent, such as methanol, ethanol or isopropyl alcohol, in a predetermined ratio.
- HF hydrogen fluoride
- an alcoholic solvent such as methanol, ethanol or isopropyl alcohol
- IPA isopropyl alcohol
- a method is also needed for selectively removing a damaged portion of a ferroelectric layer using the cleaning solution.
- a cleaning solution is provided that is capable of selectively removing a damaged portion of a ferroelectric layer, the cleaning solution comprising a fluoride, an organic acid with carboxyl group, an alkaline pH adjusting agent, and water. It is preferable that the pH of the cleaning solution is in the range of about 4.5 to about 6.0.
- the fluoride comprises hydrogen fluoride, hydroboron tetrafluoride or ammonium fluoride
- the organic acid comprises formic acid, acetic acid or citric acid
- the alkaline pH adjusting agent comprises ammonium hydroxide, potassium hydroxide, tetramethylammonium hydroxide or tetraethylammonium hydroxide.
- the fluoride content is from about 0.01% to about 1% by weight
- the content of the organic acid with carboxyl group is from about 1% to about 50% by weight
- the content of the alkali pH adjusting agent is from about 0.25% to about 15% by weight based on the total weight of the cleaning solution.
- a method of selectively removing a damaged portion of a ferroelectric layer with a cleaning solution comprising: providing an integrated circuit substrate having an exposed ferroelectric layer with a damaged portion; and making the exposed ferroelectric layer contact the cleaning solution, the cleaning solution including a fluoride, an organic acid with carboxyl group, an alkaline pH adjusting agent and water.
- the exposed ferroelectric layer includes the surface of the ferroelectric layer which is passed through annealing after deposition on an integrated circuit substrate.
- the exposed ferroelectric layer is contacted with the cleaning solution to etch back the ferroelectric layer by a thickness of between about 100 ⁇ to about 500 ⁇ from the top of the ferroelectric layer.
- the exposed ferroelectric layer is interposed between upper and lower electrode layers, and the method further comprises forming a capacitor by patterning the upper electrode layer, the ferroelectric layer and the lower electrode layer before contacting the exposed ferroelectric layer with the cleaning solution.
- a cleaning solution according to the present invention is able to effectively remove a damaged portion of the ferroelectric layer, while maintaining a consistent cleaning capability for a longer period of time.
- FIG. 1 is an exemplary flowchart illustrating use of a cleaning solution according to an aspect of the present invention in the manufacture of a ferroelectric random access memory (FRAM) capacitor.
- FRAM ferroelectric random access memory
- FIG. 2 is an exemplary graph showing etching rate variations with respect to hydrogen fluoride content in the cleaning solution according to an aspect of the present invention, which were measured to determine an appropriate hydrogen fluoride content of the cleaning solution.
- FIG. 3 is an exemplary graph showing etching rate variations with respect to a pH of the cleaning solution according to an aspect of the present invention, which were measured to determine an appropriate pH level of the cleaning solution.
- FIG. 4 is an exemplary graph showing etching rate variations with respect to cleaning time for determining an appropriate cleaning time for a cleaning process using the cleaning solution according to an aspect of the present invention.
- FIG. 5 is an exemplary graph showing etching rate variations of the cleaning solution according to the present invention over time, which were measured to determine a lifetime of the cleaning solution.
- FIG. 6 is an exemplary graph showing remnant polarization in a FRAM capacitor after a conventional cleaning solution and the inventive cleaning solution is applied to sidewalls of the FRAM capacitor.
- FIG. 7 is an exemplary graph showing a leakage current characteristic of a FRAM capacitor after the conventional cleaning solution and the inventive cleaning solution are each applied to the sidewalls of the FRAM capacitor.
- the cleaning solution according to an aspect of the present invention which for convenience will be referred to as Samsung selective Cleaning Solution or “S.C.S”, preferably includes a fluoride, an organic acid with carboxyl group, an alkaline pH adjusting agent, and water.
- the S.C.S. includes a range of about 0.01% to about 1% by weight fluoride, about 1% to about 50% by weight organic acid with carboxyl group, about 0.25% to about 15% by weight alkaline pH adjusting agent, and a remaining balance of water.
- a cleaning time of 30 minutes or less is desirable. If the fluoride content is less than 0.01% by weight, it is impossible to completely remove a damaged portion of a ferroelectric layer within the maximum desired period of cleaning time. However, if the fluoride content exceeds 1% by weight, the etching rate over the damaged ferroelectric layer is so high that accurate controlling of the cleaning process is difficult.
- the organic acid content is less than 1% by weight, the cleaning capability with respect to the damaged portion of the ferroelectric layer decreases. Also, for a greater cleaning efficiency and processing margin, it is desirable that the organic acid content does not exceed about 50% by weight.
- the pH adjusting agent content varies depending on the fluoride and organic acid contents. Preferably, the pH adjusting agent content is in the range of between about 0.25% to about 15% by weight based on the total weight of S.C.S.
- the pH level of the S.C.S is about 6.6 or less. If the pH level of the S.C.S is higher than about 6.6, the damaged portion of the ferroelectric layer cannot be completely removed within the maximum desired cleaning time. However, if the S.C.S exhibits strong acidity less than about pH 4.5, electrode layers formed above and below the ferroelectric layer are damaged. In a pH range from about 6.0 to about 6.6, the damaged portion of the ferroelectric layer can be removed with the S.C.S., but the etching selectivity with respect to the damaged portion of the ferroelectric layer drops. Therefore, to selectively remove the damaged portion of the ferroelectric layer at a constant etching rate without removing an undamaged portion, it is more preferable that the pH of the S.C.S. ranges from about 4.5 to about 6.0.
- the fluoride for use in the cleaning solution is hydrogen fluoride (HF), hydroboron tetrafluoride (HBF 4 ) or ammonium fluoride (NH 4 F).
- the organic acid with carboxyl group is formic acid (HCOOH), acetic acid (CH 3 COOH) or citric acid (C 3 H 4 (OH)(COOH) 3 ).
- the alkaline pH adjusting agent is ammonium hydroxide (NH 4 OH), potassium hydroxide (KOH), tetramethyl ammonium hydroxide ((CH 3 ) 4 NH 4 OH), or tetraethyl ammonium hydroxide ((CH 3 CH 2 ) 4 NH 4 OH).
- the type of ferroelectric layer to which the S.C.S. can be applied includes a STO (SrTiO 3 ) layer, a BST (Ba,Sr)TiO 3 ) layer, a PZT (Pb(Zr x Ti 1-x )O 3 layer, and a PLZT (La-doped PZT) layer.
- the main cause of damage to the ferroelectric layer are oxides of the constituent elements of the ferroelectric layers. These oxides, such as PbO 2 , ZrO 2 , TiO 2 , TiO 3 , BaO, or SrO, can be removed by the following method.
- Fluorine ion (F ⁇ ) derived from fluoride which has a strong reducing power, reduces the metal of a metallic oxide.
- fluorine ion ammonium and hydroxy ions originating from a pH adjusting agent and hydrogen ions dissociated from an organic acid also serve as reductants.
- Reduction of a metallic oxide (for example, titanium oxide (TiO 3 )) by a fluoride (for example, hydrogen fluoride (HF) is expressed, for example, by the following reaction scheme:
- the reduced metallic component is dissolved in the organic acid by chelation with the organic acid having a carboxyl group, or in water that is a polar solvent contained in the cleaning solvent.
- the organic acid according to the present invention which serves as a reductant and a dissolving agent as described previously, protects an exposed capacitor electrode layer formed on the surface of an integrated circuit substrate, for example, an iridium (Ir), ruthenium (Ru) or platinum (Pt) layer, or an iridium oxide (IrO 2 ) or ruthenium oxide (RuO 2 ) layer, from corrosion or damage.
- an iridium (Ir), ruthenium (Ru) or platinum (Pt) layer or an iridium oxide (IrO 2 ) or ruthenium oxide (RuO 2 ) layer
- a metallic oxide layer is spontaneously formed on the exposed electrode layer.
- the organic acid forms a chelate complex with the metal ions.
- the exposed surface of the electrode layer is covered with the stable chelate complex, so that the exposed electrode layer is protected from corrosion or damage.
- the pH adjusting agent according to the present invention is used for appropriately adjusting the pH level of the S.C.S, such that the etching selectivity with respect to the damaged portion of the ferroelectric layer increases while keeping the reducing power of the fluoride constant.
- the pH adjusting agent properly adjusts the pH of the S.C.S. to minimize the damage of the electrode layer.
- a suitable pH level of the S.C.S adjusted by the pH adjusting agent preferably ranges from about 4.5 to about 6.0.
- a method for manufacturing a FRAM capacitor using the S.C.S. according to the present invention will be described with reference to FIG. 1.
- a storage electrode layer which is electrically connected to a source region, is formed over a semiconductor substrate with a sub structure (step 100 ).
- the storage electrode layer may be formed of the platinum group metals including platinum (Pt), iridium (Ir), ruthenium (Ru) and rhodium (Rh).
- the storage electrode layer may be formed of a metallic oxide layer, such as an IrO 2 , RuO 2 , RhO 2 or LaSrCoO 3 layer.
- a ferroelectric layer is formed over the storage electrode layer (step 110 ).
- the ferroelectric layer may be formed of a STO, BST, PZT or PLZT layer.
- the ferroelectric layer having a desired thickness can be formed by a single deposition and annealing, or alternatively, deposition to a predetermined thickness and a baking process can be repeated until a ferroelectric layer having a desired thickness is formed. In the latter case, after the ferroelectric layer reaches the desired thickness, annealing is carried out on the resultant structure. The deposition and baking processes can be repeated to make the composition and properties of the ferroelectric layer uniform.
- step 120 the ferroelectric layer is made to contact with the S.C.S. according to the present invention (step 120 ).
- Step 120 is performed for a predetermined time period in which the ferroelectric layer can be etched back between about 100 ⁇ to about 500 ⁇ .
- step 120 is carried out for about 30 to 600 seconds, but more preferably, for about 30 to about 180 seconds.
- the substrate with the ferroelectric layer may be dipped in a S.C.S. bath or the S.C.S may be spread over the ferroelectric layer.
- the step 120 of removing a damaged portion of the ferroelectric layer using the S.C.S. can be omitted.
- a plate electrode layer is formed over the resultant structure (step 130 ).
- the plate electrode layer may be formed of the same material used for the storage electrode, i.e., a Pt group metal or an oxide of the Pt group metal.
- the plate electrode layer, the ferroelectric layer and the storage electrode layer are consequently patterned to form a capacitor (step 140 ).
- This patterning is carried out by dry etching using an etching gas containing, for example, Ar, F or Cl.
- active components of the etching gas such as, for example, Ar, F or Cl, react with the the electrode materials or ferroelectric material, thereby resulting in byproducts such as, for example, PbO 2 , ZrO 2 , TiO 2 or TiO 3 , on the sidewalls of the ferroelectric layer, which cause damage to sidewalls of the ferroelectric layer.
- the substrate with the FRAM capacitor is cleaned with the S.C.S. to remove a damaged portion of the ferroelectric layer (step 150 ).
- the inventive S.C.S. does not contain a highly volatile alcoholic solvent.
- the inventive S.C.S. does not contain a highly volatile alcoholic solvent.
- the cleaning process can be performed at low temperatures of 60° C. or less, and particularly, at room temperature.
- an S.C.S. solution according to the present invention does not cause corrosion or damage of electrode layers, so that contact with the substrate for a longer time period is allowed.
- the substrate is preferably contacted with the S.C.S. solution for about 30 to about 600 seconds, but more preferably, for about 30 to about 180 seconds.
- the substrate is rinsed with deionized water so as to remove the S.C.S. in which the damaged portion separated from the ferroelectric layer is dissolved (step 160 ).
- the rinsing process may be performed through two stages as needed.
- the substrate is dried by spin drying or by using isopropyl alcohol to evaporate deionized water from the surface of the substrate, thereby resulting in a complete FRAM capacitor (step 170 ). After the drying is completed, the resultant substrate is transferred for a next step that is required to integrate a circuit on the substrate.
- inventive S.C.S. is an aqueous solution
- a single rinse with deionized water is sufficient to completely remove the S.C.S. from the surface of the substrate.
- IPA isopropyl alcohol
- the inventive S.C.S. exhibits a high etching rate and a high etching selectivity with respect to a damaged portion of the ferroelectric layer, so that the damaged portion of the ferroelectric layer can be effectively removed, thereby improving the electrical properties of the FRAM capacitor.
- samples of the S.C.S. each containing 0.1%, 0.2%, 0.3% and 0.4% HF by weight based on the total weight of the S.C.S were prepared.
- Two S.C.S. samples were prepared for each HF concentration.
- a (Pb(Zr x Ti 1-x )O 3 (PZT) layer was deposited to a thickness of 500 ⁇ on 8 substrates, and baked. This deposition and baking was repeated once more, and an annealing process was carried out at 350° C. or more on the resultant structure, thereby forming a PZT layer having a thickness of 1000 ⁇ on the substrates.
- Plasma etching was performed on four substrates with a gas mixture containing halogen gas, CF x gas and O 2 gas, which caused damage to the PZT layers.
- the four substrates with the damaged PZT layers were immersed for 30 seconds in the respective S.C.S samples containing HF at the four different concentrations.
- the other four substrates with the whole PZT layers were immersed for 30 seconds in the respective S.C.S samples containing HF at the four different concentrations.
- the etching rate of the PZT layer was measured for the eight substrates. The results are shown in FIG. 2.
- the damaged PZT layer can be selectively removed at 0.3% or less by weight HF.
- the etching rate of the S.C.S solution with respect to the PZT layer decreases.
- the pH level of the S.C.S is preferably about 4.5 to about 6.0 to allow an adjustment of the etching rate and to selectively remove the damaged PZT layer in the cleaning step.
- the appropriate cleaning time is between about 80 to about 100 seconds, and more preferably, about 90 seconds.
- an indium (In) oxide layer and a platinum (Pt) layer were formed in sequence as lower electrode conductive layers and deposited in sequence over the oxide layer.
- an In oxide layer and an iridium (Ir) layer which serve as upper electrode conductive layers, were deposited over the resultant structure, and dry etched using a gas mixture including a halogen gas, thereby resulting in 7 FRAM capacitors.
- One FRAM capacitor was cleaned using a conventional cleaning solution containing methanol and HF as a control sample, and the other six FRAM capacitors were separately cleaned using an S.C.S. according to the present invention.
- the cleaning time with the S.C.S. was varied at 60, 90 and 120 seconds.
- Two FRAM capacitors (A and B) were cleaned at each cleaning time. Remnant polarization and leakage current properties of the capacitors were measured after the cleaning was completed. The results are shown in FIGS. 6 and 7.
- FIG. 6 capacitance of the FRAM capacitors can be improved with the inventive S.C.S. by about 20%, compared to the case of using the conventional cleaning solution.
- FIG. 7 shows that the leakage current properties of the FRAM capacitors treated with the S.C.S., exclusive of the FRAM capacitors cleaned for 60 seconds, are similar to those of the FRAM capacitor treated in the conventional cleaning solution.
- an S.C.S. is able to effectively remove a damaged portion of a ferroelectric layer, and does not corrode or damage electrode layers.
- inventive S.C.S. in the manufacture of a FRAM capacitor, electrical properties, such as leakage current and capacitance, of the FRAM capacitor can be improved.
- inventive S.C.S. does not contain a highly volatile alcoholic solvent, and thus its lifetime is prolonged.
- inventive S.C.S. is aqueous, a single rinsing process with deionized water is sufficient to completely remove the inventive S.C.S. when it is used to remove a damaged ferroelectric layer.
- a rinsing process with isopropyl alcohol which is required when using a conventional cleaning solution, is unnecessary in the case of using the inventive S.C.S.
Abstract
A cleaning solution for use in removing a damaged portion of a ferroelectric layer, and a cleaning method using the solution. The cleaning solution includes a fluoride, an organic acid with carboxyl group, an alkaline pH adjusting agent and water.
Description
- 1. Technical Field
- The present invention relates to a cleaning solution for use in removing a damaged portion of a ferroelectric layer, and a method for removing a damaged portion of a ferroelectric layer using the cleaning solution.
- 2. Discussion of Related Art
- A ferroelectric random access memory (FRAM) can retain its contents without power for years. FRAM capacitors are kept in a charged state while the supply of power is suspended. During a patterning process for forming a FRAM capacitor, active components of etching gases used for the patterning, such as argon (Ar), fluorine (F) or chlorine (Cl), react with electrode materials or ferroelectric materials, thereby resulting in byproducts such as PbO2, ZrO2, TiO2 or TiO3, on the surface of a ferroelectric layer. As a result, the ferroelectric layer is damaged by the byproducts. The damaged ferroelectric layer serves as a leakage current path between upper and lower electrodes, thereby degrading the electrical properties of the FRAM capacitor.
- In the manufacture of the FRAM capacitor, annealing is carried out so as to provide the FRAM capacitor with a stable perovskite structure. However, even after the annealing is completed, a pyrochlore structure, which is a semi-stable phase, appears from the top of the ferroelectric layer to a predetermined depth. If an upper electrode layer is deposited over the ferroelectric layer having the pyrochlore structure, a desirable FRAM capacitor having superior performance cannot be obtained. In this aspect, the ferroelectric layer having the pyrochlore structure is regarded as a kind of damaged layer, relative to the whole ferroelectric layer with the perovskite structure.
- Thus, there is a need to perform a cleaning step for removing such a ferroelectric layer having the semi-stable pyrochlore structure and a portion of the ferroelectric layer that is damaged during an etching process in the manufacture of the FRAM capacitor. A conventional cleaning solution used in the cleaning step includes hydrogen fluoride (HF) diluted with an alcoholic solvent, such as methanol, ethanol or isopropyl alcohol, in a predetermined ratio. However, because the alcoholic solvent of the cleaning solution is highly volatile, the alcoholic solvent evaporates with time, hence the cleaning (etching) capability of the cleaning solution cannot be kept constant, thereby shortening the lifetime of the cleaning solution. Another disadvantage in using the conventional cleaning solution lies in that after the cleaning is completed, a further rinsing step with isopropyl alcohol (IPA) is needed before a rinsing step with deionized water. This is because the rinsing step with deionized water is insufficient to completely remove the cleaning solution from the surface of the substrate, which causes corrosion of the substrate.
- Therefore, a need exists for providing a cleaning solution capable of selectively removing a damaged portion of a ferroelectric layer, and has a consistent cleaning capability for a longer period of time.
- A method is also needed for selectively removing a damaged portion of a ferroelectric layer using the cleaning solution.
- According to an aspect of the present invention, a cleaning solution is provided that is capable of selectively removing a damaged portion of a ferroelectric layer, the cleaning solution comprising a fluoride, an organic acid with carboxyl group, an alkaline pH adjusting agent, and water. It is preferable that the pH of the cleaning solution is in the range of about 4.5 to about 6.0.
- It is preferable that the fluoride comprises hydrogen fluoride, hydroboron tetrafluoride or ammonium fluoride, the organic acid comprises formic acid, acetic acid or citric acid, and the alkaline pH adjusting agent comprises ammonium hydroxide, potassium hydroxide, tetramethylammonium hydroxide or tetraethylammonium hydroxide.
- It is preferable that the fluoride content is from about 0.01% to about 1% by weight, the content of the organic acid with carboxyl group is from about 1% to about 50% by weight, and the content of the alkali pH adjusting agent is from about 0.25% to about 15% by weight based on the total weight of the cleaning solution.
- According to another aspect of the present invention, there is provided a method of selectively removing a damaged portion of a ferroelectric layer with a cleaning solution, the method comprising: providing an integrated circuit substrate having an exposed ferroelectric layer with a damaged portion; and making the exposed ferroelectric layer contact the cleaning solution, the cleaning solution including a fluoride, an organic acid with carboxyl group, an alkaline pH adjusting agent and water.
- It is preferable that the exposed ferroelectric layer includes the surface of the ferroelectric layer which is passed through annealing after deposition on an integrated circuit substrate. Preferably, the exposed ferroelectric layer is contacted with the cleaning solution to etch back the ferroelectric layer by a thickness of between about 100 Å to about 500 Å from the top of the ferroelectric layer.
- It is preferable that the exposed ferroelectric layer is interposed between upper and lower electrode layers, and the method further comprises forming a capacitor by patterning the upper electrode layer, the ferroelectric layer and the lower electrode layer before contacting the exposed ferroelectric layer with the cleaning solution.
- Therefore, a cleaning solution according to the present invention is able to effectively remove a damaged portion of the ferroelectric layer, while maintaining a consistent cleaning capability for a longer period of time.
- These and other aspects, features and advantages of the present invention will described or become apparent from the following detailed description of the preferred embodiments, which is to be read in connection with the accompanying drawings.
- FIG. 1 is an exemplary flowchart illustrating use of a cleaning solution according to an aspect of the present invention in the manufacture of a ferroelectric random access memory (FRAM) capacitor.
- FIG. 2 is an exemplary graph showing etching rate variations with respect to hydrogen fluoride content in the cleaning solution according to an aspect of the present invention, which were measured to determine an appropriate hydrogen fluoride content of the cleaning solution.
- FIG. 3 is an exemplary graph showing etching rate variations with respect to a pH of the cleaning solution according to an aspect of the present invention, which were measured to determine an appropriate pH level of the cleaning solution.
- FIG. 4 is an exemplary graph showing etching rate variations with respect to cleaning time for determining an appropriate cleaning time for a cleaning process using the cleaning solution according to an aspect of the present invention.
- FIG. 5 is an exemplary graph showing etching rate variations of the cleaning solution according to the present invention over time, which were measured to determine a lifetime of the cleaning solution.
- FIG. 6 is an exemplary graph showing remnant polarization in a FRAM capacitor after a conventional cleaning solution and the inventive cleaning solution is applied to sidewalls of the FRAM capacitor.
- FIG. 7 is an exemplary graph showing a leakage current characteristic of a FRAM capacitor after the conventional cleaning solution and the inventive cleaning solution are each applied to the sidewalls of the FRAM capacitor.
- A cleaning solution and a cleaning method using the cleaning solution according to the present invention will now be described more fully. The cleaning solution according to an aspect of the present invention, which for convenience will be referred to as Samsung selective Cleaning Solution or “S.C.S”, preferably includes a fluoride, an organic acid with carboxyl group, an alkaline pH adjusting agent, and water.
- The S.C.S. includes a range of about 0.01% to about 1% by weight fluoride, about 1% to about 50% by weight organic acid with carboxyl group, about 0.25% to about 15% by weight alkaline pH adjusting agent, and a remaining balance of water.
- In terms of efficiency in the manufacture of semiconductor devices, a cleaning time of 30 minutes or less is desirable. If the fluoride content is less than 0.01% by weight, it is impossible to completely remove a damaged portion of a ferroelectric layer within the maximum desired period of cleaning time. However, if the fluoride content exceeds 1% by weight, the etching rate over the damaged ferroelectric layer is so high that accurate controlling of the cleaning process is difficult.
- If the organic acid content is less than 1% by weight, the cleaning capability with respect to the damaged portion of the ferroelectric layer decreases. Also, for a greater cleaning efficiency and processing margin, it is desirable that the organic acid content does not exceed about 50% by weight. The pH adjusting agent content varies depending on the fluoride and organic acid contents. Preferably, the pH adjusting agent content is in the range of between about 0.25% to about 15% by weight based on the total weight of S.C.S.
- It is preferable that the pH level of the S.C.S is about 6.6 or less. If the pH level of the S.C.S is higher than about 6.6, the damaged portion of the ferroelectric layer cannot be completely removed within the maximum desired cleaning time. However, if the S.C.S exhibits strong acidity less than about pH 4.5, electrode layers formed above and below the ferroelectric layer are damaged. In a pH range from about 6.0 to about 6.6, the damaged portion of the ferroelectric layer can be removed with the S.C.S., but the etching selectivity with respect to the damaged portion of the ferroelectric layer drops. Therefore, to selectively remove the damaged portion of the ferroelectric layer at a constant etching rate without removing an undamaged portion, it is more preferable that the pH of the S.C.S. ranges from about 4.5 to about 6.0.
- Preferably, the fluoride for use in the cleaning solution is hydrogen fluoride (HF), hydroboron tetrafluoride (HBF4) or ammonium fluoride (NH4F).
- Preferably, the organic acid with carboxyl group is formic acid (HCOOH), acetic acid (CH3COOH) or citric acid (C3H4(OH)(COOH)3).
- Preferably, the alkaline pH adjusting agent is ammonium hydroxide (NH4OH), potassium hydroxide (KOH), tetramethyl ammonium hydroxide ((CH3)4NH4OH), or tetraethyl ammonium hydroxide ((CH3CH2)4NH4OH).
- The type of ferroelectric layer to which the S.C.S. can be applied, includes a STO (SrTiO3) layer, a BST (Ba,Sr)TiO3) layer, a PZT (Pb(ZrxTi1-x)O3 layer, and a PLZT (La-doped PZT) layer.
- The main cause of damage to the ferroelectric layer are oxides of the constituent elements of the ferroelectric layers. These oxides, such as PbO2, ZrO2, TiO2, TiO3, BaO, or SrO, can be removed by the following method.
- Fluorine ion (F−) derived from fluoride, which has a strong reducing power, reduces the metal of a metallic oxide. In addition to the fluorine ion, ammonium and hydroxy ions originating from a pH adjusting agent and hydrogen ions dissociated from an organic acid also serve as reductants. Reduction of a metallic oxide (for example, titanium oxide (TiO3)) by a fluoride (for example, hydrogen fluoride (HF), is expressed, for example, by the following reaction scheme:
- The reduced metallic component is dissolved in the organic acid by chelation with the organic acid having a carboxyl group, or in water that is a polar solvent contained in the cleaning solvent.
- The organic acid according to the present invention, which serves as a reductant and a dissolving agent as described previously, protects an exposed capacitor electrode layer formed on the surface of an integrated circuit substrate, for example, an iridium (Ir), ruthenium (Ru) or platinum (Pt) layer, or an iridium oxide (IrO2) or ruthenium oxide (RuO2) layer, from corrosion or damage. In particular, a metallic oxide layer is spontaneously formed on the exposed electrode layer. As the metallic oxide layer is reduced into metal ions by the reaction with a reductant contained in the S.C.S, the organic acid forms a chelate complex with the metal ions. As a result, the exposed surface of the electrode layer is covered with the stable chelate complex, so that the exposed electrode layer is protected from corrosion or damage.
- The pH adjusting agent according to the present invention is used for appropriately adjusting the pH level of the S.C.S, such that the etching selectivity with respect to the damaged portion of the ferroelectric layer increases while keeping the reducing power of the fluoride constant. In addition, the pH adjusting agent properly adjusts the pH of the S.C.S. to minimize the damage of the electrode layer. Considering these aspects, a suitable pH level of the S.C.S adjusted by the pH adjusting agent preferably ranges from about 4.5 to about 6.0.
- A method for manufacturing a FRAM capacitor using the S.C.S. according to the present invention will be described with reference to FIG. 1. A storage electrode layer, which is electrically connected to a source region, is formed over a semiconductor substrate with a sub structure (step100). The storage electrode layer may be formed of the platinum group metals including platinum (Pt), iridium (Ir), ruthenium (Ru) and rhodium (Rh). To improve the fatigue characteristic, the storage electrode layer may be formed of a metallic oxide layer, such as an IrO2, RuO2, RhO2 or LaSrCoO3 layer.
- Next, a ferroelectric layer is formed over the storage electrode layer (step110). The ferroelectric layer may be formed of a STO, BST, PZT or PLZT layer. The ferroelectric layer having a desired thickness can be formed by a single deposition and annealing, or alternatively, deposition to a predetermined thickness and a baking process can be repeated until a ferroelectric layer having a desired thickness is formed. In the latter case, after the ferroelectric layer reaches the desired thickness, annealing is carried out on the resultant structure. The deposition and baking processes can be repeated to make the composition and properties of the ferroelectric layer uniform. Although the ferroelectric layer is completed through these processes, a semi-stable pyrochlore phase also forms on the top of the ferroelectric layer. To remove the damaged portion having the semi-stable pyrochlore phase from the ferroelectric layer, the ferroelectric layer is made to contact with the S.C.S. according to the present invention (step 120). Step 120 is performed for a predetermined time period in which the ferroelectric layer can be etched back between about 100 Å to about 500 Å. Preferably,
step 120 is carried out for about 30 to 600 seconds, but more preferably, for about 30 to about 180 seconds. Instep 120, the substrate with the ferroelectric layer may be dipped in a S.C.S. bath or the S.C.S may be spread over the ferroelectric layer. - If the ferroelectric layer has a whole perovskite structure through the annealing performed after the deposition, the
step 120 of removing a damaged portion of the ferroelectric layer using the S.C.S. can be omitted. - After the damaged portion of the ferroelectric layer has been removed, a plate electrode layer is formed over the resultant structure (step130). The plate electrode layer may be formed of the same material used for the storage electrode, i.e., a Pt group metal or an oxide of the Pt group metal.
- Next, the plate electrode layer, the ferroelectric layer and the storage electrode layer are consequently patterned to form a capacitor (step140). This patterning is carried out by dry etching using an etching gas containing, for example, Ar, F or Cl. During the patterning, active components of the etching gas, such as, for example, Ar, F or Cl, react with the the electrode materials or ferroelectric material, thereby resulting in byproducts such as, for example, PbO2, ZrO2, TiO2 or TiO3, on the sidewalls of the ferroelectric layer, which cause damage to sidewalls of the ferroelectric layer.
- Subsequently, the substrate with the FRAM capacitor is cleaned with the S.C.S. to remove a damaged portion of the ferroelectric layer (step150).
- Unlike a conventional cleaning solution, the inventive S.C.S. does not contain a highly volatile alcoholic solvent. Thus, even though cleaning is performed several times with the inventive S.C.S., there are no problems associated with a changing volume or composition ratio of the S.C.S. due to evaporation of an alcoholic solvent. As a result, the cleaning efficiency of S.C.S. is consistent. Furthermore, when the inventive cleaning solution is utilized, the cleaning process can be performed at low temperatures of 60° C. or less, and particularly, at room temperature.
- In addition, an S.C.S. solution according to the present invention does not cause corrosion or damage of electrode layers, so that contact with the substrate for a longer time period is allowed. To maximize the process efficiency and the complete removal of the damaged portion of the ferroelectric layer, the substrate is preferably contacted with the S.C.S. solution for about 30 to about 600 seconds, but more preferably, for about 30 to about 180 seconds.
- After the cleaning process is completed, the substrate is rinsed with deionized water so as to remove the S.C.S. in which the damaged portion separated from the ferroelectric layer is dissolved (step160). The rinsing process may be performed through two stages as needed. Lastly, the substrate is dried by spin drying or by using isopropyl alcohol to evaporate deionized water from the surface of the substrate, thereby resulting in a complete FRAM capacitor (step 170). After the drying is completed, the resultant substrate is transferred for a next step that is required to integrate a circuit on the substrate.
- Because the inventive S.C.S. is an aqueous solution, a single rinse with deionized water is sufficient to completely remove the S.C.S. from the surface of the substrate. Thus, a further rinsing process with isopropyl alcohol (IPA), which was required when using a conventional cleaning solution, is unnecessary when using the inventive S.C.S. In addition, the inventive S.C.S. exhibits a high etching rate and a high etching selectivity with respect to a damaged portion of the ferroelectric layer, so that the damaged portion of the ferroelectric layer can be effectively removed, thereby improving the electrical properties of the FRAM capacitor.
- The present invention will be described in greater detail by means of the following examples. The following examples are for illustrative purposes and are not intended to limit the scope of the invention.
- To determine an appropriate HF content in the S.C.S., samples of the S.C.S. each containing 0.1%, 0.2%, 0.3% and 0.4% HF by weight based on the total weight of the S.C.S were prepared. Two S.C.S. samples were prepared for each HF concentration. A (Pb(ZrxTi1-x)O3 (PZT) layer was deposited to a thickness of 500 Å on 8 substrates, and baked. This deposition and baking was repeated once more, and an annealing process was carried out at 350° C. or more on the resultant structure, thereby forming a PZT layer having a thickness of 1000 Å on the substrates. Plasma etching was performed on four substrates with a gas mixture containing halogen gas, CFx gas and O2 gas, which caused damage to the PZT layers. Next, the four substrates with the damaged PZT layers were immersed for 30 seconds in the respective S.C.S samples containing HF at the four different concentrations. Also, the other four substrates with the whole PZT layers were immersed for 30 seconds in the respective S.C.S samples containing HF at the four different concentrations. After the cleaning in the S.C.S. samples, the etching rate of the PZT layer was measured for the eight substrates. The results are shown in FIG. 2.
- As shown in FIG. 2, the damaged PZT layer can be selectively removed at 0.3% or less by weight HF.
- To determine an appropriate pH level of the S.C.S. at which it exhibits the full cleaning capability, various S.C.S. samples at pH levels of 4.5, 5.5, 6.0, and 9.0 were prepared. Two S.C.S. samples were prepared for each pH level. Four substrates with a damaged PZT layer and four substrates with a whole PZT layer were prepared in the same way as in Experimental Example 1 above. A substrate with the damaged PZT layer and a substrate with the undamaged PZT layer were immersed for 30 seconds in the two S.C.S. samples at the same pH level, respectively. After the cleaning in the S.C.S. samples, the etching rate with respect to the PZT layer was measured. The results are shown in FIG. 3.
- As shown in FIG. 3, as the pH of the S.C.S. changes from weak acidity to weak alkalinity, the etching rate of the S.C.S solution with respect to the PZT layer decreases. It can be noticed that the pH level of the S.C.S is preferably about 4.5 to about 6.0 to allow an adjustment of the etching rate and to selectively remove the damaged PZT layer in the cleaning step.
- An appropriate cleaning time was determined using an S.C.S sample whose composition was optimized based on the results from Experimental Examples 1 and 2 above. Four substrates with a damaged PZT layer were prepared in the same way as in Experimental Example 1. Next, the four substrates were immersed in the optimized S.C.S samples for 60, 90, 120 and 180 seconds, respectively. The amount of etching was measured for each substrate. The results are shown in FIG. 4.
- Considering that the thickness of the PZT layer damaged after the formation of a capacitor is usually about 100 Å, it can be noticed that the appropriate cleaning time is between about 80 to about 100 seconds, and more preferably, about 90 seconds.
- To measure the storage stability (i.e., the “lifetime”) of the S.C.S. according to the present invention, four S.C.S. samples were prepared and left for 0, 4, 8 and 16 hours, respectively. Four substrates with a damaged PZT layer were prepared in the same way as in Experimental Example 1, and immersed in the respective S.C.S. samples for 60 seconds. After the cleaning in the S.C.S. samples, the etching rate was measured for each sample. The results are shown in FIG. 5.
- As shown in FIG. 5, even after 16 hours have passed from the preparation of the S.C.S, the cleaning capability of the inventive S.C.S. remains consistent. In other words, the S.C.S. according to the present invention has a longer lifetime.
- After depositing an oxide layer over a substrate, an indium (In) oxide layer and a platinum (Pt) layer were formed in sequence as lower electrode conductive layers and deposited in sequence over the oxide layer. Next, an In oxide layer and an iridium (Ir) layer, which serve as upper electrode conductive layers, were deposited over the resultant structure, and dry etched using a gas mixture including a halogen gas, thereby resulting in 7 FRAM capacitors. One FRAM capacitor was cleaned using a conventional cleaning solution containing methanol and HF as a control sample, and the other six FRAM capacitors were separately cleaned using an S.C.S. according to the present invention. The cleaning time with the S.C.S. was varied at 60, 90 and 120 seconds. Two FRAM capacitors (A and B) were cleaned at each cleaning time. Remnant polarization and leakage current properties of the capacitors were measured after the cleaning was completed. The results are shown in FIGS. 6 and 7.
- As shown in FIG. 6, capacitance of the FRAM capacitors can be improved with the inventive S.C.S. by about 20%, compared to the case of using the conventional cleaning solution. FIG. 7 shows that the leakage current properties of the FRAM capacitors treated with the S.C.S., exclusive of the FRAM capacitors cleaned for 60 seconds, are similar to those of the FRAM capacitor treated in the conventional cleaning solution.
- As previously described, an S.C.S. according to the present invention is able to effectively remove a damaged portion of a ferroelectric layer, and does not corrode or damage electrode layers. Thus, by utilizing the inventive S.C.S. in the manufacture of a FRAM capacitor, electrical properties, such as leakage current and capacitance, of the FRAM capacitor can be improved. In addition, the inventive S.C.S. does not contain a highly volatile alcoholic solvent, and thus its lifetime is prolonged. Furthermore, because the inventive S.C.S. is aqueous, a single rinsing process with deionized water is sufficient to completely remove the inventive S.C.S. when it is used to remove a damaged ferroelectric layer. Thus, a rinsing process with isopropyl alcohol, which is required when using a conventional cleaning solution, is unnecessary in the case of using the inventive S.C.S.
- Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by persons ordinarily skilled in the art without departing from the scope or spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as defined by the appended claims.
Claims (19)
1. A cleaning solution capable of selectively removing a damaged portion of a ferroelectric layer, the cleaning solution comprising:
a fluoride;
an organic acid with carboxyl group;
an alkaline pH adjusting agent; and
water.
2. The cleaning solution of claim 1 , wherein the pH of the cleaning solution is about 4.5 to about 6.0.
3. The cleaning solution of claim 1 , wherein the fluoride is hydrogen fluoride, hydroboron tetrafluoride or ammonium fluoride.
4. The cleaning solution of claim 1 , wherein the organic acid is formic acid, acetic acid or citric acid.
5. The cleaning solution of claim 1 , wherein the alkaline pH adjusting agent is ammonium hydroxide, potassium hydroxide, tetramethylammonium hydroxide or tetraethylammonium hydroxide.
6. The cleaning solution of claim 1 , wherein the content of the fluoride is about 0.01% to about 1% by weight based on the total weight of the cleaning solution.
7. The cleaning solution of claim 1 , wherein the content of the organic acid with carboxyl group is about 1% to about 50% by weight based on the total weight of the cleaning solution.
8. The cleaning solution of claim 1 , wherein the content of the alkali pH adjusting agent is about 0.25% to about 15% by weight based on the total weight of the cleaning solution.
9. The cleaning solution of claim 1 , wherein the damaged portion of the ferroelectric layer to be removed with the cleaning solution includes the surface of the ferroelectric layer passed through annealing after deposition, or the surface of the ferroelectric layer passed through an etching process.
10. A method of selectively removing a damaged portion of a ferroelectric layer with a cleaning solution, the method comprising:
providing an integrated circuit substrate having an exposed ferroelectric layer with the damaged portion; and
contacting the exposed ferroelectric layer with the cleaning solution, said cleaning solution including a fluoride, an organic acid with carboxyl group, an alkaline pH adjusting agent, and water.
11. The method of claim 10 , wherein the exposed ferroelectric layer includes the surface of the ferroelectric layer passed through annealing after deposition on the integrated circuit substrate, and the step of making the exposed ferroelectric layer contact the cleaning solution includes etching back the ferroelectric layer by about 100 Å to about 500 Å from the top of the ferroelectric layer.
12. The method of claim 10 , wherein the exposed ferroelectric layer is interposed between upper and lower electrode layers, and the method further comprises forming a capacitor by patterning the upper electrode layer, the ferroelectric layer and the lower electrode layer, before contacting the exposed ferroelectric layer with the cleaning solution.
13. The method of claim 10 , wherein the pH of the cleaning solution is about 4.5 to about 6.0.
14. The method of claim 10 , wherein the fluoride is hydrogen fluoride, hydroboron tetrafluoride or ammonium fluoride.
15. The method of claim 10 , wherein the organic acid is formic acid, acetic acid or citric acid.
16. The method of claim 10 , wherein the alkaline pH adjusting agent is ammonium hydroxide, potassium hydroxide, tetramethylammonium hydroxide or tetraethylammonium hydroxide.
17. The method of claim 10 , wherein the content of the fluoride is about 0.01% to about 1% by weight based on the total weight of the cleaning solution.
18. The method of claim 10 , wherein the content of the organic acid with carboxyl group is about 1% to about 50% by weight based on the total weight of the cleaning solution.
19. The method of claim 10 , wherein the content of the alkali pH adjusting agent is about 0.25% to about 15% by weight based on the total weight of the cleaning solution.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/727,962 US7135413B2 (en) | 2000-06-27 | 2003-12-04 | Cleaning solution for removing damaged portion of ferroelectric layer and cleaning method using the same |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR00-35705 | 2000-06-27 | ||
KR1020000035705A KR100363092B1 (en) | 2000-06-27 | 2000-06-27 | Cleaning solution for removing damaged layer of ferroelectric layer and cleaning method using the same |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/727,962 Division US7135413B2 (en) | 2000-06-27 | 2003-12-04 | Cleaning solution for removing damaged portion of ferroelectric layer and cleaning method using the same |
Publications (1)
Publication Number | Publication Date |
---|---|
US20020003123A1 true US20020003123A1 (en) | 2002-01-10 |
Family
ID=19674224
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/797,454 Abandoned US20020003123A1 (en) | 2000-06-27 | 2001-03-01 | Cleaning solution for removing damaged portion of ferroelectric layer and cleaning method using the same |
US10/727,962 Expired - Fee Related US7135413B2 (en) | 2000-06-27 | 2003-12-04 | Cleaning solution for removing damaged portion of ferroelectric layer and cleaning method using the same |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/727,962 Expired - Fee Related US7135413B2 (en) | 2000-06-27 | 2003-12-04 | Cleaning solution for removing damaged portion of ferroelectric layer and cleaning method using the same |
Country Status (4)
Country | Link |
---|---|
US (2) | US20020003123A1 (en) |
JP (1) | JP2002025967A (en) |
KR (1) | KR100363092B1 (en) |
TW (1) | TW575661B (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050115925A1 (en) * | 2003-08-01 | 2005-06-02 | Vasile Paraschiv | Method for selective removal of high-k material |
US20050239218A1 (en) * | 2004-04-21 | 2005-10-27 | Texas Instruments Incorporated | Ferroelectric capacitor having a substantially planar dielectric layer and a method of manufacture therefor |
US20170012981A1 (en) * | 2015-07-08 | 2017-01-12 | T-Mobile Usa, Inc. | Trust policy for telecommunications device |
EP1688798B1 (en) * | 2005-02-03 | 2017-02-22 | Air Products and Chemicals, Inc. | Aqueous based residue removers comprising fluoride |
US10186655B2 (en) * | 2015-03-30 | 2019-01-22 | Sumitomo Chemical Company, Limited | Method for manufacturing ferroelectric thin film device |
US10211044B2 (en) | 2015-03-26 | 2019-02-19 | Sumitomo Chemical Company, Limited | Method for manufacturing ferroelectric thin film device |
US10276777B2 (en) | 2015-03-26 | 2019-04-30 | Sumitomo Chemical Company, Limited | Ferroelectric thin-film laminated substrate, ferroelectric thin-film device,and manufacturing method of ferroelectric thin-film laminated substrate |
US10497855B2 (en) | 2015-03-26 | 2019-12-03 | Sumitomo Chemical Company, Limited | Ferroelectric thin-film laminated substrate, ferroelectric thin-film device, and manufacturing method of ferroelectric thin-film laminated substrate |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4010819B2 (en) | 2002-02-04 | 2007-11-21 | Necエレクトロニクス株式会社 | Manufacturing method of semiconductor device |
CN1678961B (en) * | 2002-08-22 | 2010-05-05 | 大金工业株式会社 | Removing solution |
KR100705761B1 (en) * | 2005-08-10 | 2007-04-10 | 주식회사 대우일렉트로닉스 | Doorknob assembly |
JP4998337B2 (en) * | 2008-03-11 | 2012-08-15 | Tdk株式会社 | Dielectric element manufacturing method |
JP6353636B2 (en) * | 2013-06-21 | 2018-07-04 | 東京エレクトロン株式会社 | Method and apparatus for removing titanium oxide film |
JP2018121077A (en) * | 2018-04-19 | 2018-08-02 | 東京エレクトロン株式会社 | Method and device for removing titanium oxide film |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5520299A (en) * | 1995-02-15 | 1996-05-28 | Texas Instruments Incorporated | Etching pyroelectric devices post ion milling |
JP3201251B2 (en) * | 1996-03-18 | 2001-08-20 | 松下電器産業株式会社 | Method for manufacturing dielectric element |
US6030932A (en) * | 1996-09-06 | 2000-02-29 | Olin Microelectronic Chemicals | Cleaning composition and method for removing residues |
KR100497835B1 (en) * | 1997-01-27 | 2005-09-08 | 미쓰비시 가가꾸 가부시키가이샤 | Surface treatment composition and method for treating surface of substrate by using rhe same |
JPH1188101A (en) * | 1997-07-08 | 1999-03-30 | Toshiba Corp | Surface acoustic wave element and manufacture of the surface acoustic wave element |
US5977041A (en) * | 1997-09-23 | 1999-11-02 | Olin Microelectronic Chemicals | Aqueous rinsing composition |
US6593282B1 (en) * | 1997-10-21 | 2003-07-15 | Lam Research Corporation | Cleaning solutions for semiconductor substrates after polishing of copper film |
KR100464305B1 (en) * | 1998-07-07 | 2005-04-13 | 삼성전자주식회사 | How to Clean PZT Thin Film Using Enchantment |
-
2000
- 2000-06-27 KR KR1020000035705A patent/KR100363092B1/en not_active IP Right Cessation
-
2001
- 2001-03-01 US US09/797,454 patent/US20020003123A1/en not_active Abandoned
- 2001-03-07 TW TW90105298A patent/TW575661B/en active
- 2001-03-16 JP JP2001076596A patent/JP2002025967A/en active Pending
-
2003
- 2003-12-04 US US10/727,962 patent/US7135413B2/en not_active Expired - Fee Related
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050115925A1 (en) * | 2003-08-01 | 2005-06-02 | Vasile Paraschiv | Method for selective removal of high-k material |
US7132370B2 (en) * | 2003-08-01 | 2006-11-07 | Interuniversitair Microelektronica Centrum (Imec) | Method for selective removal of high-k material |
US20050239218A1 (en) * | 2004-04-21 | 2005-10-27 | Texas Instruments Incorporated | Ferroelectric capacitor having a substantially planar dielectric layer and a method of manufacture therefor |
US7153706B2 (en) * | 2004-04-21 | 2006-12-26 | Texas Instruments Incorporated | Ferroelectric capacitor having a substantially planar dielectric layer and a method of manufacture therefor |
EP1688798B1 (en) * | 2005-02-03 | 2017-02-22 | Air Products and Chemicals, Inc. | Aqueous based residue removers comprising fluoride |
US10211044B2 (en) | 2015-03-26 | 2019-02-19 | Sumitomo Chemical Company, Limited | Method for manufacturing ferroelectric thin film device |
US10276777B2 (en) | 2015-03-26 | 2019-04-30 | Sumitomo Chemical Company, Limited | Ferroelectric thin-film laminated substrate, ferroelectric thin-film device,and manufacturing method of ferroelectric thin-film laminated substrate |
US10497855B2 (en) | 2015-03-26 | 2019-12-03 | Sumitomo Chemical Company, Limited | Ferroelectric thin-film laminated substrate, ferroelectric thin-film device, and manufacturing method of ferroelectric thin-film laminated substrate |
US10186655B2 (en) * | 2015-03-30 | 2019-01-22 | Sumitomo Chemical Company, Limited | Method for manufacturing ferroelectric thin film device |
US20170012981A1 (en) * | 2015-07-08 | 2017-01-12 | T-Mobile Usa, Inc. | Trust policy for telecommunications device |
Also Published As
Publication number | Publication date |
---|---|
KR20020000670A (en) | 2002-01-05 |
US20040112870A1 (en) | 2004-06-17 |
JP2002025967A (en) | 2002-01-25 |
US7135413B2 (en) | 2006-11-14 |
TW575661B (en) | 2004-02-11 |
KR100363092B1 (en) | 2002-12-05 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7135413B2 (en) | Cleaning solution for removing damaged portion of ferroelectric layer and cleaning method using the same | |
US5258093A (en) | Procss for fabricating a ferroelectric capacitor in a semiconductor device | |
JP3114916B2 (en) | Dry etching method of layered structure oxide thin film | |
US6162738A (en) | Cleaning compositions for high dielectric structures and methods of using same | |
CN100380665C (en) | Ferroelectric memory element and its manufacturing method | |
KR100239417B1 (en) | Capacitor of semiconductor device amd manufacturing method thereof | |
US6245650B1 (en) | Process for production of semiconductor device | |
JP4898030B2 (en) | Cleaning process after etching | |
CN1790610A (en) | Method for fabricating capacitor of semiconductor device | |
US20050263489A1 (en) | Ruthenium silicide wet etch | |
KR20010085551A (en) | Process for manufacturing a semiconductor device | |
US6258608B1 (en) | Method for forming a crystalline perovskite ferroelectric material in a semiconductor device | |
JP3159257B2 (en) | Method for manufacturing semiconductor device | |
KR20000007792A (en) | Cleaning method of a pzt thin film | |
JP4416230B2 (en) | Manufacturing method of electronic device | |
US7015049B2 (en) | Fence-free etching of iridium barrier having a steep taper angle | |
JP3173598B2 (en) | Method and apparatus for cleaning semiconductor substrate | |
DE10058886C1 (en) | Production of an integrated semiconductor product used as ferroelectric random access memories comprises forming semiconductor wafer, molding connections, exposing the connections, applying protective layer and polishing | |
US20050263807A1 (en) | Semiconductor device and method for forming a ferroelectric capacitor of the semiconductor device | |
KR19980082844A (en) | Cleaning solution for semiconductor device containing platinum, cleaning method using same and manufacturing method of memory device using same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: SAMSUNG ELECTRONICS CO., LTD., KOREA, REPUBLIC OF Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LEE, KWANG-WOOK;PARK, IM-SOO;LEE, KUN-TACK;AND OTHERS;REEL/FRAME:011592/0480;SIGNING DATES FROM 20010219 TO 20010221 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |