CN102299064A - Method for oxidizing grid structure - Google Patents
Method for oxidizing grid structure Download PDFInfo
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- CN102299064A CN102299064A CN2010102177756A CN201010217775A CN102299064A CN 102299064 A CN102299064 A CN 102299064A CN 2010102177756 A CN2010102177756 A CN 2010102177756A CN 201010217775 A CN201010217775 A CN 201010217775A CN 102299064 A CN102299064 A CN 102299064A
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Abstract
The invention discloses a method for oxidizing a grid structure. The method comprises the following steps: manufacturing a grid structure on a silicon substrate of a semiconductor part; adopting a rapid thermal oxidation method to form seed oxidization layers on the grid structure and the exposed silicon substrate; adopting a wet oxidization method to form wet oxidization layers on the seed oxidization layer; and causing the sum of the thicknesses of the seed oxidization layers and the wet oxidization layer to be equal to the thickness of an oxidation film formed on the grid structure. The thin and even oxidation film is formed on the grid structure by using the method provided by the invention.
Description
Technical field
The present invention relates to technical field of semiconductors, the method for particularly a kind of grid structure oxidation.
Background technology
In the manufacturing process of semiconductor device, usually relate to crystal column surface is carried out oxidation processes.By suitable production control, formed oxide layer has high-quality and stable dielectric property.Because these characteristics, oxidation technology is vital in the manufacturing process of semiconductor device, particularly for the grid structure oxidation in metal-oxide semiconductor (MOS) (MOS) technology.
Fig. 1 is the method flow diagram of prior art to the oxidation of grid structure, and the generalized section to the oxidation of grid structure in conjunction with shown in Fig. 2 a～Fig. 2 c is elaborated to this method:
Before this step, in silicon substrate 101, form P trap and N trap, and between formation P trap and N trap, formed the shallow-trench isolation (STI) that is used to isolate by twin well process, do not express in the drawings;
In this step, the process of patterned polysilicon layer 103 is: be coated with photoresist layer on polysilicon layer 103, figure according to the grid structure, behind the photoresist layer exposure imaging, formation has the photoresist layer of grid structure graph, be mask with this photoresist layer then,, on silicon substrate 101, form grid structure 104 polysilicon layer 103 and gate oxide 102 etchings with grid structure graph;
In this step, the oxide-film 105 that obtains of thermal oxidation is a kind of hard and fine and close silicon dioxide (SiO
2) structure, it is as a kind of effective barrier layer, and active device on the protection silicon substrate 101 and silicon face are not scratched and damage during such as technologies such as source-drain electrode ion injections in follow-up manufacturing process.
The method that adopts thermal oxidation technique to form oxide-film 105 among Fig. 1 has two kinds, is respectively boiler tube thermal oxidation process and rapid thermal oxidation process.Wherein, the process of furnace oxidation method is: a collection of wafer of oxidation of wanting is placed in the high temperature furnace of aerating oxygen, adopts the high temperature greater than 700 degrees centigrade to continue 3～5 hours then, form oxide-film at the crystal column surface of wanting oxidation; The process of rapid thermal oxidation process is: the wafer of oxidation to be placed in the reaction chamber that is higher than 800 degrees centigrade a slice, in the short period, form oxide-film such as hundred seconds inherent crystal column surfaces of oxidation of wanting.
Along with development of semiconductor, (CD) is also more and more littler for the characteristic size of manufacturing semiconductor device, and the CD of corresponding grid structure is more and more littler, causes the thickness of oxide-film of grid structure also more and more thinner, about about 1～2 nanometer.If adopt the boiler tube thermal oxidation process, in order to obtain relatively thinner oxide-film, can realize by reducing the amount of oxygen method that feeds in the high temperature furnace, but, the oxide layer that obtains has very poor step blanketing effect, this is because not only have the oxygen of feeding in boiler tube, also has the oxygen in the natural environment, the thickness of oxide-film is subjected to the influence of this two classes oxygen simultaneously, along with the oxide thickness that will obtain reduces, can't be to the control of the amount of oxygen in the natural environment, the amount of oxygen that can only control feeding makes it fewer and feweri, this is to be difficult to control, so be not easy the thickness of controlled oxidation film and caused very poor step blanketing effect.If adopt rapid thermal oxidation process to obtain relatively thinner oxide-film, owing to be the oxidizing process that a slice a slice is carried out wafer, then for a collection of wafer, the time that needs is long, can't finish at short notice.
Summary of the invention
In view of this, the invention provides the method for a kind of grid structure oxidation, this method can obtain very thin and uniform oxide-film on the grid structure, and the time ratio of cost is less.
For achieving the above object, technical scheme of the invention process specifically is achieved in that
The method of a kind of grid structure oxidation is made the grid structure on the silicon substrate of semiconductor device, this method also comprises:
Reach employing rapid thermal oxidation process formation seed oxide layer on the exposed silicon substrate in the grid structure;
On the seed oxide layer, adopt the wet oxygen method to form the wet oxidation layer;
The thickness sum of described seed oxide layer and wet oxidation layer is will be at the structrural build up oxide thickness of grid.
Described seed thickness of oxide layer is 0.5～1.5 nanometer.
Described rapid thermal oxidation process is to carry out in reaction chamber, and the reaction chamber temperature of described employing is 600～700 degrees centigrade, and the amount of oxygen of feeding is that 1～20 per minute standard rises slm, and the nitrogen amount of feeding is 5～30slm, and the reaction time is 5～780 seconds.
The thickness of described wet oxidation layer is 0.5～2 nanometer.
Described wet oxygen method is to carry out in the oxidation chamber in position, and the in-situ oxidation cavity temperature of employing is 550～700 degrees centigrade, and the steam oxygen content of feeding is 0.1～10slm or feeds steam 3-30slm that the time is 5～50 seconds.
Described formation seed oxide layer and formation wet oxidation layer are respectively to be finished by two control system controls;
Perhaps described formation seed oxide layer and formation wet oxidation layer are to be finished by a control system control.
As seen from the above technical solution, method provided by the invention adopts two steps to form oxide-film on the grid structure, and first step adopts rapid thermal oxidation process oxidation on the grid structure to obtain the seed oxide layer; Second step adopts wet oxidation process to continue oxidation on the seed oxide layer, finally obtains oxide-film.Because wet oxidation process does not need very high temperature; such as just obtaining the relatively good and very thin oxide-film of step blanketing effect less than 700 degrees centigrade and little time; and the grid structures that before adopting wet oxidation process, adopted the seed protect oxide layer, the damage that the hydrogen that prevents to generate in the wet oxidation process process causes the grid oxide layer in the grid structure.In addition, adopting rapid thermal oxidation process oxidation on the grid structure to obtain in the seed oxide layer process, owing to the oxide-film of seed oxide layer than prior art, thickness becomes multiple to reduce, so the time that forms also reduces greatly.Therefore, method provided by the invention obtains very thin and uniform oxide-film on the grid structure, and the time ratio of cost is less.
Description of drawings
Fig. 1 is the method flow diagram of prior art to the oxidation of grid structure;
Fig. 2 a～Fig. 2 c is the generalized section of prior art to the oxidation of grid structure;
Fig. 3 is the method flow diagram of the present invention to the oxidation of grid structure;
Fig. 4 a～Fig. 4 b is the generalized section of the present invention to the oxidation of grid structure.
Embodiment
For making purpose of the present invention, technical scheme and advantage clearer, below with reference to the accompanying drawing embodiment that develops simultaneously, the present invention is described in further detail.
From prior art as can be seen, when adopting the boiler tube thermal oxidation process on the grid structure, to obtain thicker oxide-film, can't guarantee at low temperatures that its step blanketing effect is relatively good.But, along with the CD of semiconductor device is more and more littler, in the time of need on the grid structure, obtaining relatively thinner oxide-film, because the limitation characteristic of boiler tube thermal oxidation process self just can't realize the oxide-film that the step blanketing effect is relatively good and thickness is relatively thinner.Therefore, need to adopt rapid thermal oxidation process to realize, just a slice is wanted the wafer of oxidation to be placed in the reaction chamber, in the short period, such as hundred seconds inherent oxide-films of wanting crystal column surface formation 1～2 nanometer of oxidation, but, then need long time could obtain oxide-film respectively for a collection of wafer.
Therefore, in order to overcome this problem, the present invention is in order to obtain very thin and uniform oxide-film on the grid structure, and the time ratio of cost is less, has adopted two steps to carry out:
First step adopts rapid thermal oxidation process oxidation on the grid structure to obtain the seed oxide layer.This seed thickness of oxide layer is 0.5～1.5 nanometer; Second step adopts wet oxidation process to continue oxidation on the seed oxide layer, obtains the wet oxidation layer, and thickness is 0.5～2 nanometer.Thickness after final seed oxide layer and the wet oxidation layer equals the thickness of oxide-film, has just formed oxide-film on the grid structure.Because wet oxidation process does not need very high temperature; such as just obtaining the relatively good and very thin oxide-film of step blanketing effect less than 700 degrees centigrade and little time; and the grid structures that before adopting wet oxidation process, adopted the seed protect oxide layer, the damage that the hydrogen that prevents to generate in the wet oxidation process process causes the grid oxide layer in the grid structure.In addition, adopting rapid thermal oxidation process oxidation on the grid structure to obtain in the seed oxide layer process, because the seed oxide layer is than the oxide-film of prior art, thickness becomes multiple to reduce, and the time that rapid thermal oxidation process adopts is to be directly proportional with the thickness of oxide-film, so the time that forms also reduces greatly.
Fig. 3 is the method flow diagram of the present invention to the oxidation of grid structure, in conjunction with the present invention shown in Fig. 4 a～Fig. 4 b the generalized section of grid structure oxidation is elaborated:
Before this step, in silicon substrate 101, form P trap and N trap, and between formation P trap and N trap, formed the STI that is used to isolate by twin well process;
In this step, the process of patterned polysilicon layer 103 is: be coated with photoresist layer on polysilicon layer 103, figure according to the grid structure, behind the photoresist layer exposure imaging, formation has the photoresist layer of grid structure graph, be mask with this photoresist layer then,, on silicon substrate 101, form grid structure 104 polysilicon layer 103 and gate oxide 102 etchings with grid structure graph;
The rapid thermal oxidation process that step 303, employing are lower than 700 degree celsius temperature forms seed oxide layer 201 on the surface of the silicon substrate 101 of grid structure 104 and exposure, and thickness is 0.5～1.5 nanometer, shown in Fig. 4 a;
In this step, the reaction chamber temperature of employing is 600～700 degrees centigrade, and the amount of oxygen of feeding is 1～20 per minute standard liter (slm), and the nitrogen amount of feeding is 5～30slm, and the reaction time is 5～780 seconds;
In this step, formed seed oxide layer 201 guarantees that the follow-up hydrogen that generates in when forming the wet oxidation layer causes damage to the grid oxide layer in the grid structure;
In this step, the thickness of seed oxide layer 201 is less than will be at 1/2 of the formed oxide thickness of grid structure, and thickness is far smaller than will be at the formed oxide thickness of grid structure;
In this step, wet oxidation process is finished in the oxidation chamber in position, just adopt steam to substitute dried oxygen and feed in-situ oxidation chamber with a collection of wafer, in oxidizing process, wet oxidation process can produce layer of silicon dioxide film and hydrogen, it generates fast many of the speed ratio thermal oxidation process of oxide-film, generates the relatively good and thin wet oxidation layer 202 of step blanketing effect at short notice and under the lower situation of temperature easily;
In this step, the in-situ oxidation cavity temperature that adopts is 550～700 degrees centigrade, temperature is lower, the steam oxygen content that feeds is 0.1～10slm or feeds steam 3-30slm, time is 5～50 seconds, the hydrogen that obtains is 0.05～5slm, because the protection of seed oxide layer 201 is arranged, so can not cause damage to the gate oxide under the grid structure 102;
In this step, the thickness of formed wet oxidation layer 202 is greater than will be at 1/2 of the formed oxide thickness of grid structure, but also than little at the formed oxide thickness of grid structure.
Like this, just adopt two steps provided by the invention that the grid structure has been carried out oxidation, the thickness after final seed oxide layer and the wet oxidation layer equals the thickness of oxide-film, has just formed oxide-film on the grid structure.
In the present invention, the process of step 303 and step 304 can be finished by a control system control, this control system is controlled rapid thermal oxidation chamber and in-situ oxidation cavity respectively, makes wafer finish the generation that the generation of seed oxide layer and subsequent transfer are finished the wet oxidation layer in the in-situ oxidation cavity at reaction chamber respectively.The process of step 303 and step 304 also can be finished by different control system control respectively; Different control system are controlled reaction chamber and in-situ oxidation cavity respectively, the control system control wafer of control reaction chamber is finished the generation of seed oxide layer in reaction chamber, the control system control subsequent transfer of control in-situ oxidation cavity is finished the generation of wet oxidation layer in the in-situ oxidation cavity.
Through overtesting, compare adopting existing rapid thermal oxidation process, boiler tube thermal oxidation process, wet oxidation process and the inventive method that the grid structure is carried out condition and quality that oxidation obtains oxide-film, as shown in Table 1:
Table one
As can be seen from Table I, the method for the present invention's employing obviously is better than the method that prior art adopts.
More than lift preferred embodiment; the purpose, technical solutions and advantages of the present invention are further described; institute is understood that; the above only is preferred embodiment of the present invention; not in order to restriction the present invention; within the spirit and principles in the present invention all, any modification of being done, be equal to and replace and improvement etc., all should be included within protection scope of the present invention.
Claims (6)
1. the method for grid structure oxidation is made the grid structure on the silicon substrate of semiconductor device, it is characterized in that this method also comprises:
Reach employing rapid thermal oxidation process formation seed oxide layer on the exposed silicon substrate in the grid structure;
On the seed oxide layer, adopt the wet oxygen method to form the wet oxidation layer;
The thickness sum of described seed oxide layer and wet oxidation layer is will be at the structrural build up oxide thickness of grid.
2. the method for claim 1 is characterized in that, described seed thickness of oxide layer is 0.5～1.5 nanometer.
3. method as claimed in claim 2, it is characterized in that, described rapid thermal oxidation process is to carry out in reaction chamber, the reaction chamber temperature of described employing is 600～700 degrees centigrade, the amount of oxygen that feeds is that 1～20 per minute standard rises slm, the nitrogen amount that feeds is 5～30slm, and the reaction time is 5～780 seconds.
4. the method for claim 1 is characterized in that, the thickness of described wet oxidation layer is 0.5～2 nanometer.
5. method as claimed in claim 4, it is characterized in that described wet oxygen method is to carry out in the oxidation chamber in position, the in-situ oxidation cavity temperature of employing is 550～700 degrees centigrade, the steam oxygen content that feeds is 0.1～10slm or feeds steam 3-30slm that the time is 5～50 seconds.
6. the method for claim 1 is characterized in that, described formation seed oxide layer and formation wet oxidation layer are respectively to be finished by two control system controls;
Perhaps described formation seed oxide layer and formation wet oxidation layer are to be finished by a control system control.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111785612A (en) * | 2020-08-21 | 2020-10-16 | 中电晶华(天津)半导体材料有限公司 | Preparation method of silicon dioxide layer for VDMOS power device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56157024A (en) * | 1980-05-06 | 1981-12-04 | Fujitsu Ltd | Manufacture of semiconductor device |
| US5573965A (en) * | 1991-03-27 | 1996-11-12 | Lucent Technologies Inc. | Method of fabricating semiconductor devices and integrated circuits using sidewall spacer technology |
| JPH08306797A (en) * | 1995-05-11 | 1996-11-22 | Ricoh Co Ltd | Fabrication of semiconductor device |
-
2010
- 2010-06-28 CN CN 201010217775 patent/CN102299064B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56157024A (en) * | 1980-05-06 | 1981-12-04 | Fujitsu Ltd | Manufacture of semiconductor device |
| US5573965A (en) * | 1991-03-27 | 1996-11-12 | Lucent Technologies Inc. | Method of fabricating semiconductor devices and integrated circuits using sidewall spacer technology |
| JPH08306797A (en) * | 1995-05-11 | 1996-11-22 | Ricoh Co Ltd | Fabrication of semiconductor device |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111785612A (en) * | 2020-08-21 | 2020-10-16 | 中电晶华(天津)半导体材料有限公司 | Preparation method of silicon dioxide layer for VDMOS power device |
| CN111785612B (en) * | 2020-08-21 | 2022-05-17 | 中电晶华(天津)半导体材料有限公司 | Preparation method of silicon dioxide layer for VDMOS power device |
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