WO2013038023A1

WO2013038023A1 - Vapor source for depositing thin films

Info

Publication number: WO2013038023A1
Application number: PCT/EP2012/068280
Authority: WO
Inventors: Karsten Reihs
Original assignee: Amf Gmbh
Priority date: 2011-09-16
Filing date: 2012-09-17
Publication date: 2013-03-21
Also published as: DE102011113406A1

Abstract

The invention relates to a device for feeding the vapor of a liquid or solid precursor into a coating chamber for depositing a coating, comprising a closed precursor cartridge, which is located completely or partially in a housing that has a connection to a coating chamber. In order to feed the vapor into the coating chamber, the cartridge is opened in such a way that the cartridge cannot be reclosed, such that vapor can enter the housing and can be conducted to the coating chamber.

Description

Steam source for the deposition of thin layers

The invention relates to a device for supplying the vapor of a fluid and / or solid precursor into a coating chamber for depositing a coating with a closed precursor cartridge which is wholly or partially in a housing which has a connection to a coating chamber. To deliver the vapor into the coating chamber, the cartridge is not reclosed open so that steam may enter the housing which is directed to the coating chamber.

background

By vapor deposition of substances, thin films are deposited on substrates by chemical vapor deposition (CVD) or by related techniques such as atomic layer deposition (ALD) and molecular layer deposition (MLD) The chemical reactions can take place both in the gas phase and on the surface of the substrate, and in the case of liquid or solid precursors, they must first be evaporated.

It is known to carry out CVD, ALD and MLD processes in a gas flow over a substrate which may be heated simultaneously. A brief introductory overview of CVD processes is given by JA Vernables, Cambridge University Press, Cambridge, 2001, to Surface and Thin Film Processes. For a detailed overview, see L. Choy, Chemical Vapor Deposition of Coatings, in: Progress in Materials Science. 48, No. 2, 57-170 (2003), as well as JL Vossen, W. Kern (eds.), Thin Film Processes II, Academic Press, London, 1991, which also deals with various CVD variants. For a review of ALD and MLD processes, see SM George, Chemical Review 1 10, 1 1 1 (2010). To provide the vapor of a precursor, an inert carrier gas is often passed through the liquid precursor. The carrier gas saturated with the vapor is optionally diluted with a further stream of inert gas and then flows in the coating chamber over the substrate. This classic bubbler as a vapor delivery device is described, for example, in L. Choy, Chemical Vapor Deposition of Coatings, in: Progress in Materials Science 48, No. 2, 57-170 (2003) US Patent Nos. 5,288,325 and 6,579,372 B2 all share the prior art with a larger amount of precursor being charged into a sealed vessel, and a valve introduces a stream of carrier gas into the vessel which is saturated with steam via at least one other valve flows into the coating chamber.

Another method for metering and delivering the vapor of a precursor is described in US Patent Application 2010 / 0203244A1. The liquid precursor is filled into a container from which quantities defined with a liquid flow control device can be withdrawn. The metered amount of liquid precursors is completely evaporated together with a known amount of gas in a container at a higher temperature. The vapor / gas mixture is then introduced into the coating chamber.

Another known technique for delivering and metering the vapor of a precursor is described in D.M. Hausmann, E. Kim, J. Becker, R.G. Gordon, Chemistry of Materials 14, 4350 (2002). Here, liquid precursor is placed in a stainless steel container. From this container, a smaller reservoir is filled with steam. The reservoir is now separated from the container with liquid precursor and the vapor from the reservoir is passed into a coating chamber along with a continuous carrier gas stream.

Also known is a method for supplying and metering the vapor of a precursor described in T.M. Mayer, M.P. de Boer, N.D. Shinn, P.J. Clews, T.A. Michalske, Journal of Vacuum Science and Technology B18 (5), 2433 (2000). In this widely used method, the liquid precursor is placed in a storage vessel, from which steam is introduced into the coating chamber via corresponding valves. The dosage is carried out by means of a pressure measurement in the coating chamber.

Another technique for delivering and metering the vapor of a precursor is described in US Pat. No. 7,413,774 B2. Here, the liquid precursor is filled into a reservoir, which may be heated and via a valve with a steam tank connected is. After opening the valve to the reservoir, the vapor container is filled with steam of the precursor. After closing the valve to the reservoir, the contents of the vapor container are then completely expanded via a valve into the coating chamber.

Also known is a device for metering a precursor, which is described in US 2009/263578 A1. Again, the liquid or solid precursor is filled in a storage vessel and dosed at a suitable time during the coating process in the reaction chamber. The storage vessel is constructed such that it can be reversibly connected to the coating system and removed again. For this purpose, various embodiments of a mechanism are described, which establishes a connection to the steam of the precursor after the attachment of the storage vessel to the coating system. Before dismantling the storage vessel, this compound can be interrupted again, so that after the degradation no steam can escape from the storage vessel, or foreign substances can get to Präcursor in the storage vessel. The attachment and removal is reversible and can be repeated as often as desired.

Many coating processes require the precise metering of precise amounts of precursor vapor into the coating chamber. In these cases, it is often necessary to remove the foreign gas (e.g., dissolved air) dissolved in the liquid precursor prior to use, otherwise, besides the vapor, the foreign gas present in the vapor space is also metered into the coating chamber. Since normally the proportions of foreign gas and vapor precursor in the gas phase are not known and can only be determined with great effort, the foreign gas present adulterates the dosage depending on its content and can possibly lead to large dosing errors. In addition, the foreign gas may also interfere with the coating process itself.

One technique well known to those skilled in the art of degassing liquids is the cycle of freeze-pump-thaw cycles in which the liquid contains a lesser amount of dissolved gas after each cycle.

Also known is a technique for in-line degassing of liquid precursors on a coating line prior to the delivery of the precursor vapor in US Pat. No. 7,687,110 B2. Here, a vapor or a vapor / gas mixture is filled into a reservoir from the container with liquid precursor. This filling is introduced into the coating chamber only if the pressure of the known vapor pressure of Precursors at the selected temperature corresponds to two successive fillings of the reservoir give the same pressure. If the latter conditions are not met, the contents of the reservoir are discarded and the reservoir refilled, the refill then containing less gas in the vapor space.

All techniques for feeding and metering vapor of a precursor have in common that the precursors are first filled as liquids or solids directly into a vessel in which the vapor is generated. This vessel is either directly connected to the coating apparatus and is filled there or it is first filled at another location, optionally closed with valves and then connected to the coating apparatus. If necessary, the degassing is carried out after filling the precursor before the steam supply into the coating chamber.

A disadvantage of the known delivery techniques is that precursors, which are very often sensitive to moisture and / or air, have to be handled when filling with inert gas. This requires e.g. the handling in a glove box, which is filled with Intergas. Such a device must therefore be a corresponding part of the coating apparatus. Otherwise, the precursor must be filled in an external glove box into a container, which can be closed with valves before it is transported through the air and attached to the coating apparatus.

In the case of precursors, which are only moderately sensitive to ambient air, the said protective measures may possibly be omitted for cost reasons and a certain decomposition of ambient air during filling is permitted. However, this decomposition can then lead to degraded properties and lower yields of the coating.

Another disadvantage is that precursors, which are toxic or harmful to the environment, may only be handled with special safety precautions. These measures complicate and increase the cost of handling the coating equipment, or in turn require external handling at a suitable location with closed transport to the coating equipment.

A further disadvantage is that precursors, which are corrosive, can only be handled in vessels made of particularly corrosion-resistant materials. This material requirement is particularly important when the precursor with the vessel material in high Concentrations, ie in the liquid state or in vapor form at elevated vapor pressures, at higher temperatures or for a long time in contact. The use of metallic materials for vessels is very advantageous in terms of the simultaneously required vacuum technology, but disadvantageous or expensive in terms of corrosion resistance. The use of corrosion-resistant glass for vessels is again disadvantageous or expensive with regard to the vacuum technology (seals, glass-metal compounds).

At the same time, the time-consuming filling and preparation of the known precursors containers is disadvantageous if coating processes with different precursors have to be carried out within a short time in a coating installation.

A longer residence time of a larger amount of liquid or solid precursors in the storage vessel, which normally consist of metal, in particular for precursors with low vapor pressures and thus necessary elevated temperatures, is disadvantageous. Upon prolonged contact with hot metal walls, the precursor can be thermally decomposed and form byproducts, which can either degrade the coating properties or reduce the yield of the coating.

The object of the invention is therefore to provide a simple device for supplying vapors liquid or solid precursors, which does not have the disadvantages of the prior art.

Description of the invention

This object is achieved by a device for supplying the vapor of a liquid or solid precursor into a coating chamber for depositing a coating, which is characterized in that the liquid or solid precursor is in a closed precursor cartridge which is wholly or partly in a housing which has a connection to a coating chamber. To deliver the vapor into the coating chamber, the cartridge is not re-closed so that steam can enter the housing which can be directed to the coating chamber.

Furthermore, the invention relates to a method for supplying the vapor of a liquid or solid precursor into a coating chamber for depositing a coating with the device according to the invention. In addition, the invention relates to a precursor cartridge which is not resealable after a single opening and contains no foreign gas.

The device on which the invention is based is particularly suitable for supplying the vapor of liquid or solid precursors to a coating process, because the precursors can be easily filled into a cartridge, stored in a stable manner against decomposition processes and fed to the process.

For filling, degassing and handling of liquid and solid precursors, a suitable inert gas device, such as e.g. a glove box with the required safety devices used. This device provided only once allows the necessary, adequate and safe handling of Präcursoren for a variety of coating equipment in a very short time. As a result, the effort of handling is significantly reduced.

The degassed and filled precursors can be stored in the sealed cartridges in a vacuum-tight, even at low temperatures. This ensures the purity of the precursors over a long period of time until coating, and thus improves the properties and yield of the coatings.

Changing the precursors in the coating unit is easy, clean and quick by inserting the cartridges into the vapor source. The amount of precursor used may be that for a single coating process. This use of portion cartridges minimizes thermal damage to sensitive precursors over the storage of larger quantities of precursor for multiple processes in the vapor source.

Particularly advantageous over the prior art is the use of a non-reclosable cartridge that can be opened in a simple and controlled manner. The construction of the cartridge in an embodiment of a fused glass ampoule offers, for example, the advantage of a very simple production from a virtually inert, ie non-degradable, material with respect to each precursor. Such a cartridge of degassed precursor 1H, 1H, 2H, 2H-perfluorodecyltrichlosilan could be stored in storage trials for months as a solid over dry ice at -78 ° C, without a noticeable leakage has occurred. Advantage of the precursor cartridge according to the invention is in particular the less expensive construction. Thus, in the case of the precursor cartridges according to the invention, no container material has to be selected which can be used with the often very aggressive precursors and at the same time allows the construction of the resealable opening. It is also advantageous that the use of elastic sealing materials is not necessary by the single use, since they have the disadvantage to quickly degrade against liquid or vapor precursors with correspondingly high vapor pressures in the vapor sources and thus must be replaced frequently.

Another advantage of the non-reclosable precursor cartridge is the maximum seal of the device over percusor cartridges with resealable orifice. For reversibly closable openings in these applications are Hochbzw. Ultra-high vacuum valves whose leakage rates are on the order of 10-8 mbar L s-1 are required (see also JF O ^' Hanlon, A User ^'s Guide to Vacuum Technology, 3rd edition, John Wiley & Sons, Hoboken, 2003, page 331) et seq.). With such a leakage rate, for example, in a cartridge volume of 10 mL over a period of only 10 days, a pressure increase of 1 mbar is obtained. Frequently, however, process pressures of precursors are only 0.1 mbar, so that such an increase in pressure in the cartridge would lead to a large dosing error and would therefore no longer be tolerable. Stockpiling of precursors in resealable cartridges is therefore only possible for a very limited period of time. The production of a larger number of cartridges for later use is therefore very limited. Often, storage of the reactive precursors at low temperatures is desirable to slow down the decomposition processes. Since under these conditions, the leakage rates are still much higher than in the example mentioned, storage at low temperatures virtually eliminated.

The described disadvantages for percusor cartridges with resealable opening have in practice against the background of the aforementioned possible degradation of the sealing materials in the presence of aggressive precursors even more serious.

Embodiments are shown in Figures 1 to 13 and will be described in more detail below.

Show it:

Figure 1: An embodiment of the precursor cartridge according to the invention Figure 2: An open embodiment of the precursor cartridge according to the invention before sealing

Figure 3: Connection of an embodiment of the precursor cartridge according to the invention to a device for degassing and sealing

Figure 4: An embodiment of the device according to the invention for degassing and closing precursor cartridges

Figure 5: A perspective view of an embodiment of the invention

steam source

Figure 6: The exploded view of the steam source according to Figure 5

Figure 7: The perspective view of the steam source as shown in Figure 5 with a

Sectional view of the housing before opening the precursor cartridge

Figure 8: The perspective view of the steam source as shown in Figure 5 with a

Sectional view of the housing after opening the precursor cartridge

Figure 9: Embodiments of vapor sources according to the invention in one

coater

Figure 10: A perspective view of another embodiment of a vapor source according to the invention with integrated heating

Figure 1 1: Exploded view of the steam source according to Figure 10

Figure 12: The perspective view of the steam source according to Figure 10 with a

Sectional view of the housing after opening the precursor cartridge

Figure 13: Steam source according to Figure 10 with housing

FIG. 1 shows a preferred embodiment of the precursor cartridge 100 according to the invention, which is designed as glass breaker ampoule. On the cylindrical hollow body 101 is located at a constriction an annular predetermined breaking point 102 on which the upper part of the hollow body can be broken off by lateral pressure. The ampoule contains the liquid or solid precursor 103.

To fill the precursor cartridge, the liquid or solid precursor 103 can be placed in the initially open container 104 (Figure 2). If the precursor 103 is a substance which can not be handled in normal ambient air, the filling operation is preferably carried out in a dry inert gas environment, for example in a nitrogen-filled glove box. Examples of such precursors are 1H, 1H, 2H, 2H-perfluorododecyltrichlorosilane (CI 3 Si-CH 2 -CH 2 - (CF 2) 10-F) or 1 H, 1 H, 2H, 2H-perfluorotetradecyltrichlorosilane (CI 3 Si-CH 2 -CH 2 - CF2) 12-F), which due to their high sensitivity to hydrolysis can not be handled in normal ambient air. But also less strongly hydrolysis-sensitive precursors, such as the substances frequently used for coatings: 1H, 1H, 2H, 2H-perfluorocyclotrichlorosilane (CI3Si-CH2-CH2- (CF2) 6-F) or 1H, 1H, 2H, 2H -

Perfluorodecyltrichlorosilane (CI3Si-CH2-CH2- (CF2) 8-F) are advantageously transferred in a glove box, since even here - depending on the handling time - partial hydrolysis can be avoided and the handling is facilitated.

After filling the precursor 103, the still open container 104 can be inserted into a device for degassing and melting (Figure 3). The ampoule opening is thereby mounted vacuum-tight with the aid of an O-ring 108 on a flange 105. Degassing of the precursor serves to release gas dissolved in the substance, e.g. Air or the protective gas used in the synthesis or handling to remove. This ensures that when vaporizing the precursor in the coating system only the pure vapor is metered and used for coating and no unknown amounts of gas can distort the dosage or interfere with coating.

During degassing, precursor 103 is carefully freed from dissolved gas by multiple cyclic sequences of freezing, pumping, and melting processes (Figure 4). For this purpose, liquid precursors 103 are first frozen by cooling with liquid nitrogen. Subsequently, the container 104, in which the solidified liquid is evacuated by means of a vacuum pump 109 via the valve 1 10. The final pressure can be controlled by means of a manometer 1 1 1. Subsequently, valve 1 10 is closed and the precursor is melted by heating to room temperature, so that dissolved gas can escape from the liquid, which can be seen by a blistering during melting. Once the substance has completely melted, takes place further freezing, pumping, melting cycle, until the melting process proceeds without the formation of bubbles.

Precursors, which are solid at room temperature, are degassed in the same way, which must be heated to melt here and the freezing process takes place without further cooling. To prevent condensation of the precursor outside of the vessel 104, the apparatus is heated during melting to the required melting temperature by means of a heater 1 12. A thermometer 1 13 serves to control or regulate the temperature.

After degassing, the vessel 104 is closed by melting (Figure 3). For this purpose, the precursor is first frozen and then the glass of the vessel by means of the flame 106 of a cartridge gas burner 1 14 by circular movements of the burner by means of the holder 1 15 at a deep groove ball bearing 107 around the vessel 104 around uniformly heated. The glass jar constricts thereby evenly and is melted off.

The precursor cartridge 101 can be mounted in a vapor source 16 (Figure 5). The exploded view in Figure 6 shows the structure of a preferred embodiment. The cartridge 101 is inserted into the housing 1 17 of the steam source. A sealing ring 1 19 and a lock nut 120 seal the housing at the bottom vacuum-tight. With the connection 1 18, the steam source is connected to the coating apparatus. A pneumatically operated cylinder 121 with a shear fork 123 serves to open the precursor cartridge. A thermometer 122 is used to measure and control the temperature of the precursor. Figures 7 and 8 show a preferred embodiment of the vapor source with the precursor cartridge closed (Figure 7) and opened (Figure 8).

Figure 9 shows an example of the connection of two vapor sources 1 16 and 216 to a coating chamber 124 in a coating apparatus 125 for coating a substrate 139. The connection is made via the valves 126 and 226.

In order to achieve a sufficiently high vapor pressure of the precursor in the vapor source, the vapor sources with heaters 127 and 227 can be heated. The thermometers 122 and 222 serve to control and regulate the temperatures. After using the precursor cartridges into the vapor sources, the valves 126, 226, and 129 are opened and the housings of the sources are evacuated by the vacuum pump 138 to a base pressure, which is measured on the gauge 132. The value of this base pressure depends on the type of substances. For precursors 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane and water, a pressure <10-5 mbar has been shown to be advantageous.

Subsequently, the valves 126, 226 and 129 are closed and opened that precursor cartridge whose vapor is to be introduced into the coating chamber. After the cartridge 101 is broken, steam flows into the housing 17 of the vapor source and the vapor of the precursor can be introduced into the coating chamber 124 by opening valves 126 and 130. The preselected pressure is measured on the manometer 133. Subsequently, the valves 126 and 130 are closed and evacuated via the valves 140 and 145, the steam supply line. The protective trap 147 is cooled, here the steam is frozen until later disposal. In the same way as previously described for the steam source 16, steam can then be introduced from the source 226 into the coating chamber.

To avoid condensation of the vapors all steam-carrying parts of the apparatus 125 are heated accordingly.

Upon completion of the coating of the substrate 139, the vapor from the coating chamber is directed via valve 142 into a cooled waste and protective trap. This is used to capture, freeze and collect residues and reaction products of the precursors before they are collected after several coating operations.

Unnecessary precursors in the open cartridge of the vapor source may e.g. for the steam source 1 16 are also passed through the valves 126 and 140 in the waste and protective trap. Subsequently, the steam source is optionally briefly boiled by increasing the temperature and evacuated via the valves 1 16 and 129 with the turbomolecular pump 138. The steam source is thereby cleaned and ready for use with a new cartridge after removal of the likewise clean and dry lower and upper part of the cartridge.

When using precursor cartridges with quantities for a single coating operation, the residual excess of the small excess takes place immediately after the steam extraction. As a result, corrosion processes on the metal parts of the Steam source can be minimized. At the same time, the coating system can be used very variably for different precursors. Moreover, the risk of decomposition of precursors before use is minimized.

Figures 10 and 11 show a further embodiment of the vapor source 151 according to the invention with integrated heaters. With the aid of heating rods 155 in the housing 153 and a heating sleeve 154 on the pneumatic cylinder 152 of the shear pin 160, the parts of the vapor source which come into contact with the vapor of the precursor are heated to a homogeneously distributed temperature. The temperature is measured and controlled by means of a thermometer 159. The housing 153 of the vapor source is connected by means of the flange 158 to the coating apparatus and is closed with the flange 156 via a seal 163 and stud bolts 164 and hex nuts 157. After actuation of the pneumatic cylinder 152, the shear pin 160 moves to the predetermined breaking point of the cartridge 162, whereupon the top of which breaks open controlled (Figure 12), so that steam of the precursor into the inner volume of the housing 153 entry.

Figure 13 shows the steam source as shown in Figure 10 in its full construction with a 165 and 166 panel used for thermal insulation. About fastening bolts 168 and the flange 158, the source is firmly attached to the coating apparatus. To change the precursor cartridge, the source is cooled to an appropriate temperature, the base 166 of the panel removed by loosening the screws 167. After opening the flange 156, the precursor cartridge can be exchanged.

Embodiments of the present invention relate to apparatus for supplying the vapor of a liquid or solid precursor into a coating chamber for depositing a coating, the liquid or solid precursor being in a sealed precursor cartridge which is wholly or partly enclosed by a housing. in the after opening of the cartridge, the steam enters the precursor, wherein

- The precursor cartridge can be made of glass or other mineral material.

- The precursor cartridge can be broken open.

- To break the precursor cartridge a shear bar can be used. - The housing can be evacuated before opening the precursor cartridge.

Further, embodiments of the present invention relate to sealed containers having a liquid or solid precursor for depositing a coating on the precursor vapor, the container not being resealable after the opening and containing no foreign gas.

Further, the present invention relates to methods for supplying the vapor of a liquid or solid Precursors in a coating chamber for depositing a coating, wherein

a) the liquid or solid precursor is contained in a sealed precursor cartridge which is completely or partially enclosed by a housing,

b) the cartridge is opened in the housing and steam of the precursor enters the housing,

c) steam of the precursor is passed into the coating chamber for deposition of a coating.

Further particular embodiments of the present invention relate to devices for supplying the vapor of a liquid or solid precursor into a coating chamber for depositing a coating, wherein the liquid or solid precursor is contained in a sealed precursor cartridge which is non-resealable for removal of the precursor becomes., where

- The precursor cartridge can be made of glass or other mineral material.

- The precursor cartridge can be broken open.

- To break the precursor cartridge a shear bar can be used.

- The housing in which the precursor cartridge is located in front of the opening of the cartridge can be evacuated.

Further, the present invention relates to a sealed container having a liquid or solid precursor for depositing a coating with the vapor of the precursor. wherein the container after the opening is not resealable and contains no foreign gas.

b) a non-reclosable connection is made between the vapor of the precursor and the housing and vapor of the precursor enters the housing; c) vapor of the precursor is directed into the coating chamber to deposit a coating.

Claims

claims

A steam source for supplying the vapor of a fluid and / or solid precursor into a coating chamber for depositing a coating comprising an exchangeable precursor cartridge inserted into a housing of the vapor source, the hollow body of which contains a fluid and / or solid precursor, the hollow body being attached to a The non-reclosable location may be opened and the vapor source contains a suitable means to open the precursor cartridge at that location.

The vapor source of claim 1, wherein the precursor cartridge (100) includes a fluid and / or solid precursor (103) at one end of the hollow body (101), a break line (102) in the neck region of the precursor cartridge (100 ) and wherein the vapor source includes a suitable means for opening the precursor cartridge (100) at the break line (102).

3. A vapor source according to claim 1 or 2, wherein the precursor cartridge is made of glass or other mineral material.

4. Steam source according to one of claims 1 to 3, wherein there is no foreign gas in the hollow body of the precursor cartridge.

A vapor source according to any one of claims 2 to 4, wherein the means for opening the precursor cartridge (100) at the break line (102) is a shear fork (123).

A vapor source according to any one of claims 1 to 5, wherein the housing into which the precursor cartridge is inserted is evacuated.

7. precursor cartridge for storing a precursor, the hollow body of which contains a fluid and / or solid precursor, wherein the hollow body can be opened non-reclosable in one place.

8. precursor cartridge according to claim 7, wherein the precursor cartridge (100) for storing a precursor (103) whose hollow body (101) contains a fluid and / or solid precursor (103), wherein a breaking line (102) on the Wall of the hollow body is attached to the hollow body non-resealable can be opened.

9. precursor cartridge according to claim 7 or 8, wherein the precursor cartridge is made of glass or other mineral material.

10. precursor cartridge according to one of claims 7 to 9, wherein there is no foreign gas in the hollow body of the precursor cartridge.

1 1. Method for supplying the vapor of a fluid and / or solid precursor into a coating chamber for depositing a coating, comprising the steps:

Introduction of a precursor cartridge according to one of claims 7 to 10 into a vapor source according to one of claims 1 to 6, so that it is completely or partially enclosed by the housing of the vapor source,

Non-resealable opening of the precursor cartridge so that the vapor of the precursor enters the housing,

Introducing the precursor vapor into a coating chamber to deposit a coating.

12. The method of claim 11, wherein the precursor cartridge is opened at a break line with a shear fork in the vapor source.

13. The method of claim 1 1 or 12, wherein the housing in which the precursor cartridge is located in front of the opening of the cartridge is evacuated.