JP5623390B2 - Apparatus and method for removing alkali metal or alkaline earth metal from a vacuum coating chamber - Google Patents

Description

  The invention relates to a device (arrangement) and method according to the premise of claims 1 and 11.

  Modern lithium batteries are generally produced in a vacuum chamber. The substrate includes a lithium layer. The lithium layer is formed, for example, by depositing vapor phase lithium on the substrate. Lithium is so reactive that contact by the operator after opening the vacuum chamber should be avoided. Even if excess lithium is pumped out of the vacuum chamber, there remains a risk that lithium particles deposited on the inner wall or surface of the vacuum chamber and / or on the mask may harm the operator.

  There are already known methods for producing lithium batteries in which lithium is converted into vapor in a vacuum chamber and subsequently deposited on a substrate (JP 59-060866, JP 2003-007290, JP 2003-234100, JP 2007-207663). There is nothing in these publications regarding vacuum chamber cleaning.

  It is further known to remove undesired deposits inside the coating facility with a cleaning gas (JP 2003-229365). However, lithium or alkali metals are not described here.

Furthermore, it is known to clean the processing chamber with a gas containing O ₂ (US 2007/0163617 A1). Here, the cleaning is performed under elevated temperature and reduced pressure. Since the cleaning process can also be performed by plasma, it is desirable that the gas also contains H radicals. However, the walls of the processing chamber are not cleaned with lithium or another aggressive material, but with tungsten.

A further method for cleaning the coating chamber is disclosed in DE 103 38 275 A1. In this method, the processing chamber is purged with a conditioned purge gas prior to the coating process. The purge gas preferably contains O ₂ and N ₂ with a humidity value of up to 30%. The coating chamber is cleaned before the coating process and the coating material is not lithium.

US 2002/0185067 A1 discloses an apparatus and method for in-situ cleaning of a throttle valve in a CVD system. Here, a cleaning gas that may contain F ₂ , C ₂ F ₆ , O ₂ , and NF ₃ is introduced. Lithium is not discussed.

Furthermore, cleaning processes for coating chambers using N ₂ and O ₂ as cleaning gases are known (EP 1 612 857 A1). These gases are converted to plasma and then used to clean the inner walls of the CVD chamber. High frequency is used to generate plasma. However, not Li, but rather Si ₃ N ₄ or SiO ₂ has been removed.

  EP 0 441 368 A discloses an apparatus and method for removing excess material from a PVD chamber. During the cleaning cycle, a vacuum is created in the PVD chamber, and a mixed gas containing reaction gas is introduced into the PVD chamber. Here, the reactive gas is activated through plasma discharge. The purpose of cleaning is also screening. However, the material to be removed is Ti, W, Al, not Li.

  JP 2002-206160 discloses an apparatus for producing a thin film of lithium metal or lithium alloy. In order to remove the lithium metal attached to the inner wall of the apparatus, a heater for melting the lithium metal attached to the inner wall is provided. By melting and removing the lithium metal attached to the device, the risk of ignition and explosion due to the reaction between moisture and lithium metal when the device is opened to the atmosphere can be avoided.

  The present invention is directed to the problem of cleaning parts of a vacuum coating chamber, such as masking and metal lining sheets, which are unintentionally coated during the manufacture of thin film batteries.

  This problem is solved by the configurations of claims 1 and 11.

  The advantages obtained with the present invention include, in particular, unintentionally coated parts being cleaned in a simple manner, reducing cycle time or service time. Further, since the cleaning can be performed periodically, the coating facility can be operated without interruption.

Accordingly, the present invention relates to a cleaning method for removing alkali metal or alkaline earth metal residues from a vacuum coating chamber of a coating facility for coating a substrate with an alkali metal or alkaline earth metal. For this purpose, a gas from the group of N ₂ , O ₂ , or air is introduced into the chamber that reacts with the alkali metal or alkaline earth metal to form the corresponding solid compound. It is also possible to introduce additional water into the vacuum coating chamber.

  After the alkali metal or alkaline earth metal has reacted with the gas, the corresponding solid compound is removed from the vacuum coating chamber.

  Examples of embodiments of the present invention are shown in the figures and are described in more detail below. The drawings show the following:

A vacuum chamber for coating a substrate with a vaporized material.

  A cross section of a coating facility 1 capable of coating a substrate 2 is shown in FIG. The coating equipment 1 includes a vacuum coating chamber 3 whose two side walls 4 and 5 are evident. The masking 6 is disposed between the substrate 2 and the steam supply system 7, and the steam supply system 7 includes an evaporator crucible 8, a valve 9, and steam inlets 10 to 13. The end of the steam inlet is formed by a straight distributor 14 provided as a vertically oriented tube with a linearly formed opening. These openings are located on the opposite side of the masking 6. Covers in the vacuum chamber 3 are indicated by 15 and 16.

  For example, lithium for manufacturing a thin film lithium battery melts and evaporates in the evaporator crucible 8. Instead of lithium, another reactive metal from the group of alkali metals and alkaline earth metals such as cesium can be used.

  The evaporating material reaches the distributor 14 through the vapor inlets 10-13 and from here reaches the substrate 2 via a masking 6 which does not need to be provided in all cases. Furthermore, the evaporating material also reaches the covers 15, 16 and other parts that it is not intended to reach.

  When the coating of the substrate 2 is complete, the uncoated parts are coated so that they are not harmed by the reactive lithium when the operator opens the vacuum chamber 3 and removes the coated substrate 2. Must be removed.

  However, in order for humans not to come into contact with lithium or other alkaline earth metals or alkali metals, these metals must be removed from the facility. After the coating process is complete and the substrate is transported from the coating facility 1 via a vacuum lock not shown in FIG. 1, removal of these highly reactive metals from the facility takes place. After the substrate has been removed from the coating facility 1, one or several gases are introduced into the vacuum chamber 3 before opening the vacuum chamber 3.

For this purpose, several gas containers 20, 21, 22 containing N ₂ , O ₂ or air gases are provided outside the vacuum chamber 3. Gas activation is not absolutely necessary. These gas containers 20, 21, 22 are connected to the vacuum chamber 3 through supply pipes 23, 24, 25 and valves 26, 27, 28. If N ₂ is introduced into the vacuum chamber 3, the N ₂ molecule binds to lithium according to the reaction formula 6Li + N ₂ → 2Li ₃ N. This final product is a solid that falls from the vertical surface of the vacuum chamber 3 to the bottom or adheres to the reaction site.

If O ₂ is introduced into the vacuum chamber 3, based on the formula 4Li + O ₂ , a colorless powdery solid compound Li ₂ O is formed, which is also non-toxic and falls from the vertical part.

It is understood that it is also possible to introduce air into the vacuum chamber 3 instead of pure oxygen. Here, this air is rich in O ₂ . Air contains both oxygen as well as nitrogen, so that lithium reacts not only with oxygen but also with nitrogen. Here, it is advantageous if the air has a certain humidity. For this reason, it can add so that water may become abundant in air. If the air also contains water, the following reaction occurs:
Li + H ₂ O → LiOH + 1 / 2H ₂

When air and water are introduced, LiOH and Li ₂ CO ₃ are also formed in addition to Li ₃ N and Li ₂ O.

For example, Li ₂ CO ₃ is formed through the following reaction: 2LiOH + CO ₂ → Li ₂ CO ₃ + H ₂ O.

At high temperatures, Li ₂ CO ₃ decomposes again into Li ₂ O and CO ₂ . The same applies to LiOH, which decomposes into Li ₂ O and H ₂ O. Lithium compounds must be non-toxic in all cases and stable in air.

Since the reaction of H ₂ O, O ₂ and N ₂ generates heat, it is advantageous to cool the vacuum chamber 3. This can be done by a cooling system not shown in FIG.

  In principle, metal Li or other alkali metals and alkaline earth metals can also be reacted with other substances such as, for example, halogens or hydrogen compounds of these halogens.

  However, since these halogens or halogen compounds are very reactive and may chemically attack the chamber, they are chemically insensitive to these compounds when used. It is necessary to make the chamber with an active material.

  Although activation of the gas is not absolutely necessary, it is nevertheless advantageous to carry out the reaction at an elevated temperature. A temperature in the range from 30 ° C. to 200 ° C. can be selected and the reaction starts at this temperature. It is clear that the reaction proceeds faster at higher temperatures. It is advantageous if the reaction takes place at pressures up to 100 mbar. The choice of temperature and pressure depends substantially on the design of the vacuum chamber 3. If only pure oxygen is used as the gas, for example, a temperature of 80 ° C. and an oxygen pressure of 100 mbar are possible. This ensures optimal reaction conditions.

  It is advantageous if the reaction is monitored by the gas sensor 32 during the cleaning process. Possible gas sensors 32 are, for example, mass spectrometers, lambda probes, or IR or NIR spectrometers. Via these measuring devices the gas volume can be determined during processing. If a lambda probe is used, it is desirable to add oxygen to the gas or gas mixture. In this case, the oxygen content can be determined during processing. As long as lithium is still present in the chamber and reacts with the gas, the concentration of the reactive gas is lowered by the lithium, and thus is lower than the gas concentration before introducing the gas into the vacuum chamber 3. As soon as lithium reacts with the gas, the concentration of the gas again reaches its initial value. This indicates that the reaction process is complete. The gas volume determined by the gas sensor 32 is supplied to the evaluation device 33. When the process is completed, the powder at the bottom of the vacuum chamber 3 can be sucked out by the pump 30 and the extraction fitting 31. It is also possible to vent the vacuum chamber 3 and then remove the powder with a dust collector. Here, it is advantageous to drop and remove the lithium salt adhering to the wall of the vacuum chamber 3 by ultrasonic waves to the bottom. This makes the cleaning operation considerably easier. For example, the reaction with lithium can be accelerated by setting parameters such as pressure, temperature, moisture content present in the gas or gas mixture in the form of water. In order to fill the gas with moisture, water is introduced into the vacuum chamber 3 through the feed pipe 35.

  Whether the lithium salt remains attached to the surface after the cleaning process or breaks and then falls to the bottom of the vacuum chamber 3 depends substantially on the thickness of the lithium salt layer formed. If the lithium layer formed by the coating reaction is very thin, a salt with a very small particle size is formed by the cleaning process. Such a lithium layer desirably remains well attached to the walls of the vacuum chamber 3. If a thick lithium layer is formed on the wall of the vacuum chamber during the coating process, the layer is formed by a cleaning reaction with the gas, and such a layer is under mechanical stress, which leads to the breaking of the coating. There is a possibility of connection. For these reasons, it may be advantageous to ultrasonically remove salt residues still adhering to the walls of the vacuum chamber 3.

  Those skilled in the art will appreciate that various modifications and alternatives may be made in the invention, its use, and its construction to achieve substantially the same results as those achieved by the embodiments described herein. It can be easily recognized. Accordingly, it is not intended that the invention be limited to the disclosed exemplary forms. Many variations, modifications and alternative constructions fall within the scope and spirit of the disclosed invention as expressed in the claims.

DESCRIPTION OF SYMBOLS 1 Coating equipment 2 Substrate 3 Vacuum coating chamber 4 Side wall 5 Side wall 6 Masking 7 Steam supply system 8 Evaporator crucible 9 Valve 10 Steam inlet 11 Steam inlet 12 Steam inlet 13 Steam inlet 14 Straight distributor 15 Cover 16 Cover 20 Gas container 21 Gas Container 22 Gas container 23 Supply pipe 24 Supply pipe 25 Supply pipe 26 Valve 27 Valve 28 Valve 30 Pump 31 Extraction fitting 32 Gas sensor 33 Evaluation device 35 Feed pipe

Claims (15)

An apparatus for removing alkali metals or alkaline earth metals from a vacuum coating chamber (3),
The vacuum coating chamber (3) has at least one gas container (20-22) connected to the vacuum coating chamber (3) via a supply pipe (23-25);
The gas container viewed including the gas from N _2, O ₂ or the group of air, the vacuum coating chamber (3), the pump (30) connected to the extraction fitting (31) or a dust collector device including the bottom of.   The apparatus according to claim 1, characterized in that a valve (26-28) is provided between the at least one gas container (20-22) and the vacuum coating chamber (3). The vacuum coating chamber (3) is a feed pipe for the _{H 2} O (35), is of _{H 2} O through the feed pipe (35) can be introduced into the vacuum coating chamber (3) in the feed 2. An apparatus according to claim 1, characterized in that the pipe (35) and the vacuum coaching chamber (3) comprise at least one element from the group consisting of means allowing exposure to ultrasound .   The apparatus according to claim 1, characterized in that the vacuum coating chamber (3) comprises at least one gas sensor (32). The apparatus of claim 4, wherein the gas sensor (32) is selected from the group consisting of a mass spectrometer , a lambda probe, and an IR or NIR spectrometer .   The apparatus of claim 1, wherein the metal is lithium. A method for removing alkali metal or alkaline earth metal from a vacuum coating chamber (3) of a coating facility (1), comprising:
a) After the coating process is completed, the vacuum coating chamber (3) is set under vacuum,
b) A gas consisting of a group of N ₂ , O ₂ or air is introduced into the vacuum coating chamber (3), and the gas reacts with the alkali metal or alkaline earth metal in the vacuum coating chamber (3). Forming a solid compound,
c) The solid compound is removed from the vacuum coating chamber (3). The method of claim 7 , wherein the metal is lithium. The method of claim 7, wherein the H 2 _O are introduced additionally into the vacuum coating chamber (3) within. It said air The method of claim 7, wherein the O ₂ is rich. The method of claim 7, wherein the gas volume during the reaction is determined by an element selected from the group consisting of a gas sensor (32) , a mass spectrometer, and an IR or NIR spectrometer . The method according to claim 7 , wherein at the beginning of the treatment, the temperature is set to a temperature selected from the group consisting of a temperature of 30 ° C. to 200 ° C. and a temperature of 80 ° C. 8. Method according to claim 7 , characterized in that the pressure is set to 100 mbar. The solid compound is extracted fitting (31) connected to the pump (30), and according to claim 7, characterized in that it is removed from the vacuum coating chamber (3) by an element selected from the group consisting of dust collector the method of. 15. The method of claim 14 , wherein the formed solid compound is ultrasonically removed from the wall of the vacuum coating chamber (3) before being removed from the vacuum coating chamber (3).

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