Coater conditioning mode

Abstract

A method for conditioning a coater to remove water and / or moisture from a processing area of ​​the coater is provided, the processing area including at least one pump compartment (10) and at least one sputtering compartment (11). The method includes the steps of loading a conditioning substrate (5) into the processing area such that the processing area is substantially filled with the conditioning substrate (5) and conditioning the coater by initiating a sputtering process in the processing area and / or by heating the at least one pump compartment (10). During conditioning, the conditioning substrate (5) undergoes a vibrational motion within the processing area.

Description

[Technical Field]

[0001] The present invention relates to coating equipment, in particular to large area coaters for coating glass substrates by a sputtering process. The present invention particularly relates to the conditioning of coaters after maintenance processes.

[0002] Typically, after a maintenance process on a large area coater, the machine is closed and pumped down. After pumping, the coater needs to be "conditioned." "Conditioning" is generally synonymous with pumping water out of the coater. Water is adsorbed on all surfaces inside the coater, and in order to pump the water out efficiently, the water needs to be separated from the surfaces, a process that requires heat. Two different state-of-the-art conditioning processes are known:

[0003] As soon as the pressure that allows the cathodes to start is reached, the sputtering process begins throughout the coater. The process power, provided between 10 kW and 120 kW per cathode, is converted primarily into thermal energy, heating the coater primarily in the area of ​​the process compartment where the sputtering process is active, but not the pump compartment. While heating is the desired effect, separating and pumping water from the surface, it has two undesirable effects: (1) the sputtering target is consumed without producing coated glass, and (2) the sputtered material is deposited in the empty compartment, building up a thick layer of coating material with inherent stresses that later increases the risk of debris (product failure) when the coater is in production mode.

[0004] To minimize the risk of debris, the conditioning procedure can be modified as follows: During sputtering, for example, off-spec glass is continuously passed through the coater. In this way, the sputtered material is not deposited in the empty compartment, but rather on the low-quality glass that carries the sputtered material out of the coater. The coated glass can be returned to the atmosphere and reused for this process. For this purpose, the coated glass needs to be transported from the coater outlet back to the coater inlet. At the end of the conditioning process, the coated glass is discarded. In this way, the risk of debris during production can be reduced. However, this risk reduction also creates several disadvantages: (1) The glass passing through the coater while all sputtering processes are active is significantly heated, which also serves to condition the pumping compartment where heating processes are not available. When exiting the coater, the glass reaches a temperature of approximately 60°C to 70°C and therefore extracts a significant amount of energy from the vacuum, which is actually required for conditioning. Upon returning to the atmosphere, the glass simply cools during its return to the coater inlet, where it passes through a washing machine and re-enters the coater where it is reheated and protects the compartment surfaces from sputtering. (2) Multiple cycles of the glass through the coater, from the outlet back to the inlet, build up a significant buildup on the glass, resulting in significant inherent stresses and loss of adhesion. Consequently, some of this coated material is removed in an intense washing operation before the coater inlet, which is actually designed to wash away uncoated glass. These coating particles, mechanically removed by brushes, contaminate the washing machine, which must be cleaned prior to the start of production.

[0005] As described in U.S. Patent Application Publication No. 2007 / 254096 A1, the coater chamber is purged with a conditioned purge gas prior to a coating operation, the moisture content of the purge gas being set to a predetermined moisture level, in particular a maximum relative moisture content of 30%. The chamber may be at least partially heated to a temperature between 20°C and 60°C before and / or during a cleaning operation.

[0006] According to WO 2006 / 127472 A1, in order to dry the (deposition) chamber of a coater quickly and cheaply, dry air is blown into the chamber to remove contaminating moisture within the chamber before use.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an improved conditioning method and coater apparatus that, inter alia, overcomes the above-mentioned problems.

[0008] The invention is defined by independent claims 1 and 14. The dependent claims define embodiments of the invention.

[0009] The present invention provides a method for conditioning a coater to remove water and / or moisture from a processing region of the coater. The processing region includes at least one pump compartment and at least one sputtering compartment. According to the method of the present invention, a conditioning substrate is loaded into the processing region of the coater so that the entire processing region, preferably the transfer chamber, is substantially filled with the conditioning substrate. The coater conditioning process is then carried out by initiating a sputtering process in the processing region and / or by heating at least one pump compartment. During conditioning, the conditioning substrate performs an oscillatory motion (back and forth) within the processing region.

[0010] The conditioning substrate may be a metal substrate, particularly a substrate having a specific heat capacity of at least 350 J / (kg*K), such as an aluminum substrate. The conditioning substrate is preferably cleaned after conditioning the coater and reused.

[0011] Alternatively, the conditioning substrate is a low-quality glass substrate, which may be discarded after conditioning the coater.

[0012] The length of the conditioning substrate preferably corresponds substantially to the length of the sputtering section. The distance between two consecutive substrates in the coater, the so-called "gap," should be as small as possible to prevent the target material from being sputtered in the coater. Typically, the gap is about 30 mm to 100 mm. In relation to the length of the substrates used for conditioning, the gap, i.e., the distance between two consecutive substrates in the coater, should be at most about 1 / 8 to 1 / 12 of the length of the shortest substrate.

[0013] The minimum amplitude of the vibration preferably corresponds substantially to the length of the sputtering section, and the maximum amplitude of the vibration preferably corresponds to the length of the transfer chamber, and if the coater is equipped with a buffer chamber, the maximum amplitude can be increased to include the buffer chamber.

[0014] The heated conductance tunnel may be used to heat at least one pump compartment.

[0015] The length of the conditioning substrate and / or the amplitude of vibration is preferably selected so that only a single conditioning substrate is positioned within the sputtering compartment during vibration.

[0016] The coating material can be recycled from the conditioned substrate after conditioning the coater.

[0017] The separated water is preferably pumped during sputtering and / or heating.

[0018] During conditioning, it may be preferable to temporarily stop the sputtering process at least once and at least partially vent the coater with any dry gas or atmosphere, such as Ar, O, N, or air, after which the conditioning process can be restarted by pumping down the coater again and resuming sputtering.

[0019] Preferably, the conditioning process is stopped when conditioning is determined to be complete by detecting that the partial pressure of residual water in the coater is below a predetermined threshold, which is preferably detected by using a residual gas analyzer and / or a spectroscopic plasma emission monitoring system.

[0020] The present invention further provides an apparatus for coating a substrate, particularly configured to carry out the conditioning method described above, comprising a processing region including at least one pump compartment and at least one sputtering compartment, and drive means for moving the substrate through the processing region, the drive means being configured to move the substrate such that the substrate undergoes an oscillatory motion within the processing region during sputtering and / or heating conditioning.

[0021] The device preferably further comprises heating means, in particular a heated conductance tunnel, and / or means for determining the partial pressure of the water.

[0022] According to the present invention, in order to combine the advantages of the above-mentioned conditioning procedures of the prior art while simultaneously eliminating their disadvantages, the following procedure according to one embodiment of the present invention is proposed: The entire coater process area, potentially including the entrance or exit transfer chambers, is filled with low-quality or off-specification glass, or any alternative substrate material that provides high heat capacity, preferably a metal substrate such as stainless steel or aluminum. The coater is closed at both ends and pumped down, and a sputtering process and / or alternative or additional heating means are operated to heat the coater. The substrate is now oscillated within the coater with an amplitude the length of the transfer chamber, or any other preferred amplitude.

[0023] In this way, the following advantages can be achieved: (1) the heat required for conditioning is provided by the ongoing sputtering process; (2) the glass or alternative substrate material protects surfaces in the coater from being coated with sputtered material, thereby reducing the risk of debris mentioned above; and (3) the vibration causes the pump compartment adjacent to the process compartment to be heated by the hot substrate moving from the high energy sputtering compartment to the "cold" pump compartment, which is not necessarily actively heated, and back again.

[0024] Because the glass or alternative substrate material is vibrating within the coater, the following inconveniences can be eliminated: (1) Because the substrate is no longer out of vacuum, the coater does not lose the energy carried by the substrate. The process heat is stored in the substrate and distributed to the cooler area of ​​the coater (the pump compartment), thereby reducing the sputtering energy required for conditioning without adversely affecting the conditioning time. (2) There is no need to return the substrate material from the coater outlet to the coater inlet. (3) The cleaning machine is not contaminated with coating particles removed from the multiply coated conditioned substrate during the cleaning procedure. Therefore, specific cleaning procedures for the cleaning machine are no longer required.

[0025] If low-quality glass is used as the substrate during conditioning, it can be discarded after the conditioning process. If any metal sheets are used, they can be cleaned (e.g., by sandblasting) and reused for the next conditioning process.

[0026] To avoid thermal stresses in the substrate material, especially when glass is used as the conditioning substrate, it is advantageous to use an alternative glass size other than jumbo length, most preferably a glass size similar to the compartment length, which may be about 850 mm. Smaller dimensions may also be advantageous when metal sheets are used, as the smaller size allows for easier handling during the loading and unloading process, as well as for cleaning procedures (e.g., sandblasting).

[0027] To effectively recycle valuable materials (e.g., silver) coated on conditioned substrates, the substrates can be cut to specific dimensions and arranged so that only silver is deposited on one substrate. After the conditioning process, these specific substrates can be sorted, and the deposited valuable material can be recycled from the substrate surface. All other substrates can be cleaned by sandblasting.

[0028] Since the sputtering process is utilized to provide the energy required for conditioning, the only remaining disadvantage is the wastage of target material during the conditioning procedure, which is lost to production. This disadvantage can be eliminated by using a heated conductance tunnel in the pumping section, or any other heating means or heatable component in the coater, which effectively transfers heat to the conditioning substrate. If thermal energy can be transferred to the substrate material by a heated conductance tunnel or alternative component, the sputtering process can be reduced for the purpose of conditioning, or even stopped to completely eliminate the wastage of target material.

[0029] Ideally, the optimized conditioning procedure according to the invention can be complemented by an "alternating pumping and venting process." In a first alternating sequence, the substrate is heated by the sputtering process and / or by the heated conductance tunnel while the separated water is pumped away. In a second sequence, the sputtering process is stopped, the coater is partially vented with dry air or the above-mentioned alternative gas, and then pumped again while the substrate is continuously heated by the heatable conductance tunnel and / or by the sputtering process as soon as the pressure starts the cathode.

[0030] Finally, the entire conditioning procedure, with all the described features and advantages, can be completed with a suitable endpoint detection for the partial pressure of residual water. A residual gas analyzer (RGA) can be applied to the most relevant compartment for this purpose (e.g., the cold pump compartment, the Ag or ZnO seed layer before the adjacent Ag compartment, or any other suitable location within the coater). As a valid alternative, a spectroscopic plasma emission monitoring system (PEM) can also be applied to monitor the relevant water emission wavelengths within the essential process compartment as long as the plasma is turned on. Any other system that senses the partial pressure of residual water can be used for endpoint detection. [Brief explanation of the drawings]

[0031] The present invention will now be described in more detail with reference to the drawings.

[0032] [Figure 1] 1 shows a coater performing a conditioning method according to the prior art. [Figure 2] 1 shows a coater performing a conditioning method according to one embodiment of the present invention. [Figure 3]1 shows a coater including a precious material processing compartment implementing a conditioning method according to one embodiment of the present invention. [Figure 4] 1 shows a coater including a pump compartment equipped with a heatable conductance tunnel for implementing a conditioning method according to an embodiment of the present invention.

[0033] FIG. 1 shows a coater that performs the conditioning process known in the prior art. The coater includes a loading and unloading compartment, a buffer / transfer compartment B / T, and a processing region 1 composed of multiple processing compartments P. The processing region 1 is subdivided into a pumping compartment and a sputtering compartment, which will be described below with reference to FIG. 2. The sputtering process is performed in the processing region by heating the processing region while continuously moving an "endless train" of substrates 5 through the processing region, as indicated by the arrow below the coater shown in FIG. 1. According to the prior art, the substrates used in conditioning the coater correspond to the substrates typically used to produce coated substrates. However, these prior art processes suffer from the problems mentioned above, such as wasted energy and coated material.

[0034] According to the present invention, as shown in FIG. 2, the substrate undergoes a vibrational movement in the processing area 1 during conditioning, as indicated by the arrow below the coater in FIG. 2. Preferably, the substrate vibrates in the coater with an amplitude corresponding to the length (T or BT) of the transfer section. Specific conditioning substrates may be used during conditioning, such as low-quality glass substrates or metal substrates with sufficient heat capacity. However, regular substrates commonly used in coaters may also be used during conditioning.

[0035] As shown in FIG. 2, the processing region 1, which includes the processing compartment P, can be generally subdivided into a pump compartment 10 and a sputtering compartment 11. Operating the sputtering compartment 11 heats the (conditioning) substrate, which in turn heats the portion of the processing region that is not actively heated during sputtering, i.e., the pump compartment 10. This is indicated by the curved arrows in the processing region, which show the flow of heat from the substrate region currently being sputtered to other compartments in the processing region. Heat may alternatively or additionally be introduced into the processing region during conditioning by using other heating means, such as a heatable conductance tunnel, as described below with reference to FIG. 4.

[0036] During the sputtering process, the separated water is pumped out of the processing area. To improve conditioning efficiency, sputtering may be temporarily stopped during conditioning to at least partially ventilate the coater with dry air. The coater may then be pumped down again to continue the conditioning process, and the sputtering process continues.

[0037] Endpoint detection can be performed to detect whether the coater is sufficiently conditioned. This can be done by determining the partial pressure of residual water. As soon as the detected partial pressure of residual water drops below a predetermined threshold, conditioning can be stopped and the coater is ready for production. As mentioned above, any suitable system and method for measuring the partial pressure of residual water can be applied.

[0038] The amplitude of vibration of the substrate during conditioning may, for example, correspond substantially to the length of the transfer chamber T, or may include the buffer chamber B. For sputtering with precious materials, other amplitudes or substrate lengths may be advantageous, as will be explained below with reference to FIG. 3. The distance between subsequent substrates should be kept as small as possible to ensure that substantially the entire coater is filled with substrates during conditioning. For example, a distance of approximately 30 mm to 100 mm, or 1 / 8 to 1 / 12 of the shortest substrate length, may be appropriate.

[0039] To avoid thermal stresses in the substrate material, particularly when glass is used as the conditioning substrate, it is advantageous to use alternative glass sizes other than those normally used in large area coaters, the most preferred glass size being similar to the compartment length, which may be about 850 mm. Smaller dimensions may be advantageous when metal sheets are used as the conditioning substrate, as smaller sizes allow for easier handling during the loading and unloading process, as well as for cleaning procedures, such as sandblasting.

[0040] In addition to the illustration of FIG. 2, FIG. 3 shows compartment 111 where coating with a valuable material, such as silver (Ag) in the example shown in FIG. 3, is performed. In this case, to enable effective recycling of the valuable material, the conditioning substrates can be cut to specific dimensions and arranged so that only the valuable material is coated on one substrate due to the specific length of the substrate together with a vibration amplitude that can be specifically adapted to the length of the substrate. After the conditioning process, these specific conditioned substrates coated only with the valuable material are sorted, and the deposited valuable material can be recycled from the substrate surface. All other substrates can be cleaned, for example by sandblasting, and reused or simply discarded.

[0041] Since the sputtering process is utilized to provide the energy required for conditioning, one remaining disadvantage may be the waste of target material during the conditioning procedure, which is lost to production. This drawback can be eliminated by using a heating means or heatable component in the coater that effectively transfers heat to the conditioning substrate, for example, a heated conductance tunnel in the pumping compartment, as shown in FIG. 4. If thermal energy can be transferred to the substrate material by the heated conductance tunnel 101, the sputtering process can be reduced or even stopped for conditioning purposes to completely eliminate the waste of target material. In general, additional heating means can be installed at any suitable position in the coater so that thermal energy for conditioning can be introduced in addition to or instead of introducing heat by operating the sputtering process. The conductance tunnel is designed to provide a passage for the substrate from one processing compartment to another while simultaneously avoiding excessive process gas flow between the processing compartments. Therefore, the height of the conductance tunnel is minimized, resulting in a small distance between the "tunnel roof" and the substrate surface. This makes the conductance tunnel 101 a preferred component, and when heated, provides effective heat transfer to the nearby substrate, as shown in FIG.

[0042] According to the present invention, a vibrating glass or alternative substrate is placed in the coater during conditioning to reduce the risk of debris during production and to maintain the energy required for conditioning in the processing area and simultaneously distribute it to the pumping section without heat loss to the atmosphere. To avoid excessive heat buildup in the coater, the sputtering power can be reduced, resulting in an energy-efficient conditioning process. Furthermore, in this way, movement of the substrate through the atmosphere from the coater outlet to the coater inlet can be avoided. Furthermore, contamination by coating particles of the cleaning machine required by the prior art to clean the coated substrate before reintroducing it into the coater can be avoided.

[0043] Compared to low quality glass, substrates with higher heat capacity may be suitable as conditioning substrates (eg, stainless steel or aluminum) that can be cleaned by sandblasting after the conditioning process and reused.

[0044] The substrate size (length) should be optimized to avoid thermal stresses caused by heated and unheated areas on one substrate, which in the case of glass could lead to substrate breakage. If metal sheets are used, there is no risk of breakage, but smaller substrates offer the advantage of easier handling (e.g., loading, unloading, cleaning).

[0045] The conditioning substrates are preferably arranged so that only one substrate is vibrated under the precious material sputtering process, in this way the deposited material can be efficiently recycled from that particular substrate after the conditioning process.

[0046] The heatable conductance tunnel 101 or other heating means or heatable components in the coater can be applied in addition to or instead of heating the conditioning substrate to provide conditioning heat by performing the sputtering process, thus eliminating waste of sputtering material.

[0047] The conditioning process can be completed by alternating pumping and aeration sequences. In a first alternating sequence, the substrate is heated by a heatable conductance tunnel while the separated water is pumped up. In a second alternating sequence, the coater is partially aerated with dry air or an alternative gas to help separate the water more efficiently, and then pumped down again while the substrate is continuously heated by the heatable conductance tunnel.

Claims

1. 1. A method for conditioning a coater to remove water and / or moisture from a processing area of ​​said coater, said processing area (1) comprising at least one pump compartment (10) and at least one sputtering compartment (11), - loading said treatment area (1) with said conditioning substrate (5) so that said treatment area (1) is substantially filled with said conditioning substrate (5); conditioning the coater by initiating a sputtering process in the processing area (1) and / or by heating at least one pump compartment (10), wherein during conditioning the conditioning substrate (5) undergoes a vibratory movement in the processing area.

2. 2. The method according to claim 1, wherein the conditioning substrate (5) is a metal substrate, in particular a substrate having a specific heat capacity of at least 350 J / (kg*K), and the conditioning substrate (5) is preferably cleaned and reused after conditioning the coater.

3. 3. The method according to claim 1 or 2, wherein the conditioning substrate (5) is a low quality glass substrate, and the conditioning substrate is preferably discarded after conditioning the coater.

4. The method according to any one of claims 1 to 3, wherein the length of the conditioning substrate (5) substantially corresponds to the length of the sputtering section (11).

5. The method according to any one of claims 1 to 4, wherein the distance between two successive substrates (5) in the coater is about 30 to 100 mm.

6. The method according to any one of the preceding claims, wherein the minimum amplitude of the vibrations corresponds substantially to the length of the sputtering section (11).

7. The method according to any one of the preceding claims, wherein heating means, preferably a heated conductance tunnel (101), are used to heat the at least one pump compartment.

8. 8. The method according to any one of claims 1 to 7, wherein the length of the conditioning substrate (5) and / or the amplitude of vibration are selected such that during vibration only a single conditioning substrate (5) is located in the sputtering compartment (11).

9. A method according to any one of claims 1 to 8, wherein preferably valuable coating material is recycled from the conditioned substrate after conditioning the coater.

10. The method according to any one of claims 1 to 9, wherein the separated water is pumped during sputtering and / or heating.

11. The method according to any one of claims 1 to 10, wherein during conditioning, sputtering is temporarily stopped and the coater is at least partially vented with a drying gas before being pumped down again.

12. 12. The method of claim 1, further comprising the step of stopping the conditioning when it is determined that the conditioning is complete by detecting that the partial pressure of residual water in the coater is below a predetermined threshold.

13. 13. The method of claim 12, wherein the partial pressure of the water in the coater is detected by using a residual gas analyzer and / or a spectroscopic plasma emission monitoring system.

14. 1. An apparatus for coating a substrate, comprising: a processing region (1) including at least one pumping compartment (10) and at least one sputtering compartment (11); drive means for moving the substrate (5) through the processing region (1), the drive means being configured to move the substrate (5) such that it undergoes an oscillatory motion within the processing region (1) during sputtering and / or thermal conditioning, The apparatus pumps away separated water from the treatment area (1) during the conditioning while the drive means moves the substrate (5) so that the substrate undergoes an oscillatory motion within the treatment area (1).

15. 15. The apparatus of claim 14, further comprising a heated conductance tunnel (101) and / or means for determining the partial pressure of the water.

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