COATING CHAMBER FOR IMPLEMENTING OF A VACUUM-ASSISTED COATING PROCESS, HEAT SHIELD, AND COATING PROCESS

Abstract

The invention relates to a coating chamber (1) for performing a vacuum-assisted coating process, in particular PVD or CVD or electric arc coating chamber or hybrid coating chamber.

The coating chamber (1) comprises a heat shield (3, 31, 32, 33), which is arranged on a temperature-controllable chamber wall (2) of the coating chamber (1) and is intended for adjusting an exchange of a predeterminable amount of thermal radiation between the heat shield (3, 31, 32, 33) and the temperature-controllable chamber wall (2). According to the invention the heat shield (3, 31, 32, 33) comprises at least one exchangeable radiating shield (31), which is directly adjacent to an inner side (21) of the chamber wall (2), wherein a first radiation surface (311) of the radiating shield (31),that is directed towards the chamber wall (2) has a first predeterminable heat exchange coefficient (.sub.D1) and a second radiation surface (312) of the radiating shield (31) that is directed away from the chamber wall (2) has a second predeterminable heat exchange coefficient (.sub.D2), wherein the first heat exchange coefficient (.sub.D1) higher than the second heat exchange coefficient (.sub.D2). The invention further relates to a heat shield for a coating chamber as well as a coating method.

Claims

1. A coating chamber for performing a vacuum-assisted coating process, comprising: a temperature-controllable chamber wall; a heat shield, which is arranged on the temperature-controllable chamber wall, for an exchange of a predeterminable amount of thermal radiation between the heat shield and the temperature-controllable chamber wall wherein the heat shield comprises at least one exchangeable radiating shield, which is directly adjacent to an inner side of the chamber wall, having a first radiation surface directed towards the chamber wall with a first predeterminable heat exchange coefficient (.sub.D1) and a second radiation surface directed away from the chamber wall with a second predeterminable heat exchange coefficient (.sub.D2), and wherein the first heat exchange coefficient (.sub.D1) is greater than the second heat exchange coefficient (.sub.D2).

2. The coating chamber according to claim 1, wherein the heat shield further comprises at least one protection shield having a first protection surface directed towards the chamber wall and a second protection surface directed away from the chamber wall, wherein each of the first and second protection surfaces have a shiny reflecting surface with a processing status according to at least one of DIN EN10088 of at least 2D and DIN EN10088 of at least 2R.

3. The coating chamber according to claim 1, wherein at least one of the first radiation surface for adjusting the first predeterminable heat exchange coefficient (.sub.D1) and the second radiation surface for adjusting the second predeterminable heat exchange coefficient (.sub.D2) of the radiating shield is rough.

4. The coating chamber according to claim 1, wherein the first radiation surface has at least one of a black surface and a surface coating with a high first heat exchange coefficient (.sub.D1) in the range of at least one of: 1 0.1 to 1.0, between 0.5 and 0.95, between 0.7 and 0.9, approximately 0.85, compared to a black heat exchange coefficient (.sub.Sch) of a black radiator with .sub.Sch=1.0.

5. The coating chamber according to claim 2, wherein at least one of the first radiation surface and the second radiation surface comprises a surface coating wherein the surface coating at least one of: is an optically dense deposited coating; has a coating thickness of 100 nm to a few 1000 nm; has a coating thickness between 300 nm to 800 nm, and has a coating thickness of at least 500 nm.

6. The coating chamber according to claim 5, wherein, for applying low temperature coatings in a range of up to a maximum temperature of parts of 250 C., the heat shield comprises exactly only one radiating shield, which is coated only on the first radiation surface.

7. The coating chamber according to claim 2, further comprising one or more additional radiation shields arranged between the radiating shield and the protection shield.

8. The coating chamber according to claim 7, wherein at least one of the radiating shield, the protection shield and the radiation shield comprise an assembly area and is fixed to a holding device of a shield holder at the chamber wall in an assembly area.

9. The coating chamber according to claim 7, wherein the radiating shield, the protection shield and the radiation shield are geometrically designed at least in the assembly area in such an identically manner, that they can be applied interchangeably in each holding device, so that different characteristics of the heat exchange can be adjusted flexibly between the chamber wall and the heat shield and wherein at least one of the radiating shield, the protection shield and the radiation shield is connected electrically insulated with the chamber wall.

10. The coating chamber according to claim 1, wherein the coating chamber comprising a double-walled designed chamber wall, so that a thermostating fluid, especially water or an oil, is circulable inside the double-walled chamber wall for thermostating.

11. The coating chamber according to claim 1, wherein at least one of: the inner side of the chamber wall has a roughness in the range of at least one of: Ra=1 m0.2 m to 10 m2 m and Rz=10 m20 m, and the inner side has a coating with a high chamber exchange coefficient (.sub.K) in the range of at least one of: 0.1 to 1.0, between 0.2 and 0.8, between 0.3 and 0.6, and approximately 0.4, compared to a black heat exchange coefficient of a black radiator with .sub.Sch=1.0.

12. The coating chamber according to claim 1, wherein the inner side of the chamber wall comprises a chamber coating, wherein the chamber coating at least one of: is an optically dense deposited coating; has a coating thickness of 100 nm to a few 1000 nm; has a coating thickness between 300 nm to 800 nm, and has a coating thickness of at least 500 nm.

13. A heat shield for a coating chamber according to claim 1, wherein the heat shield is a retrofit part.

14. A coating process using the coating chamber according to claim 1 and the heat shield is a retrofit part, the method comprising: coating a substrate via at least one of: a PVD process, a PVD process comprising magnetron sputtering, HIPIMS, or a plasma-assisted CVD process, a cathodic or an anodic vacuum arc vaporization process or a combination process formed of these processes or another vacuum-assisted coating process.

15. Coating process according to claim 14, wherein at least one of: the coating process is a low temperature coating and the coating chamber is thermostated by a thermostating fluid, especially water or oil, from a temperature in the range of 10 C. to 30 C., and the coating process is a high temperature process and the coating chamber is thermostated with the fluid, in particular water or oil with a temperature in the range of 40 C. to 60 C.

16. The coating chamber according to claim 3, wherein the at least one of the first radiation surface and the second radiation surface has at least one of a roughness of Ra=1 m 0.2 m to 10 m2 m and/or a roughness of Rz=10 m2 m to 100 m20 m.

17. The coating chamber according to claim 5, wherein the surface coating comprises a coating that is at least one of deposited by PVD, a Al.sub.66Cr.sub.33N coating, and a suitable DLC-coating, and the coating has a coating thickness of 300 nm to 800 nm and in particular at least 500 nm.

18. The coating chamber according to claim 17, wherein the surface coating deposited by PVD comprises at least one of Al.sub.xTi.sub.yN, Al.sub.66Ti.sub.33N and an AlCrN and the DLC-coating comprises an a-C, a-C:H, a-C.H:X, a-C:H:Me coating.

19. The coating chamber according to claim 7, wherein the one or more additional radiation shields comprises up to three radiation shields arranged between the radiating shield and the protection shield.

20. The coating chamber according to claim 12, wherein the chamber coating comprises a coating that is at least one of deposited by PVD, a Al.sub.66Cr.sub.33N coating, and a suitable DLC-coating, and the coating has a coating thickness of 300 nm to 800 nm and in particular at least 500 nm.

21. The coating chamber according to claim 20, wherein the chamber coating deposited by PVD comprises at least one of Al.sub.xTi.sub.yN, Al.sub.66Ti.sub.33N and an AlCrN and the DLC-coating comprises an a-C, a-C:H, a-C.H:X, a-C:H:Me coating.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] The invention will be explained in more detail with reference to the schematic drawings. It is shown:

[0080] FIG. 1 schematically, a coating chamber according to the invention;

[0081] FIG. 2 a coating chamber with only one radiating shield;

[0082] FIG. 3 a coating chamber with radiating shield, protection shield, and radiation shield for HTB operation

[0083] FIG. 4 a schematic presentation of the arrangement of basic elements of a vacuum chamber according to the present invention.

[0084] FIG. 5 the course of the temperature of substrates to be treated, each were treated in a vacuum chamber to the state of the art (broken line) and in a vacuum chamber according to the invention (solid line).

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0085] FIG. 1 schematically shows a first simple embodiment of a coating chamber according to the invention, which e.g. can be used particularly advantageously for performing a high temperature coating process.

[0086] The coating chamber 1 according to the invention for performing a vacuum-assisted coating process according to FIG. 1 comprises a heat shield 3, 31, 32, 33, which is arranged on a temperature controllable chamber wall 2 of the coating chamber and is intended for adjusting an exchange of a predeterminable amount of thermal radiation between the heat shield 3, 31, 32, 33 and the temperature-controllable chamber wall 2. According to the present invention the heat shield 3, 31, 32, 33 comprises an exchangeable radiating shield 31, which is directly adjacent to an inner side 21 of the chamber wall 2, having a first radiation surface 311 of the radiating shield 31, that is directed towards the chamber wall 2, with a first predeterminable heat exchange coefficient .sub.D1, whereby a second radiation surface 312 of the radiating shield 31, that is directed away from the chamber wall 2 has a second predeterminable heat exchange coefficient .sub.D2, and the first heat exchange coefficient .sub.D1 is higher than the second heat exchange coefficient .sub.D2. For reasons of clarity, the radiating shield 32 in FIG. 1 is not shown in detail. The specific structure of the radiating shield 31 is essentially identical to that of FIG. 2 or FIG. 3, respectively, so that for details of the structure of the radiating shield 32 it can be referred to FIG. 2 or FIG. 3, respectively.

[0087] The coating chamber 1 comprises in a manner known per se in the art, a heater for pre-heating the parts to be coated, which are during operation e.g. on a rotating part holder inside the coating chamber 1 and are not shown here, as well as plasma sources 7 for coating, which are also known in many variations from the state of the art. Details as e.g. the heater, the plasma sources, the part holder for the parts to be coated etc. are of little importance for the understanding of the invention.

[0088] A plurality of further radiation shields 33 is provided between the radiating shield 31, which is directly adjacent to the chamber wall and the protection shield 32 between the radiating shield and the protection shield 32.

[0089] The coating chamber 1 itself has a double-walled chamber wall 2, so that a thermostating fluid 5, here water, is circulable inside the double-walled chamber wall 2 for thermostating.

[0090] The inner side 21 of the chamber wall 2 is either only rough blasted and/or provided with a chamber coating 20, comprising a coating, deposited by PVD, e.g. an Al.sub.xTi.sub.yN, an AlCrN coating or a suitable DLC-coating comprises, wherein the coating is an optically dense deposited coating has a coating thickness of 100 nm up to several 1000 nm.

[0091] FIG. 2 shows a special coating chamber having only one radiating shield 31 for NTB operation. Thus the heat shield 3 consists of even only one radiating shield 31 only coated on the first radiation surface 311 for using use in low temperature coating processes in the range of up to a maximum temperature of parts of about 250 C.

[0092] For adjusting the first predeterminable heat exchange coefficient .sub.D1 and the second predeterminable heat exchange coefficient .sub.D2 of the radiating shield 31, the first radiation surface 311 and the second radiation surface 312 are rough and have a roughness of R.sub.a=1 m0.2 m to 10 m2 m respectively a roughness of R.sub.z=10 m2 m to 100 m20 m.

[0093] Additionally the first radiation surface 311 is provided with a surface coating 30, which has a high first heat exchange coefficient .sub.D1 in the range of 0.7 to 0.9, compared to the black heat exchange coefficient .sub.Sch of the black body radiator with .sub.Sch=1.0.

[0094] The surface coating 30 is a coating, deposited by PVD, especially an Al.sub.xTi.sub.yN, an AlCrN, or a suitable DLC-coating, especially an a-C, a-C:H, a-C.H:X, a-C:H:Me coating, whereby the coating is an optically dense deposited coating and has a coating thickness of 100 nm up to several 1000 nm. e.g. 500 nm.

[0095] The radiating shield 31 is fixed to a holding device 41 of a shield holder 4 by a shield holder 4 at the chamber wall 2 in an assembly area, whereby the radiating shield 41 is a radiating metal sheet, which is simply clamped in a holding device 41 of the shield holder configured as a groove so that it can be replaced easily and quickly.

[0096] Finally, in FIG. 3 a special embodiment of a coating chamber 1 is shown with radiating shield 31, protection shield 32 and radiation shield 33, arranged in between. This arrangement is particularly suitable for high temperature operation.

[0097] In a further embodiment, the present invention relates to a vacuum chamber and a coating system with a special arrangement to increase heat dissipation.

[0098] Conventional coating systems are usually designed in such a way, that a predeterminable coating temperature inside the coating chamber or of the recipient, respectively can be realized and maintained. The surfaces inside the coating chamber are often made of shiny or blasted stainless steel or aluminum. Since the inner walls of the coating chamber can be undesirably coated during performing coating processes, a shielding is usually used, in order to avoid the build-up of thicker coatings on the inner walls. Above all, the use of such a shielding is very helpful, when several coating processes should be performed one after the other without service and, as a result, several coatings accumulate on one another and flaking occurs during coating and after coating. Such a shielding is often also made of shiny or blasted stainless steel or aluminum. This design is normally applied uniformly throughout the recipient respectively along the outer surface, the top surface and the bottom surface.

[0099] Coating sources, heating and cooling elements are usually distributed inside the coating chamber as individual components in such a way, that some inner surfaces or inner chamber wall surfaces, respectively, will remain free of sources and/or elements. As a result these free surfaces act as heat removing elements or in a manner similar to cooling elements, respectively.

[0100] Usually the relation between heat supply by heating and coating sources for example, and heat removal through the outer surface of the coating chamber plays an important role when adjusting the operating point of the system regarding coating temperature, in particular when both the top surface and the bottom surface are thermally insulated. Thermally insulation of top surfaces and bottom surfaces results in a homogeneous distribution of temperature over the coating height, even if, for example, operating heaters without temperature control.

[0101] Already when starting a coating process a determined temperature, i.e. a determined temperature of the substrate surface to be coated should be realized. Heating elements are often arranged on a chamber wall surface for heat supply, at least until starting the coating process, so that these warm surfaces emit heat to the substrate.

[0102] After starting and during operating the coating process, an additional heat supply is produced by operating the coating sources, which can be particularly high when operating a great number of arc evaporation sources with high arc currents.

[0103] If substrates in a coating system were coated with a certain coating, but it was intended to establish an increased coating rate, this could be realized by using, for example, an increased number of coating sources. But in this case a corresponding increase in heat supply into the coating chamber must be expected, resulting directly in an increase of the coating temperature, if the heat removal is not accordingly adjusted or increased. This problem is particularly severe, when using arc evaporation sources.

[0104] Further embodiments of the invention is to provide a solution, which makes it possible to control the heat removal in a coating chamber in such a way, that the coating temperature does not rise uncontrolled due to an increase in the heat supply but can be held at the desired operating point.

[0105] For a better understanding of the above mentioned facts of the present invention, it is referred to FIGS. 4 and 5: [0106] FIG. 4 shows a schematic representation of the arrangement of basic elements of a vacuum chamber according to the present invention. [0107] FIG. 5 shows the course of the temperature of substrates to be treated, each were treated in a vacuum chamber from the state of the art (broken line) and in a vacuum chamber according to the invention (solid line).

[0108] The present invention basically discloses a vacuum chamber for treating substrates, comprising at least the following elements: [0109] heat supply elements for the heat supply into a treatment area of the vacuum chamber, in which at least one substrate 100 can be treated, [0110] a chamber wall 200, through which heat can be removed from the treatment area, comprising an inner and an outer chamber wall side, and: [0111] a shielding wall 300, which is arranged between the chamber wall 200 and the treatment area, such that an averted shielding wall side with respect to the treatment area is placed opposite the inner chamber wall side, [0112] and characterized in, that [0113] the shielding wall side placed opposite the inner chamber wall side is at least partially, preferred largely applied with a first coating 310 which has an emission coefficient 0.65.

[0114] According to a preferred embodiment of the present invention, the inner chamber wall side is also at least partially, preferably at least largely applied with a second coating 210, which has an emission coefficient 0.65.

[0115] According to a further preferred embodiment of the present invention the chamber wall 200 comprises an integrated cooling system 150.

[0116] The emission coefficient of the first coating 310 is preferably greater than or equal to 0.80, more preferably greater than or equal to 0.90.

[0117] The emission coefficient of the second coating 210 is also preferably higher than or equal to 0.80, more preferably higher than or equal to 0.90.

[0118] Generally, the inventors have observed a particularly significant increase in heat removal from 0.8, in particular from 0.9. Even more preferably is close to 1.

[0119] According to another preferred embodiment of the present invention the first coating 310 and/or the second coating 210 are deposited at least partially by a PVD-process and/or a PACVD-process (PVD: Physical Vapor Deposition; PACVD: Plasma assisted chemical vapor deposition).

[0120] According to another preferred embodiment of the present invention the first coating 310 and/or the second coating 210 comprises aluminum and/or titanium.

[0121] Also preferred the first coating 310 and/or the second coating 210 comprises nitrogen and/or oxygen.

[0122] The inventors have also found, that coatings comprising titanium aluminum nitride or aluminum titanium nitride or are of titanium aluminum nitride or aluminum titanium nitride, are very suitable as first coating 310 and/or second coating 210 in the context of the present invention.

[0123] Also coatings comprising aluminum oxide or consisting of aluminum oxide are well suited as first coating 310 and/or second coating 210 in the context of the present invention.

[0124] The present invention also discloses a coating system with a vacuum chamber according to the invention as coating chamber as described above.

[0125] According to a preferred embodiment of a coating system according to the invention, the coating chamber is established as a PVD-coating chamber.

[0126] A shielding wall 300 is preferably provided for reducing or avoiding coating of the inner chamber wall side during performing a PVD-process inside the PVD-coating chamber.

[0127] Both top surfaces and bottom surfaces of the PVD-coating chamber are preferably thermally insulated, to realize a more homogeneous distribution of temperature over the coating height (respectively over the entire height of the treatment area).

[0128] The chamber wall 200 or the chamber walls 200, respectively, are preferably not provided with functional elements such as coating elements, plasma treating elements or heating elements.

[0129] As required, all chamber walls 200, at which preferably no such functional elements are arranged, can be provided with a second coating 210 in the inner chamber wall side and provided with a shielding wall 300 with a first coating 310 according to the present invention.

[0130] It can also be advantageous, that all these chamber walls 200 are provided with integrated cooling systems 150 for realizing an even higher heat removal.

[0131] As already mentioned above, FIG. 5 shows the comparison of the course of the substrate temperature in the same vacuum chamber, whereby once for the embodiment according to the invention, shielding walls 300 and chamber walls 200, as described above, are provided with corresponding first coatings 310 and second coatings 210 according to the invention (solid line), and another time for the example to the state of the art the same vacuum chamber arrangement was used, but without coatings 310 and 210 (broken line). Both examples were performed with equal heat supply into the coating chamber.

[0132] For the above mentioned embodiment according to the invention, a PVD deposited titanium aluminum nitride coating with an emission coefficient from about 0.9 was used as first coating 310 as well as second coating 210.

[0133] According to a preferred embodiment of the present invention the inner side of all shielded chamber walls can be coated at least largely with a corresponding second coating 210 and the side of all shielding walls opposite to the chamber walls at least largely with a corresponding first coating 310.

[0134] According to the present invention both the coating 210 and the coating 310 should be made of materials, which are vacuum suitable. It is also important, that these materials are not magnetic, to avoid malfunctions during coating.

[0135] The coatings 210 and/or 310 preferably have at least one of the following characteristics: [0136] a coating thickness not larger than 50 m, [0137] a dense coating structure, so that there is possibly no outgassing by the coating, [0138] a good adhesion to the carrier material for ensuring a good heat transfer, [0139] a high temperature stability, which allows performing coating processes at increased temperatures, preferred up to at least 600 C., [0140] good abrasion resistance, so that these coatings are not rapidly worn off in a harsh production environment.

[0141] The coatings 210 and/or 310 are preferably deposited by PVD techniques, so that they can be applied, for example, on the corresponding chamber wall sides and shielding walls sides in the same coating chamber. In this case, for example, the inner chamber walls can first be coated with the coating 210 without shielding walls in a coating process. Afterwards, however, the shielding walls can be placed in the opposite direction in the coating chamber, so that the desired shielding wall side, which will be later opposite the inner chamber wall side, can be coated with the coating 310. A single application of the coatings 210 and 310 is sufficient, in order to operate the coating system several times with a coating chamber provided according to the invention.

[0142] For performing a PVD coating process for coating substrates in a coating chamber according to the invention, the shielding walls are arranged in the coating system such, that the inner chamber walls or the inner side of the chamber walls, respectively, are protected, in order to minimize or to avoid an undesired coating of these walls. In this way, basically only the shielding wall side without a coating 310 is also coated during the coating of substrates. Therefore both the applied coating 310 and the applied coating 210 remain intact after each coating process.

[0143] Needless to say, that the described embodiments are to be understood only as examples and that the extent of protection is not limited to the explicitly described embodiments. In particular each suitable combination of embodiments is also comprised by the invention.