COATING APPARATUS, PROCESS CHAMBER, AND METHOD OF COATING A SUBSTRATE AND SUBSTRATE COATED WITH AT LEAST ONE MATERIAL LAYER

Abstract

The present invention relates to a coating apparatus for coating a substrate of a substrate material with at least one material layer of a layer material. The present invention also relates to a process chamber for a coating apparatus for coating a substrate of a substrate material with at least one material layer of a layer material. The present invention further relates to a method of coating a substrate of a substrate material with at least one material layer of a layer material in a coating apparatus. A further aspect of the invention relates to a substrate coated with at least one material layer, comprising the substrate of a substrate material that is coated with at least one material layer of a layer material.

Claims

1. A coating apparatus for coating a substrate of a substrate material with at least one material layer of a layer material, said coating apparatus comprising a process chamber having a process volume for receiving a substrate holder for arranging the substrate in a fixed position in the process volume, wherein the process chamber has a chamber wall for at least substantially completely enclosing the process volume; a gas system connected in a fluid-communicating manner to the process volume for generating a coating atmosphere in the process volume; and a source holder arranged in the process volume and having at least one source material, wherein the source holder and the substrate holder are further arranged relative to one another such that thermally evaporated and/or sublimated source material can be deposited on the substrate for an at least partial formation of the layer material of the material layer, said coating apparatus further comprising a source heating laser, wherein the source heating laser is configured to provide laser light continuously or at least substantially continuously and the process chamber has a coupling-in apparatus having at least one coupling-in section in the chamber wall for conducting laser light of a source heating laser into the process volume, with the laser light being at least sectionally present as a light beam in the process volume and the source material being able to be heated and being able to thermally evaporated and/or sublimated below a plasma generation threshold of the source material by the laser light.

2. The coating apparatus in accordance with claim 1, wherein the source material can be directly heated and thermally evaporated and/or sublimated by the laser light by a direct irradiation of the laser light onto a source surface of the source material.

3. The coating apparatus in accordance with claim 1, wherein the light beam encloses an angle of incidence between 0° and 90° with a surface normal to a crucible surface of the source crucible having source material and/or with a surface normal to a source surface of the source material.

4. The coating apparatus in accordance with claim 1, wherein at least one of an intensity and a wavelength of the laser light is adapted to the corresponding source material.

5. The coating apparatus in accordance with claim 1, wherein the process chamber has, at an inner side of the chamber wall, at least one beam catcher for at least partly absorbing reflected laser light, with the beam catcher being arranged in a spatial plane, which the light beam and the surface normal to the crucible surface of the source crucible and/or to the source surface of the source material span, and at a section of the chamber wall disposed opposite the coupling-in section in accordance with the angle of incidence.

6. The coating apparatus in accordance with claim 1, wherein the source holder has two or more source materials, with each source material being able to be heated and thermally evaporated and/or sublimated by a separate light beam of laser light.

7. The coating apparatus in accordance with claim 6, wherein the coupling-in apparatus has a common coupling-in section for conducting at least two of the separate light beams into the process volume.

8. The coating apparatus in accordance with claim 6, wherein the coupling-in apparatus has at least two separate coupling-in sections for conducting a respective at least one of the separate light beams into the process volume.

9. The coating apparatus in accordance with claim 1, wherein at least one of the light beams has a focal area, with, in the focal area, the light beam having a minimum extent perpendicular to a light direction of the light beam, with the focal area further being arranged in the process volume between the coupling-in section and the corresponding source material or the corresponding source crucible.

10. The coating apparatus in accordance with claim 9, wherein the focal areas of at least two of the light beams overlap.

11. The coating apparatus in accordance with claim 9, wherein the process chamber has at least one heating laser aperturei having an aperture opening, with the heating laser aperture being arranged in the process volume such that the focal area of at least one of the light beams coincides or at least substantially coincides with the aperture opening.

12. The coating apparatus in accordance with claim 11, wherein the aperture opening is formed in the heating laser aperture by the laser light of the source heating laser.

13. The coating apparatus in accordance with claim 1, wherein the process chamber has at least one thermocouple for determining a temperature of the at least one source material and/or of the corresponding source crucible.

14. The coating apparatus in accordance with claim 1, wherein the coupling-in apparatus has at least one further coupling-in section in the chamber wall for conducting laser light of a substrate heating laser into the process volume, with the laser light at least sectionally being present as a light beam in the process volume and the substrate material of the substrate being heatable by the laser light.

15. The coating apparatus in accordance with claim 1, wherein the gas system has a process gas supply for supplying a process gas into the process volume and a pump system for generating an underpressure in the process volume, with the pump system comprising a magnetically levitated turbopump.

16. A process chamber for a coating apparatus for coating a substrate of a substrate material with at least one material layer of a layer material, wherein the process chamber is configured for a use in a coating apparatus in accordance with claim 1.

17. A method of coating a substrate of a substrate material with at least one material layer of a layer material in a coating apparatus in accordance with claim 1, wherein a source material is used for at least partly providing the layer material, said source material being heated and being thermally evaporated and/or sublimated below a plasma generation threshold of the source material by a continuous or at least substantially continuous laser light of a source heating laser.

18. The method in accordance with claim 17, wherein the source material is directly heated and thermally evaporated and/or sublimated by the laser light by a direct irradiation of the laser light onto a source surface of the source material.

19. The method in accordance with claim 17, wherein the substrate material of the substrate is heated by laser light of a substrate heating laser.

20. The method in accordance with claim 17, wherein a coating atmosphere having a pressure between 10.sup.−10 mbar and 1 mbar is provided in the process volume by the gas system of the coating apparatus.

21. The method in accordance with claim 17, wherein a coating atmosphere having a gaseous substance adapted to the layer material of the material layer as the process gas is provided in the process volume by the gas system of the coating apparatus.

22. The method in accordance with claim 17, wherein an oxide having a perovskite structure is produced as the layer material, the oxide comprising a first metal element and a second metal element, with the first metal element and the second metal element being provided as the source material and molecular oxygen and/or ozone being used as the process gas in the coating atmosphere.

23. A substrate coated with at least one material layer, comprising the substrate of a substrate material that is coated with at least one material layer of a layer material, wherein the substrate coated with at least one material layer is produced in a coating apparatus in accordance with claim 1.

Description

[0108] Further features and advantages of the invention will be described in the following with reference to Figures. Elements with the same functionality and mode of operation are provided with the same reference numerals in the individual figures. There are schematically shown:

[0109] FIG. 1 a coating atmosphere in accordance with the invention;

[0110] FIG. 2 a process chamber of a coating apparatus in accordance with the invention;

[0111] FIG. 3 a first embodiment of a laser radiation;

[0112] FIG. 4 a second embodiment of a laser radiation;

[0113] FIG. 5 a third embodiment of a laser radiation;

[0114] FIG. 6 a light beam having a heating beam aperture;

[0115] FIG. 7 a source holder; and

[0116] FIG. 8 a special source crucible design.

[0117] FIG. 1 shows the substantial outer design of a coating apparatus 1 in accordance with the invention that is configured to carry out a method in accordance with the invention. Thus, the coating apparatus 1 in accordance with the invention in particular comprises a process chamber 10, preferably a process chamber 10 in accordance with the invention, that forms the core of the system. The coating process, not visible in this Figure, takes place in the interior of the process chamber 10. A possible internal design of a process chamber 10, in particular a process chamber 10 in accordance with the invention, or of the process volume 12 (not shown) is shown in FIG. 2. A gas system 30 provides a coating atmosphere 40 (not shown) in the interior of the process chamber 10. For this purpose, the gas system 30 in particular has a process gas supply 32 through which a process gas 42 can be conducted into the interior of the process chamber 10. A pump system 34, in particular having a magnetically levitated turbopump 36 arranged directly adjoining the process chamber, generates the necessary pressure level in the interior of the process chamber 10. In particular pressure levels over a wide range of pressures can preferably be provided by a pump system in accordance with the invention, for example having a pressure between 10.sup.−10 mbar and 1 mbar, preferably less than 10.sup.−3 mbar.

[0118] In a manner essential to the invention, provision is made in a coating apparatus 1 in accordance with the invention that the source material 66 (not shown) can be heated and thermally evaporated and/or sublimated by light beams 86 of laser light 84 of a source heating laser 80. The at least one source heating laser 80 is in particular an element of the coating apparatus 1 in accordance with the invention. This laser light 84, shown split into three light beams 86 here, can be conducted into the interior of the process chamber 10 via a coupling-in section 20 of a coupling-in apparatus 18.

[0119] A substrate heating laser 82 is further shown by which, likewise coupled in via a coupling-in section 20 of the coupling-in apparatus 18, a substrate 52 (not shown) can be heated in the interior of the process chamber 10. Due to the use of externally supplied laser light 84, provision can in particular be made that electrical components can at least substantially be omitted in the interior of the process chamber 10.

[0120] Restrictions with respect to a pressure of the coating atmosphere 40 or a selection of the process gas 42 that are caused by these electrical components, such as are required for MBE, can in this way be avoided in a coating apparatus 1 in accordance with the invention. Thus, coating atmospheres 40 having the wide pressure range of 10.sup.−10 mbar to 1 mbar already listed above can, for example, be used, wherein highly corrosive process gases 42 such as molecular oxygen and/or ozone and/or nitrogen and/or gaseous selenium compounds and/or gaseous sulfur compounds can also be used at least substantially without limitation. This, for example, enables a provision of oxides having a perovskite structure also and in particular having a modulated doping, for example strontium titanate having a modulated niobium doping.

[0121] FIG. 2 shows, by way of example, a design in the interior of the process chamber 10 and thus of the process volume 12 of a coating apparatus 1 in accordance with the invention. The process chamber 10, in particular its chamber wall 14, forms the process volume 12 in which the coating atmosphere 40, comprising a process gas 42 at a certain pressure level, is arranged.

[0122] The chamber wall 14 can, as shown here, be of multilayer design, whereby a cooling plate is formed within the process chamber 10 or the vacuum, said cooling plate, for example, being filled with liquid nitrogen during operation and thus being able to be cooled to approximately 77 K. This cooling plate, as in the prior art of MBE, forms a thermal shield and reduces the partial pressures of unwanted elements and compounds in the residual gas or the coating atmosphere 40 by freezing out impurities.

[0123] The inner side 16 of the chamber wall 14 at least substantially completely encloses the process volume 12, wherein leadthroughs through the chamber wall 14 are closed and sealed to bound and hold the coating atmosphere 40 in the process volume 12. A substrate holder 50 having a substrate 52 is arranged in the interior of the process volume 12. Furthermore, a source holder 60 is arranged in the interior of the process volume 12 and, as shown, can hold a plurality of source crucibles 62 that preferably have different source materials 66. In alternative or additional embodiments of a coating apparatus 1 in accordance with the invention, not shown in FIG. 2, suitable source materials 66 can also be arranged without source crucibles 62 in the source holder 60, for example in bar-shaped and/or rod-shaped embodiments.

[0124] The source heating laser 80 of the coating apparatus 1 in accordance with the invention is further shown, whose three light beams 86 of laser light 84 are associated with the individual source materials 66 in the source crucibles 62 and preferably irradiate them directly and immediately to heat and thermally evaporate and/or sublimate them.

[0125] In this respect, the source heating laser 80 is configured to continuously or at least substantially continuously provide laser light 84. This makes it possible to irradiate the respective laser light 84 continuously or at least substantially continuously onto the corresponding source material 66, in particular to provide a particularly constant and controllable or adjustable energy input of the laser light 84 into the corresponding source material 66. A constant and/or controllable and adjustable temperature of the respective source material 66, and thus a resulting evaporation rate and/or sublimation rate, can be made possible in this manner. Furthermore, an energy of the laser light 84 of the source heating laser 80 is set such that a plasma generation threshold of the source material 66 is not reached by the laser light 84. In other words, no plasma is generated on the incidence of the laser light 84 on the source material 66. A purely thermal evaporation and/or sublimation of the respective source material 66 can thereby be ensured.

[0126] As shown, the substrate holder 50 and the source holder 60 can preferably be arranged directly opposite one another, whereby a particularly good evaporation and/or sublimation of the source material 66 or evaporation of the source material 66 onto the substrate 52 can take place.

[0127] Furthermore, an intensity and/or a wavelength of the respective laser light 84 can preferably be adapted to the corresponding source material 66 to further improve the heating and in particular the thermal evaporation and/or sublimation of the respective source material 66. Parameters of the laser light 84 can, for example, be an intensity from 0.01 W to 50 kW and/or a wavelength from 10.sup.−8 m to 10.sup.−5 m.

[0128] A particularly good adaptation of the respective laser light 84 used to the corresponding source material 66 can thereby be provided. The light beams 86 can furthermore have a focal area 90 that, as shown, can preferably also overlap for the individual light beams 86. A heating laser aperture 100 having an aperture opening 102 is arranged adapted to this overlapping focal area 90.

[0129] In this respect, provision can preferably again be made that the aperture opening 102 has been introduced into the heating laser aperture 100 by the light beam 86 of the source heating laser 80 itself. As can clearly be seen, the heating laser aperture 100 can be arranged between the source holder 60 and the coupling-in section 20 of the coupling-in apparatus 18, whereby an impact of evaporated and/or sublimated source material 66 on the coupling-in section 20 can be reduced or even completely avoided.

[0130] This arrangement is furthermore also shown in FIG. 3 in which the three light beams 86 of laser light 84 are even better recognizable. Furthermore, it is clearly recognizable in FIG. 3 that the three light beams 86 can be introduced into the process volume 12 or into the coating atmosphere 40 by a common coupling-in section 20 of the coupling-in apparatus 18. It is also clearly recognizable that the direct path between the source holder 60 and the coupling-in section 20 is covered by the heating laser aperture 100 except for the small region of the aperture opening 102. Evaporated and/or sublimated material of the source material 66 is thus completely or at least substantially completely deposited on the heating laser aperture 100 and does not reach up to the coupling-in section 20.

[0131] FIG. 4 shows an alternative embodiment in which, in contrast to FIG. 3, six different positions for source materials 66 are now provided on the source holder 60, but only three of them are occupied by source materials 66 in source crucibles 62 in the Figure shown. Provision is now made for the irradiation of the source crucibles 62 in each case by a separate light beam 86 of laser light 84 that these light beams 86 irradiate onto the source holder 60 from two different sides. This can be made possible in that the coupling-in apparatus 18 has two mutually separate coupling-in sections 20 (not shown).

[0132] Each of these triples of light beams 86 of laser light 84 of the source heating laser 80 in turn has a common focal region 90 at which the aperture opening 102 of a heating laser aperture 100 is correspondingly in each case arranged again.

[0133] In this way, the substrate 52 in the substrate holder 50 can overall again be arranged opposite to and in parallel with the source materials 66 in the source holder 60 and can furthermore be coated with a wide range of different source materials 66. A substrate 52 in accordance with the invention that is coated with at least one material layer 56 (cf. FIG. 8) can in particular be produced using a coating apparatus 1 in accordance with the invention and/or using a method in accordance with the invention.

[0134] As shown, the two coupling-in sections 20 of the coupling-in apparatus 18 can preferably be arranged such that the spatial planes 114 (not shown), which the respective light beam 86, which is conducted into the process volume 12 by one of the separate coupling-in sections 20, and the surface normal 112 to the crucible surface 64 of the corresponding source crucible 62 and/or to the source surface 68 of the corresponding source material 66 span, enclose an angle of less than 180°, preferably between 90° and 150°, particularly preferably of 120°.

[0135] For a better overview, only one crucible surface 64 or one source surface 66 and only one of the surface normals 112 are shown. A reflection of a light beam 86 coming from one coupling-in section 20 to the other coupling-in section 20 can thereby be avoided.

[0136] A source crucible 62 with arranged source material 66 is likewise schematically shown in FIG. 5. A light beam 86 of a laser light 84 is conducted into the process volume 12 such that it is incident on the source surface 68 of the source material 66 or, if correspondingly widened, on a crucible surface 64 of the source crucible 62 at an angle of incidence 110, in particular an angle of incidence 110 between 30° and 70°, preferably 50°. As already described with respect to FIG. 4, it can happen that the laser light 84 is reflected, as is indicated by dashed lines in FIG. 5.

[0137] To prevent a heating of a chamber wall 14 by the reflected laser light 84, a beam catcher 22 is arranged at an inner side 16 of the chamber wall 14. The arrangement location of the beam catcher 22 is in particular preferably disposed in a spatial plane 114 that is spanned by the surface normal 112 and the light direction 88 of the laser light 86. Furthermore, the arrangement location is determined in accordance with the angle of incidence 110 that is at least substantially also the angle of reflection. A heating of the chamber wall 14 and thereby a possible source of contamination in the interior of the process volume 12 can be avoided by the beam catcher 22 that can also be designed as cooled.

[0138] FIG. 6 shows a schematic representation of the light beam 86 of laser light 84, coming from the source heating laser 80, again in the spatial plane 114 that has already been described in FIG. 5. It is particularly clearly visible that the light beam 86 has its smallest extent at the focal area 90 perpendicular to the light direction 88. Accordingly, the aperture opening 102 of the heating laser aperture 100 is arranged at this focal area 90. Source material 66 that is evaporated and/or sublimated by the irradiated laser light 84 is thus almost completely captured by the heating laser aperture 100 and thus cannot reach the coupling-in section 20 of the coupling-in apparatus 18. A service life of the coupling-in section 20, in particular a coupling-in window as part of the coupling-in section 20, can be extended in this way.

[0139] Possible embodiments of source crucibles 62 in a source holder 60 are shown in FIG. 7. The two source crucibles 62 are each filled with a different source material 66, wherein one of the source materials 66 is directly and immediately irradiated, heated, and thermally evaporated and/or sublimated by a light beam 86 of laser light 84 of a source heating laser 80. A temperature of the respective source material 66 can be determined by a thermocouple 70 in its measurement position 72. For a movement, for example a replacement, of the source holder 60, the thermocouples 70 can have a movable fastening section 76, whereby the thermocouples 70 can be moved from their measurement position 72 into a release position 74. An impediment of a movement of the source holder 60 by the thermocouples 70 can be avoided in this way. Alternatively or additionally, a mechanism can also be provided in which the thermocouples 70 are fixedly, or substantially fixedly, fastened in the measurement position 72 and the releasable contact with the lower sides of the source crucibles 62 is achieved by lowering or raising the source holder 60 on a transfer (not shown).

[0140] FIG. 8 now shows an alternative embodiment of source crucibles 62 and source material 66 arranged therein. In contrast to the source crucibles shown in FIG. 7, these source crucibles 62 are formed with larger depth in FIG. 8. A correspondingly larger amount of source material 66 can be arranged in these alternative source crucibles 62.

[0141] In FIG. 8, a shutter cover 24 is likewise shown by which, as shown in dashed lines, evaporated and/or sublimated source material 66 can be captured and an evaporation of the substrate material 54 of the substrate 52 can thereby be switched on or switched off. The layer material 58 of the material layer 56, which is produced on the substrate material 54 of the substrate 52 in a coating apparatus 1 in accordance with the invention (not shown) or by a method in accordance with the invention, can in this way be controlled particularly well and stoichiometrically precisely. A substrate heating laser 82 by which the substrate 52 can be heated or heated up is furthermore shown in FIG. 8. Furthermore, the source heating laser 80 having a light beam 86 of laser light 84 and a heating laser aperture 100 having an aperture opening 102 are also again shown.

REFERENCE NUMERAL LIST

[0142] 1 coating apparatus

[0143] 10 process chamber

[0144] 12 process volume

[0145] 14 chamber wall

[0146] 16 inner side

[0147] 18 coupling-in apparatus

[0148] 20 coupling-in section

[0149] 2 beam catcher

[0150] 24 shutter cover

[0151] 3 gas system

[0152] 32 process gas supply

[0153] 34 pump system

[0154] 36 turbopump

[0155] 40 coating atmosphere

[0156] 42 process gas

[0157] 50 substrate holder

[0158] 52 substrate

[0159] 54 substrate material

[0160] 56 material layer

[0161] 58 layer material

[0162] 60 source holder

[0163] 62 source crucible

[0164] 64 crucible surface

[0165] 66 source material

[0166] 68 source surface

[0167] 70 thermocouple

[0168] 72 measurement position

[0169] 74 release position

[0170] 76 fastening section

[0171] 80 source heating laser

[0172] 82 substrate heating laser

[0173] 84 laser light

[0174] 86 light beam

[0175] 88 light direction

[0176] 90 focal area

[0177] 100 heating laser aperture

[0178] 102 aperture opening

[0179] 110 angle of incidence

[0180] 112 surface normal

[0181] 114 spatial plane