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JP-2026075076-A - Diamond-coated AIN substrate and method for manufacturing it

JP2026075076AJP 2026075076 AJP2026075076 AJP 2026075076AJP-2026075076-A

Abstract

[Problem] To provide a method for coating the surface of an aluminum nitride substrate with a diamond layer using a CVD reactor. [Solution] The present invention relates to a device having a substrate 2 made of aluminum nitride, which has an upper surface 4 and a lower surface 6 facing the upper surface 4, and the upper surface 4 is coated with a diamond layer 8, wherein the coated area of the lower surface 6 has a carbon-containing coating 10 containing at least 50% sp2 hybrid carbon, the free area 12 of the lower surface 6 has a carbon-containing coating 10 that is thinner than the coated area, and regardless of the thickness profile of the carbon-containing coating in the coated area of the lower surface, the thickness of the coating 10 in the free area 12 is smaller than in the portion of the coated area that directly surrounds or directly adjacent to the free area 12, and the free area 12 forms at most 10% of the lower surface 6 of the substrate 2. [Selection Diagram] Figure 1

Inventors

  • ベンジャミン・シーマン
  • トビアス・グラスル
  • ディルク・マティアク
  • トルステン・マテ
  • リーケ・ノイバー

Assignees

  • コンディアス・ゲーエムベーハー

Dates

Publication Date
20260507
Application Date
20251020
Priority Date
20241021

Claims (14)

  1. An apparatus having a substrate (2) made of aluminum nitride, having an upper surface (4) and a lower surface (6) facing the upper surface (4), the upper surface (4) being coated with a diamond layer (8), wherein the coated area of the lower surface (6) has a carbon-containing coating (10) containing at least 50% sp2 hybridized carbon, the free area (12) of the lower surface (6) has a carbon-containing coating (10) that is thinner than the coated area, and regardless of the thickness profile of the carbon-containing coating in the coated area of the lower surface, the thickness of the coating (10) in the free area (12) is smaller than in the portion of the coated area that directly surrounds or directly adjacent to the free area (12), and the free area (12) forms at most 10% of the lower surface (6) of the substrate (2).
  2. The apparatus according to claim 1, characterized in that the free region (12) extends in an annular shape.
  3. The apparatus according to claim 1, characterized in that the free region (12) is composed of a plurality of mutually separated sub-regions (16).
  4. The apparatus according to any one of claims 1 to 3, characterized in that the free region (12) forms at least 6%, and particularly preferably at least 3%, of the lower surface (6) of the substrate (2).
  5. The apparatus according to any one of claims 1 to 4, characterized in that the upper surface (4) of the substrate (2) has at least one structural element (14), particularly at least one protrusion and/or at least one recess.
  6. The apparatus according to any one of claims 1 to 5, characterized in that the lower surface (6) of the substrate (2) has at least one structural element (14), particularly a raised portion and/or at least one recess.
  7. The apparatus according to claim 6, characterized in that at least one of the structural elements (14) on the lower surface (6) is located in the free region (12) of the lower surface (6).
  8. The apparatus according to any one of claims 1 to 7, characterized in that the diamond layer (8) on the upper surface (4) of the substrate (2) contains less than 5%, preferably less than 3%, and particularly preferably less than 1% of sp2 hybridized carbon.
  9. The apparatus according to any one of claims 1 to 8, characterized in that the carbon-containing coating (10) on the lower surface (6) of the substrate (2) contains at least 70%, and particularly preferably at least 90%, of sp2 hybridized carbon.
  10. The apparatus according to any one of claims 1 to 9, characterized in that the diamond layer (8) is doped, and the doping preferably contains boron and/or phosphorus and/or nitrogen.
  11. The apparatus according to any one of claims 1 to 10, characterized in that the diamond layer (8) is at its thickest point by a maximum of 2 μm, preferably a maximum of 1 μm, and particularly preferably a maximum of 0.2 μm, compared to the thinnest point of the diamond layer.
  12. The apparatus according to any one of claims 1 to 11, characterized in that the lower surface (6) of the substrate (2) also has a diamond coating, and a carbon-containing coating is disposed above and/or below it.
  13. In a method for coating the upper surface (4) of a substrate (2) made of aluminum nitride with a diamond layer (8) using a CVD reactor, the method comprises the following steps, namely: a. A step in which the upper surface (4) is etched with an etching agent outside the CVD reactor, thereby creating the prepared upper surface (4), b. A step of seeding diamond particles onto the prepared upper surface (4), c. The substrate having the seeded upper surface (4) is positioned on the sample stage, and at this time the substrate is supported on at least one support portion; d. A step in which the sample stage is positioned together with the substrate (2) in the CVD reactor, e. A step in which the CVD reactor and the substrate (2) are heated to an operating temperature, f. A step in which a diamond layer (8) is deposited on the upper surface (4), and a carbon-containing coating (10) containing at least 50% sp2 hybridized carbon is deposited on the lower surface (6) of the substrate (2), Methods that include...
  14. The method according to claim 13, further characterized in that a diamond layer (8) is deposited on the lower surface (6) of the substrate (2) in a separate step, and the substrate (2) is preferably turned over beforehand.

Description

This invention relates to an apparatus having a substrate made of aluminum nitride (AIN) having an upper surface and a lower surface facing the upper surface, and whose surface is coated with a diamond layer. Furthermore, this invention relates to a method for coating the surface of an aluminum nitride substrate with a diamond layer using a CVD reactor. From prior art, it is known that a diamond layer is often applied to a substrate to take advantage of the desirable properties of diamond. For example, to take advantage of the fact that the diamond layer is chemically inert and highly mechanically and thermally stable, electrodes for electrochemical cells are coated with a doped diamond layer. This doping is necessary to enhance the conductivity of the diamond layer, which would otherwise be electrically insulating. In another application, the mechanical hardness and durability of diamond are utilized. For example, CVD reactors are often used to coat a diamond layer onto a substrate such as a silicon single crystal. CVD stands for "chemical vapor deposition." The CVD method is a well-known prior art technique. The carbon required for the formation of the diamond layer is obtained from methane introduced into the reactor. The challenge lies in selecting process parameters so that the diamond layer is actually deposited, and no other possible carbon layers are deposited. For example, when a silicon single crystal is used as the substrate, the adhesion of the deposited diamond layer is usually high enough to use the coating substrate for each application. A substrate coated on both sides with a diamond layer, intended as an electrode for electrochemical applications, is known from German Patent Application Publication No. 102021110587A1. The type and quality of the deposited diamond layer depend on a series of parameters, which should be adjusted as precisely as possible. This is clarified, for example, regarding temperature in German Patent Application Publication No. 69629980T. In the prior art, attempts have been made to coat a substrate made from aluminum nitride, i.e., ceramic, with a diamond layer, applying the CVD method in the process. This can be seen, for example, in German Patent Application Publication No. 19710202A1 and Chinese Patent Application Publication No. 113755819A. However, this leads to poorer-than-expected adhesion of the diamond layer deposited on the substrate. In the sense of this invention, the aluminum nitride substrate is an aluminum nitride ceramic, which may additionally contain additives used in the manufacture of ceramics to affect the chemical, thermal, and/or mechanical properties of ceramics that are often subjected to a sintering process. Thus, coating aluminum nitride ceramics has proven difficult for several reasons. Metallic aluminum residue, i.e., a somewhat large area consisting of metallic aluminum, can be problematic, and under the high temperatures generated during CVD coating, this can melt. Aluminum has a melting point of approximately 660°C. CVD reactors reach temperatures of up to 900°C, causing the metallic aluminum to melt. Where metallic aluminum is present on the surface, the substrate liquefies, potentially preventing the formation of a diamond layer. Furthermore, due to the high vapor pressure of aluminum, a significant proportion of the aluminum transitions to a gaseous state. Thus, the gaseous atmosphere generated in the CVD reactor can severely contaminate not only the deposited coating but also the reactor itself, resulting in a time-consuming, costly, and expensive thorough cleaning before reuse is possible. Another problem can arise when the additives added to ceramics, such as Y₂O₃ , are often unknown. Not only their composition, but also their melting point, boiling point, or gas pressure are often unknown, making it almost impossible to predict how the additives will behave when coating the surface of the substrate, whether they will be durable enough for the coating, or whether they will be suitable at all. Another difficulty lies in the fact that the aluminum nitride substrate and the diamond layer to be coated have very different crystallographic properties. Aluminum nitride is a polycrystalline ceramic, and aluminum nitride crystals have an HDP lattice. The abbreviation HDP stands for "hexagonal close-packed." In contrast, the diamond layer grows in a cubic crystal lattice, and the (1 1 1) plane of this cubic lattice has a high degree of incompatibility with the HGP lattice. German Patent Application Publication No. 102021110587A1German Patent Application Publication No. 69629980T SpecificationGerman Patent Application Publication No. 19710202A1Chinese Patent Application Publication No. 113755819A The object of this invention is to improve upon the apparatus described in the premise of claim 1 and propose a method for coating the surface of an aluminum nitride substrate with a diamond layer using a CVD reactor. This invention solves the probl