| CPC C30B 33/02 (2013.01) [B23K 26/382 (2015.10); B23K 26/402 (2013.01); C30B 29/403 (2013.01); C30B 33/04 (2013.01); B23K 2103/52 (2018.08); H01L 21/02389 (2013.01); H01L 21/0243 (2013.01)] | 3 Claims |

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1. A method for manufacturing an aluminum nitride substrate, comprising a strained layer removal step of removing a strained layer of an aluminum nitride substrate by etching the aluminum nitride substrate through a heat treatment under a nitrogen atmosphere,
wherein the heat treatment is performed under a condition where the heating temperature of the aluminum nitride substrate is 1700° C. or less, and the nitrogen back pressure is 1 kPa or more; or
wherein the heat treatment is performed under a condition where the nitrogen back pressure is 20 kPa or more.
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