US 12,467,161 B2
Method for manufacturing semiconductor device, and semiconductor wafer
Junji Ohara, Nisshin (JP); Takashi Ishida, Nisshin (JP); Yoshitaka Nagasato, Nisshin (JP); Daisuke Kawaguchi, Hamamatsu (JP); Chiaki Sasaoka, Nagoya-shi (JP); Shoichi Onda, Nagoya (JP); and Jun Kojima, Nagoya (JP)
Assigned to DENSO CORPORATION, Kariya (JP); TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP); MIRISE Technologies Corporation, Nisshin (JP); HAMAMATSU PHOTONICS K.K., Hamamatsu (JP); and National University Corporation Tokai National Higher Education and Research System, Nagoya (JP)
Filed by DENSO CORPORATION, Kariya (JP); TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP); MIRISE Technologies Corporation, Nisshin (JP); HAMAMATSU PHOTONICS K.K., Hamamatsu (JP); and National University Corporation Tokai National Higher Education and Research System, Nagoya (JP)
Filed on Nov. 16, 2022, as Appl. No. 17/988,379.
Claims priority of application No. 2021-188623 (JP), filed on Nov. 19, 2021.
Prior Publication US 2023/0160104 A1, May 25, 2023
Int. Cl. C30B 33/04 (2006.01); B23K 26/382 (2014.01); C30B 25/20 (2006.01); C30B 29/40 (2006.01); H01L 21/268 (2006.01); H01L 21/78 (2006.01)
CPC C30B 33/04 (2013.01) [B23K 26/382 (2015.10); C30B 25/20 (2013.01); C30B 29/406 (2013.01); H01L 21/268 (2013.01); H01L 21/7806 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A method for manufacturing a semiconductor device, the method comprising:
preparing a processed wafer that includes a gallium nitride wafer containing a single crystal of gallium nitride and an epitaxial layer that contains a single crystal of gallium nitride and layered on the gallium nitride wafer, the processed wafer having a front surface adjacent to the epitaxial layer and a back surface adjacent to the gallium nitride wafer;
forming a front surface-side device-constituent part constituting a part of a device in a portion of the processed wafer adjacent to the front surface;
forming a modified layer extending in a direction along the front surface in an inside of the processed wafer by applying a laser beam on a side of the back surface of the processed wafer so as to irradiate the inside of the processed wafer with the laser beam; and
dividing the processed wafer at the modified layer into a device constituent wafer including the front surface and a back surface-side wafer including the back surface, wherein
in the preparing of the processed wafer, the processed wafer prepared includes a reflective layer for reflecting the laser beam in the epitaxial layer and at a position separated from a planned formation position, where the modified layer is to be formed, toward the front surface of the processed wafer by a predetermined distance, and
the reflective layer includes a layer having a refractive index different from a refractive index of the single crystal of the gallium nitride of the epitaxial layer.