Wafer producing method

Patent metadata

Field	Value
Publication number	US-2016288250-A1
Application number	US-201615088386-A
Country	US
Kind code	A1
Filing date	Apr 1, 2016
Priority date	Apr 6, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

A hexagonal single crystal wafer is produced from a hexagonal single crystal ingot. A wafer producing method includes a separation start point forming step of applying a laser beam to the ingot to form a modified layer parallel to the upper surface of the ingot and cracks extending from the modified layer, thus forming a separation start point. The focal point of the laser beam is relatively moved in a first direction perpendicular to a second direction where a c-axis in the ingot is inclined by an off angle with respect to a normal to the upper surface. The off angle is formed between the upper surface and a c-plane perpendicular to the c-axis, thereby linearly forming the modified layer extending in the first direction. The laser beam is applied to the ingot with the direction of the polarization plane of the laser beam set to the first direction.

First claim

What is claimed is:

1 . A wafer producing method for producing a hexagonal single crystal wafer from a hexagonal single crystal ingot having a first surface, a second surface opposite to the first surface, a c-axis extending from the first surface to the second surface, and a c-plane perpendicular to the c-axis, the wafer producing method comprising:
a separation start point forming step of setting a focal point of a laser beam having a transmission wavelength to the ingot inside the ingot at a predetermined depth from the first surface, which depth corresponds to a thickness of the wafer to be produced, and next applying the laser beam to the first surface as relatively moving the focal point and the ingot to thereby form a modified layer parallel to the first surface and cracks extending from the modified layer along the c-plane, thus forming a separation start point; and a wafer separating step of separating a plate-like member having a thickness corresponding to the thickness of the wafer from the ingot at the separation start point after performing the separation start point forming step, thus producing the wafer from the ingot; the separation start point forming step including
a modified layer forming step of relatively moving the focal point of the laser beam in a first direction perpendicular to a second direction where the c-axis is inclined by an off angle with respect to a normal to the first surface and the off angle is formed between the first surface and the c-plane, thereby linearly forming the modified layer extending in the first direction, and
an indexing step of relatively moving the focal point in the second direction to thereby index the focal point by a predetermined amount;
a direction of a polarization plane of the laser beam being set to the first direction perpendicular to the second direction in the modified layer forming step.

2 . The wafer producing method according to claim 1 , wherein the hexagonal single crystal ingot is selected from a SiC single crystal ingot, GaN single crystal ingot, and AlN single crystal ingot.

Assignees

• Disco Corp

Inventors

• Hirata Kazuya
• Takahashi Kunimitsu
• Nishino Yoko

Classifications

• B23K26/04

  Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light · CPC title

• B28D5/0011

  with preliminary treatment, e.g. weakening by scoring · CPC title

• B23K2101/40

  Semiconductor devices · CPC title

• B23K26/53 Primary

  for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks · CPC title

• B23K26/0823

  Devices involving rotation of the workpiece · CPC title