Wafer producing method

Patent metadata

Field	Value
Publication number	US-9517530-B2
Application number	US-201614988310-A
Country	US
Kind code	B2
Filing date	Jan 5, 2016
Priority date	Jan 6, 2015
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

A hexagonal single crystal wafer is produced from a hexagonal single crystal ingot. A separation start point is formed by setting a focal point of a laser beam inside the ingot at a predetermined depth from the upper surface of the ingot, which depth corresponds to the thickness of the wafer to be produced, and next applying the laser beam to the upper surface of the ingot while relatively moving the focal point and the ingot to thereby form a modified layer parallel to the upper surface of the ingot and form cracks extending from the modified layer along a c-plane, thus forming a separation start point. The focal point is indexed by relatively moving the focal point in the direction where an off angle is formed and the c-plane is inclined downward.

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-shaped 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 where the off angle is formed and the c-plane is inclined downward to thereby index the focal point by a predetermined amount.

Assignees

• Disco Corp

Inventors

• Hirata Kazuya
• Takahashi Kunimitsu
• Nishino Yoko

Classifications

• H10P95/00

  Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass · CPC title

• H10P36/00 Primary

  Gettering within semiconductor bodies · CPC title

• B23K2103/56

  being semiconducting · CPC title

• C30B29/406

  Gallium nitride · CPC title

• B28D5/0011

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