# US 9,517,530 B2 · Wafer producing method

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 9,517,530 B2
- Document ID: US9517530B2
- Status: Granted
- Kind: B2
- Application number: 14/988,310
- Filed: 2016-01-05
- Published: 2016-07-07
- Granted: 2016-12-13
- Earliest claimed: 2015-01-06
- Assignees: Disco Corporation
- Applicants: Disco Corporation
- Inventors: Kazuya Hirata; Kunimitsu Takahashi; Yoko Nishino
- Web page: https://patentgrep.com/patent/US9517530B2

## CPC

- H10P 36/00: Gettering within semiconductor bodies
- B23K 26/0006: {taking account of the properties of the material involved (B23K26/32, B23K26/40 take precedence)}
- B23K 26/53: for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks
- B28D 5/0011: {with preliminary treatment, e.g. weakening by scoring}
- C30B 29/406: {Gallium nitride}
- H10P 95/00: Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass
- B23K 2103/56: {being semiconducting}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B28D: WORKING STONE OR STONE-LIKE MATERIALS
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR

## 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.

## Claims

### Claim 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.