# US 2023/0066601 A1 · Method of processing monocrystalline silicon wafer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2023/0066601 A1 - Document ID: US20230066601A1 - Status: Published application - Kind: A1 - Application number: 17/821,556 - Filed: 2022-08-23 - Published: 2023-03-02 - Earliest claimed: 2021-08-30 - Assignees: Disco Corporation - Applicants: Disco Corporation - Inventors: Hayato IGA; Kazuya HIRATA; Shunichiro HIROSAWA - Web page: https://patentgrep.com/patent/US20230066601A1 ## CPC - B23K 26/53: for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks - B23K 26/0006: {taking account of the properties of the material involved (B23K26/32, B23K26/40 take precedence)} - B23K 26/032: {using optical means} - B23K 26/0622: by shaping pulses - B23K 26/0676: {into dependently operating sub-beams, e.g. an array of spots with fixed spatial relationship or for performing simultaneously identical operations} - B23K 26/0853: {Devices involving movement of the workpiece in at least two axial directions, e.g. in a plane} - H10P 54/00: Cutting or separating of wafers, substrates or parts of devices - B23K 2101/40: Semiconductor devices - B23K 2103/56: {being semiconducting} - 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 - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract A monocrystalline silicon wafer fabricated such that a particular crystal plane, e.g., a crystal plane (100), included in crystal planes {100} is exposed on each of face and reverse sides of the monocrystalline silicon wafer is irradiated with a laser beam along a first direction parallel to the particular crystal plane and inclined to a particular crystal orientation, e.g., a crystal orientation [010], included in crystal orientations <100> at an angle of 5° or less, thereby forming a peel-off layer that functions as separation initiating points between a part of the monocrystalline silicon wafer that belongs to the face side thereof and a part of the monocrystalline silicon wafer that belongs to the reverse side thereof. ## Claims ### Claim 1 A method of processing a monocrystalline silicon wafer fabricated such that a particular crystal plane included in crystal planes {100} is exposed on each of face and reverse sides of the monocrystalline silicon wafer, having a plurality of devices formed on the face side, and having a beveled outer circumferential region, by applying a laser beam having a wavelength transmittable through the monocrystalline silicon wafer while positioning a focused spot of the laser beam within the monocrystalline silicon wafer, thereby forming a peel-off layer within the monocrystalline silicon wafer, and thereafter separating the monocrystalline silicon wafer along the peel-off layer that functions as separation initiating points, the method comprising: an affixing step of affixing the face side of the monocrystalline silicon wafer to a face side of a support wafer; a first peel-off layer forming step of applying the laser beam from the reverse side of the monocrystalline silicon wafer to an annular first region of the monocrystalline silicon wafer that is positioned radially inwardly of the outer circumferential region of the monocrystalline silicon wafer, thereby forming a first peel-off layer that functions as separation initiating points between a region of the monocrystalline silicon wafer where the devices are formed and the outer circumferential region thereof; a second peel-off layer forming step of applying the laser beam from the reverse side of the monocrystalline silicon wafer to a second region of the monocrystalline silicon wafer that is positioned radially inwardly of the outer circumferential region of the monocrystalline silicon wafer, thereby forming a second peel-off layer that functions as separation initiating points between a part of the monocrystalline silicon wafer that belongs to the face side thereof and a part of the monocrystalline silicon wafer that belongs to the reverse side thereof; and a separating step of, after the affixing step, the first peel-off layer forming step and the second peel-off layer forming step, exerting external forces on the monocrystalline silicon wafer, thereby separating the monocrystalline silicon wafer along the first peel-off layer and the second peel-off layer as the separation initiating points, wherein the second peel-off layer forming step includes a laser beam applying step of applying the laser beam to a straight region of the monocrystalline silicon wafer along a first direction included in the second region while moving the monocrystalline silicon wafer and the focused spot relatively to each other along the first direction that lies parallel to the particular crystal plane and is inclined to a particular crystal orientation included in crystal orientations <100> at an angle of 5° or less, and an indexing feed step of moving a position in the monocrystalline crystal wafer where the focused spot is formed by the applied laser beam along a second direction parallel to the particular crystal plane and perpendicular to the first direction, and the laser beam applying step and the indexing feed step are repeatedly carried out to form the second peel-off layer. ### Claim 2 (depends on 1) The method according to claim 1, wherein the first peel-off layer forming step is carried out before the second peel-off layer forming step. ### Claim 3 (depends on 1) The method according to claim 1, wherein the second region is positioned radially inwardly of the first region. ### Claim 4 (depends on 1) The method according to claim 1, wherein the first peel-off layer forming step includes the step of forming the first peel-off layer so as to terminate short of the reverse side of the monocrystalline crystal wafer. ### Claim 5 (depends on 1) The method according to claim 1, wherein the first peel-off layer forming step includes the step of forming the first peel-off layer along a side surface of a truncated cone having a first bottom surface positioned near the face side of the monocrystalline crystal wafer and a second bottom surface smaller in diameter than the first bottom surface and positioned within the monocrystalline crystal wafer, by applying the laser beam such that the focused spot thereof is progressively closer to the face side of the monocrystalline crystal wafer toward the outer circumferential region thereof.