# US 9,040,432 B2 · Method for facilitating crack initiation during controlled substrate spalling > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,040,432 B2 - Document ID: US9040432B2 - Status: Granted - Kind: B2 - Application number: 13/774,643 - Filed: 2013-02-22 - Published: 2014-08-28 - Granted: 2015-05-26 - Earliest claimed: 2013-02-22 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Stephen W. Bedell; Keith E. Fogel; Bahman Hekmatshoartabari; Paul A. Lauro; Devendra K. Sadana; Davood Shahrjerdi - Web page: https://patentgrep.com/patent/US9040432B2 ## CPC - H10P 14/6516: {of treatments performed after formation of the materials} - H10F 71/1395: {for thin-film devices} - H10P 90/00: Preparation of wafers not covered by a single main group of this subclass, e.g. wafer reinforcement - H10P 90/1904: {Preparing vertically inhomogeneous wafers} - Y02E 10/50: Photovoltaic [PV] energy - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A method is provided in which a substrate including various materials of different fracture toughness (KIc) can be spalled in a controlled manner. In particular, a surface step region is formed within a surface portion of the substrate prior to formation of a stressor layer. The presence of the surface step region within the surface portion of the substrate controls the depth and ease at which crack initiation occurs within the substrate. ## Claims ### Claim 1 A method for removing a material layer from a substrate, said method comprising: providing a substrate comprising, from bottom to top, a base portion comprising at least one first material having a first fracture toughness and having an entirely planar topmost surface and a surface portion comprising at least one second material having a second fracture toughness and having a bottommost surface forming an interface with said topmost surface of said base portion, wherein the second fracture toughness differs from the first fracture toughness and wherein a surface step region is located at each vertical edge and on a front side of the substrate, wherein said surface step region comprises a recessed portion of said first material or a region void of said first material; forming a stressor layer atop the front side of the substrate; and removing a material layer from the substrate by spalling, wherein crack propagation occurs only in one of the first material or the second material. ### Claim 2 (depends on 1) The method of claim 1, wherein said providing the substrate comprises blanket depositing said surface portion on said base portion, and patterning said surface portion to include said surface step region therein. ### Claim 3 (depends on 2) The method of claim 2, wherein said patterning comprising lithography and etching. ### Claim 4 (depends on 3) The method of claim 3, wherein said etching completely removes exposed regions of the surface portion. ### Claim 5 (depends on 3) The method of claim 3, wherein said etching partially removes exposed regions of the surface portion. ### Claim 6 (depends on 5) The method of claim 5, wherein said partially removed exposed regions of the surface portion have a first thickness than is less than a second thickness of an adjoining region of the surface portion. ### Claim 7 (depends on 2) The method of claim 2, wherein said patterning comprises laser ablation. ### Claim 8 (depends on 2) The method of claim 2, wherein said patterning comprises reactive ion etching. ### Claim 9 (depends on 1) The method of claim 1, wherein said providing the substrate comprises a selective deposition process in which the surface portion is formed on a predetermined region of the base portion. ### Claim 10 (depends on 1) The method of claim 1, wherein said first fracture toughness is greater than the second fracture toughness. ### Claim 11 (depends on 1) The method of claim 1, wherein said first fracture toughness is less than the second fracture toughness. ### Claim 12 (depends on 1) The method of claim 1, further comprising forming a metal-containing adhesion layer between the stressor layer and the substrate. ### Claim 13 (depends on 1) The method of claim 1, wherein the stressor layer comprises a metal, a polymer, a spalling inducing tape or any combination thereof. ### Claim 14 (depends on 1) The method of claim 1, wherein said stressor layer is Ni. ### Claim 15 (depends on 14) The method of claim 14, wherein said handle layer is a tape formed directly on the stressor layer wherein said spalling comprises peeling or pulling said tape. ### Claim 16 (depends on 1) The method of claim 1, further comprises forming a handle substrate on an exposed surface of the stressor layer. ### Claim 17 (depends on 1) The method of claim 1, wherein said spalling is performed at room temperature. ### Claim 18 (depends on 1) The method of claim 1, further comprising removing at least said stressor layer from said material layer. ### Claim 19 (depends on 1) The method of claim 1, wherein surface step region has a width which extends inwards from one of said vertical edges from 1 μm to 1 cm. ### Claim 20 (depends on 1) The method of claim 1, wherein said stressor layer directly contacts said front side of the substrate including said surface step region. ### Claim 21 (depends on 1) The method of claim 1, wherein said first material comprises sapphire or SiC and said second material comprises a semiconductor material. ### Claim 22 (depends on 1) The method of claim 1, wherein said first material comprises Si or Ge and said second material comprises a semiconductor material. ### Claim 23 (depends on 1) The method of claim 1, wherein said second material comprises one or more III-V compound semiconductors. ### Claim 24 (depends on 1) The method of claim 1, wherein said surface portion comprises one or more semiconductor devices built thereon.