# US 9,437,719 B2 · Method for manufacturing semiconductor device having grooved surface > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,437,719 B2 - Document ID: US9437719B2 - Status: Granted - Kind: B2 - Application number: 14/620,768 - Filed: 2015-02-12 - Published: 2015-09-03 - Granted: 2016-09-06 - Earliest claimed: 2014-03-03 - Assignees: Toyota Jidosha Kabushiki Kaisha - Applicants: Toyota Jidosha Kabushiki Kaisha - Inventors: Shuhei Oki; Masaru Senoo - Web page: https://patentgrep.com/patent/US9437719B2 ## CPC - H10D 12/411: {Insulated-gate bipolar transistors [IGBT]} - H10D 8/422: {PN diodes having the PN junctions in mesas} - H10D 12/01: Manufacture or treatment - H10D 12/038: {having a recessed gate, e.g. trench-gate IGBTs} - H10D 12/481: {having gate structures on slanted surfaces, on vertical surfaces, or in grooves, e.g. trench gate IGBTs} - H10D 62/128: {Anode regions of diodes} - H10D 62/142: {Anode regions of thyristors or collector regions of gated bipolar-mode devices} - H10D 62/57: the imperfections being on the surface of the semiconductor body, e.g. the body having a roughened surface - H10D 64/117: {Recessed field plates, e.g. trench field plates or buried field plates} - H10D 84/811: {Combinations of field-effect devices and one or more diodes, capacitors or resistors} - H10P 34/42: with electromagnetic radiation, e.g. laser annealing (laser cutting H10P54/20) - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract A technology for reducing contact resistance between a semiconductor substrate and an electrode is provided. A provided method for manufacturing a semiconductor device includes: forming an oxide film 62 on a surface 12b of a semiconductor substrate 12 by bringing the surface 12b into contact with ammonia-hydrogen peroxide water mixture; forming a groove 60 on the surface 12b by irradiating light to heat the surface 12b covered with the oxide film 62; removing the oxide film 62 to expose the surface 12b; and forming an electrode 16 on the exposed surface 12b. ## Claims ### Claim 1 A method for manufacturing a semiconductor device, the semiconductor device comprises: a p-type collector region of an IGBT, the p-type collector region being exposed at a surface of a semiconductor substrate; an n-type cathode region of a diode, the n-type cathode region being exposed at the surface of the semiconductor substrate and adjacent to the p-type collector region; an n-type buffer region, the n-type buffer region being adjacent to the p-type collector region and the n-type cathode region from a deeper side, wherein an n-type impurity concentration in the n-type buffer region is lower than that in the n-type cathode region; and an n-type drift region, the n-type drift region being adjacent to the n-type buffer region from the deeper side, wherein an n-type impurity concentration in the n-type drift region is lower than that in the n-type buffer region, the method comprising: forming an oxide film on the surface of the semiconductor substrate by bringing the surface into contact with ammonia-hydrogen peroxide water mixture; forming a groove in the surface by irradiating light to heat the surface covered with the oxide film; removing the oxide film to expose the surface; and forming an electrode on the exposed surface. ### Claim 2 (depends on 1) A method of claim 1, wherein a range to which the forming of the oxide film and the heating of the surface are performed includes the surface in the p-type collector region located near a boundary between the n-type cathode region and the p-type collector region. ### Claim 3 (depends on 1) A method of claim 1, wherein the p-type collector region is located so as to surround the n-type cathode region; and a range to which the forming of the oxide film and the heating of the surface are performed is arranged on the surface in the p-type collector region so as to surround the n-type cathode region. ### Claim 4 (depends on 1) A method of claim 1, wherein a range to which the forming of the oxide film and the heating of the surface are performed does not include at least a part of the surface in the n-type cathode region, the method further comprises: removing the oxide film on the part of the surface in the n-type cathode region; and heating the part of the surface in the n-type cathode region after the removal of the oxide film on the part of the surface in the n-type cathode region, and in the forming of the electrode, the electrode is formed on the part of the surface in the heated n-type cathode region after the heating of the part of the surface in the n-type cathode region. ### Claim 5 A method for manufacturing a semiconductor device, the method comprising: forming an oxide film on a surface of a semiconductor substrate by bringing the surface into contact with ammonia-hydrogen peroxide water mixture; forming a groove in the surface by irradiating light to heat the surface covered with the oxide film; removing the oxide film to expose the surface after forming the groove; and forming an electrode on the exposed surface. ### Claim 6 (depends on 5) A method of claim 5, wherein the semiconductor device comprises: a p-type collector region of an IGBT, the p-type collector region being exposed at the surface; an n-type cathode region of a diode, the n-type cathode region being exposed at the surface and adjacent to the p-type collector region; an n-type buffer region, the n-type buffer region being adjacent to the p-type collector region and the n-type cathode region from a deeper side, wherein an n-type impurity concentration in the n-type buffer region is lower than that in the n-type cathode region; and an n-type drift region, the n-type drift region being adjacent to the n-type buffer region from the deeper side, wherein an n-type impurity concentration in the n-type drift region is lower than that in the n-type buffer region. ### Claim 7 (depends on 6) A method of claim 6, wherein a range to which the forming of the oxide film and the heating of the surface are performed includes the surface in the p-type collector region located near a boundary between the n-type cathode region and the p-type collector region. ### Claim 8 (depends on 6) A method of claim 6, wherein the p-type collector region is located so as to surround the n-type cathode region; and a range to which the forming of the oxide film and the heating of the surface are performed is arranged on the surface in the p-type collector region so as to surround the n-type cathode region. ### Claim 9 (depends on 6) A method of claim 6, wherein a range to which the forming of the oxide film and the heating of the surface are performed does not include at least a part of the surface in the n-type cathode region, the method further comprises: removing the oxide film on the part of the surface in the n-type cathode region; and heating the part of the surface in the n-type cathode region after the removal of the oxide film on the part of the surface in the n-type cathode region, and in the forming of the electrode, the electrode is formed on the part of the surface in the heated n-type cathode region after the heating of the part of the surface in the n-type cathode region. ### Claim 10 A method for manufacturing a semiconductor device, the method comprising: forming an oxide film on a surface of a semiconductor substrate by bringing the surface into contact with ammonia-hydrogen peroxide water mixture; forming a groove in the surface by irradiating light to melt a portion of the surface without melting the oxide film; removing the oxide film to expose the surface; and forming an electrode on the exposed surface. ### Claim 11 (depends on 10) A method of claim 10, wherein the semiconductor device comprises: a p-type collector region of an IGBT, the p-type collector region being exposed at the surface; an n-type cathode region of a diode, the n-type cathode region being exposed at the surface and adjacent to the p-type collector region; an n-type buffer region, the n-type buffer region being adjacent to the p-type collector region and the n-type cathode region from a deeper side, wherein an n-type impurity concentration in the n-type buffer region is lower than that in the n-type cathode region; and an n-type drift region, the n-type drift region being adjacent to the n-type buffer region from the deeper side, wherein an n-type impurity concentration in the n-type drift region is lower than that in the n-type buffer region. ### Claim 12 (depends on 11) A method of claim 11, wherein a range to which the forming of the oxide film and the heating of the surface are performed includes the surface in the p-type collector region located near a boundary between the n-type cathode region and the p-type collector region. ### Claim 13 (depends on 11) A method of claim 11, wherein the p-type collector region is located so as to surround the n-type cathode region; and a range to which the forming of the oxide film and the heating of the surface are performed is arranged on the surface in the p-type collector region so as to surround the n-type cathode region. ### Claim 14 (depends on 11) A method of claim 11, wherein a range to which the forming of the oxide film and the heating of the surface are performed does not include at least a part of the surface in the n-type cathode region, the method further comprises: removing the oxide film on the part of the surface in the n-type cathode region; and heating the part of the surface in the n-type cathode region after the removal of the oxide film on the part of the surface in the n-type cathode region, and in the forming of the electrode, the electrode is formed on the part of the surface in the heated n-type cathode region after the heating of the part of the surface in the n-type cathode region.