# US 12,191,358 B2 · Semiconductor device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,191,358 B2 - Document ID: US12191358B2 - Status: Granted - Kind: B2 - Application number: 17/385,974 - Filed: 2021-07-27 - Published: 2021-11-18 - Granted: 2025-01-07 - Earliest claimed: 2019-08-09 - Assignees: Fuji Electric Co., Ltd. - Applicants: Fuji Electric Co., Ltd. - Inventors: Kota Ohi; Yoshihiro Ikura; Yosuke Sakurai; Mutsumi Kitamura; Yuichi Onozawa; Yoshiharu Kato; Toru Ajiki - Web page: https://patentgrep.com/patent/US12191358B2 ## CPC - H10D 8/422: {PN diodes having the PN junctions in mesas} - H10D 62/60: Impurity distributions or concentrations - H10D 8/00: Diodes (variable-capacitance diodes H10D1/64; gated diodes H10D12/00) - H10D 12/038: {having a recessed gate, e.g. trench-gate IGBTs} - H10D 12/441: {Vertical IGBTs} - H10D 12/481: {having gate structures on slanted surfaces, on vertical surfaces, or in grooves, e.g. trench gate IGBTs} - H10D 62/127: {of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs} - H10D 62/393: {Body regions of DMOS transistors or IGBTs (cell layout of DMOS H10D62/127)} - H10D 62/53: the imperfections being within the semiconductor body - H10D 64/519: {characterised by their top-view geometrical layouts} - H10D 84/406: {Combinations of FETs or IGBTs with vertical BJTs and with one or more of diodes, resistors or capacitors} - H10P 30/20: into semiconductor materials, e.g. for doping - H10D 62/142: {Anode regions of thyristors or collector regions of gated bipolar-mode devices} - 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} - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract Provided is a semiconductor device, including: a drift region of a first conductivity type which is provided in a semiconductor substrate, and a buffer region of the first conductivity type which is provided between the drift region and a lower surface of the semiconductor substrate, and has three or more concentration peaks higher than a doping concentration of the drift region of the semiconductor substrate in a depth direction. Three or more of the concentration peaks includes a shallowest peak closest to the lower surface of the semiconductor substrate, a high concentration peak arranged at an upper side than the lower surface of the semiconductor substrate than the shallowest peak, and one or more low concentration peaks arranged at an upper side than the lower surface of the semiconductor substrate than the high concentration peak and of which the doping concentration is ⅕ or less of the high concentration peak. ## Claims ### Claim 1 A semiconductor device, comprising: a drift region of a first conductivity type which is provided in a semiconductor substrate; and a buffer region of the first conductivity type which is provided between the drift region and a lower surface of the semiconductor substrate, and has three or more concentration peaks higher than a doping concentration of the drift region of the semiconductor substrate in a depth direction, wherein three or more of the concentration peaks includes a shallowest peak closest to the lower surface of the semiconductor substrate, a high concentration peak arranged at an upper side than the lower surface of the semiconductor substrate than the shallowest peak, and one or more low concentration peaks which are arranged at an upper side than the lower surface of the semiconductor substrate than the high concentration peak; and of which the doping concentration is ⅕ or less of the high concentration peak; and wherein the three or more of the concentration peaks include two or more of the low concentration peaks, and the shallowest peak has a doping concentration higher than the high concentration peak. ### Claim 2 (depends on 1) The semiconductor device according to claim 1, wherein the buffer region has a hydrogen concentration peak corresponding to the concentration peak. ### Claim 3 (depends on 1) The semiconductor device according to claim 1, further comprising: a collector region of a second conductivity type which is provided between the buffer region and the lower surface of the semiconductor substrate. ### Claim 4 (depends on 1) The semiconductor device according to claim 1, wherein the low concentration peak is a deepest peak which is arranged farthest from the lower surface of the semiconductor substrate among the concentration peaks. ### Claim 5 (depends on 1) The semiconductor device according to claim 1, wherein the three or more of the concentration peaks include a deepest peak arranged farthest from the lower surface of the semiconductor substrate, and wherein the low concentration peak is arranged between the high concentration peak and the deepest peak. ### Claim 6 (depends on 1) The semiconductor device according to claim 1, wherein two or more of the low concentration peaks are two or more of the concentration peaks arranged farthest from the lower surface of the semiconductor substrate among the concentration peaks. ### Claim 7 (depends on 1) The semiconductor device according to claim 1, wherein the doping concentration of the low concentration peak is 50 times or less of a bulk donor concentration of the semiconductor substrate. ### Claim 8 (depends on 1) The semiconductor device according to claim 1, wherein the doping concentration of the low concentration peak is 50 times or less of the doping concentration in a center of the semiconductor substrate in the depth direction. ### Claim 9 (depends on 1) The semiconductor device according to claim 1, wherein the three or more of the concentration peaks include a first peak which is arranged farthest from the lower surface of the semiconductor substrate and a second peak which is adjacent to the first peak in the depth direction, and wherein an average value of peak values of the doping concentrations of the first peak and the second peak is ⅕ or less of a peak value of the doping concentration of the high concentration peak. ### Claim 10 (depends on 9) The semiconductor device according to claim 9, wherein an average value of peak values of the doping concentrations of the first peak and the second peak is 50 times or less of a bulk donor concentration of the semiconductor substrate. ### Claim 11 (depends on 9) The semiconductor device according to claim 9, wherein an average value of peak values of the doping concentrations of the first peak and the second peak is 50 times or less of the doping concentration in a center of the semiconductor substrate in the depth direction. ### Claim 12 (depends on 1) The semiconductor device according to claim 1, wherein the buffer region includes a recombination center, and wherein a density peak of the recombination center in the depth direction is arranged between the shallowest peak and the high concentration peak. ### Claim 13 (depends on 12) The semiconductor device according to claim 12, wherein the density peak is arranged between the shallowest peak and the high concentration peak from the shallowest peak. ### Claim 14 (depends on 1) The semiconductor device according to claim 1, wherein the doping concentration of a deepest peak arranged farthest from the lower surface of the semiconductor substrate among the concentration peaks is 1.1 times or more than the doping concentration of the concentration peak adjacent to the deepest peak in the depth direction, or 5 times or less. ### Claim 15 (depends on 1) The semiconductor device according to claim 1, wherein the doping concentration of a deepest peak arranged farthest from the lower surface of the semiconductor substrate among the concentration peaks is 1.0×1014 atoms/cm3 or more, and 5.0×1014 atoms/cm3 or less. ### Claim 16 (depends on 1) The semiconductor device according to claim 1, wherein the buffer region is arranged between the lower surface of the semiconductor substrate and a center of the semiconductor substrate in the depth direction. ### Claim 17 (depends on 1) The semiconductor device according to claim 1, wherein a deepest peak arranged farthest from the lower surface of the semiconductor substrate among the concentration peaks is arranged between an upper surface of the semiconductor substrate and a center of the semiconductor substrate in the depth direction. ### Claim 18 (depends on 1) The semiconductor device according to claim 1, wherein the low concentration peak and the high concentration peak are arranged to be adjacent in the depth direction. ### Claim 19 (depends on 1) The semiconductor device according to claim 1, wherein the three or more concentration peaks include a first peak arranged farthest from the lower surface of the semiconductor substrate and a second peak adjacent to the first peak in the depth direction, and wherein a highly concentrated region where a doping concentration is higher than the drift region and a doping concentration distribution is almost flat is provided between the first peak and the second peak. ### Claim 20 (depends on 19) The semiconductor device according to claim 19, wherein the highly concentrated region includes a center of the semiconductor substrate in the depth direction. ### Claim 21 (depends on 19) The semiconductor device according to claim 19, wherein the first peak is the low concentration peak.