# US 7,465,968 B2 · Semiconductor device and method for fabricating the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,465,968 B2 - Document ID: US7465968B2 - Status: Granted - Kind: B2 - Application number: 11/600,067 - Filed: 2006-11-16 - Published: 2007-05-24 - Granted: 2008-12-16 - Earliest claimed: 2005-11-21 - Assignees: Panasonic Corporation - Inventors: Tetsuzo Ueda; Satoshi Nakazawa; Tatsuo Morita - Web page: https://patentgrep.com/patent/US7465968B2 ## CPC - H10D 62/85: being Group III-V materials, e.g. GaAs - H10D 30/871: {Vertical FETs having Schottky gate electrodes (Vertical SIT or PBT H10D30/202)} - H10D 62/126: {Top-view geometrical layouts of the regions or the junctions} - H10D 62/405: {Orientations of crystalline planes} - H10D 62/852: being Group III-V materials comprising three or more elements, e.g. AlGaN or InAsSbP - H10D 64/62: Electrodes ohmically coupled to a semiconductor - H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN} - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES ## Abstract A semiconductor device includes: a first nitride semiconductor layer having at least one projection on an upper surface thereof; a second nitride semiconductor layer formed on a top surface of the projection of the first nitride semiconductor layer and having a higher carrier concentration than the first nitride semiconductor layer; a first electrode formed on the second nitride semiconductor layer so as to overhang like a canopy and functioning as one of a source and a drain; and a second electrode formed to the side of the projection on the first nitride semiconductor layer and functioning as a gate. ## Claims ### Claim 1 A semiconductor device, comprising: a first nitride semiconductor layer having at least one projection on an upper surface thereof, a second nitride semiconductor layer formed on a top surface of the projection of the first nitride semiconductor layer and having a higher carrier concentration than the first nitride semiconductor layer; a first electrode formed on the second nitride semiconductor layer so as to overhang like a canopy and functioning as one of a source and a drain; and a second electrode formed to the side of the projection on the first nitride semiconductor layer and functioning as a gate. ### Claim 2 (depends on 1) The semiconductor device of claim 1, wherein a conductive film made of the same material as the second electrode is formed on the first electrode. ### Claim 3 (depends on 1) The semiconductor device of claim 1, wherein the second nitride semiconductor layer is made of a quaternary mixed crystal of InAlGaN. ### Claim 4 (depends on 3) The semiconductor device of claim 3, wherein the quaternary mixed crystal has a composition that allows the quaternary mixed crystal to achieve lattice matching with the first nitride semiconductor layer. ### Claim 5 (depends on 3) The semiconductor device of claim 3, wherein an amount of polarization occurring in the quaternary mixed crystal is greater than or equal to an amount of polarization occurring in the first nitride semiconductor layer. ### Claim 6 (depends on 1) The semiconductor device of claim 1, wherein a high-resistance region is formed in part of the first nitride semiconductor layer located under the second electrode. ### Claim 7 (depends on 6) The semiconductor device of claim 6, wherein the high-resistance region is formed in an entire part of the first nitride semiconductor layer located under a peripheral portion of the second electrode. ### Claim 8 (depends on 1) The semiconductor device of claim 1, wherein a high-resistance region is formed in part of the first nitride semiconductor layer below the first electrode. ### Claim 9 (depends on 1) The semiconductor device of claim 1, wherein part of the second nitride semiconductor layer below the first electrode is selectively removed. ### Claim 10 (depends on 1) The semiconductor device of claim 1, further comprising an insulating film formed in a region between the first electrode and the second nitride semiconductor layer. ### Claim 11 (depends on 1) The semiconductor device of claim 1, wherein each side of a perimeter of the first electrode is a line segment in a <1-100> or <11-20> direction of a zone axis of the second nitride semiconductor layer. ### Claim 12 (depends on 1) The semiconductor device of claim 1, wherein part of the first electrode is made of tungsten silicide (WSi). ### Claim 13 (depends on 1) The semiconductor device of claim 1, wherein a region around the first electrode is filled with a resin material made of benzocyclobutene. ### Claim 14 (depends on 1) The semiconductor device of claim 1, wherein surfaces of the first and second nitride semiconductor layers are non-polarized surfaces in which the number of nitrogen atoms and the number of group III metal atoms are equal to each other. ### Claim 15 (depends on 1) The semiconductor device of claim 1, wherein surfaces of the first and second nitride semiconductor layers are nitrogen surfaces containing only nitrogen atoms, and the plane orientation thereof is (000-1). ### Claim 16 (depends on 1) The semiconductor device of claim 1, further comprising a conductive substrate made of gallium nitride and functioning as an underlying layer for the first nitride semiconductor layer; and a third electrode formed on a surface of the conductive substrate away from the first nitride semiconductor layer and functioning as the other of the source and the drain.