# US 9,041,066 B2 · Protection device for normally-on and normally-off high electron mobility transistors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,041,066 B2 - Document ID: US9041066B2 - Status: Granted - Kind: B2 - Application number: 14/054,918 - Filed: 2013-10-16 - Published: 2014-02-06 - Granted: 2015-05-26 - Earliest claimed: 2012-06-04 - Assignees: Infineon Technologies Austria AG - Applicants: Infineon Technologies Austria AG - Inventors: Walter Rieger; Oliver Häberlen - Web page: https://patentgrep.com/patent/US9041066B2 ## CPC - H10D 30/47: having two-dimensional [2D] charge carrier gas channels, e.g. nanoribbon FETs or high electron mobility transistors [HEMT] - H02M 1/32: Means for protecting converters other than automatic disconnection - H02M 3/1588: {comprising at least one synchronous rectifier element (H02M3/1582, H02M3/1584 take precedence)} - H10D 30/475: {having wider bandgap layer formed on top of lower bandgap active layer, e.g. undoped barrier HEMTs such as i-AlGaN/GaN HEMTs} - H10D 84/01: Manufacture or treatment - H10D 84/0158: {the components including FinFETs} - H10D 89/60: Integrated devices comprising arrangements for electrical or thermal protection, e.g. protection circuits against electrostatic discharge [ESD] - H10D 62/343: {Gate regions of field-effect devices having PN junction gates} - H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN} - H10D 64/514: {characterised by the insulating layers} - Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract A transistor device includes a compound semiconductor body, a normally-on high electron mobility field effect transistor (HEMT) formed in the compound semiconductor body and a protection device monolithically integrated in the same compound semiconductor body as the normally-on HEMT. The normally-on HEMT has a source, a drain, a gate, and a threshold voltage. The protection device has a source and a drain each shared with the normally-on HEMT, a gate and a positive threshold voltage that is less than a difference of the threshold voltage of the normally-on HEMT and a gate voltage used to turn off the normally-on HEMT. The protection device is operable to conduct current in a reverse direction when the normally-on HEMT is switched off. A transistor device including a normally-off HEMT and a monolithically integrated protection device is also provided. ## Claims ### Claim 1 A transistor device, comprising: a compound semiconductor body; a normally-on high electron mobility field effect transistor (HEMT) formed in the compound semiconductor body and having a source, a drain, a gate, and a threshold voltage; and a protection device monolithically integrated in the same compound semiconductor body as the normally-on HEMT and having a source and a drain each shared with the normally-on HEMT, a gate and a positive threshold voltage that is less than a difference of the threshold voltage of the normally-on HEMT and a gate voltage used to turn off the normally-on HEMT, the protection device operable to conduct current in a reverse direction when the normally-on HEMT is switched off. ### Claim 2 (depends on 1) The transistor device of claim 1, wherein the gate of the normally-on HEMT is isolated from the compound semiconductor body by a first dielectric, the gate of the protection device is isolated from the compound semiconductor body by a second dielectric, and the first dielectric has a different thickness than the second dielectric. ### Claim 3 (depends on 2) The transistor device of claim 2, wherein the gate of the normally-on HEMT is disposed in a first trench extending into the compound semiconductor body, the gate of the protection device is disposed in a second trench extending into the compound semiconductor body, and the first trench extends to a different depth in the compound semiconductor body than the second trench. ### Claim 4 (depends on 2) The transistor device of claim 2, wherein the first dielectric and the second dielectric are formed from the same insulating layer. ### Claim 5 (depends on 4) The transistor device of claim 4, wherein the insulating layer comprises aluminum oxide, silicon nitride or silicon oxide. ### Claim 6 (depends on 4) The transistor device of claim 4, further comprising an additional insulating layer on the insulating layer. ### Claim 7 (depends on 6) The transistor device of claim 6, wherein the additional insulating layer comprises SiN, Zr oxide or Hf oxide. ### Claim 8 (depends on 1) The transistor device of claim 1, wherein the gate of the normally-on HEMT is disposed in a first trench extending into the compound semiconductor body, the gate of the protection device is disposed in a second trench extending into the compound semiconductor body, and the first trench extends to a different depth in the compound semiconductor body than the second trench. ### Claim 9 (depends on 8) The transistor device of claim 8, wherein the gate of the normally-on HEMT is isolated from the compound semiconductor body by a first dielectric, the gate of the protection device is isolated from the compound semiconductor body by a second dielectric, and the first dielectric has a different thickness than the second dielectric. ### Claim 10 (depends on 1) The transistor device of claim 1, wherein the gate of the normally-on HEMT contacts the compound semiconductor body and the gate of the protection device contacts the compound semiconductor body. ### Claim 11 (depends on 1) The transistor device of claim 1, wherein the normally-on HEMT and the protection device share a two-dimensional charge carrier gas channel region arising in the compound semiconductor body, and wherein the two-dimensional charge carrier gas channel region is disrupted between the normally-on HEMT and the protection device. ### Claim 12 (depends on 11) The transistor device of claim 11, further comprising an implanted region which disrupts the two-dimensional charge carrier gas channel region between the normally-on HEMT and the protection device. ### Claim 13 A transistor device, comprising: a compound semiconductor body; a normally-off high electron mobility field effect transistor (HEMT) formed in the compound semiconductor body and having a source, a drain, a threshold voltage, and a p-doped III-nitride gate in contact with the compound semiconductor body; and a protection device monolithically integrated in the same compound semiconductor body as the normally-off HEMT and having a source and a drain each shared with the normally-off HEMT, a gate and a threshold voltage less than the threshold voltage of the normally-off HEMT, the protection device operable to conduct current in a reverse direction when the normally-off HEMT is switched off. ### Claim 14 (depends on 13) The transistor device of claim 13, wherein the gate of the protection device is a p-doped III-nitride gate in contact with the compound semiconductor body. ### Claim 15 (depends on 14) The transistor device of claim 14, wherein the p-doped III-nitride gate of the normally-off HEMT and the p-doped III-nitride gate of the protection device each comprise p-doped GaN. ### Claim 16 (depends on 14) The transistor device of claim 14, wherein the p-doped III-nitride gate of the protection device has a lower p-doping concentration than the p-doped III-nitride gate of the normally-off HEMT. ### Claim 17 (depends on 13) The transistor device of claim 13, wherein the gate of the protection device comprises metal or poly-Si and is isolated from the compound semiconductor body by a dielectric. ### Claim 18 (depends on 13) The transistor device of claim 13, wherein the gate of the protection device is undoped or n-doped. ### Claim 19 (depends on 13) The transistor device of claim 13, wherein the normally-off HEMT and the protection device share a two-dimensional charge carrier gas channel region arising in the compound semiconductor body, and wherein the two-dimensional charge carrier gas channel region is disrupted between the normally-off HEMT and the protection device. ### Claim 20 (depends on 19) The transistor device of claim 19, further comprising an implanted region which disrupts the two-dimensional charge carrier gas channel region between the normally-off HEMT and the protection device.