# US 12,112,944 B2 · Preparation method of GaN field effect transistor based on diamond substrate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,112,944 B2 - Document ID: US12112944B2 - Status: Granted - Kind: B2 - Application number: 17/728,643 - Filed: 2022-04-25 - Published: 2022-08-11 - Granted: 2024-10-08 - Earliest claimed: 2021-02-05 - Assignees: The 13th Research Institute of China Electronics Technology Group Corporation - Applicants: The 13Th Research Institute of China Electronics Technology Group Corporation - Inventors: Yuangang Wang; Shaobo Dun; Yuanjie Lv; Xingchang Fu; Shixiong Liang; Xubo Song; Hongyu Guo; Zhihong Feng - Web page: https://patentgrep.com/patent/US12112944B2 ## CPC - H10P 14/3216: {Nitrides} - H10D 30/015: {of FETs having heterojunction interface channels or heterojunction gate electrodes, e.g. HEMT} - 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 62/8325: {Silicon carbide} - H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN} - H10P 14/22: using physical deposition, e.g. vacuum deposition or sputtering - H10P 14/2903: {Carbon, e.g. diamond-like carbon} - H10P 14/3416: {Nitrides} - H10D 64/254: {for lateral devices wherein the source or drain electrodes extend entirely through the semiconductor bodies, e.g. via-holes for back side contacts} - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES ## Abstract The disclosure provides a preparation method of GaN field effect transistor based on diamond substrate, and relates to the technical field of semiconductor manufacturing. The method includes the following steps: preparing a GaN heterojunction layer on the front-side of a SiC substrate; thinning the SiC substrate; etching the SiC substrate; growing a diamond layer; removing a sacrificial layer and the diamond layer on the sacrificial layer; preparing a source electrode, a drain electrode and a gate electrode on the front surface of the GaN heterojunction layer; etching the SiC substrate and the GaN heterojunction layer to form a source through hole communicated with the source electrode; and removing the through hole mask layer, and preparing back grounding metal to complete the preparation of the diamond substrate GaN transistor device. ## Claims ### Claim 1 A preparation method of a gallium nitride (GaN) field effect transistor, comprising following steps: step 1, preparing a GaN heterojunction layer on a front-side of a silicon carbide (SiC) substrate; step 2, thinning a backside of the SiC substrate to obtain a thinned SiC substrate; step 3, growing a sacrificial layer on a backside of the thinned SiC substrate; step 4, coating a photoresist on the sacrificial layer; step 5, exposing and developing the photoresist to form a metal mask area graphics on the sacrificial layer; step 6, evaporating and stripping a metal on the metal mask area graphics to form a metal mask layer on the metal mask area graphics; step 7, removing a part of the sacrificial layer that is outside an area covered by the metal mask layer to form a groove area on the sacrificial layer and to obtain a remaining sacrificial layer; step 8, removing the metal mask layer using a wet process; step 9, using the remaining sacrificial layer as a mask, and etching the thinned SiC substrate such that the groove area extends to a backside of the GaN heterojunction layer and to obtain a remaining SiC substrate; step 10, growing a diamond layer on the remaining sacrificial layer and the backside of the GaN heterojunction layer; step 11, removing a part of the diamond layer that covers the remaining sacrificial layer using the wet process to obtain a remaining diamond layer, and removing the remaining sacrificial layer using the wet process; step 12, preparing a source electrode, a drain electrode and a gate electrode on a front-side of the GaN heterojunction layer; step 13, preparing a through hole mask layer on the remaining diamond layer and the remaining SiC substrate; step 14, using the through hole mask layer as a mask, and etching the remaining SiC substrate and the GaN heterojunction layer to form a source through hole that is in communication with the source electrode; and step 15, removing the through hole mask layer, and preparing a back grounding metal on the remaining diamond layer and the remaining SiC substrate, to complete preparation of the GaN field effect transistor, the back grounding metal being in communication with the source through hole. ### Claim 2 (depends on 1) The method according to claim 1, wherein in the step 1, the GaN heterojunction layer comprises a buffer layer, a channel layer and a barrier layer. ### Claim 3 (depends on 2) The method according to claim 2, wherein in the step 1, the barrier layer is an AlGaN layer, 0