# US 8,785,266 B2 · Semiconductor device and manufacturing method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,785,266 B2 - Document ID: US8785266B2 - Status: Granted - Kind: B2 - Application number: 13/345,940 - Filed: 2012-01-09 - Published: 2012-07-12 - Granted: 2014-07-22 - Earliest claimed: 2011-01-12 - Assignees: Semiconductor Energy Laboratory Co., Ltd. - Applicants: Shunpei Yamazaki - Inventors: Shunpei Yamazaki - Web page: https://patentgrep.com/patent/US8785266B2 ## CPC - H10D 30/6756: {Amorphous oxide semiconductors} - H10D 30/6706: {for preventing leakage current (TFTs characterised by the properties of the source or drain H10D30/6713)} - H10D 30/673: {characterised by the shapes, relative sizes or dispositions of the gate electrodes} - H10D 30/6748: {having a multilayer structure or superlattice structure} - H10D 30/6755: {Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate} - H10D 30/6757: {characterised by the structure of the channel, e.g. transverse or longitudinal shape or doping profile (TFTs having channel structures for preventing kink or snapback effects H10D30/6708; TFTs having lightly-doped source or drain extensions H10D30/6715)} - H10D 62/151: {of IGFETs (of IGFETs having LDD or DDD structure H10D30/601; of thin film transistors H10D30/6713)} - H10D 62/235: {of IGFETs (IGFETs having buried channels H10D30/637)} - H10D 62/405: {Orientations of crystalline planes} - H10D 62/80: characterised by the materials - H10D 86/40: characterised by multiple TFTs - H10D 86/423: {comprising semiconductor materials not belonging to the Group IV, e.g. InGaZnO} - H10D 86/431: {having different compositions, shapes, layouts or thicknesses of gate insulators in different TFTs} - H10D 86/441: {Interconnections, e.g. scanning lines} - H10D 86/451: {characterised by the compositions or shapes of the interlayer dielectrics} - H10D 86/471: {having different architectures, e.g. having both top-gate and bottom-gate TFTs} - H10D 86/60: wherein the TFTs are in active matrices - H10D 99/00: Subject matter not provided for in other groups of this subclass - H10K 59/1213: {the pixel elements being TFTs} - H10K 59/1216: {the pixel elements being capacitors} - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES ## Abstract A first oxide insulating film is formed over a substrate. After a first oxide semiconductor film is formed over the first oxide insulating film, heat treatment is performed, so that hydrogen contained in the first oxide semiconductor film is released and part of oxygen contained in the first oxide insulating film is diffused into the first oxide semiconductor film. Thus, a second oxide semiconductor film with reduced hydrogen concentration and reduced oxygen defect is formed. Then, the second oxide semiconductor film is selectively etched to form a third oxide semiconductor film, and a second oxide insulating film is formed. The second oxide insulating film is selectively etched and a protective film covering an end portion of the third oxide semiconductor film is formed. Then, a pair of electrodes, a gate insulating film, and a gate electrode are formed over the third oxide semiconductor film and the protective film. ## Claims ### Claim 1 A method for manufacturing a semiconductor device, comprising steps of: forming a first oxide insulating film over a substrate; forming an oxide semiconductor film over the first oxide insulating film; performing heat treatment to the oxide semiconductor film; selectively etching the oxide semiconductor film to have an end portion of the oxide semiconductor film, wherein the end portion of the oxide semiconductor film comprises a side surface and a top surface of the oxide semiconductor film; forming a second oxide insulating film over the oxide semiconductor film; selectively etching the second oxide insulating film, thereby forming a protective film covering the end portion of the oxide semiconductor film; forming a pair of wirings in direct contact with the protective film and the oxide semiconductor film; forming a gate insulating film in direct contact with the top surface of the oxide semiconductor film after forming the protective film; and forming a gate electrode overlapping with the oxide semiconductor film over the gate insulating film. ### Claim 2 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, further comprising a step of: adding a dopant to the oxide semiconductor film after forming the gate electrode, so that a first oxide semiconductor region overlapping with the gate electrode, a pair of second oxide semiconductor regions between which the first oxide semiconductor region is sandwiched, and a pair of third oxide semiconductor regions which overlaps with the pair of wirings and between which the pair of second oxide semiconductor regions is sandwiched are formed. ### Claim 3 (depends on 2) The method for manufacturing a semiconductor device according to claim 2, wherein the pair of second oxide semiconductor regions is regions containing the dopant, and wherein the dopant is at least one of nitrogen, phosphorus, arsenic, hydrogen, helium, neon, argon, krypton, and xenon. ### Claim 4 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein an oxide insulating film from which part of oxygen is released by heat treatment is formed as the first oxide insulating film and the second oxide insulating film. ### Claim 5 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein an oxide insulating film containing oxygen at a proportion exceeding a stoichiometric proportion is formed as the first oxide insulating film and the second oxide insulating film. ### Claim 6 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein the heat treatment is performed at a temperature higher than or equal to 150° C. and lower than a strain point of the substrate. ### Claim 7 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein the oxide semiconductor film includes at least one element selected from In, Ga, Sn, and Zn. ### Claim 8 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein the heat treatment is performed at a temperature at which hydrogen is released from the oxide semiconductor film and oxygen contained in the first oxide insulating film is diffused into the oxide semiconductor film. ### Claim 9 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein the heat treatment is performed at a temperature at which hydrogen is released from the oxide semiconductor film and oxygen contained in the first oxide insulating film and the second oxide insulating film is diffused into the oxide semiconductor film. ### Claim 10 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein the gate insulating film is formed to be in direct contact with top surfaces of the pair of wirings. ### Claim 11 A method for manufacturing a semiconductor device, comprising steps of: forming a first oxide insulating film over a substrate; forming an oxide semiconductor film over the first oxide insulating film; performing heat treatment to the oxide semiconductor film; selectively etching the oxide semiconductor film to have an end portion of the oxide semiconductor film; forming a second oxide insulating film over the oxide semiconductor film; selectively etching the second oxide insulating film, thereby forming a protective film covering the end portion of the oxide semiconductor film, wherein the end portion of the oxide semiconductor film comprises a side surface and a top surface of the oxide semiconductor film; forming a pair of wirings in direct contact with the protective film and the oxide semiconductor film; forming a gate insulating film in direct contact with the top surface of the oxide semiconductor film after forming the protective film; and forming a gate electrode overlapping with the oxide semiconductor film over the gate insulating film, wherein the step of selectively etching the oxide semiconductor film is performed after the step of performing heat treatment. ### Claim 12 (depends on 11) The method for manufacturing a semiconductor device according to claim 11, further comprising a step of: adding a dopant to the oxide semiconductor film after forming the gate electrode, so that a first oxide semiconductor region overlapping with the gate electrode, a pair of second oxide semiconductor regions between which the first oxide semiconductor region is sandwiched, and a pair of third oxide semiconductor regions which overlaps with the pair of wirings and between which the pair of second oxide semiconductor regions is sandwiched are formed. ### Claim 13 (depends on 12) The method for manufacturing a semiconductor device according to claim 12, wherein the pair of second oxide semiconductor regions is regions containing the dopant, and wherein the dopant is at least one of nitrogen, phosphorus, arsenic, hydrogen, helium, neon, argon, krypton, and xenon. ### Claim 14 (depends on 11) The method for manufacturing a semiconductor device according to claim 11, wherein an oxide insulating film from which part of oxygen is released by heat treatment is formed as the first oxide insulating film and the second oxide insulating film. ### Claim 15 (depends on 11) The method for manufacturing a semiconductor device according to claim 11, wherein an oxide insulating film containing oxygen at a proportion exceeding a stoichiometric proportion is formed as the first oxide insulating film and the second oxide insulating film. ### Claim 16 (depends on 11) The method for manufacturing a semiconductor device according to claim 11, wherein the heat treatment is performed at a temperature higher than or equal to 150° C. and lower than a strain point of the substrate. ### Claim 17 (depends on 11) The method for manufacturing a semiconductor device according to claim 11, wherein the oxide semiconductor film includes at least one element selected from In, Ga, Sn, and Zn. ### Claim 18 (depends on 11) The method for manufacturing a semiconductor device according to claim 11, wherein the heat treatment is performed at a temperature at which hydrogen is released from the oxide semiconductor film and oxygen contained in the first oxide insulating film is diffused into the oxide semiconductor film. ### Claim 19 (depends on 11) The method for manufacturing a semiconductor device, according to claim 11, further comprising a step of: selectively etching the second oxide insulating film, thereby forming a third oxide insulating film having a pair of openings, before forming the protective film, wherein the pair of wirings is formed in direct contact with the third oxide insulating film having the pair of openings and the oxide semiconductor film. ### Claim 20 (depends on 11) The method for manufacturing a semiconductor device according to claim 11, wherein the gate insulating film is formed to be in direct contact with top surfaces of the pair of wirings. ### Claim 21 A method for manufacturing a semiconductor device, comprising steps of: forming a first oxide insulating film over a substrate; forming an oxide semiconductor film over the first oxide insulating film; performing heat treatment to the oxide semiconductor film; selectively etching the oxide semiconductor film to have an end portion of the oxide semiconductor film; forming a second oxide insulating film over the oxide semiconductor film; selectively etching the second oxide insulating film, thereby forming a protective film covering the end portion of the oxide semiconductor film, wherein the end portion of the oxide semiconductor film comprises a side surface and a top surface of the oxide semiconductor film; forming a pair of wirings in direct contact with the protective film and the oxide semiconductor film; forming a gate insulating film in direct contact with the top surface of the oxide semiconductor film after forming the protective film; and forming a gate electrode overlapping with the oxide semiconductor film over the gate insulating film, wherein the step of performing heat treatment is performed after the step of selectively etching the oxide semiconductor film. ### Claim 22 (depends on 21) The method for manufacturing a semiconductor device according to claim 21, further comprising a step of: adding a dopant to the oxide semiconductor film after forming the gate electrode, so that a first oxide semiconductor region overlapping with the gate electrode, a pair of second oxide semiconductor regions between which the first oxide semiconductor region is sandwiched, and a pair of third oxide semiconductor regions which overlaps with the pair of wirings and between which the pair of second oxide semiconductor regions is sandwiched are formed. ### Claim 23 (depends on 22) The method for manufacturing a semiconductor device according to claim 22, wherein the pair of second oxide semiconductor regions is regions containing the dopant, and wherein the dopant is at least one of nitrogen, phosphorus, arsenic, hydrogen, helium, neon, argon, krypton, and xenon. ### Claim 24 (depends on 21) The method for manufacturing a semiconductor device according to claim 21, wherein an oxide insulating film from which part of oxygen is released by heat treatment is formed as the first oxide insulating film and the second oxide insulating film. ### Claim 25 (depends on 21) The method for manufacturing a semiconductor device according to claim 21, wherein an oxide insulating film containing oxygen at a proportion exceeding a stoichiometric proportion is formed as the first oxide insulating film and the second oxide insulating film. ### Claim 26 (depends on 21) The method for manufacturing a semiconductor device according to claim 21, wherein the heat treatment is performed at a temperature higher than or equal to 150° C. and lower than a strain point of the substrate. ### Claim 27 (depends on 21) The method for manufacturing a semiconductor device according to claim 21, wherein the oxide semiconductor film includes at least one element selected from In, Ga, Sn, and Zn. ### Claim 28 (depends on 21) The method for manufacturing a semiconductor device according to claim 21, wherein the heat treatment is performed at a temperature at which hydrogen is released from the oxide semiconductor film and oxygen contained in the first oxide insulating film and the second oxide insulating film is diffused into the oxide semiconductor film. ### Claim 29 (depends on 21) The method for manufacturing a semiconductor device, according to claim 21, further comprising a step of: selectively etching the second oxide insulating film, thereby forming a third oxide insulating film having a pair of openings, before forming the protective film, wherein the pair of wirings is formed in direct contact with the third oxide insulating film having the pair of openings and the oxide semiconductor film. ### Claim 30 (depends on 21) The method for manufacturing a semiconductor device according to claim 21, wherein the gate insulating film is formed to be in direct contact with top surfaces of the pair of wirings.