# US 2013/0157411 A1 · Method for manufacturing semiconductor device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0157411 A1 - Document ID: US20130157411A1 - Status: Published application - Kind: A1 - Application number: 13/767,335 - Filed: 2013-02-14 - Published: 2013-06-20 - Earliest claimed: 2009-06-30 - Assignees: Semiconductor Energy Laboratory Co., Ltd. - Inventors: Toshinari SASAKI; Junichiro SAKATA; Hiroki OHARA; Shunpei YAMAZAKI - Web page: https://patentgrep.com/patent/US20130157411A1 ## CPC - H10D 99/00: Subject matter not provided for in other groups of this subclass - H10D 30/031: {of thin-film transistors [TFT]} - H10D 30/6704: {having supplementary regions or layers in the thin films or in the insulated bulk substrates for controlling properties of the device} - H10D 30/6713: {characterised by the properties of the source or drain regions, e.g. compositions or sectional shapes} - H10D 30/673: {characterised by the shapes, relative sizes or dispositions of the gate electrodes} - 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 62/80: characterised by the materials - H10D 64/512: {Disposition of the gate electrodes, e.g. buried gates} - H10D 86/423: {comprising semiconductor materials not belonging to the Group IV, e.g. InGaZnO} - H10D 86/441: {Interconnections, e.g. scanning lines} - H10D 86/60: wherein the TFTs are in active matrices - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES ## Abstract It is an object to provide a highly reliable semiconductor device which includes a thin film transistor having stable electric characteristics. It is another object to manufacture a highly reliable semiconductor device at lower cost with high productivity. In a method for manufacturing a semiconductor device which includes a thin film transistor where a semiconductor layer having a channel formation region, a source region, and a drain region are formed using an oxide semiconductor layer, heat treatment (heat treatment for dehydration or dehydrogenation) is performed so as to improve the purity of the oxide semiconductor layer and reduce impurities such as moisture. Moreover, the oxide semiconductor layer subjected to the heat treatment is slowly cooled under an oxygen atmosphere. ## Claims ### Claim 1 A method for manufacturing a semiconductor device comprising the steps of: forming an insulating layer over a substrate, forming a first oxide semiconductor layer over the insulating layer; forming a second oxide semiconductor layer over the first oxide semiconductor layer; performing a first heat treatment on the first oxide semiconductor layer and the second oxide semiconductor layer; after the first heat treatment, cooling the first oxide semiconductor layer and the second oxide semiconductor layer in an atmosphere containing oxygen; forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer after the first heat treatment; etching the conductive film to form a source electrode layer and a drain electrode layer; and forming an oxide insulating film in contact with part of the second oxide semiconductor layer. ### Claim 2 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein a condition for forming the first oxide semiconductor layer and a condition for forming the second oxide semiconductor layer are different from each other. ### Claim 3 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein the first heat treatment is performed under reduced pressure. ### Claim 4 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein the first heat treatment is performed in an inert atmosphere. ### Claim 5 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein hydrogen concentrations in the first oxide semiconductor layer and the second oxide semiconductor layer are reduced by the first heat treatment. ### Claim 6 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein the first heat treatment is performed by a gas rapid thermal anneal method or a lamp thermal anneal method. ### Claim 7 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, further comprising a step of forming an electrode over the oxide insulating film. ### Claim 8 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, further comprising a step of performing a second heat treatment after the oxide insulating film is formed. ### Claim 9 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein each of the first oxide semiconductor layer and the second oxide semiconductor layer includes indium and zinc. ### Claim 10 A method for manufacturing a semiconductor device comprising the steps of: forming an insulating layer over a substrate, forming a first oxide semiconductor layer over the insulating layer; forming a second oxide semiconductor layer over the first oxide semiconductor layer; performing a first heat treatment on the first oxide semiconductor layer and the second oxide semiconductor layer; after the first heat treatment, cooling the first oxide semiconductor layer and the second oxide semiconductor layer in an atmosphere containing oxygen; forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer after the first heat treatment; etching the conductive film to form a source electrode layer and a drain electrode layer; forming an oxide insulating film in contact with part of the second oxide semiconductor layer; and performing a second heat treatment after the oxide insulating film is formed, wherein the first heat treatment is performed at a first temperature higher or equal to 400° C. ### Claim 11 (depends on 10) The method for manufacturing a semiconductor device according to claim 10, wherein a condition for forming the first oxide semiconductor layer and a condition for forming the second oxide semiconductor layer are different from each other. ### Claim 12 (depends on 10) The method for manufacturing a semiconductor device according to claim 10, wherein the first heat treatment is performed under reduced pressure. ### Claim 13 (depends on 10) The method for manufacturing a semiconductor device according to claim 10, wherein the first heat treatment is performed in an inert atmosphere. ### Claim 14 (depends on 10) The method for manufacturing a semiconductor device according to claim 10, wherein the second heat treatment is performed at a second temperature which is lower than the first temperature. ### Claim 15 (depends on 10) The method for manufacturing a semiconductor device according to claim 10, wherein hydrogen concentrations in the first oxide semiconductor layer and the second oxide semiconductor layer are reduced by the first heat treatment. ### Claim 16 (depends on 10) The method for manufacturing a semiconductor device according to claim 10, further comprising a step of forming an electrode over the oxide insulating film. ### Claim 17 (depends on 10) The method for manufacturing a semiconductor device according to claim 10, wherein each of the first oxide semiconductor layer and the second oxide semiconductor layer includes indium and zinc. ### Claim 18 A method for manufacturing a semiconductor device comprising the steps of: forming an insulating layer over a substrate, forming a first oxide semiconductor layer over the insulating layer; forming a second oxide semiconductor layer including crystals over the first oxide semiconductor layer; performing a first heat treatment on the first oxide semiconductor layer and the second oxide semiconductor layer; after the first heat treatment, cooling the first oxide semiconductor layer and the second oxide semiconductor layer in an atmosphere containing oxygen; forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer after the first heat treatment; etching the conductive film to form a source electrode layer and a drain electrode layer; and forming an oxide insulating film in contact with part of the second oxide semiconductor layer. ### Claim 19 (depends on 18) The method for manufacturing a semiconductor device according to claim 18, wherein a condition for forming the first oxide semiconductor layer and a condition for forming the second oxide semiconductor layer are different from each other. ### Claim 20 (depends on 18) The method for manufacturing a semiconductor device according to claim 18, wherein the first heat treatment is performed under reduced pressure. ### Claim 21 (depends on 18) The method for manufacturing a semiconductor device according to claim 18, wherein the first heat treatment is performed in an inert atmosphere. ### Claim 22 (depends on 18) The method for manufacturing a semiconductor device according to claim 18, wherein hydrogen concentrations in the first oxide semiconductor layer and the second oxide semiconductor layer are reduced by the first heat treatment. ### Claim 23 (depends on 18) The method for manufacturing a semiconductor device according to claim 18, further comprising a step of forming an electrode over the oxide insulating film. ### Claim 24 (depends on 18) The method for manufacturing a semiconductor device according to claim 18, further comprising a step of performing a second heat treatment after the oxide insulating film is formed. ### Claim 25 (depends on 18) The method for manufacturing a semiconductor device according to claim 18, wherein the first oxide semiconductor layer includes crystal after the first heat treatment is performed. ### Claim 26 (depends on 18) The method for manufacturing a semiconductor device according to claim 18, wherein each of the first oxide semiconductor layer and the second oxide semiconductor layer includes indium and zinc. ### Claim 27 A method for manufacturing a semiconductor device comprising the steps of: forming an insulating layer over a substrate, forming a first oxide semiconductor layer over the insulating layer; forming a second oxide semiconductor layer over the first oxide semiconductor layer; performing a first heat treatment on the first oxide semiconductor layer and the second oxide semiconductor layer; after the first heat treatment, supplying oxygen to the first oxide semiconductor layer and the second oxide semiconductor layer in an atmosphere containing oxygen; forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer after the first heat treatment; etching the conductive film to form a source electrode layer and a drain electrode layer; and forming an oxide insulating film in contact with part of the second oxide semiconductor layer. ### Claim 28 (depends on 27) The method for manufacturing a semiconductor device according to claim 27, wherein a condition for forming the first oxide semiconductor layer and a condition for forming the second oxide semiconductor layer are different from each other. ### Claim 29 (depends on 27) The method for manufacturing a semiconductor device according to claim 27, wherein the first heat treatment is performed under reduced pressure. ### Claim 30 (depends on 27) The method for manufacturing a semiconductor device according to claim 27, wherein the first heat treatment is performed in an inert atmosphere. ### Claim 31 (depends on 27) The method for manufacturing a semiconductor device according to claim 27, wherein hydrogen concentrations in the first oxide semiconductor layer and the second oxide semiconductor layer are reduced by the first heat treatment. ### Claim 32 (depends on 27) The method for manufacturing a semiconductor device according to claim 27, wherein the first heat treatment is performed by a gas rapid thermal anneal method or a lamp thermal anneal method. ### Claim 33 (depends on 27) The method for manufacturing a semiconductor device according to claim 27, further comprising a step of forming an electrode over the oxide insulating film. ### Claim 34 (depends on 27) The method for manufacturing a semiconductor device according to claim 27, further comprising a step of performing a second heat treatment after the oxide insulating film is formed. ### Claim 35 (depends on 27) The method for manufacturing a semiconductor device according to claim 27, wherein each of the first oxide semiconductor layer and the second oxide semiconductor layer includes indium and zinc.