# US 8,785,241 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 8,785,241 B2 - Document ID: US8785241B2 - Status: Granted - Kind: B2 - Application number: 13/174,960 - Filed: 2011-07-01 - Published: 2012-01-19 - Granted: 2014-07-22 - Earliest claimed: 2010-07-16 - Assignees: Semiconductor Energy Laboratory Co., Ltd. - Applicants: Shinya Sasagawa; Hitoshi Nakayama; Masashi Tsubuku; Daigo Shimada - Inventors: Shinya Sasagawa; Hitoshi Nakayama; Masashi Tsubuku; Daigo Shimada - Web page: https://patentgrep.com/patent/US8785241B2 ## CPC - H10D 99/00: Subject matter not provided for in other groups of this subclass - H10D 30/031: {of thin-film transistors [TFT]} - H10D 30/6739: {Conductor-insulator-semiconductor electrodes} - H10D 30/6755: {Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate} - H10D 64/62: Electrodes ohmically coupled to a semiconductor - H10D 84/83: of only insulated-gate FETs [IGFET] - H10D 86/0231: {using masks, e.g. half-tone masks} - H10D 86/40: characterised by multiple TFTs - H10D 86/423: {comprising semiconductor materials not belonging to the Group IV, e.g. InGaZnO} - H10D 86/60: wherein the TFTs are in active matrices - H10P 74/207: {Electrical properties, e.g. testing or measuring of resistance, deep levels or capacitance-voltage characteristics} - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract When a transistor having bottom gate bottom contact structure is manufactured, for example, a conductive layer constituting a source and a drain has a three-layer structure and two-step etching is performed. In the first etching process, an etching method in which the etching rates for at least the second film and the third film are high is employed, and the first etching process is performed until at least the first film is exposed. In the second etching process, an etching method in which the etching rate for the first film is higher than that in the first etching process and the etching rate for a “layer provided below and in contact with the first film” is lower than that in the first etching process is employed. The side wall of the second film is slightly etched when a resist mask is removed after the second etching process. ## Claims ### Claim 1 A method for manufacturing a semiconductor device, comprising the steps of: forming a first wiring layer; forming an insulating layer covering the first wiring layer; forming a semiconductor layer over the insulating layer; forming a first conductive film over the semiconductor layer, a second conductive film over the first conductive film, and a third conductive film over the second conductive film; forming a resist mask over the third conductive film; performing etching including at least two steps on the first to third conductive films to form a second wiring layer having a three-layer structure; and removing the resist mask by a resist stripper after the etching step, wherein the two-step etching comprises: a first etching process performed until at least the first conductive film is exposed, and a second etching process performed under a condition that an etching rate for the first conductive film is higher than the etching rate in the first etching process and an etching rate for the semiconductor layer is lower than the etching rate in the first etching process, and wherein the resist stripper has properties of corroding the second conductive film. ### Claim 2 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein the first conductive film is thicker than the third conductive film. ### Claim 3 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein a conductive material for forming the second conductive film has higher conductivity than a conductive material for forming the first conductive film and the third conductive film, and the second conductive film is thicker than each of the first conductive film and the third conductive film. ### Claim 4 (depends on 1) The method for manufacturing a semiconductor device according to claim 1, wherein the first conductive film and the third conductive film are titanium films, and the second conductive film is an aluminum film. ### Claim 5 A method for manufacturing a semiconductor device, comprising the steps of: forming a semiconductor layer; forming a first conductive film over the semiconductor layer, a second conductive film over the first conductive film, and a third conductive film over the second conductive film in this order over the semiconductor layer; forming a resist mask over the third conductive film; performing etching including at least two steps on the first to third conductive films using the resist mask to form a first wiring layer having a three-layer structure; forming an insulating layer covering the first wiring layer and the semiconductor layer; forming a second wiring layer over the insulating layer to overlap with the semiconductor layer; and removing the resist mask by a resist stripper after the etching step, wherein the two-step etching comprises: a first etching process performed until the first conductive film is exposed, and a second etching process performed under a condition that an etching rate for the first conductive film is higher than the etching rate in the first etching process and an etching rate for the semiconductor layer is lower than the etching rate in the first etching process, and wherein the resist stripper has properties of corroding the second conductive film. ### Claim 6 (depends on 5) The method for manufacturing a semiconductor device according to claim 5, wherein the first conductive film is thicker than the third conductive film. ### Claim 7 (depends on 5) The method for manufacturing a semiconductor device according to claim 5, wherein a conductive material for forming the second conductive film has higher conductivity than a conductive material for forming the first conductive film and the third conductive film, and the second conductive film is thicker than each of the first conductive film and the third conductive film. ### Claim 8 (depends on 5) The method for manufacturing a semiconductor device according to claim 5, wherein the first conductive film and the third conductive film are titanium films, and the second conductive film is an aluminum film. ### Claim 9 A method for manufacturing a semiconductor device, comprising the steps of: forming a first wiring layer; forming an insulating layer covering the first wiring layer; forming an oxide semiconductor layer over the insulating layer; forming a first conductive film over the oxide semiconductor layer, a second conductive film over the first conductive film, and a third conductive film over the second conductive film; forming a resist mask over the third conductive film; performing etching including at least two steps on the first to third conductive films to form a second wiring layer having a three-layer structure; and removing the resist mask by a resist stripper after the etching step, wherein the two-step etching comprises: a first etching process performed until at least the first conductive film is exposed, and a second etching process performed under a condition that an etching rate for the first conductive film is higher than the etching rate in the first etching process and an etching rate for the oxide semiconductor layer is lower than the etching rate in the first etching process, wherein the first etching process is performed using a gas containing more chlorine than fluorine as its main component, and wherein the second etching process is performed using a gas containing more fluorine than chlorine as its main component. ### Claim 10 (depends on 9) The method for manufacturing a semiconductor device according to claim 9, wherein the first etching process is performed using a mixture gas of a BCl3 gas and a Cl2 gas. ### Claim 11 (depends on 9) The method for manufacturing a semiconductor device according to claim 9, wherein the second etching process is performed using a SF6 gas. ### Claim 12 (depends on 9) The method for manufacturing a semiconductor device according to claim 9, wherein the resist stripper has corrosive properties to the second conductive film. ### Claim 13 (depends on 9) The method for manufacturing a semiconductor device according to claim 9, wherein the first conductive film is thicker than the third conductive film. ### Claim 14 (depends on 9) The method for manufacturing a semiconductor device according to claim 9, wherein a conductive material for forming the second conductive film has higher conductivity than a conductive material for forming the first conductive film and the third conductive film, and the second conductive film is thicker than each of the first conductive film and the third conductive film. ### Claim 15 (depends on 9) The method for manufacturing a semiconductor device according to claim 9, wherein the first conductive film and the third conductive film are titanium films, and the second conductive film is an aluminum film. ### Claim 16 (depends on 9) The method for manufacturing a semiconductor device according to claim 9, wherein a material of the oxide semiconductor layer is IGZO. ### Claim 17 A method for manufacturing a semiconductor device, comprising the steps of: forming an oxide semiconductor layer; forming a first conductive film over the oxide semiconductor layer, a second conductive film over the first conductive film, and a third conductive film over the second conductive film in this order over the oxide semiconductor layer; forming a resist mask over the third conductive film; performing etching including at least two steps on the first to third conductive films using the resist mask to form a first wiring layer having a three-layer structure; forming an insulating layer covering the first wiring layer and the oxide semiconductor layer; forming a second wiring layer over the insulating layer to overlap with the oxide semiconductor layer; and removing the resist mask by a resist stripper after the etching step, wherein the two-step etching comprises: a first etching process performed until the first conductive film is exposed, and a second etching process performed under a condition that an etching rate for the first conductive film is higher than the etching rate in the first etching process and an etching rate for the oxide semiconductor layer is lower than the etching rate in the first etching process, wherein the first etching process is performed using a gas containing more chlorine than fluorine as its main component, and wherein the second etching process is performed using a gas containing more fluorine than chlorine as its main component. ### Claim 18 (depends on 17) The method for manufacturing a semiconductor device according to claim 17, wherein the first etching process is performed using a mixture gas of a BCl3 gas and a Cl2 gas. ### Claim 19 (depends on 17) The method for manufacturing a semiconductor device according to claim 17, wherein the second etching process is performed using a SF6 gas. ### Claim 20 (depends on 17) The method for manufacturing a semiconductor device according to claim 17, wherein the resist stripper has corrosive properties to the second conductive film. ### Claim 21 (depends on 17) The method for manufacturing a semiconductor device according to claim 17, wherein the first conductive film is thicker than the third conductive film. ### Claim 22 (depends on 17) The method for manufacturing a semiconductor device according to claim 17, wherein a conductive material for forming the second conductive film has higher conductivity than a conductive material for forming the first conductive film and the third conductive film, and the second conductive film is thicker than each of the first conductive film and the third conductive film. ### Claim 23 (depends on 17) The method for manufacturing a semiconductor device according to claim 17, wherein the first conductive film and the third conductive film are titanium films, and the second conductive film is an aluminum film. ### Claim 24 (depends on 17) The method for manufacturing a semiconductor device according to claim 17, wherein a material of the oxide semiconductor layer is IGZO.