Method of producing etching mask, etching mask precursor, and oxide layer, and method of manufacturing thin film transistor

Abstract

The etching mask 80 for screen printing according to one embodiment of the present invention includes aliphatic polycarbonate. Further, the method of producing an oxide layer (the channel 44 ) according to one embodiment of the present invention includes: an etching-mask forming step of forming a pattern of the etching mask 80 including aliphatic polycarbonate; a contact step of, after the etching-mask forming step, contacting the oxide layer with a solution for dissolving a portion of the oxide layer (the channel 44 ) which is not protected by the etching mask 80 ; and a heating step of, after the contact step, heating the oxide layer (the channel 44 ) and the etching mask 80 to or above a temperature at which the etching mask 80 is decomposed.

1 . An etching mask for screen printing, comprising aliphatic polycarbonate. 
     
     
         2 . The etching mask according to  claim 1 , wherein the aliphatic polycarbonate is substantially eliminated or removed by heating at 180° C. or more. 
     
     
         3 . The etching mask according to  claim 1 , formed from an etching mask precursor, wherein in the etching mask precursor the percentage of the aliphatic polycarbonate having a molecular weight of 6000 or more and 400000 or less is 80% by mass or more relative to the entire aliphatic polycarbonate. 
     
     
         4 . The etching mask according to  claim 1 , formed from an etching mask precursor, wherein in the etching mask precursor the aliphatic polycarbonate has a value of L/(D×v×η) of 0.25 mm −1 Pa −1  or more in which a cylindrical bar made of polytetrafluoroethylene and having a diameter “D” is dipped in a collection of the aliphatic polycarbonate having a zero-shear viscosity η as measured using a rheometer (Model AR-2000EX, TA Instruments), and the length “L” of a strand withdrawn from an outermost surface of the collection of the aliphatic polycarbonate is then measured when the cylindrical bar is pulled upwardly at a velocity “v”. 
     
     
         5 . The etching mask according to  claim 3 , wherein the contact angle of the etching mask precursor to a base material is 30° or more and 36° or less at 30 seconds after the etching mask precursor is placed on the base material, or the contact angle of the etching mask to the base material is 26° or more and 32° or less at 120 seconds after the etching mask precursor is placed on the base material. 
     
     
         6 . The etching mask according to  claim 1 , wherein a target of etching is an oxide layer, and
 the etching mask is for forming a pattern on the oxide layer, and provides a portion of the oxide layer which shows a rectification behavior, the portion of the oxide layer having had been protected by the pattern, in a case where the oxide layer is obtained by bringing the etching mask into contact with a solution for dissolving the oxide layer and then heating the etching mask to or above a temperature at which the etching mask is decomposed.   
     
     
         7 . The etching mask according to  claim 1 , wherein the target of etching is an oxide precursor layer to be oxidized into an oxide layer, and
 the etching mask is for forming a pattern on the oxide precursor layer, and provides a portion of the oxide layer which shows a rectification behavior, the portion of the oxide layer having had been protected by the pattern, in a case where the oxide layer is obtained by bringing the etching mask into contact with a solution for dissolving the oxide precursor layer and then heating the etching mask to or above a temperature at which the oxide layer is formed.   
     
     
         8 . The etching mask according to  claim 1 , wherein the target of etching is an oxide layer, and
 the etching mask is for forming a pattern on the oxide layer, and provides a portion of the oxide layer which shows a rectification behavior, the portion of the oxide layer having had been protected by the pattern, in a case where the oxide layer is obtained by exposing the etching mask to a plasma for etching the oxide layer and then heating the etching mask to or above a temperature at which the etching mask is decomposed.   
     
     
         9 . The etching mask according to  claim 1 , wherein the target of etching is an oxide precursor layer to be oxidized into an oxide layer, and
 the etching mask is for forming a pattern on the oxide precursor layer, and provides a portion of the oxide layer which shows a rectification behavior, the portion of the oxide layer having had been protected by the pattern, in a case where the oxide layer is obtained by exposing the etching mask to a plasma for etching the oxide precursor layer and then heating the etching mask to or above a temperature at which the oxide layer is formed.   
     
     
         10 . The etching mask according to  claim 1 , wherein the aliphatic polycarbonate is at least one selected from the group consisting of polyethylene carbonate and polypropylene carbonate. 
     
     
         11 . An etching mask precursor for screen printing, comprising aliphatic polycarbonate. 
     
     
         12 . The etching mask precursor for screen printing according to  claim 11 , wherein the aliphatic polycarbonate is substantially eliminated or removed by heating at 180° C. or more. 
     
     
         13 . The etching mask precursor for screen printing according to  claim 11 , wherein the percentage of the aliphatic polycarbonate having a molecular weight of 6000 or more and 400000 or less is 80% by mass or more relative to the entire aliphatic polycarbonate. 
     
     
         14 . The etching mask precursor for screen printing according to  claim 11 , wherein the aliphatic polycarbonate has a value of L/(D×v×η) of 0.25 mm −1 Pa −1  or more in which a cylindrical bar made of polytetrafluoroethylene and having a diameter “D” is dipped in a collection of the aliphatic polycarbonate having a zero-shear viscosity η as measured using a rheometer (Model AR-2000EX, TA Instruments), and the length “L” of a strand withdrawn from an outermost surface of the collection of the aliphatic polycarbonate is then measured when the cylindrical bar is pulled upwardly at a velocity “v”. 
     
     
         15 . A method of producing an oxide layer, the method comprising
 an etching-mask forming step of forming a pattern of an etching mask including aliphatic polycarbonate on the oxide layer by the screen printing method,   a contact step of, after the etching-mask forming step, contacting the oxide layer with a solution for dissolving a portion of the oxide layer not protected by the etching mask, and   a heating step of, after the contact step, heating the oxide layer and the etching mask to or above a temperature at which the etching mask is decomposed.   
     
     
         16 . A method of producing an oxide layer, the method comprising
 an etching-mask forming step of forming a pattern of an etching mask including aliphatic polycarbonate on an oxide precursor layer to be oxidized into the oxide layer by the screen printing method,   a contact step of, after the etching-mask forming step, contacting the oxide precursor layer with a solution for dissolving a portion of the oxide precursor layer not protected by the etching mask, and   a heating step of, after the contact step, heating the oxide precursor layer and the etching mask to or above a temperature at which the oxide layer is formed.   
     
     
         17 . A method of producing an oxide layer, the method comprising
 an etching-mask forming step of forming a pattern of an etching mask including aliphatic polycarbonate on the oxide layer by the screen printing method,   an exposure step of, after the etching-mask forming step, exposing the oxide layer to a plasma for etching a portion of the oxide layer not protected by the etching mask, and   a heating step of, after the exposure step, heating the oxide layer and the etching mask to or above a temperature at which the etching mask is decomposed.   
     
     
         18 . A method of producing an oxide layer, the method comprising
 an etching-mask forming step of forming a pattern of an etching mask including aliphatic polycarbonate on an oxide precursor layer to be oxidized into the oxide layer by the screen printing method,   an exposure step of, after the etching-mask forming step, exposing the oxide precursor layer to a plasma for etching a portion of the oxide precursor layer not protected by the etching mask, and   a heating step of, after the exposure step, heating the oxide precursor layer and the etching mask to or above a temperature at which the oxide layer is formed.   
     
     
         19 . The method of producing an oxide layer according to  claim 15 , wherein the heating step comprises heating to or above a temperature at which organic substances are decomposed while applying ultraviolet rays to the oxide precursor layer and/or the etching mask. 
     
     
         20 . A method of manufacturing a thin film transistor, the method comprising an oxide layer forming step of forming the portion of the oxide layer which had been protected by the etching mask formed via the heating step in the method of producing an oxide layer according to  claim 15  so that the portion of the oxide layer makes contact with a gate electrode through a gate insulator. 
     
     
         21 . The etching mask according to  claim 4 , wherein the contact angle of the etching mask precursor to a base material is 30° or more and 36° or less at 30 seconds after the etching mask precursor is placed on the base material, or the contact angle of the etching mask to the base material is 26° or more and 32° or less at 120 seconds after the etching mask precursor is placed on the base material. 
     
     
         22 . The method of producing an oxide layer according to  claim 16 , wherein the heating step comprises heating to or above a temperature at which organic substances are decomposed while applying ultraviolet rays to the oxide precursor layer and/or the etching mask. 
     
     
         23 . The method of producing an oxide layer according to  claim 17 , wherein the heating step comprises heating to or above a temperature at which organic substances are decomposed while applying ultraviolet rays to the oxide precursor layer and/or the etching mask. 
     
     
         24 . The method of producing an oxide layer according to  claim 18 , wherein the heating step comprises heating to or above a temperature at which organic substances are decomposed while applying ultraviolet rays to the oxide precursor layer and/or the etching mask. 
     
     
         25 . A method of manufacturing a thin film transistor, the method comprising an oxide layer forming step of forming the portion of the oxide layer which had been protected by the etching mask formed via the heating step in the method of producing an oxide layer according to  claim 16  so that the portion of the oxide layer makes contact with a gate electrode through a gate insulator. 
     
     
         26 . A method of manufacturing a thin film transistor, the method comprising an oxide layer forming step of forming the portion of the oxide layer which had been protected by the etching mask formed via the heating step in the method of producing an oxide layer according to  claim 17  so that the portion of the oxide layer makes contact with a gate electrode through a gate insulator. 
     
     
         27 . A method of manufacturing a thin film transistor, the method comprising an oxide layer forming step of forming the portion of the oxide layer which had been protected by the etching mask formed via the heating step in the method of producing an oxide layer according to  claim 18  so that the portion of the oxide layer makes contact with a gate electrode through a gate insulator.