Method for manufacturing semiconductor device
According to one embodiment, a method for manufacturing a semiconductor device includes forming an electrode layer on a film containing indium and etching portions of the electrode layer left exposed by a mask layer until at least a portion of the film is exposed. A spacer film is formed to cover an upper surface of the electrode layer, side surfaces of the electrode layer, and an exposed upper surface of the film. The spacer film on the upper surface of the electrode layer and the exposed upper surface of the film is removed while leaving the spacer film on the side surfaces of the electrode layer. The exposed upper surface of the film is exposed to a reductive gas plasma to reduce portions of the film. These reduced portions of the film are then etched with a chemical solution.
1 . A method for manufacturing a semiconductor device, the method comprising:
forming an electrode layer on a film containing indium; etching portions of the electrode layer left exposed by a mask layer until at least a portion of the film is exposed;
forming a spacer film so as to cover an upper surface of the electrode layer, side surfaces of the electrode layer, and an exposed upper surface of the film;
removing the spacer film on the upper surface of the electrode layer and the exposed upper surface of the film while leaving the spacer film on the side surfaces of the electrode layer;
exposing the exposed upper surface of the film to a reductive gas plasma to reduce portions of the film; and
etching the reduced portions of the film with a chemical solution.
2 . The method according to claim 1 , wherein the reductive gas plasma is formed from at least one of H 2 , NH 3 , H 2 S, and H 2 O.
3 . The method according to claim 1 , wherein the film is an oxide-based conductor material.
4 . The method according to claim 1 , wherein the film comprises an indium compound formed with at least one element this is a nonmetal element or a metalloid element selected from among Group 15 elements, Group 16 elements, and Group 17 elements.
5 . The method according to claim 1 , wherein the film additionally contains at least one of oxygen, phosphorus, boron, carbon, nitrogen, silicon, sulfur, selenium, tellurium, fluorine, chlorine, bromine, and iodine.
6 . The method according to claim 1 , wherein the film comprises at least one of indium tin oxide, indium gallium zinc oxide, indium oxide, and indium aluminum zinc oxide.
7 . The method according to claim 6 , wherein the film additionally contains at least one of oxygen, phosphorus, boron, carbon, nitrogen, silicon, sulfur, selenium, tellurium, fluorine, chlorine, bromine, and iodine.
8 . The method according to claim 6 , wherein the film has a crystallized portion.
9 . The method according to claim 1 , wherein the film has a crystallized portion.
10 . The method according to claim 1 , wherein the chemical solution is acidic.
11 . The method according to claim 1 , wherein the reductive gas plasma converts the exposed portions of the film to a substantially metallic material.
12 . The method according to claim 11 , wherein the substantially metallic material comprises nanoparticles including indium.
13 . The method according to claim 1 , wherein the film is an indium tin oxide film.
14 . The method according to claim 1 , wherein the film contacts a channel layer and a gate insulating layer of a surrounding gate transistor.
15 . A method of making a surrounding gate transistor, the method comprising:
forming a stacked body including a first electrode, a channel layer on the first electrode, a gate insulating film surrounding the channel layer, a gate electrode surrounding the gate insulating film, and interlayer insulating film surrounding the gate electrode;
forming an indium tin oxide (ITO)-based film on an upper surface of the stacked body, the ITO-based film contacting the interlayer insulating film, the gate insulating film, and the channel layer;
forming a barrier layer metal film on the ITO-based film;
forming a conductor layer film on the barrier metal film;
etching portions of the conductor layer film and the barrier metal film to form a second electrode at a position above the channel layer, the etching exposing a portion of the ITO-based film;
exposing the exposed portion of the ITO-based film to a reductive gas plasma to convert the exposed portion of the ITO-based film to an indium-containing metal film; and
etching the indium-containing metal film to expose an upper surface of the interlayer insulating film.
16 . The method according to claim 15 , further comprising:
forming a spacer film after etching the portions of the conductor layer film and the barrier metal film; and
removing portions of the spacer film from upper surfaces of the conductor film and the exposed portion of the ITO-based film.
17 . The method according to claim 15 , wherein the etching of the indium-containing metal film is performed using an acidic liquid.
18 . A method for manufacturing a semiconductor device, the method comprising:
forming an electrode layer on a film containing indium;
patterning the electrode layer by selectively etching the electrode layer, the etching exposing a portion of the film;
performing a reduction treatment on the exposed portion of the film and the electrode layer with a plasma of a reductive gas, the reduction treatment converting the exposed portion of the film to a metallic film including indium;
forming a spacer film so as to cover an upper surface of the electrode layer, side surfaces of the electrode layer, and an upper surface of the film;
removing the spacer film from the upper surface of the electrode layer and the upper surface of the film; and
wet etching the metallic film including indium with a chemical solution.
19 . The method according to claim 18 , wherein
the reduction treatment forms a nitride on the side surfaces of the electrode layer, and
the spacer film is formed on the nitride.
20 . The method according to claim 19 , wherein
the electrode layer is tungsten, and
tungsten nitride is formed on the side surfaces of the electrode layer by the reduction treatment.