Method of manufacturing semiconductor device
A method of manufacturing a semiconductor device includes forming a first nitride semiconductor layer containing Ga on a substrate; forming a first layer on the first nitride semiconductor layer; forming a second layer on the first layer; forming an opening in which the first nitride semiconductor layer is exposed in the second layer and the first layer; forming a second nitride semiconductor layer of a first conductivity type on a surface, exposed in the opening, of the first nitride semiconductor layer; removing the second layer using an acidic solution; and after removing the second layer, forming an electrode on the second nitride semiconductor layer. A first etching rate of the first layer for the acidic solution is lower than a second etching rate of the second layer for the acidic solution.
1 . A method of manufacturing a semiconductor device, the method comprising:
forming a first nitride semiconductor layer containing Ga on a substrate;
forming a first layer comprising silicon nitride on the first nitride semiconductor layer;
forming a second layer, the second layer being a zinc oxide layer, on the first layer;
forming an opening in the second layer and the first layer, wherein the first nitride semiconductor layer is exposed in the opening;
forming a second nitride semiconductor layer of a first conductivity type on a surface of the first nitride semiconductor layer exposed in the opening;
removing the second layer using an acidic solution while leaving the first layer; and
after removing the second layer, forming an electrode on the second nitride semiconductor layer,
wherein a first etching rate of the first layer for the acidic solution is lower than a second etching rate of the second layer for the acidic solution.
2 . The method of manufacturing a semiconductor device according to claim 1 , wherein
the acidic solution contains hydrochloric acid or phosphoric acid, or hydrofluoric acid.
3 . The method of manufacturing a semiconductor device according to claim 1 , wherein the second nitride semiconductor layer is an n-type GaN layer.
4 . The method of manufacturing a semiconductor device according to claim 1 , wherein the surface of the first nitride semiconductor layer in contact with the second nitride semiconductor layer is a N-polar surface.
5 . The method of manufacturing a semiconductor device according to claim 4 , wherein forming the first nitride semiconductor layer includes:
forming a barrier layer; and
forming a channel layer on the barrier layer.
6 . The method of manufacturing a semiconductor device according to claim 1 , the method further comprising subjecting a surface of the second nitride semiconductor layer to two-fluid cleaning or scrub cleaning between removing the second layer and forming the electrode.
7 . The method of manufacturing a semiconductor device according to claim 1 , the method further comprising:
forming a third layer on the second layer between forming the second layer and forming the opening, wherein the opening is also formed in the third layer; and
widening the opening formed in the second layer between forming the opening and forming the second nitride semiconductor layer.
8 . The method of manufacturing a semiconductor device according to claim 1 , further comprising, between removing the second layer and forming the electrode, subjecting a surface of the second nitride semiconductor layer to two-fluid cleaning in which a mixed fluid of a cleaning liquid and a gas is ejected toward the surface of the second nitride semiconductor layer.
9 . A method of manufacturing a semiconductor device, the method comprising:
forming a first nitride semiconductor layer containing Ga on a substrate;
forming a first silicon nitride layer on the first nitride semiconductor layer;
forming a zinc oxide layer on the first silicon nitride layer;
forming a second silicon nitride layer on the zinc oxide layer;
forming an opening in the second silicon nitride layer, the zinc oxide layer, and the first silicon nitride layer, wherein the first nitride semiconductor layer is exposed in the opening;
widening the opening formed in the zinc oxide layer;
forming a second nitride semiconductor layer of a first conductivity type on a surface of the first nitride semiconductor layer exposed in the opening;
removing the zinc oxide layer together with the second silicon nitride layer using an acidic solution containing hydrochloric acid or phosphoric acid while leaving the first silicon nitride layer; and
after removing the zinc oxide layer, forming an electrode on the second nitride semiconductor layer,
wherein the surface of the first nitride semiconductor layer in contact with the second nitride semiconductor layer is a N-polar surface.
10 . The method of manufacturing a semiconductor device according to claim 9 , wherein forming the first nitride semiconductor layer includes:
forming a barrier layer; and
forming a channel layer on the barrier layer.
11 . The method of manufacturing a semiconductor device according to claim 9 , the method further comprising subjecting a surface of the second nitride semiconductor layer to two-fluid cleaning or scrub cleaning between removing the zinc oxide layer and forming the electrode.