Method for fabricating a semiconductor device having stress/strain and protrusion
View Patent ↗A semiconductor device includes a silicon substrate having a protrusion, a gate insulating film formed over an upper surface of the protrusion of the silicon substrate, a gate electrode formed over the gate insulating film, a source/drain region formed in the silicon substrate on the side of the gate electrode, a first side wall formed over the side surface of the protrusion of the silicon substrate, the first side wall containing an insulating material, a second side wall formed over the first side wall, the second side wall having a bottom portion formed below the upper surface of the protrusion of the silicon substrate, the second side wall containing a material having a Young's modulus greater than that of the silicon substrate, and a stress film formed over the gate electrode and the second side wall.
1. A method of manufacturing a semiconductor device, comprising:
forming a gate insulating film and a gate electrode over a silicon substrate;
implanting first impurities into the silicon substrate using the gate electrode as a mask;
implanting a second impurity into a surface of an implanted silicon substrate using the gate electrode as the mask;
selectively removing the implanted surface of the silicon substrate so as to form a protrusion of the silicon substrate under the gate electrode, the protrusion having an upper surface and a side surface;
forming a first insulating film on the gate electrode and the side surface of the protrusion;
forming a second insulating layer on the first insulating layer;
selectively removing the first and second insulating film such that at least a part of the first and second insulating film remains over the side surface of the protrusion of the silicon substrate to form the first side wall spacer with the first insulating film and the second sidewall spacer with the second insulating film, the second side wall spacer containing a material having first Young's modulus greater than second Young's modulus of the silicon substrate; and
forming a stress film over the gate electrode and the second side wall spacer.
2. The method according to claim 1 , further comprising implanting second impurities into the silicon substrate using the gate electrode, the first side wall spacer and the second side wall spacer as a mask.
3. The method according to claim 1 , wherein
the forming the first side wall spacer on the side surface of the protrusion, the first side wall spacer and
the forming the second side wall spacer on the first side wall spacer, the second side wall spacer including the material having a Young's modulus greater than that of the silicon substrate further includes selectively removing the entire surface of the first insulating film such that the height of the surface of the first insulating film is lower than that of the upper surface of the protrusion of the silicon substrate.
4. The method according to claim 1 , wherein the first side wall spacer is silicon oxide and the second side wall spacer is silicon nitride.
5. The method according to claim 3 , the selectively removing the entire surface of the first insulating film such that the height of the surface of the first insulating film is lower than that of the upper surface of the protrusion of the silicon substrate is performed by anisotropic etching the first insulating film after forming the first insulating film over the silicon substrate.
6. The method according to claim 1 , selectively removing the implanted surface of the silicon substrate to form a tapered surface having an inclination of 30 to 60 degrees.