Semiconductor device, method of manufacturing the same, and method of evaluating semiconductor device
A semiconductor device has: a silicon (semiconductor) substrate; a gate insulating film and a gate electrode, which are formed on the silicon substrate in this order; and source/drain material layers formed in recesses (holes) in the silicon substrate, the recesses being located beside the gate electrode. Here, each of side surfaces of the recesses, which are closer to the gate electrode, is constituted of at least one crystal plane of the silicon substrate.
1. A semiconductor device comprising:
a silicon substrate;
a gate insulating film formed on the silicon substrate;
a gate electrode formed on the gate insulating film;
a source/drain region formed in the silicon substrate;
a SiGe layer formed in a hole in the source/drain region;
a sidewall formed on the side of the gate electrode,
an insulating film formed over the gate electrode and the SiGe layer; and
a conductive plug formed in the insulating film and electrically connected to the SiGe layer, wherein
a first side surface of the hole is located under the sidewall,
the SiGe layer is located under the sidewall and is not located under the gate electrode;
the first side surface includes two crystal planes,
a cross-sectional shape of the first side surface is concave,
each of the two crystal planes of the first side surface is defined by a (111) plane of the silicon substrate, and
an upper surface of the SiGe layer is located higher than an interface between the silicon substrate and the gate insulating film.
2. The semiconductor device according to claim 1 , wherein
one of the two crystal planes is connected to the surface of the silicon substrate, and
another of the two crystal planes is connected to a bottom surface of the hole.
3. The semiconductor device according to claim 1 further comprising:
a channel region in the silicon substrate under the gate electrode, wherein
the source/drain region is located between the (111) plane of the silicon substrate and the channel region.
4. The semiconductor device according to claim 1 , further comprising:
a silicide layer formed between the SiGe layer and the conductive plug,
wherein a bottom surface of the silicide layer is located higher than an interface between the silicon substrate and the gate insulating film.
5. The semiconductor device according to claim 4 , wherein the silicide layer includes Pt.
6. The semiconductor device according to claim 1 , further comprising
a silicide layer formed over the SiGe layer,
wherein a second side surface of the hole that faces the first side surface is composed of the silicon substrate.
7. The semiconductor device according to claim 6 , wherein
the second side surface includes two crystal planes, and
each of the two crystal planes of the second side surface is defined by a (111) plane of the silicon substrate.
8. The semiconductor device according to claim 6 , wherein the silicide layer includes Pt.
9. The semiconductor device according to claim 1 , wherein
the source/drain region is formed by implanting an impurity into the silicon substrate, and
the hole is formed by etching the source/drain region including the impurity.
10. The semiconductor device according to claim 1 , wherein the SiGe layer has a Ge concentration of 3 to 30%.