Semiconductor device n-channel type MOS transistor with gate electrode layer featuring small average polycrystalline silicon grain size
View Patent ↗In a semiconductor device including a semiconductor substrate, and an n-channel type MOS transistor produced in the semiconductor substrate, the n-channel type MOS transistor includes a gate insulating layer formed on the semiconductor substrate and having a thickness of at most 1.6 nm, and a gate electrode layer on the gate insulating layer, and the gate electrode layer is composed of polycrystalline silicon which has an average grain size falling within a range between 10 nm and 150 nm in the vicinity of the gate insulating layer.
1. A method for manufacturing a semiconductor device, which comprises:
preparing a semiconductor substrate;
forming an insulating layer on said semiconductor device, said insulating layer having a thickness of at most 1.6 nm;
forming a polycrystalline silicon layer on said insulating layer;
implanting n-type impurities into said polycrystalline silicon layer;
implanting inert gas molecules or atoms into said polycrystalline silicon layer;
forming a gate electrode structure including a gate insulating layer derived from said insulating layer, and a gate electrode layer derived from said polycrystalline silicon layer; and
subjecting said gate electrode structure to an annealing process so that the polycrystalline silicon in said gate electrode layer has an average grain size falling within a range between 10 nm and 150 nm.
2. The method as set forth in claim 1 , wherein the inert gas implantation is carried out at a density falling within a range between 2×10 15 cm −2 and 1×10 16 cm −2 .
3. A method for manufacturing a semiconductor device, which comprises:
preparing a semiconductor substrate;
forming a first insulating layer on said semiconductor device, said insulating layer having a thickness of at most 1.6 nm;
forming a first polycrystalline silicon layer on said insulating layer;
forming a second insulating layer on said first polycrystalline silicon layer;
forming a second polycrystalline silicon layer on said second insulating layer;
implanting n-type impurities into said first and second polycrystalline silicon layers;
implanting inert gas molecules or atoms into said first and second polycrystalline silicon layers;
forming a gate electrode structure including a gate insulating layer derived from said first insulating layer, a first gate electrode layer derived from said first polycrystalline silicon layer, a stopper layer derived from said second insulating layer, and a second gate electrode layer derived from said second polycrystalline silicon layer; and
subjecting said gate electrode structure to an annealing process so that the polycrystalline silicon in said first gate electrode layer has an average grain size falling within a range between 10 nm and 150 nm.
4. The method as set forth in claim 3 , wherein said second insulating layer is composed of one selected from the group consisting of silicon dioxide, silicon nitride and silicon carbide.
5. The method as set forth in claim 3 , wherein said first polycrystalline silicon layer has a thickness falling within a range between 10 nm and 50 nm.