Technique for strain engineering in Si-based Transistors by using embedded semiconductor layers including atoms with high covalent radius
By incorporating an atomic species of increased covalent radius, which may at least partially substitute germanium, a highly efficient strain mechanism may be provided, in which the risk of stress relief due to germanium conglomeration and lattice defects may be reduced. The atomic species of increased radius, such as tin, may be readily incorporated by epitaxial growth techniques on the basis of tin hydride.
1. A method, comprising:
forming, in a crystalline semiconductor layer comprising silicon, a crystalline structure on the basis of silicon and at least one further atomic species having a covalent radius that is greater than a covalent radius of germanium in contact with the crystalline semiconductor layer; and
using said crystalline structure to create strain in a first specified region of said semiconductor layer.
2. The method of claim 1 , wherein forming said crystalline structure comprises epitaxially growing said silicon and said at least one further atomic species using said crystalline semiconductor layer as a growth template.
3. The method of claim 2 , wherein epitaxially growing said silicon and said at least one further atomic species is based on a precursor comprising tin and hydrogen.
4. The method of claim 3 , wherein said precursor is comprised of tin hydride.
5. The method of claim 1 , wherein forming said crystalline structure comprises depositing said silicon and said at least one further atomic species in a substantially amorphous form and re-crystallizing said silicon and said at least one further atomic species using said crystalline semiconductor layer as a crystalline template.
6. The method of claim 1 , wherein forming said crystalline structure comprises implanting said at least one further atomic species into a first portion of said crystalline semiconductor layer and re-crystallizing said portion using said crystalline semiconductor layer as a crystalline template.
7. The method of claim 6 , further comprising forming a silicon/germanium crystal in said structure and implanting said at least one further atomic species to adjust the amount of strain in said first region.
8. The method of claim 6 , further comprising implanting said at least one further atomic species into a second portion so as to create a second strain in a second specified region of said crystalline semiconductor layer, said second strain differing from said first strain.
9. The method of claim 1 , further comprising forming a gate electrode above said crystalline semiconductor layer, wherein said crystalline structure is formed with a lateral offset to said gate electrode.
10. The method of claim 9 , further comprising forming a recess adjacent to said gate electrode and forming at least a portion of said crystalline structure within said recess.
11. The method of claim 1 , wherein said crystalline semiconductor layer comprises a buffer layer comprising silicon and at least a first atomic species other than silicon.
12. A method, comprising:
forming, in a crystalline semiconductor layer, a crystalline structure on the basis of silicon and at least one further atomic species having a covalent radius that is greater than a covalent radius of germanium by implanting said at least one further atomic species into a first portion of said crystalline semiconductor layer and re-crystallizing said portion using said crystalline semiconductor layer as a crystalline template; and
using said crystalline structure to create strain in a first specified region of said semiconductor layer.
13. A method, comprising:
forming, in a crystalline semiconductor layer, a crystalline structure on the basis of silicon and at least one further atomic species having a covalent radius that is greater than a covalent radius of germanium by depositing said silicon and said at least one further atomic species in a substantially amorphous form and re-crystallizing said silicon and said at least one further atomic species using said crystalline semiconductor layer as a crystalline template; and
using said crystalline structure to create strain in a first specified region of said semiconductor layer.
14. The method of claim 13 , further comprising forming a silicon/germanium crystal in said structure and implanting said at least one further atomic species to adjust the amount of strain in said first region.
15. The method of claim 13 , further comprising implanting said at least one further atomic species into a second portion so as to create a second strain in a second specified region of said crystalline semiconductor layer, said second strain differing from said first strain.
16. A transistor device, comprising:
a first layer comprising silicon;
a crystalline semiconductor layer in contact with said first layer and having a diamond-like crystalline structure, said crystalline semiconductor layer comprising a stress-inducing region being comprised of silicon and a further atomic species having the same valence as silicon in said crystalline structure and having a covalent radius that is greater than a covalent radius of germanium;
a gate electrode formed above said crystalline semiconductor layer; and
a strained channel region.
17. The transistor device of claim 16 , wherein said stress-inducing region is formed in a drain and source region.
18. The transistor device of claim 16 , wherein said stress-inducing region is said strained semiconductor material so as to generate compressive strain in said channel region.
19. The transistor device of claim 16 , wherein said stress-inducing region comprises tin.
20. The transistor device of claim 19 , wherein said stress-inducing region comprises germanium.
21. The device of claim 16 , wherein the first layer comprises a buffer layer comprising silicon and at least a first atomic species other than silicon.