Method of forming an epitaxial layer for raised drain and source regions by removing surface defects of the initial crystal surface
View Patent ↗By substantially amorphizing a selectively epitaxially grown silicon layer used for forming a raised drain and source region and a portion of the underlying substrate, or just the surface region of the substrate (prior to growing the silicon overlayer), the number of interface defects located between the grown silicon layer and the initial substrate surface may be significantly reduced. Consequently, deleterious effects such as charge carrier gettering or creating diffusion paths for dopants may be suppressed.
1. A method, comprising:
forming doped regions in a crystalline silicon region adjacent to a gate electrode having sidewall spacers formed thereon, a first portion of said crystalline silicon region maintaining its crystalline structure during the formation of said doped regions, wherein forming said doped regions comprises implanting a dopant species into said silicon region prior to forming said sidewall spacers to form source and drain extension regions;
epitaxially growing a silicon layer on said doped regions;
implanting an ion species through said silicon layer and into said doped regions to substantially amorphize said silicon layer and a second portion of said silicon region; and
annealing said silicon region and said grown silicon layer to re-crystallize said second portion of said silicon region and said silicon layer.
2. The method of claim 1 , wherein said ion species is a noble gas species.
3. The method of claim 1 , wherein said ion species comprises silicon ions.
4. The method of claim 1 , wherein forming doped regions comprises introducing a dopant species into said crystalline silicon region by ion implantation.
5. The method of claim 4 , further comprising activating said dopant species by an anneal process.
6. The method of claim 5 , wherein said dopant species is activated during annealing said silicon region and said grown silicon layer.
7. The method of claim 1 , wherein said silicon layer is selectively grown on exposed silicon surfaces.
8. The method of claim 1 , wherein said ion species comprises a dopant species.
9. The method of claim 1 , further comprising forming a capping layer on a top surface of said gate electrode prior to growing said silicon layer.
10. The method of claim 1 , wherein forming said doped regions comprises introducing a dopant species into said silicon region by diffusing said dopant species into said silicon region.
11. The method of claim 1 , further comprising implanting a second dopant species through said silicon layer after implanting said ion species and prior to annealing said silicon region and said silicon layer.
12. A method, comprising:
forming an amorphous region in a crystalline silicon region adjacent to a gate electrode, at least a first portion of said crystalline silicon region maintaining its crystalline structure during the formation of said amorphous region;
forming a spacer element on sidewalls of said gate electrode;
epitaxially growing a silicon layer on said amorphous portion, said grown silicon layer having a substantially amorphous structure;
annealing said silicon region and said grown silicon layer to re-crystallize said amorphous portion of the silicon region and said silicon layer; and
forming source and drain regions by implanting a dopant species into said amorphous region, wherein forming said source and drain regions comprises performing a first implantation process prior to forming said spacer element to form source and drain extension regions and performing a second implantation process after forming said spacer element.
13. A method, comprising:
forming doped regions in a crystalline silicon region adjacent to a gate electrode having sidewall spacers formed thereon, a first portion of said crystalline silicon region maintaining its crystalline structure during the formation of said doped regions;
epitaxially growing a silicon layer on said doped regions;
implanting an ion species through said silicon layer and into said doped regions to substantially amorphize said silicon layer and a second portion of said silicon region; and
annealing said silicon region and said grown silicon layer to re-crystallize said second portion of said silicon region and said silicon layer, wherein said dopant species is activated during annealing said silicon region and said grown silicon layer.
14. A method, comprising:
forming doped regions in a crystalline silicon region adjacent to a gate electrode having sidewall spacers formed thereon, a first portion of said crystalline silicon region maintaining its crystalline structure during the formation of said doped regions;
epitaxially growing a silicon layer on said doped regions;
implanting an ion species through said silicon layer and into said doped regions to substantially amorphize said silicon layer and a second portion of said silicon region, wherein said ion species comprises a dopant species; and
annealing said silicon region and said grown silicon layer to re-crystallize said second portion of said silicon region and said silicon layer.
15. A method, comprising:
forming doped regions in a crystalline silicon region adjacent to a gate electrode having sidewall spacers formed thereon, a first portion of said crystalline silicon region maintaining its crystalline structure during the formation of said doped regions;
epitaxially growing a silicon layer on said doped regions;
implanting an ion species through said silicon layer and into said doped regions to substantially amorphize said silicon layer and a second portion of said silicon region;
annealing said silicon region and said grown silicon layer to re-crystallize said second portion of said silicon region and said silicon layer; and
forming a capping layer on a top surface of said gate electrode prior to growing said silicon layer.
16. A method, comprising:
forming doped regions in a crystalline silicon region adjacent to a gate electrode having sidewall spacers formed thereon, a first portion of said crystalline silicon region maintaining its crystalline structure during the formation of said doped regions, wherein forming said doped region comprises forming said sidewall spacers to contain a dopant species and introducing said dopant species by diffusing said dopant species into said silicon region by a heat treatment to form source and drain extension regions;
epitaxially growing a silicon layer on said doped regions;
implanting an ion species through said silicon layer and into said doped regions to substantially amorphize said silicon layer and a second portion of said silicon region; and
annealing said silicon region and said grown silicon layer to re-crystallize said second portion of said silicon region and said silicon layer.
17. The method of claim 16 , further comprising implanting a second dopant species through said silicon layer after implanting said ion species and prior to annealing said silicon region and said silicon layer.
18. A method, comprising:
forming an amorphous region in a crystalline silicon region adjacent to a gate electrode, at least a first portion of said crystalline silicon region maintaining its crystalline structure during the formation of said amorphous region;
forming a spacer element on sidewalls of said gate electrode;
epitaxially growing a silicon layer on said amorphous portion, said grown silicon layer having a substantially amorphous structure;
annealing said silicon region and said grown silicon layer to re-crystallize said amorphous portion of the silicon region and said silicon layer; and
forming source and drain regions by implanting a dopant species into said amorphous region, wherein forming source and drain regions comprises removing said spacer element, performing a first implantation process to form source and drain extension regions, forming a second spacer element and performing a second implantation process.
19. A method, comprising:
forming an amorphous region in a crystalline silicon region adjacent to a gate electrode, at least a first portion of said crystalline silicon region maintaining its crystalline structure during the formation of said amorphous region;
forming a spacer element on sidewalls of said gate electrode;
epitaxially growing a silicon layer on said amorphous portion, said grown silicon layer having a substantially amorphous structure;
annealing said silicon region and said grown silicon layer to re-crystallize said amorphous portion of the silicon region and said silicon layer; and
forming source and drain regions by implanting a dopant species into said amorphous region, wherein forming source and drain regions comprises performing a first implantation process to form deep source and drain regions, removing said spacer element and performing a second implantation process to form source and drain extension regions.