Method including a formation of a transistor and semiconductor structure including a first transistor and a second transistor
A method includes providing a semiconductor-on-insulator structure including a semiconductor substrate, a layer of electrically insulating material over the semiconductor substrate and a layer of semiconductor material over the layer of electrically insulating material. A first transistor is formed. The formation of the first transistor includes forming a dummy gate structure over the layer of semiconductor material, forming a source region of the first transistor and a drain region of the first transistor in portions of the semiconductor substrate adjacent the dummy gate structure, forming an electrically insulating structure annularly enclosing the dummy gate structure and performing a replacement gate process. The replacement gate process includes removing the dummy gate structure and a portion of the layer of semiconductor material below the dummy gate structure, wherein a recess is formed in the electrically insulating structure. The recess is filled with an electrically conductive material.
1. A method, comprising:
providing a semiconductor-on-insulator structure comprising a semiconductor substrate, a layer of electrically insulating material over said semiconductor substrate and a layer of semiconductor material over said layer of electrically insulating material;
forming a first transistor, the formation of said first transistor comprising:
forming a dummy gate structure over said layer of semiconductor material;
forming a source region of said first transistor and a drain region of said first transistor in portions of said semiconductor substrate adjacent said dummy gate structure;
forming an electrically insulating structure annularly enclosing said dummy gate structure; and
performing a replacement gate process to form a first gate structure of said first transistor, wherein said replacement gate process comprises:
removing said dummy gate structure and a portion of said layer of semiconductor material below said dummy gate structure to form a recess in said electrically insulating structure; and
filling said recess with an electrically conductive material; and
forming a second transistor, the formation of said second transistor comprising:
forming a second gate structure above said layer of semiconductor material; and
forming a source region, a drain region and a channel region in said layer of semiconductor material, wherein said channel region is positioned below said second gate structure of said second transistor.
2. The method of claim 1 , wherein said replacement gate process further comprises removing portions of said electrically conductive material formed outside said recess, a portion of said electrically conductive material in said recess forming at least a part of a gate electrode of said first transistor.
3. The method of claim 1 , wherein forming said electrically insulating structure comprises:
forming one or more sidewall spacers adjacent said dummy gate structure;
depositing a layer of interlayer dielectric; and
performing a polishing process wherein said dummy gate structure is exposed, portions of said one or more sidewalls spacers and said layer of interlayer dielectric that are not removed in said polishing process forming said electrically insulating structure.
4. The method of claim 3 , wherein forming said source region and said drain region of said first transistor comprises:
removing portions of said layer of electrically insulating material and said layer of semiconductor material adjacent said dummy gate structure; and
performing an implantation of ions of a dopant into portions of said semiconductor substrate adjacent said dummy gate structure, wherein at least a part of said implantation of ions is performed after said formation of said one or more sidewall spacers and before said deposition of said layer of interlayer dielectric.
5. The method of claim 4 , further comprising performing an activation anneal after said implantation of ions.
6. The method of claim 1 , wherein removing said dummy gate structure and said portion of said layer of semiconductor material below said dummy gate structure comprises:
forming a mask over said second transistor, wherein at least said dummy gate structure is not covered by said mask; and
performing one or more etch processes adapted to selectively remove one or more materials of said dummy gate structure and said layer of semiconductor material relative to a material of said mask and one or more materials of said electrically insulating structure.
7. The method of claim 1 , wherein said dummy gate structure and said gate structure of said second transistor are formed from a common gate stack.
8. The method of claim 1 , wherein said second transistor is a logic transistor and said first transistor is a high-voltage transistor adapted for operation at a higher voltage of operation than said second transistor.
9. The method of claim 1 , wherein said electrically conductive material comprises at least one of doped polysilicon and a metal.
10. The method of claim 1 , wherein said first transistor is an input/output transistor.
11. The method of claim 1 , wherein said first transistor is a laterally-diffused metal-oxide-semiconductor transistor.
12. A method, comprising:
providing a semiconductor-on-insulator structure comprising a semiconductor substrate, a layer of electrically insulating material over said semiconductor substrate and a layer of semiconductor material over said layer of electrically insulating material;
forming a first transistor, the formation of said first transistor comprising:
forming a dummy gate structure over said layer of semiconductor material;
forming a source region of said first transistor and a drain region of said first transistor in portions of said semiconductor substrate adjacent said dummy gate structure;
forming an electrically insulating structure annularly enclosing said dummy gate structure; and
performing a replacement gate process to form a first gate structure of said first transistor, wherein said replacement gate process comprises:
forming a recess in said electrically insulating structure, wherein forming said recess comprises removing said dummy gate structure and a portion of said layer of semiconductor material below said dummy gate structure while leaving a portion of said electrically insulating material at a bottom of said recess; and
filling said recess with an electrically conductive material; and
forming a second transistor, the formation of said second transistor comprising:
forming a second gate structure above said layer of semiconductor material; and
forming a source region, a drain region and a channel region in said layer of semiconductor material, wherein said channel region is positioned below said second gate structure of said second transistor.
13. The method of claim 12 , wherein filling said recess with said electrically conductive material comprises depositing said electrically conductive material directly on said portion of said layer of electrically insulating material left at said bottom of said recess.
14. The method of claim 12 , wherein said portion of said layer of electrically insulating material left at said bottom of said recess provides a gate insulation layer of said first transistor.
15. The method of claim 12 , wherein forming said electrically insulating structure comprises:
forming one or more sidewall spacers adjacent said dummy gate structure;
depositing a layer of interlayer dielectric above and around said dummy gate structure and said one or more sidewall spacers; and
performing a polishing process on said layer of interlayer dielectric to expose said dummy gate structure, wherein portions of said one or more sidewall spacers and said layer of interlayer dielectric that are not removed during said polishing process form said electrically insulating structure.
16. The method of claim 15 , wherein forming said source region and said drain region of said first transistor comprises:
removing portions of said layer of electrically insulating material and said layer of semiconductor material adjacent said dummy gate structure; and
performing an implantation process to implant dopant ions into portions of said semiconductor substrate adjacent said dummy gate structure, wherein at least a part of said implantation process is performed after forming said one or more sidewall spacers and before depositing said layer of interlayer dielectric.
17. The method of claim 16 , further comprising performing an activation anneal after performing said implantation process.
18. The method of claim 12 , wherein forming said recess further comprises:
forming a mask over said second transistor, wherein at least said dummy gate structure is exposed by said mask; and
performing one or more etch processes adapted to selectively remove one or more materials of said dummy gate structure and said layer of semiconductor material relative to a material of said mask and one or more materials of said electrically insulating structure.