Semiconductor structure having a source and a drain with reverse facets

• US 9,190,471 B2
• Filed: 04/13/2012
• Issued: 11/17/2015
• Est. Priority Date: 04/13/2012
• Status: Expired due to Fees

• Current Assignee: Alsephina Innovations Inc. (Quarterhill Inc. (f/k/a Wi-LAN Inc.))
• Original Assignee: Globalfoundries INS (GlobalFoundries, Inc.)
• Inventors: Adam, Thomas N., Cheng, Kangguo, Khakifirooz, Ali, Li, Jinghong, Reznicek, Alexander
• Primary Examiner(s): Tornow, Mark
• Assistant Examiner(s): RAMPERSAUD, PRIYA M
• Application Number:
  US13/446,350
• Publication Number:
  US 20130270611A1
• Time in Patent Office: 1,313 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/02609 Crystal orientation
• CPC Class Codes: H01L 21/84 the substrate being other than a semiconductor body, e.g. being an insulating body
• CPC Class Codes: H01L 29/0657 characterised by the shape of the body
• CPC Class Codes: H01L 29/0847 of field-effect transistors with insulated gate H01L29/0653 takes precedence; with a passive supplementary region between source or drain and substrate related to punch-through, capacity or isolation phenomena H01L29/1079; with LDD or DDD structure H01L29/7833; for thin film transistors H01L29/78618
• CPC Class Codes: H01L 29/66636 with source or drain recessed by etching or first recessed by etching and then refilled
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence

Abstract

A semiconductor structure including a semiconductor wafer. The semiconductor wafer includes a gate structure, a first trench in the semiconductor wafer adjacent to a first side of the gate structure and a second trench adjacent to a second side of the gate structure, the first and second trenches filled with a doped epitaxial silicon to form a source in the filled first trench and a drain in the filled second trench such that each of the source and drain are recessed and have an inverted facet. In a preferred exemplary embodiment, the epitaxial silicon is doped with boron.

Claims

1. A semiconductor structure comprising:

a semiconductor wafer comprising a gate structure, a first trench in the semiconductor wafer adjacent to a first side of the gate structure and a second trench adjacent to a second side of the gate structure, the first and second trenches each having vertical sides at a 90 degree angle with respect to a bottom of the trench and filled with an epitaxial silicon that is not an alloy or compound of silicon and is doped to form a doped epitaxial silicon to form a source in the filled first trench and a drain in the filled second trench such that each of the source and drain are recessed and have an inverted facet wherein the inverted facet comprises vertical side walls at the vertical sides at an outer periphery of the source and drain and angled walls that extend from the vertical side walls towards a center and a bottom of the source and drain.

2. The structure of claim 1 wherein the doped epitaxial silicon is doped with boron.

3. The structure of claim 2 wherein the concentration of the boron is 1×

10¹⁹ to 8×

10²⁰ atoms/cm³.

4. The structure of claim 1 wherein the doped epitaxial silicon is doped with aluminum, gallium, indium or thallium and combinations thereof.

5. The structure of claim 1 wherein the first and second trenches each have a bottom surface and a side surface and the semiconductor wafer is oriented such that the bottom surface of the first and second trenches has a crystal plane orientation of {100} and the side surface of the first and second trenches has a crystal plane orientation of {110}.

6. The structure of claim 1 wherein a bottom of the recessed source and drain is flat.

7. The structure of claim 1 wherein a bottom of the recessed source and drain is flat and the angled walls meet the bottom.

8. The structure of claim 1 wherein the angled walls meet at the center of the source and drain.

9. The structure of claim 1 wherein the angled walls have a crystal plane orientation of {111}.

10. The structure of claim 1 wherein the semiconductor wafer is a bulk semiconductor wafer consisting of silicon or a semiconductor on insulator wafer having an active layer consisting of silicon.

11. A semiconductor structure comprising:

a semiconductor wafer comprising a gate structure, a first trench in the semiconductor wafer adjacent to a first side of the gate structure and a second trench adjacent to a second side of the gate structure, the first and second trenches each having vertical sides at a 90 degree angle with respect to a bottom of the trench and filled with a doped epitaxial silicon consisting of silicon and a dopant selected from the group consisting of boron, aluminum, gallium, indium and thallium to form a source in the filled first trench and a drain in the filled second trench such that each of the source and drain are recessed and have an inverted facet wherein the inverted facet comprises vertical side walls at eth vertical sides at an outer periphery of the source and drain and angled walls that extend from the vertical side walls towards a center and a bottom of the source and drain.