UNIAXIAL STRAIN RELAXATION OF BIAXIAL-STRAINED THIN FILMS USING ION IMPLANTATION

• US 20080171426A1
• Filed: 01/12/2007
• Published: 07/17/2008
• Est. Priority Date: 01/12/2007
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Saenger, Katherine L., Yin, Haizhou, Ren, Zhibin
• Granted Patent: US 7,494,886 B2
• Time in Patent Office: Days
• US Class Current: 438/530
• CPC Class Codes: H01L 21/26506 in group IV semiconductors
• CPC Class Codes: H01L 21/823807 with a particular manufacturing method of the channel structures, e.g. channel implants, halo or pocket implants, or channel materials
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence
• CPC Class Codes: H01L 29/7848 the means being located in the source/drain region, e.g. SiGe source and drain
• CPC Class Codes: Y10S 438/938 Lattice strain control or utilization

Abstract

A method for achieving uniaxial strain on originally biaxial-strained thin films after uniaxial strain relaxation induced by ion implantation is provided. The biaxial-strained thin film receives ion implantation after being covered by a patterned implant block structure. The strain in the uncovered region is relaxed by ion implantation, which induces the lateral strain relaxation in the covered region. When the implant block structure is narrow (dimension is comparable to the film thickness), the original biaxial strain will relax uniaxially in the lateral direction.

Claims

1. A method for uniaxially relaxing strain in a biaxially strained semiconductor film comprising:

providing a patterned structure on a surface of a biaxially strained semiconductor film, said patterned structure protects at least one portion of said film while leaving at least one other portion of said film exposed; and

performing an ion implant into said at least one other portion of said film not covered by said patterned structure, wherein said ion implant damages said at least one other portion of said film and causes strain relaxation in said at least one other portion of said film, while inducing lateral strain relaxation in said at least one portion of said film That is protected by said patterned structure.

2. The method of claim 1 further comprising an annealing step that heals said damages caused by ion implantation.

3. The method of claim 1 wherein said patterned structure is an ion implant block mask that has a length dimension less than five times a thickness of said biaxially strained semiconductor film.

4. The method of claim 3 wherein said ion implant block mask is a photoresist, a dielectric material, or a dielectric stack.

5. The method of claim 1 wherein said biaxially strained semiconductor film comprises tensile strained silicon or compressive strained silicon.

6. The method of claim 1 wherein said ion implant comprises implantation of an ion species comprising at least one of Ge, Xe, Si and As.

7. The method of claim 1 wherein said ion implant is performed under conditions that are effective in amorphizing said at least one other portion of said film not covered by said patterned structure.

8. The method of claim 1 wherein said biaxially strained semiconductor film comprises tensile strained Si and said patterned structure is a pFET including a patterned gate stack and a spacer located on sidewalls of said patterned gate stack.

9. A method for uniaxially relaxing strain in a biaxially strained semiconductor film comprising:

forming an ion implant block mask over a biaxially strained film, said ion implant block mask protects at least one portion of said film while leaving at least one other portion of said film exposed; and

performing an ion implant into said at least one other portion of said film not covered by said ion implant block mask, wherein said ion implant damages said at least one other portion of said film and causes strain relaxation in said at least one other portion of said film, while inducing lateral strain relaxation in said at least one portion of said film that is protected by said ion implant block mask.

10. The method of claim 9 further comprising an annealing step that heals said damages caused by ion implantation.

11. The method of claim 9 wherein said ion implant block mask is a photoresist, a dielectric material, or a dielectric stack that has a length dimension less than five times a thickness of said biaxially strained semiconductor film.

12. The method of claim 9 wherein said biaxially strained semiconductor film comprises tensile strained silicon or compressive strained silicon.

13. The method of claim 9 wherein said ion implant comprises implantation of an ion species comprising at least one of Ge, Xe, Si and As.

14. The method of claim 9 wherein said ion implant is performed under conditions that are effective in amorphizing said at least one other portion of said film not covered by said ion implant block mask.

15. A method for uniaxially relaxing strain in a biaxially strained semiconductor film comprising

providing a patterned structure comprising a patterned gate stack and a sidewall spacer on a surface of a biaxially strained semiconductor film, said patterned structure protects at least one portion of said film while leaving at least one other portion of said film exposed, the patterned gate stack and the sidewall spacer having a length dimension less than five times a thickness of said biaxially strained semiconductor film;

and

performing an ion implant into said at least one other portion of said film not covered by said patterned structure, wherein said ion implant damages said at least one other portion of said film and causes strain relaxation in said at least one other portion of said film, while inducing lateral strain relaxation in said at least one portion of said film that is protected by said patterned structure.

16. The method of claim 15 further comprising an annealing step that heals said damages caused by ion implantation.

17. The method of claim 15 wherein said ion implant comprises implantation of an ion species comprising at least one of Ge, Xe, Si and As.

18. The method of claim 15 wherein said biaxially strained semiconductor film comprises tensile strained Si and said patterned structure is a pFET.

19. The method of claim 15 wherein said ion implant is performed under conditions that are effective in amorphizing said at least one other portion of said film not covered by said patterned structure.