Transmission balancing for phase shift mask with a trim mask

• US 9,341,939 B1
• Filed: 10/30/2014
• Issued: 05/17/2016
• Est. Priority Date: 10/30/2014
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Yu, Dan, Bowser, Aaron, Liu, Yi
• Primary Examiner(s): YOUNG, CHRISTOPHER G
• Application Number:
  US14/528,174
• Publication Number:
  US 20160124299A1
• Time in Patent Office: 565 Days
• Field of Search: 430/5
• US Class Current: 1/1
• CPC Class Codes: G03F 1/30 Alternating PSM, e.g. Levenson-Shibuya PSM; Preparation thereof
• CPC Class Codes: G03F 1/70 Adapting basic layout or design of masks to lithographic process requirements, e.g., second iteration correction of mask patterns for imaging
• CPC Class Codes: G03F 7/20 Exposure; Apparatus therefor photographic printing apparatus for making copies G03B27/00
• CPC Class Codes: G03F 7/70558 Dose control, i.e. achievement of a desired dose
• CPC Class Codes: G03F 7/70625 Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness
• CPC Class Codes: G03F 7/70633 Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
• CPC Class Codes: G03F 9/7007 Alignment other than original with workpiece

Abstract

Implementations described and claimed herein include photolithography technology to alleviate the imbalance of transmission intensity induced. In one implementation, a method comprises exposing an alternating phase shift mask (Alt-PSM) and a trim mask, wherein an exposure placement of the trim mask is shifted relative to an exposure placement of the Alt-PSM.

Claims

1. A photolithography system, comprising:

a light source;

an alternating phase shift mask (Alt-PSM); and

a trim mask, wherein an exposure placement of the trim mask is shifted relative to an exposure placement of the Alt-PSM.

2. The photolithography system of claim 1, wherein a width of the trim mask is approximately 200 nm.

3. The photolithography system of claim 1, wherein a width of the trim mask is less than 500 nm.

4. The photolithography system of claim 1, wherein a center of the trim mask is shifted compared to a phase transition edge of the Alt-PSM.

5. The photolithography system of claim 4, wherein the center of the trim mask is shifted compared to the phase transition edge of the Alt-PSM by at least 2 nm.

6. The photolithography system of claim 4, wherein the center of the trim mask is shifted compared to the phase transition edge of the Alt-PSM by approximately 8 nm.

13. The photolithography system of claim 1, further comprising a chrome area on the trim mask.

14. The photolithography system of claim 13, wherein a size of the chrome area is less than 500 nm.

17. The photolithography system of claim 1, wherein a phase of the Alt-PSM changes from 180°

to 0°

at a phase transition edge of the Alt-PSM.

19. The photolithography system of claim 1, wherein the trim mask relative to the Alt-PSM is swept from approximately −

12 nm to approximately 12 nm.

21. The photolithography system of claim 13, wherein the chrome area has zero light transmission.

7. A photolithography mask assembly, comprising:

an alternating phase shift mask (Alt-PSM); and

a trim mask, wherein an exposure placement of the trim mask is shifted relative to an exposure placement of the Alt-PSM.

8. The photolithography mask assembly of claim 7, wherein a center of the trim mask is shifted compared to a phase transition edge of the Alt-PSM.

9. The photolithography mask assembly of claim 8, wherein the center of the trim mask is shifted compared to the phase transition edge of the Alt-PSM by at least 2 nm.

10. The photolithography mask assembly of claim 8, wherein the center of the trim mask is shifted compared to the phase transition edge of the Alt-PSM by approximately 8 nm.

11. The photolithography mask assembly of claim 9, wherein a width of the trim mask is approximately 200 nm.

12. The photolithography mask assembly of claim 9, wherein the width of the trim mask is less than 500 nm.

15. The photolithography mask assembly of claim 7, further comprising a chrome area on the trim mask.

16. The photolithography mask assembly of claim 15, wherein a size of the chrome area is less than 500 nm.

18. The photolithography mask assembly of claim 9, wherein a phase of the Alt-PSM changes from 180°

to 0°

at a phase transition edge of the Alt-PSM.

20. The photolithography mask assembly of claim 7, wherein the trim mask relative to the Alt-PSM is swept from approximately −

12 nm to approximately 12 nm.