Transmission balancing for phase shift mask with a trim mask

Patent metadata

Field	Value
Publication number	US-2016246183-A1
Application number	US-201615144368-A
Country	US
Kind code	A1
Filing date	May 2, 2016
Priority date	Oct 30, 2014
Publication date	Aug 25, 2016
Grant date	—

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.

First claim

What is claimed is:

1 . A method of photolithography, comprising:
exposing a wafer using an alternating phase shift mask (Alt-PSM) and a trim mask, wherein a center of the trim mask is shifted relative to a center of the alternating phase shift mask.

2 . The method of claim 1 , further comprising shifting the center of the trim mask compared to a phase transition edge of the Alt-PSM.

3 . The method of claim 2 , wherein the phase of the Alt-PSM changes from 180° to 0° at the phase transition edge of the Alt-PSM.

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

5 . The method of claim 2 , wherein the center of the trim mask is shifted compared to the phase transition edge of the Alt-PSM by approximately 8 nm.

6 . The method of claim 2 , further comprising iteratively determining a combination of Alt-PSM exposure dose and a shift between the trim mask and the Alt-PSM to generate a target critical dimension.

7 . The method of claim 3 , wherein the trim mask has a width of approximately 200 nm.

8 . The method of claim 1 , further comprising using chrome on the trim mask, wherein a size of chrome area is less than 500 nm.

9 . A method of photolithography, comprising:
exposing a wafer using 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.

10 . The method of claim 9 , further comprising shifting a center of the trim mask compared to a phase transition edge of the Alt-PSM.

11 . The method of claim 10 , further comprising shifting a center of the trim mask compared to the phase transition edge of the Alt-PSM by at least 2 nm.

12 . The method of claim 10 , further comprising shifting the center of the trim mask compared to the phase transition edge of the Alt-PSM by approximately 8 nm.

13 . The method of claim 9 , wherein a width of the trim mask is approximately 200 nm.

14 . The method of claim 9 , wherein a width of the trim mask is less than 500 nm.

15 . A method of photolithography comprising:
simulating different critical dimensions with a series of alternating phase shift mask (Alt-PSM) exposure doses and relative trim mask shifts; determining a first Alt-PSM exposure dose; determining a first trim mask shift with the first Alt-PSM exposure dose; and simulating a first critical dimension with the trim mask shift.

16 . The method of claim 15 , wherein determining the first Alt-PSM exposure dose is based on a function of critical dimension vs. Alt-PSM dose.

17 . The method of claim 15 , wherein determining the trim mask shift is based on where the first critical dimension is maximized when sweeping the shift with the first Alt-PSM dose.

18 . The method of claim 15 , further comprising determining whether the first critical dimension is equal to a targeted critical dimension.

19 . The method of claim 18 , wherein an Alt-PSM dose and relative trim mask shift for the first critical dimension is achieved if the first critical dimension is equal to the targeted critical dimension.

20 . The method of claim 18 , further comprising repeating the simulating different critical dimensions with a series of Alt-PSM exposure doses and relative trim mask shifts operations if the critical dimension is not equal to the targeted critical dimension.

Assignees

• Seagate Technology Llc

Inventors

• Yu Dan
• Bowser Aaron
• Liu Yi

Classifications

• G03F7/20

  Exposure; Apparatus therefor (photographic printing apparatus for making copies G03B27/00) · CPC title

• G03F7/70558 Primary

  Dose control, i.e. achievement of a desired dose · CPC title

• G03F1/30 Primary

  Alternating PSM, e.g. Levenson-Shibuya PSM; Preparation thereof · CPC title

• G03F7/70633 Primary

  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 title

• G03F9/7007

  Alignment other than original with workpiece · CPC title