Lithography mask having overlay mark and related method

Patent metadata

Field	Value
Publication number	US-2025355344-A1
Application number	US-202519290038-A
Country	US
Kind code	A1
Filing date	Aug 4, 2025
Priority date	Aug 14, 2023
Publication date	Nov 20, 2025
Grant date	—

Abstract

A method includes: generating a designed mask overlay mark associated with an actual mask overlay mark to be formed in a mask; forming the actual mask overlay mark in the mask based on the designed mask overlay mark, the actual mask overlay mark including a plurality of overlay patterns; forming a device feature pattern adjacent to the actual mask overlay mark; forming an alignment of the mask by a mask metrology apparatus including a light source having a wavelength and a numerical aperture, wherein a pitch between adjacent two of the plurality of overlay patterns does not exceed the wavelength divided by twice the numerical aperture; and forming a pattern in a layer of a wafer by transferring the device feature pattern while the mask is under the alignment.

First claim

What is claimed is:

1 . A mask, comprising:
a device feature pattern; and a mask overlay mark adjacent the device feature pattern, the mask overlay mark including an array of overlay patterns, wherein from a top view:
each of the plurality of overlay patterns has no dimension that exceeds about 100 nanometers (nm); and
a first pitch between an adjacent two of the plurality of overlay patterns is less than about 2×(λ/(4·NA)), λ being a wavelength of a measuring light of a mask metrology apparatus and NA being a numerical aperture of the measuring light.

2 . The mask of claim 1 , wherein the plurality of overlay patterns is arranged having the first pitch along a first direction and a second pitch along a second direction that is transverse the first direction.

3 . The mask of claim 2 , wherein the first pitch is different than the second pitch.

4 . The mask of claim 2 , wherein the first pitch and the second pitch each do not exceed a resolution of the mask metrology apparatus.

5 . The mask of claim 4 , wherein the resolution is about 160 nm.

6 . The mask of claim 1 , wherein the array of overlay patterns includes:
a first row of first overlay patterns; and a second row of second overlay patterns.

7 . The mask of claim 6 , wherein:
the first overlay patterns have a rectangular shape; and the second overlay patterns have the rectangular shape.

8 . The mask of claim 7 , wherein the first row of first overlay patterns and the second row of second overlay patterns define:
a first column of respective overlay patterns including at least one of the first overlay patterns and at least one of the second overlay patterns; and a second column of respective overlay patterns including at least one of the first overlay patterns and at least one of the second overlay patterns.

9 . The mask of claim 6 , wherein the first overlay patterns are offset relative to the second overlay patterns.

10 . The mask of claim 1 , wherein the array of overlay patterns includes:
a first column of first overlay patterns; and a second column of second overlay patterns.

11 . The mask of claim 10 , wherein the first overlay patterns of the first column are offset from the second overlay patterns of the second column.

12 . The mask of claim 11 , wherein the first overlay patterns and the second overlay patterns have a rectangular shape.

13 . The mask of claim 1 , wherein the array of overlay patterns are rectangular and define a row.

14 . The mask of claim 1 , wherein the array of overlay patterns are rectangular and define a column.

15 . A mask, comprising:
a device feature pattern; and a mask overlay mark adjacent the device feature pattern, the mask overlay mark including an array of overlay patterns having a diamond shape, wherein from a top view:
each of the plurality of overlay patterns has no dimension that exceeds about 100 nanometers (nm); and
a first pitch between an adjacent two of the plurality of overlay patterns is less than about 2×(λ/(4·NA)), λ being a wavelength of a measuring light of a mask metrology apparatus and NA being a numerical aperture of the measuring light.

16 . The mask of claim 15 , wherein the array of overlay patterns having the diamond shape include:
a first group of the diamond shape overlay patterns defining a first row; and a second group if the diamond shape overlay patterns defining a second row.

17 . The mask of claim 15 , wherein the first row of the first group of the diamond shape overlay patterns and the second row of the second group of the overlay patterns define:
a first column including at least one of the first group of the diamond shape overlay patterns and at least one of the second group of the diamond shape overlay patterns; and a second column including at least one of the first group of the diamond shape overlay patterns and at least one of the second group of the diamond shape overlay patterns.

18 . The mask of claim 15 , wherein the first group of the diamond shape overlay patterns defining the first row are offset from the second group of the diamond shape overlay patterns defining the second row.

19 . A mask, comprising:
a device feature pattern; and a mask overlay mark adjacent the device feature pattern, the mask overlay mark including an array of overlay patterns including a row of triangle overlay patterns and a row of square mark patterns, wherein from a top view:
each of the plurality of overlay patterns has no dimension that exceeds about 100 nanometers (nm); and
a first pitch between an adjacent two of the plurality of overlay patterns is less than about 2×(λ/(4·NA)), λ being a wavelength of a measuring light of a mask metrology apparatus and NA being a numerical aperture of the measuring light.

20 . The mask of claim 19 , wherein each respective triangle overlay pattern is aligned with a corresponding square overlay patterns.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Lee Cheng-Yeh
• Yu Ching-Fang
• Huang Hsueh-Wei
• Ho Yen-Cheng
• Lin Wei-Cheng
• Yin Hsin-Yi

Classifications

• G06T7/73

  using feature-based methods · CPC title

• G03F9/7092

  Signal processing · CPC title

• G03F9/708

  Mark formation · CPC title

• G03F9/7046

  Strategy, e.g. mark, sensor or wavelength selection · CPC title

• G03F1/42 Primary

  Alignment or registration features, e.g. alignment marks on the mask substrates · CPC title