Sub-resolution assist features

Patent metadata

Field	Value
Publication number	US-12416857-B2
Application number	US-202318447425-A
Country	US
Kind code	B2
Filing date	Aug 10, 2023
Priority date	Jul 23, 2019
Publication date	Sep 16, 2025
Grant date	Sep 16, 2025

Abstract

Methods of semiconductor device fabrication are provided. In an embodiment, a method of semiconductor device fabrication includes receiving a first mask design comprising a first mask function, determining a transmission cross coefficient (TCC) of an exposure tool, decomposing the TCC into a plurality orders of eigenvalues and a plurality orders of eigenfunctions, calculating a kernel based on the plurality orders of eigenvalues and the plurality orders of eigenfunctions; and determining a first sub-resolution assist feature (SRAF) seed map by convoluting the first mask function and the kernel.

First claim

What is claimed is:

1. A method, comprising:
determining a transmission cross coefficient (TCC) of an exposure tool;
decomposing the TCC into a plurality orders of eigenvalues and a plurality orders of eigenfunctions;
calculating a kernel based on the plurality orders of eigenvalues and the plurality orders of eigenfunctions;
storing the kernel in a memory medium;
receiving a mask design comprising a mask function
determining a sub-resolution assist feature (SRAF) seed map by convoluting the mask function and the stored kernel;
processing the SRAF seed map to obtain an SRAF map;
modifying the mask design according to the SRAF map to obtain a modified mask design; and
performing photolithography using the exposure tool and the modified mask design.

2. The method of claim 1 , wherein the mask function is determined based on an assumption that the mask design has an infinitely small thickness.

3. The method of claim 1 ,
wherein the mask function is determined based on an assumption that the mask design has a finite thickness,
wherein a mask three-dimensional (3D) effect of the mask design comprises an X-X diffraction component (M xx ), an X-Y diffraction component (M xy ), a Y-X diffraction component (M yx ), and a Y-Y diffraction component (M yy ).

4. The method of claim 3 , wherein the mask function comprises an X-X component (a Mxx (x, y)), an X-Y component (a Mxy (x, y)), a Y-X component (a Myx (x, y)), and a Y-Y component (a Myy (x, y)).

5. The method of claim 4 ,
wherein the X-X component (a Mxx (x, y)) of the mask function is obtained by taking a Fourier Transform of the X-X diffraction component (M xx ),
wherein the X-Y component (a Mxy (x, y)) of the mask function is obtained by taking a Fourier Transform of the X-Y diffraction component (M xy ),
wherein the Y-X component (a Myx (x, y)) of the mask function is obtained by taking a Fourier Transform of the Y-X diffraction component (M yx ),
wherein the Y-Y component (a Myy (x, y)) of the mask function is obtained by taking a Fourier Transform of the Y-Y diffraction component (M yy ).

6. The method of claim 1 , wherein the exposure tool comprises an extreme ultraviolet (EUV) exposure tool or a deep ultraviolet (DUV) exposure tool.

7. The method of claim 1 , wherein the TCC comprises information about an illumination intensity of the exposure tool, a numerical aperture of the exposure tool, a thickness of a resist stack to be patterned, or a range of an aberration.

8. The method of claim 1 , wherein the SRAF map comprises:
a plurality of SRAFs; and
a polygonal shape of each of the plurality of SRAFs.

9. A method, comprising:
determining a transmission cross coefficient (TCC) of an exposure tool;
decomposing the TCC into a plurality orders of eigenvalues and a plurality orders of eigenfunctions;
calculating a kernel based on the plurality orders of eigenvalues and the plurality orders of eigenfunctions;
storing the kernel in a memory medium;
receiving a mask design comprising a mask function
determining a sub-resolution assist feature (SRAF) seed map by convoluting the mask function and the stored kernel;
processing the SRAF seed map to obtain an SRAF map;
modifying the mask design according to the SRAF map to obtain a modified mask design; and
performing photolithography using the exposure tool and the modified mask design,
wherein the TCC comprises information about an illumination intensity of the exposure tool, a numerical aperture of the exposure tool, a thickness of a resist stack to be patterned, or a range of an aberration.

10. The method of claim 9 , wherein the mask function is determined based on an assumption that the mask design has an infinitely small thickness.

11. The method of claim 9 ,
wherein the mask function is determined based on an assumption that the mask design has a finite thickness,
wherein a mask three-dimensional (3D) effect of the mask design comprises an X-X diffraction component (M xx ), an X-Y diffraction component (M xy ), a Y-X diffraction component (M yx ), and a Y-Y diffraction component (M yy ).

12. The method of claim 11 , wherein the mask function comprises an X-X component (a Mxx (x, y)), an X-Y component (a Mxy (x, y)), a Y-X component (a Myx (x, y)), and a Y-Y component (a Myy (x, y)).

13. The method of claim 12 ,
wherein the X-X component (a Mxx (x, y)) of the mask function is obtained by taking a Fourier Transform of the X-X diffraction component (M xx ),
wherein the X-Y component (a Mxy (x, y)) of the mask function is obtained by taking a Fourier Transform of the X-Y diffraction component (M xy ),
wherein the Y-X component (a Myx (x, y)) of the mask function is obtained by taking a Fourier Transform of the Y-X diffraction component (M yx ),
wherein the Y-Y component (a Myy (x, y)) of the mask function is obtained by taking a Fourier Transform of the Y-Y diffraction component (M yy ).

14. The method of claim 9 , wherein the exposure tool comprises an extreme ultraviolet (EUV) exposure tool or a deep ultraviolet (DUV) exposure tool.

15. The method of claim 9 , wherein the SRAF map comprises:
a plurality of SRAFs; and
a polygonal shape of each of the plurality of SRAFs.

16. The method of claim 9 , further comprising retrieving the stored kernel for reuse.

17. The method of claim 16 , wherein the processing of the SRAF seed map comprises:
filtering the SRAF seed map to remove noise to obtain a filtered SRAF seed map; and
fitting polygonal shapes onto the filtered SRAF seed map.

18. A method, comprising:
receiving a mask design comprising a mask function;
determining a sub-resolution assist feature (SRAF) seed map by convoluting the mask function and a kernel stored in a memory medium, wherein the kernel is unique to a set of exposure conditions unique to an exposure tool and the SRAF seed map includes a local-minimum interference distribution, a local maximum interference distribution, and noise;
processing the SRAF seed map to obtain an SRAF map;
modifying the mask design according to the SRAF map to obtain a modified mask design; and
performing photolithography using the exposure tool and the modified mask design.

19. The method of claim 18 , wherein the processing of the SRAF seed map comprises:
filtering the SRAF seed map to remove the noise to obtain a filtered SRAF seed map; and
fitting polygonal shapes onto the filtered SRAF seed map.

20. The method of claim 18 , further comprising:
determining a transmission cross coefficient (TCC) of the exposure tool based on the set of exposure conditions;
decomposing the TCC into a plurality orders of eigenvalues and a plurality orders of eigenfunctions;
calculating the kernel based on the plurality orders of eigenvalues and the plurality orders of eigenfunctions; and
storing the kernel in the memory medium.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Yamazoe Kenji
• Lei Junjiang
• Peng Danping

Classifications

• H10P76/4085

  characterised by the processes involved to create the masks · CPC title

• G03F1/44

  Testing or measuring features, e.g. grid patterns, focus monitors, sawtooth scales or notched scales · CPC title

• G03F1/42

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

• G03F7/2004

  characterised by the use of a particular light source, e.g. fluorescent lamps or deep UV light · CPC title

• G06F17/16

  Matrix or vector computation {, e.g. matrix-matrix or matrix-vector multiplication, matrix factorization (matrix transposition G06F7/78)} · CPC title