Sub-resolution assist features

Patent metadata

Field	Value
Publication number	US-10990002-B2
Application number	US-201916674439-A
Country	US
Kind code	B2
Filing date	Nov 5, 2019
Priority date	Jul 23, 2019
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

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 of semiconductor device fabrication, comprising:
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;
determining a first sub-resolution assist feature (SRAF) seed map by convoluting the first mask function and the kernel;
storing the kernel in a memory medium;
receiving a second mask design comprising a second mask function different from the first mask function;
retrieving the kernel stored in the memory medium;
determining a second SRAF seed map by convoluting the second mask function and the stored kernel;
processing the second SRAF seed map to obtain a second SRAF map;
modifying the second mask design according to the second SRAF map to obtain a second modified mask design; and
performing photolithography using the exposure tool and the second modified mask design.

2. The method of claim 1 , wherein the first SRAF seed map comprises coordinates of peak positions for placement of a plurality of SRAFs.

3. The method of claim 1 , further comprising:
processing the first SRAF seed map to obtain a first SRAF map;
modifying the first mask design according to the first SRAF map to obtain a first modified mask design; and
performing photolithography using the exposure tool and the first modified mask design.

4. The method of claim 3 , wherein the first SRAF map comprises:
a plurality of SRAFs; and
a polygonal shape of each of the plurality of SRAFs.

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

6. 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.

7. The method of claim 1 ,
wherein the plurality orders of eigenvalues are denoted as λ i ,
wherein the plurality orders of eigenfunctions are denoted as ϕ i ,
wherein the kernel is denoted as Ω(x,y),
wherein the calculating of the kernel comprises use of the following mathematical formula:

Ω
⁡

(

x
,
y

)

=

Re
⁡

[

∑

i
=
1

N

⁢

λ
i

⁢

ϕ
i

*

(

0
,
0

)

⁢

ϕ
i

⁡

(

-
x

,

-
y

)

]

.

8. A method of semiconductor device fabrication, comprising:
receiving a first mask design comprising a first mask function (a (x,y));
providing an exposure tool that includes a set of exposure conditions;
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 (Xi) and a plurality orders of eigenfunctions (ϕ i (x,y));
calculating a kernel (Ω(x,y)) based on the following mathematical formulae:

Ω
⁡

(

x
,
y

)

=

Re
⁡

[

∑

i
=
1

N

⁢

λ
i

⁢

ϕ
i

*

(

0
,
0

)

⁢

ϕ
i

⁡

(

-
x

,

-
y

)

]

and
determining a first sub-resolution assist feature (SRAF) seed map (Γ(x,y)) by convoluting the kernel and the first mask function using the following mathematical formula:
Γ( x,y )= a ( x,y )⊗Ω( x,y ).

9. The method of claim 8 , further comprising:
determining a first sub-resolution assist feature (SRAF) seed map (Γ(x,y)) by convoluting the kernel and the first mask function using the following mathematical formula:
Γ( x,y )= a ( x,y )⊗Ω( x,y ),

wherein the first mask design is assumed to be implemented as an ideal mask.

10. The method of claim 8 ,
wherein

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

• G03F1/70 Primary

  Adapting basic layout or design of masks to lithographic process requirements, e.g., second iteration correction of mask patterns for imaging · CPC title

• G03F1/44

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

• G03F7/2004

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

• G03F7/70425

  Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning · CPC title