Projection exposure method and projection exposure apparatus for microlithography

Patent metadata

Field	Value
Publication number	US-10678144-B2
Application number	US-201916692537-A
Country	US
Kind code	B2
Filing date	Nov 22, 2019
Priority date	Sep 20, 2016
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

The disclosure provides a projection exposure method for exposing a substrate arranged in the region of an image plane of a projection lens with at least one image of a pattern of a mask arranged in the region of an object plane of the projection lens. A substrate is coated with a radiation-sensitive multilayer system including a first photoresist layer composed of a first photoresist material and, between the first photoresist layer and the substrate and a separately applied second photoresist layer composed of a second photoresist material. The first photoresist material has a relatively high first sensitivity in a first wavelength range and a second sensitivity, which is lower relative to the first sensitivity, in a second wavelength range separate from the first wavelength range. The second photoresist material has an exposure-suitable second sensitivity in the second wavelength range.

First claim

What is claimed is:

1. A method for exposing a substrate arranged in a region of an image plane of a projection lens with at least one image of a pattern of a mask arranged in region of an object plane of the projection lens, the substrate being coated with a radiation-sensitive multilayer system comprising first and second photoresist layers, the first photoresist layer comprising a first photoresist material, the second photoresist layer comprising a second photoresist material, the second photoresist layer being between the first photoresist layer and the substrate, the first photoresist material having a relatively high first sensitivity in a first wavelength range and a second sensitivity, which is lower relative to the first sensitivity, in a second wavelength range separate from the first wavelength range, and the second photoresist material having an exposure-suitable second sensitivity in the second wavelength range, the method comprising:
exposing the substrate coated with the radiation-sensitive multilayer system with the image of the pattern using radiation of a radiation source having an operating wavelength range comprising the first and second wavelength ranges; and
using a projection lens to correct for the first and second wavelength ranges so that a first focus region associated with the first wavelength range is offset relative to a second focus region associated with the second wavelength range by a focal distance,
wherein the first focus region is within the first photoresist layer, and the second focus region is within the second photoresist layer.

2. The method of claim 1 , wherein the first photoresist material and the second photoresist material have different spectral sensitivity characteristics.

3. The method of claim 1 , wherein at least one of the following holds:
the first photoresist material is such that between 10% and 60% of the photons in the first wavelength range are absorbed within the first photoresist layer; and
the second photoresist material is such that between 10% and 60% of the photons in the second wavelength range are absorbed within the second photoresist layer.

4. The method of claim 1 , wherein:
the first photoresist material is such that between 10% and 60% of the photons in the first wavelength range are absorbed within the first photoresist layer; and
the second photoresist material is such that between 10% and 60% of the photons in the second wavelength range are absorbed within the second photoresist layer.

5. The method of claim 1 , wherein at least one of the following holds:
the first photoresist material is such that a number of the photons in the first wavelength range that are absorbed in the first photoresist layer is at least 50% greater than a number of the photons in the second wavelength range that are absorbed in the first photoresist layer; and
the second photoresist material is such that a number of the photons in the second wavelength range that are absorbed in the second photoresist layer is at least 50% greater than a number of the photons in the first wavelength range that are absorbed in the second photoresist layer.

6. The method of claim 1 , wherein:
the first photoresist material is such that a number of the photons in the first wavelength range that are absorbed in the first photoresist layer is at least 50% greater than a number of the photons in the second wavelength range that are absorbed in the first photoresist layer; and
the second photoresist material is such that a number of the photons in the second wavelength range that are absorbed in the second photoresist layer is at least 50% greater than a number of the photons in the first wavelength range that are absorbed in the second photoresist layer.

7. The method of claim 1 , wherein the first photoresist material is such that fewer than 30% of photons in the second wavelength range are absorbed within the first photoresist layer.

8. The method of claim 1 , wherein the substrate further comprises a color filter layer between the first and second photoresist layers, and the color filter layer comprises a material having a greater transmission in the second wavelength range than in the first wavelength range.

9. The method of claim 1 , wherein:
the projection lens is configured so that the focal distance lies in a range of RU M to RU M /4;
RU M =λ M /NA 2 ;

λ M is an operating wavelength averaged from the first and second wavelength ranges; and
NA is an image-side numerical aperture of the projection lens.

10. The method of claim 1 , wherein at least one of the following holds:
a layer thickness of the first photoresist layer lies in the range of RU 1 bis RU 1 /4, RU 1 =λ 1 /NA 2 , λ 1 is a centroid wavelength of the first wavelength range, and NA is an image-side numerical aperture of the projection lens;
a layer thickness of the second photoresist layer lies in the range of RU 2 to RU 2 /4, RU 2 =λ 2 /NA 2 , λ 2 is a centroid wavelength of the second wavelength range, and NA is an image-side numerical aperture of the projection lens.

11. The method of claim 1 , wherein:
a layer thickness of the first photoresist layer lies in the range of RU 1 bis RU 1 /4, RU 1 =λ 1 /NA 2 , λ 1 is a centroid wavelength of the first wavelength range, and NA is an image-side numerical aperture of the projection lens;
a layer thickness of the second photoresist layer lies in the range of RU 2 to RU 2 /4, RU 2 =λ 2 /NA 2 , λ 2 is a centroid wavelength of the second wavelength range, and NA is an image-side numerical aperture of the projection lens.

12. The method of claim 1 , wherein at least one of the following holds:
a layer thickness of the first photoresist layer is in a range of 50 nm to 1500 nm; and
a layer thickness of the second photoresist layer in a range of 50 nm to 1500 nm.

13. The method of claim 1 , wherein:
a layer thickness of the first photoresist layer is in a range of 50 nm to 1500 nm; and
a layer thickness of the second photoresist layer in a range of 50 nm to 1500 nm.

14. The method of claim 1 , wherein a spectral separation Δλ between a centroid wavelength of the first wavelength range and a centroid wavelength of the second wavelength range is at least 10 nm.

15. The method of claim 1 , wherein:
the radiation source comprises a mercury vapor lamp;
the first wavelength range contains exactly one of the mercury lines having a centroid wavelength at approximately 365 nm (i-line), approximately 405 nm (h-line), and approximately 436 nm (g-line); and
the second wavelength range contains exactly one different mercury line from among the mercury lines.

16. A method of producing a coated substrate for use in a projection exposure method using radiation of a radiation source having an operating wavelength range including a first wavelength range and a second wavelength range separate from the first wavelength range, the method comprising:
coating the substrate with a radiation-sensitive multilayer system comprising a first photoresist layer comprising a first photoresist material and, between the first photoresist layer and the substrate, a second photoresist layer comprising a second photoresist material,
wherein:
the first photoresist material has a relatively high first sensitivity in a first wavelength range and a second sensitivity, which is lower relative to the first sensitivity, in a second wavelength range separate from the first wavelength range;
the second photoresist material has a second sensitivity in the second wavelength range; and
at least one of the following holds:
the first photoresist m

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Patra Michael

Classifications

• G03F7/70333

  Focus drilling, i.e. increase in depth of focus for exposure by modulating focus during exposure [FLEX] · CPC title

• G03F7/095 Primary

  having more than one photosensitive layer (G03F7/075 takes precedence) · CPC title

• G03F7/70466 Primary

  Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature (stitching G03F7/70475) · CPC title

• G03F7/70575 Primary

  Wavelength control, e.g. control of bandwidth, multiple wavelength, selection of wavelength or matching of optical components to wavelength · CPC title

• G03F7/70458

  Mix-and-match, i.e. multiple exposures of the same area using a similar type of exposure apparatus, e.g. multiple exposures using a UV apparatus · CPC title