Lithography model for 3D features

• US 10,685,158 B2
• Filed: 11/24/2015
• Issued: 06/16/2020
• Est. Priority Date: 12/18/2014
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Liu, Peng
• Primary Examiner(s): Lo, Suzanne
• Application Number:
  US15/529,908
• Publication Number:
  US 20170262564A1
• Time in Patent Office: 1,666 Days
• Field of Search: None
• CPC Class Codes: G03F 7/70416 2.5D lithography
• CPC Class Codes: G03F 7/70433 Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions
• CPC Class Codes: G03F 7/70941 Stray fields and charges, e.g. stray light, scattered light, flare, transmission loss
• CPC Class Codes: G06F 2119/18 Manufacturability analysis or optimisation for manufacturability
• CPC Class Codes: G06F 30/367 Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods

Abstract

Disclosed herein is a computer-implemented method of image simulation for a device manufacturing process, the method comprising: identifying regions of uniform optical properties from a portion or an entirety of a substrate or a patterning device, wherein optical properties are uniform within each of the regions; obtaining an image for each of the regions, wherein the image is one that would be formed from the substrate if the entirety of the substrate or the patterning device has the same uniform optical properties as that region; forming a stitched image by stitching the image for each of the regions according to locations of the regions in the portion or the entirety of the substrate of the patterning device; forming an adjusted image by applying adjustment to the stitched image for at least partially correcting for or at least partially imitating an effect of finite sizes of the regions.

Claims

1. A method of image simulation for a device manufacturing process, the method comprising:

identifying regions of uniform optical properties from a portion or an entirety of a substrate, wherein optical properties are uniform within each of the regions;

obtaining an image for each of the regions, wherein the image is one that would be formed from the substrate if the entirety of the substrate has the same uniform optical properties as that region;

forming a stitched image by stitching the image for each of the regions according to locations of the regions in the portion or the entirety of the substrate; and

forming, by a hardware computer, an adjusted image by applying adjustment to the stitched image for at least partially correcting for, or at least partially imitating an effect of, finite sizes of the regions.

2. The method of claim 1, wherein at least one of the regions comprises structures having a finite height.

3. The method of claim 1, wherein the adjusted image is an image in a resist layer on the substrate.

4. The method of claim 1, wherein a stack of structures within each of the regions is substantially uniform.

5. The method of claim 1, wherein the optical properties are dictated by one or more parameters selected from:

absorbance, refractive index, thickness, composition, order, and/or reflection of structures in or under a resist layer.

6. The method of claim 1, wherein obtaining the image for each of the regions comprises retrieving the image from a database.

7. The method of claim 1, wherein the image for each of the regions is on a same image plane, and/or is obtained under same conditions apart from the substrate.

8. The method of claim 4, wherein the adjustment reflects an effect of a finite height of the structures.

9. The method of claim 1, wherein the adjustment comprises a smooth transition at boundaries between the images for the regions or an effect of scattering from edges of the regions.

10. The method of claim 1, wherein the adjustment reflects an effect of scattering from corners of the regions and/or from two adjacent edges of the regions.

11. The method of claim 1, wherein applying the adjustment comprises a convolution of a location function that represents locations of characteristics of the regions and a kernel function that represents physical effects of the characteristics.

12. The method of claim 11, wherein applying the adjustment comprises retrieving the kernel function from a database and/or calculating the location function from the substrate.

13. The method of claim 4, wherein the structures are under a resist layer on the substrate.

14. The method of claim 1, wherein the device manufacturing process is a lithography process using extreme ultraviolet radiation to expose a design layout on a patterning device to the substrate.

15. A non-transitory computer program product comprising a computer readable medium having instructions therein, the instructions, upon execution by a computer system, configured to cause the computer system to at least:

identify regions of uniform optical properties from a portion or an entirety of a substrate, wherein optical properties are uniform within each of the regions;

obtain an image for each of the regions, wherein the image is one that would be formed from the substrate if the entirety of the substrate has the same uniform optical properties as that region;

form a stitched image by stitching the image for each of the regions according to locations of the regions in the portion or the entirety of the substrate; and

form an adjusted image by applying adjustment to the stitched image for at least partially correcting for, or at least partially imitating an effect of, finite sizes of the regions.

16. The computer program product of claim 15, wherein at least one of the regions comprises structures having a finite height.

17. The computer program product of claim 15, wherein the adjusted image is an image in a resist layer on the substrate.

18. A method of image simulation for a device manufacturing process, the method comprising:

identifying regions of uniform optical properties from a portion or an entirety of a patterning device, wherein optical properties are uniform within each of the regions;

obtaining an image for each of the regions, wherein the image is one that would be formed from the patterning device if the entirety of the patterning device has the same uniform optical properties as that region;

forming a stitched image by stitching the image for each of the regions according to locations of the regions in the portion or the entirety of the patterning device; and

forming, by a hardware computer, an adjusted image by applying adjustment to the stitched image for at least partially correcting for, or at least partially imitating an effect of, finite sizes of the regions.

19. The method of claim 18, wherein at least one of the regions comprises structures having a finite height.

20. The method of claim 18, wherein the adjusted image is an image downstream of the patterning device.

21. A non-transitory computer program product comprising a computer readable medium having instructions therein, the instructions, upon execution by a computer system, configured to cause the computer system to at least:

identify regions of uniform optical properties from a portion or an entirety of a patterning device, wherein optical properties are uniform within each of the regions;

obtain an image for each of the regions, wherein the image is one that would be formed from the patterning device if the entirety of the patterning device has the same uniform optical properties as that region;

form a stitched image by stitching the image for each of the regions according to locations of the regions in the portion or the entirety of the patterning device; and

form an adjusted image by applying adjustment to the stitched image for at least partially correcting for, or at least partially imitating an effect of, finite sizes of the regions.