Lithography Model for 3D Topographic Wafers

• US 20130042211A1
• Filed: 08/08/2012
• Published: 02/14/2013
• Est. Priority Date: 08/09/2011
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Liu, Peng
• Granted Patent: US 9,835,955 B2
• Time in Patent Office: Days
• US Class Current: 716/53
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions

Abstract

Described herein is a method for simulating an image formed within a resist layer on a substrate resulting from an incident radiation, the method comprising: calculating a forward propagating electric field or forward propagating magnetic field resultant from the incident radiation at a depth in the resist layer; calculating a backward propagating electric field or backward propagating magnetic field resultant from the incident radiation at the depth in the resist layer; calculating a radiation field at the depth in the resist layer from the forward propagating electric field or forward propagating magnetic field and from the backward propagating electric field or backward propagating magnetic field while ignoring an interference between the forward propagating electric field or forward propagating magnetic field and the backward propagating electric field or backward propagating magnetic field.

Claims

1. A method for simulating an image formed within a resist layer on a substrate resulting from an incident radiation, the substrate having features in or underlying the resist layer, the method comprising:

determining a substrate-specific scattering function using one or more scattering functions based on characteristics of the features, wherein the substrate-specific scattering function characterizes scattering of the incident radiation within the resist layer by the features.

2. The method of claim 1, wherein the determining a substrate-specific scattering function is further based on characteristics of the resist layer.

3. The method of claim 1, further comprising computing a resist image formed within the resist layer by using the substrate-specific scattering function.

4. The method of claim 3, wherein computing the resist image formed within the resist layer is further based on characteristics of the resist layer.

5. The method of claim 3, wherein computing the image formed within the resist layer is further based on characteristics of the incident radiation.

6. The method of claim 5, wherein the characteristics of the incident radiation are selected from the group consisting of an electromagnetic field at a surface of the resist layer, an electric field at a surface of the resist layer and a magnetic field at a surface of the resist layer.

7. The method of claim 1, wherein the one or more scattering functions characterize scattering of radiation due to a characteristic of a feature element, and/or wherein the one or more scattering functions are computed using a rigorous solver.

8. The method of claim 1, further comprising computing an electromagnetic field at a surface of the resist layer resulting from the incident radiation based on characteristics of one or more of a source of radiation, at least a part of a design layout and projection optics;

wherein the surface of the resist layer faces the incident radiation during exposure.

9. The method of claim 1, wherein the one or more scattering functions are independent from a direction of the incident radiation.

10. The method of claim 7 when the one or more scattering functions characterize scattering of radiation due to a characteristic of a feature element, wherein the feature element is a horizontal edge, a vertical edge, an area, a corner, or a combination thereof.

11. The method of claim 1, wherein the substrate is free of an anti-reflective coating.

12. The method of claim 1, wherein the one or more scattering functions are compiled in a library.

13. The method of claim 1, further comprising:

calculating a forward propagating electric field or forward propagating magnetic field resultant from the incident radiation at a depth in the resist layer;

calculating a backward propagating electric field or backward propagating magnetic field resultant from the incident radiation at the depth in the resist layer;

calculating a radiation field at the depth in the resist layer from the forward propagating electric field or forward propagating magnetic field and from the backward propagating electric field or backward propagating magnetic field while ignoring an interference between the forward propagating electric field or forward propagating magnetic field and the backward propagating electric field or backward propagating magnetic field.

14. The method of claim 13, wherein calculating a radiation field at the depth in the resist layer comprises calculating the radiation field using transmission cross coefficients (TCCs).

15. The method of claim 14, wherein the TCCs are calculated from a projection optics function, and/or wherein the TCCs do not represent interference between the forward propagating electric field or forward propagating magnetic field and the backward propagating electric field or backward propagating magnetic field.

18. A computer program product comprising a computer readable medium having instructions recorded thereon, the instructions when executed by a computer implementing the method of claim 1.

16. A method for determining an electromagnetic field inside a resist layer disposed on a substrate, wherein the substrate, or the resist layer, or both, have features defined by protrusions and/or recesses, the method comprising:

computing a substrate-specific scattering function based on the features and one or more scattering functions, each of the one or more scattering functions characteristic of electromagnetic scattering associated with at least one of the features;

computing the electromagnetic field inside the resist layer based on the substrate-specific scattering function and an electromagnetic field provided to the resist layer.

19. A computer program product comprising a computer readable medium having instructions recorded thereon, the instructions when executed by a computer implementing the method of claim 16.

17. A method of simulating an image of a substantial part of a design layout to be formed within a resist layer on a substrate, the substrate having features in or underlying the resist layer, the method comprising:

determining a scattering function of a feature element of a feature based on a characteristic of the feature element, wherein the scattering function characterizes scattering of incident radiation within the resist layer by the feature element,

determining a substrate-specific scattering function, wherein the substrate-specific scattering function characterizes scattering of the incident radiation from the substantial part of the design layout within the resist layer by the feature elements underlying an image area of the substantial part of the design layout, the determining of the substrate-specific scattering function comprising re-using the scattering function of the feature element.

20. A computer program product comprising a computer readable medium having instructions recorded thereon, the instructions when executed by a computer implementing the method of claim 17.

21. A computer program product comprising a computer readable medium, having a library of scattering functions of feature elements recorded thereon, wherein the feature elements are components of features in or underlying a resist layer on a substrate.

22. The computer program product of claim 21, wherein the library comprises index information.