DELTA TCC FOR FAST SENSITIVITY MODEL COMPUTATION

• US 20100260427A1
• Filed: 11/06/2009
• Published: 10/14/2010
• Est. Priority Date: 11/10/2008
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Cao, Hua, Ye, Jun, CAO, Yu, Shao, Wenjin
• Granted Patent: US 8,379,991 B2
• Time in Patent Office: Days
• US Class Current: 382/218
• CPC Class Codes: G03F 1/36 Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
• CPC Class Codes: G03F 1/70 Adapting basic layout or design of masks to lithographic process requirements, e.g., second iteration correction of mask patterns for imaging
• CPC Class Codes: G03F 7/70483 Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
• 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 7/70525 Controlling normal operating mode, e.g. matching different apparatus, remote control or prediction of failure
• CPC Class Codes: G03F 7/70991 Connection with other apparatus, e.g. multiple exposure stations, particular arrangement of exposure apparatus and pre-exposure and/or post-exposure apparatus; Shared apparatus, e.g. having shared radiation source, shared mask or workpiece stage, shared base-plate; Utilities, e.g. cable, pipe or wireless arrangements for data, power, fluids or vacuum
• CPC Class Codes: G06F 30/39 Circuit design at the physical level physical level design for reconfigurable circuits G06F30/347
• CPC Class Codes: G06F 30/398 Design verification or optimisation, e.g. using design rule check [DRC], layout versus schematics [LVS] or finite element methods [FEM] optical proximity correction [OPC] design processes G03F1/36

Abstract

A method for determining a difference between a reference image and a further image of a pattern, the method including determining a reference imaging function; determining parameters of a difference function representative of a difference between the reference imaging function and a further imaging function; calculating a difference between the reference image and the further image of the pattern based on the difference function and the determined parameters.

Claims

1. A method for determining a difference between a reference image and a further image of a pattern, the method comprising:

determining a reference imaging function;

determining parameters of a difference function representative of a difference between the reference imaging function and a further imaging function; and

calculating a difference between the reference image and the further image of the pattern based on the difference function and the determined parameters.

2. The method according to claim 1, comprising determining the further imaging function based upon the reference imaging function and the difference function.

3. The method according to claim 2, wherein the further imaging function is determined by concatenating the reference imaging function and the difference function.

4. The method according to claim 1, wherein calculating the difference in the reference image and the further image of the pattern comprises determining the difference in image intensity of the reference image and the further image of the pattern.

5. The method according to claim 4, wherein calculating the difference in the reference image and the further image of the pattern further comprises determining the difference between a measure for critical dimensions in the reference image and the further image.

6. The method according to claim 1, comprising representing at least a part of the terms of the difference function in eigenfunctions and corresponding eigenvalues, and determining a simplified difference function by disregarding eigenfunctions and eigenvalues based upon the eigenvalues.

7. The method according to claim 6, wherein the simplified difference function comprises less than 300 eigenvalues or less than 100 eigenvalues.

8. The method according to claim 1, wherein the reference image models an image of the pattern formed by a reference optical system under reference conditions, and the further image models an image of the pattern formed by a further optical system, or formed by the reference optical system under further conditions, or formed by a modified reference optical system.

9. The method according to claim 8, comprising decreasing the difference between the reference image and the further image by changing the conditions of the further optical system, the reference optical system or the modified reference optical system.

10. The method according to claim 9, wherein the reference optical system is a projection system of a lithographic exposure apparatus.

11. A computer product having machine executable instructions, the instructions to be executed by a machine to perform a method for determining a change in an image of a mask pattern as in any one of the preceding claims 1 to 10.