Method for optimizing an illumination source using full resist simulation and process window response metric

• US 6,839,125 B2
• Filed: 02/11/2003
• Issued: 01/04/2005
• Est. Priority Date: 02/11/2003
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Hansen, Steven George
• Primary Examiner(s): MATHEWS, ALAN A
• Application Number:
  US10/361,831
• Publication Number:
  US 20040156029A1
• Time in Patent Office: 693 Days
• Field of Search: 355/53, 355/67, 355/71, 355/77, 703/13, 703/22, 430/30
• US Class Current: 355/67
• CPC Class Codes: G03F 7/701 Off-axis setting using an aperture
• CPC Class Codes: G03F 7/70108 Off-axis setting using a light-guiding element, e.g. diffractive optical elements [DOEs] or light guides
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions

Abstract

A method for optimizing the illumination conditions of a lithographic apparatus by computer simulation using full resist calculation, the lithographic apparatus comprising an illuminator, a projection system, and a mask having a pattern to be printed in a layer of photoresist material formed on a substrate. This method includes defining a lithographic 0problem, which may include a lithographic pattern to be printed on a wafer; choosing a resist model of a resist process to be used to print a pattern in the layer of photoresist material; selecting a grid of source points in a pupil plane of the illuminator; calculating separate responses for individual source points, each of the responses representing a result of a single or series of simulations using the resist model; and adjusting an illumination arrangement based on analysis of accumulated results of the separate calculations.

Claims

1. A method for optimizing the illumination conditions of a lithographic apparatus by computer simulation using full resist calculation, the lithographic apparatus comprising an illuminator, a projection system, and a mask having a pattern to be printed in a layer of photoresist material formed on a substrate, the method comprising:

defining a lithographic pattern to be printed on a wafer;

choosing a resist model of a resist process to be used to print the pattern in the layer of photoresist material;

selecting a grid of source points in a pupil plane of the illuminator;

calculating separate responses for individual source points, each of the responses representing a result of a single or series of simulations using the resist model; and

adjusting an illumination arrangement based on analysis of accumulated results of the separate calculations.

2. A method according to claim 1, wherein the response is a focus exposure matrix and results in a process window that includes dose latitude and depth of focus information.

3. A method according to claim 1, further comprising calculating of response of trial illumination schemes by averaging separate responses for the individual source points contained within the illumination arrangement.

4. A method according to claim 1, wherein the response is E1:

1, dense to isolated feature bias, arbitrary feature size biases, sidelobe printing, film loss, sidewall angle, mask error enhancement factor, linear resolution, or absolute resolution.

5. A method according to claim 1, further comprising mapping the responses as a function of individual source points positions.

6. A method according to claim 3, further comprising applying a dose weighted averaging of the responses.

7. A method according to claim 1, wherein the simulated grid results are interpolated to increase the grid point density to aid in averaging.

8. A method according to claim 1, wherein adjusting the illumination arrangement includes adjusting the illumination arrangement by varying a position of an axicon/zoom module relative to a pyramidal prism, a position of a diffractive optical element, a position of an aperture blade, or by adjusting a programmable mirror array.

9. A method according to claim 8, wherein the grid spacing is within a range from 0.01 to 0.2.

10. A method according to claim 1, wherein defining the illumination arrangement includes selecting a multipole illuminator arrangement.

11. A method according to claim 1, wherein defining the illumination arrangement includes defining an illumination arrangement with a multipole generating clement.

12. A method according to claim 1, wherein the resist model is a calibrated model capable of adequately predicting experimental results.

13. A method according to claim 1, wherein defining the resist model includes defining a resist model taking into account at least one of vector effects, non-zero diffusion of active species, and finite dissolution contrast.