Lithographic system, device manufacturing method, and mask optimization method

• US 20080068569A1
• Filed: 09/18/2006
• Published: 03/20/2008
• Est. Priority Date: 09/18/2006
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Tinnemans, Patricius Aloysius Jacobus, Mulckhuyse, Wouter Frans Willem
• Granted Patent: US 8,049,865 B2
• Time in Patent Office: Days
• US Class Current: 355/53
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70508 Data handling in all parts of the microlithographic apparatus, e.g. handling pattern data for addressable masks or data transfer to or from different components within the exposure apparatus

Abstract

A lithographic system comprises an array of individually controllable elements, a projection system, datapath hardware, and a conversion system. The array of individually controllable elements is capable of modulating a radiation beam. The projection system is configured to project the modulated radiation beam onto a target portion of a substrate. The datapath hardware converts an input pattern file into a control signal for controlling the array of individually controllable elements. The conversion system is configured to convert a requested device layout pattern into an input pattern file for the datapath hardware. The input pattern file is a spatial-frequency-restricted representation of the requested device layout pattern.

Claims

1. A lithographic system, comprising:

a patterning device configured to modulate a radiation beam;

a projection system configured to project the modulated radiation beam onto a target portion of a substrate;

datapath hardware configured to convert an input pattern file into a control signal that is used to control the patterning device; and

a conversion system configured to convert a requested device layout pattern into an input pattern file for the datapath hardware, the input pattern file being a spatial-frequency-restricted representation of the requested device layout pattern.

2. The lithographic system of claim 1, wherein the spatial-frequency-restricted representation only includes spatial-frequencies configured to be imaged by the projection system.

3. The lithographic system of claim 2, wherein the spatial-frequencies included in the spatial-frequency-restricted representation are below a threshold determined by the spatial frequencies configured to be imaged by the projection system.

4. The lithographic system of claim 2, wherein the spatial-frequency-restricted representation comprises portions that correct for the absence of spatial frequencies that cannot be imaged by the projection system.

5. The lithographic system of claim 1, wherein:

the patterning device comprises a mask configured to produce the requested device layout pattern; and

the conversion system is configured to calculate a dose pattern that is projected onto the substrate by the mask and to use the calculated dose pattern as the spatial-frequency-restricted representation.

6. The lithographic system of claim 5, wherein the mask comprises optical proximity corrections.

7. The lithographic system of claim 1, wherein the spatial-frequency-restricted representation generated by the conversion system comprises a map of a dose-to-clear contour in combination with information about at least one type of spatial derivative of the dose along the dose-to-clear contour.

8. The lithographic system of claim 7, wherein the information about at least one type of spatial derivative of the dose along the dose-to-clear contour comprises a Normalized Image Log Slope or a resist profile.

9. The lithographic system of claim 1, wherein the spatial-frequency-restricted representation generated by the conversion system comprises a pixel map representation of the requested device layout pattern.

10. A device manufacturing method, comprising:

modulating a radiation beam using a patterning device;

projecting the modulated radiation beam onto a target portion of a substrate using a projection system;

converting an input pattern file into a control signal for controlling the patterning device using datapath hardware;

converting a requested device layout pattern into a spatial-frequency-restricted representation of the requested device layout pattern; and

using the spatial-frequency-restricted representation of the requested device layout pattern as the input pattern file for the datapath hardware.

11. The method of claim 10, wherein the spatial-frequency-restricted representation only includes spatial-frequencies imagable by the projection system.

12. The method of claim 11, wherein the spatial-frequencies included in the spatial-frequency-restricted representation are below a threshold determined by the spatial frequencies that are imagable by the projection system.

13. The method of claim 11, wherein the spatial-frequency-restricted representation is generated to include portions that correct for the absence of spatial frequencies that are not imagable by the projection system.

14. The method of claim 10, wherein the converting of the requested device layout pattern into the spatial-frequency-restricted representation comprises:

using a mask as the patterning device;

calculating a dose pattern for the mask that is designed to produce the requested device layout pattern; and

using the calculated dose pattern as the spatial-frequency-restricted representation.

15. The method of claim 14, further comprising forming optical proximity corrections on the mask.

16. The method of claim 10, wherein the converting step produces a spatial-frequency-restricted representation comprising a map of a dose-to-clear contour in combination with information about at least one type of spatial derivative of the dose along the dose-to-clear contour.

17. The method of claim 16, wherein the information about at least one type of spatial derivative of the dose along the dose-to-clear contour comprises a Normalized Image Log Slope or a resist profile.

18. The method of claim 10, wherein the converting step produces a spatial-frequency-restricted representation comprising a pixel map representation of the requested device layout pattern.

19. A flat panel display manufactured according to the method of claim 10.

20. An integrated circuit device manufactured according to the method of claim 10.

21. A mask optimization method, comprising:

calculating a dose pattern to be projected onto a substrate by a mask-based lithographic apparatus using a given candidate mask pattern as the mask;

using the calculated dose pattern as an input for datapath hardware in a maskless lithographic apparatus, the datapath hardware being configured to convert a dose pattern into a control signal for controlling an array of individually controllable elements;

modulating a radiation beam using the array of individually controllable elements;

projecting the modulated radiation beam onto a target portion of the substrate in order to form an exposed substrate;

processing the exposed substrate to form a device;

testing the device to evaluate its performance;

repeating the above steps for a series of the candidate mask patterns; and

selecting an optimal one of the candidate mask patterns based on a comparison of the results of the testing steps.

22. The mask optimization method of claim 21, further comprising including optical proximity corrections within the candidate mask pattern.