Using time and/or power modulation to achieve dose gray-scale in optical maskless lithography

• US 7,463,402 B2
• Filed: 01/10/2006
• Issued: 12/09/2008
• Est. Priority Date: 07/31/2003
• Status: Expired due to Term

• Current Assignee: ASML Holding NV
• Original Assignee: ASML Holding NV
• Inventors: Cebuhar, Wenceslao A., Hintersteiner, Jason D., Latypov, Azat, Volpe, Gerald
• Primary Examiner(s): Choi; William C
• Application Number:
  US11/328,179
• Publication Number:
  US 20060114546A1
• Time in Patent Office: 1,064 Days
• Field of Search: 359/224, 359/291, 359/855, 355/18, 355/35, 355/44, 355/66, 355/67, 355/71
• US Class Current: 359/290
• CPC Class Codes: G03F 7/70208 Multiple illumination paths, e.g. radiation distribution devices, microlens illumination systems, multiplexers or demultiplexers for single or multiple projection systems
• CPC Class Codes: G03F 7/70283 Mask effects on the imaging process
• 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 7/70558 Dose control, i.e. achievement of a desired dose

Abstract

In lithography applications, it is desirable to control, for example, a position or width of a printed line. An effective method of controlling these patterns and their resolution is by having as many grayscale levels as possible. The present invention comprises methods of grayscaling wherein modulation of the exposure time increases the number of grayscale levels on an object. In addition, the present invention comprises methods of grayscaling wherein modulating the power of an exposure beam provides additional grayscale levels.

Claims

1. A maskless lithography system, comprising:

an illumination source;

an object configured to be exposed to produce a pattern; and

a controller, wherein;

the controller modulates a power of a light beam from the illumination source that exposes the object to produce a range of grayscale levels on the object;

the pattern is produced by the light beam having a first power;

the controller overlaps the pattern with a light beam having a second power to produce an overlapping exposure;

the overlapping exposure creates a different range of grayscale levels on the object; and

the controller repeats the overlapping step until a desired number of grayscale levels is achieved.

2. A maskless lithography system, comprising:

an illumination source;

an object configured to be exposed to produce a pattern; and

a controller, wherein;

the controller modulates a power of a light beam from the illumination source that exposes the object to produce a range of grayscale levels on the object; and

the controller uses each exposure to produce a different non-overlapping range of grayscale levels.

3. A maskless lithography system, comprising:

an illumination source;

an object configured to be exposed to produce a pattern;

a controller;

a spatial light modulator (SLM) disposed between the illumination source and the object; and

a filter with a constant intensity transmission value, specific for every exposure to provide a variation of a laser power from one exposure to another by passing the laser beam during each exposure therethrough,

wherein;

the controller modulates a power of a light beam from the illumination source that exposes the object to produce a range of grayscale levels on the object;

the SLM has a plurality of pixels;

the controller varies the power of a laser pulse from the illumination source between successive exposures to provide additional grayscale levels over a number of grayscale levels being provided by a plurality of available discrete pixel states; and

wherein the controller combines dose grayscales from different exposures to give the additional grayscale levels.