Maskless lithography systems and methods utilizing spatial light modulator arrays

• US 7,061,591 B2
• Filed: 05/30/2003
• Issued: 06/13/2006
• Est. Priority Date: 05/30/2003
• Status: Expired due to Fees

• Current Assignee: ASML Holding NV
• Original Assignee: ASML Holding NV
• Inventors: Cebuhar, Wenceslao A., Hintersteiner, Jason D., Bleeker, Arno
• Primary Examiner(s): Nguyen, Henry Hung
• Application Number:
  US10/449,908
• Publication Number:
  US 20040239908A1
• Time in Patent Office: 1,110 Days
• Field of Search: 355/53, 355 67- 71, 430/311
• US Class Current: 355/77
• 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 7/70358 Scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
• CPC Class Codes: G03F 7/70466 Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature stitching G03F7/70475
• CPC Class Codes: G03F 7/70558 Dose control, i.e. achievement of a desired dose

Abstract

A maskless lithography system that writes patterns on an object. The system can include an illumination system, the object, spatial light modulators (SLMs), and a controller. The SLMs can pattern light from the illumination system before the object receives the light. The SLMs can include a leading set and a trailing set of the SLMs. The SLMs in the leading and trailing sets change based on a scanning direction of the object. The controller can transmit control signals to the SLMs based on at least one of light pulse period information, physical layout information about the SLMs, and scanning speed of the object. The system can also correct for dose non-uniformity using various methods.

Claims

1. A method for controlling dose in maskless lithography, comprising:

measuring a dose delivered in each pulse in a series of pulses from SLMs;

calculating a dose error based on the measuring steps;

calculating a correctional blanket dose based on the dose error; and

applying the correctional blanket dose using a final set of SLMs.

2. The method of claim 1, wherein each dose of the doses delivered in each pulse in the series of pulses is substantially less than the correctional blanket dose.

3. The method of claim 1, further comprising:

measuring the dose delivered from a subset of pulses in the series of pulses; and

calculating a dose error based on the measuring of the subset of pulses.

4. The method of claim 1, further comprising:

including patterning information in the correctional blanket dose.

5. The method of claim 1, further comprising:

excluding patterning information from the correction blanket dose.

6. A method for controlling dose in maskless lithography, comprising:

measuring an intensity of a dose from a leading set of SLMs;

subtracting the measured intensity from a predetermined value to generate an error signal;

delaying the error signal;

adding the delayed signal to another predetermined value to generate a control signal; and

using the control signal to control a dose from a trailing set of SLMs.

7. The method of claim 6, wherein the delaying step comprises:

setting a delay amount based on a number of pulses between the leading set of SLMs and the trailing set of SLMs.

8. The method of claim 6, wherein the adding step comprises:

using a setpoint or dose uniformity threshold value as the predetermined value.

9. The method of claim 6, wherein the controlling dose step comprises:

dividing the trailing set of SLMs into at least first and second sets; and

using the control signal to control a dose in each set to allow for stitching.

10. The method of claim 6, wherein an energy level in the leading set of SLMs is substantially higher than an energy level in the trailing set of SLMs.

11. The method of claim 6, wherein a ratio of energy levels of the leading set of SLMs with respect to the trailing set of SLMs is approximately 9:

1.

12. The method of claim 6, wherein during a subsequent exposure, the leading set of SLMs from a just finished exposure becomes a trailing set of SLMs and the trailing set of SLMs from a just finished exposure becomes a leading set of SLMs.

13. A method for controlling dose of an exposure field in maskless lithography, comprising:

measuring a dose delivered to the exposure field in each pulse in a series of pulses from a first SLM;

calculating a dose error based on the measuring steps;

calculating a correctional blanket dose based on the dose error; and

applying the correctional blanket dose to the exposure field using another SLM.