RET for optical maskless lithography

• US 7,618,751 B2
• Filed: 02/25/2005
• Issued: 11/17/2009
• Est. Priority Date: 02/25/2004
• Status: Active Grant

• Current Assignee: Micronic Laser Systems AB (Mycronic AB)
• Original Assignee: Micronic Laser Systems AB (Mycronic AB)
• Inventors: Martinsson, Hans, Sandstrom, Torbjorn
• Primary Examiner(s): McPherson; John A
• Assistant Examiner(s): CHACKO DAVIS, DABORAH
• Application Number:
  US11/066,828
• Publication Number:
  US 20050219502A1
• Time in Patent Office: 1,726 Days
• Field of Search: None
• US Class Current: 430/5
• CPC Class Codes: G03F 1/26 Phase shift masks [PSM]; PSM blanks; Preparation thereof
• 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

Abstract

The present invention relates to Optical Maskless Lithography (OML). In particular, it relates to providing OML with a recognizable relationship to mask and phase-shift mask techniques.

Claims

1. A method of exposing lithographic patterns, including:

providing a spatial light modulator (SLM) having at least one mirror having a complex reflection coefficient with a negative real part and an adjacent mirror having a complex reflection coefficient with a positive real part,

illuminating said SLM with a partially coherent beam,

converting vector input data to drive said SLM, said vector input data including more than two beam relaying states, including in the vector input data fully on and fully off states plus either a gray state or a phase shifting state; and

driving the mirrors having the complex reflection coefficients to emulate one or more sub-printing resolution scatterbars.

2. The method of claim 1, wherein one or more pattern edges are defined by the SLM using at least one mirror oriented to have a complex reflection coefficient with a negative real part, emulating one or more of the methods of lithographic image enhancement.

3. The method of claim 1, wherein the converted vector data is used to drive the mirrors having the complex reflection coefficient with a negative real part to a phase edge as contrasted with one or more adjacent mirrors.

4. The method of claim 1, wherein the converted vector data is used to drive the mirrors having the complex reflection coefficient with a negative real part to emulate phase interference between areas of a CPL mask.

5. The method of claim 1, wherein the converted vector data is used to drive the mirrors having the complex reflection coefficient with a negative real part to emulate an alternating aperture phase-shifting mask.

6. The method of claim 1, wherein the converted vector data is used to drive the mirrors having the complex reflection coefficient with a negative real part to emulate a three-tone phase-shifting mask.

7. The method of claim 1, wherein the converted vector data is used to drive the mirrors having the complex reflection coefficient with a negative real part to emulate a high transmission attenuating phase-shifting mask.

8. The method of claim 1, wherein the driving the mirrors having the complex reflection coefficient with a negative real part to produce a jog in a line pattern, is enhanced by a phase difference between adjacent mirrors of the SLM.

9. The method of claim 1, applied to direct writing to a workpiece, the method further including:

receiving data that describes one or more masks applying phase shifting techniques to produce an image on the workpiece;

driving complex amplitude-capable micromirrors of an SLM to emulate the image on the workpiece that would be produced by more than one mask; and

illuminating the SLM with partially coherent light and relaying the partially coherent light onto the workpiece.

10. The method of claim 9, wherein the more than one mask applying phase shifting techniques include two or more masks of a mask set used to produce an image on the workpiece for a particular pattern layer.

11. A method of forming lithographic patterns on an image plane on a workpiece using a spatial light modulator (SLM), having one or more mirrors having a complex reflection coefficient with a negative real part, using a partially coherent light source, including:

illuminating the SLM with the partially coherent light;

driving the mirrors having the complex reflection coefficient with a negative real part to emulate double-exposure dipole decomposition resolution enhancement using multiple exposures of the SLM; and

projecting the partially coherent light from the SLM through a finite aperture onto an image plane.

12. A method of exposing lithographic patterns, including:

providing a spatial light modulator (SLM) having at least one mirror having a complex reflection coefficient with a negative real part and an adjacent mirror having a complex reflection coefficient with a positive real part,

illuminating said SLM with a partially coherent beam, and

converting vector input data to drive said SLM, said vector input data including more than two beam relaying states, including in the vector input data fully on and fully off states plus either a gray state or a phase shifting state;

driving the mirrors having the complex reflection coefficients to emulate one or more sub-printing resolution serifs.

13. The method of claim 12, wherein one or more pattern edges are defined by the SLM using at least one mirror oriented to have a complex reflection coefficient with a negative real part, emulating one or more of the methods of lithographic image enhancement.

14. The method of claim 12, wherein the converted vector data is used to drive the mirrors having the complex reflection coefficient with a negative real part to a phase edge as contrasted with one or more adjacent mirrors.

15. The method of claim 12, wherein the converted vector data is used to drive the mirrors having the complex reflection coefficient with a negative real part to emulate phase interference between areas of a CPL mask.

16. The method of claim 12, wherein the converted vector data is used to drive the mirrors having the complex reflection coefficient with a negative real part to emulate an alternating aperture phase-shifting mask.

17. The method of claim 12, wherein the converted vector data is used to drive the mirrors having the complex reflection coefficient with a negative real part to emulate a three-tone phase-shifting mask.

18. The method of claim 12, wherein the converted vector data is used to drive the mirrors having the complex reflection coefficient with a negative real part to emulate a high transmission attenuating phase-shifting mask.

19. The method of claim 12, wherein the driving the mirrors having the complex reflection coefficient with a negative real part to produce a jog in a line pattern, is enhanced by a phase difference between adjacent mirrors of the SLM.