Method of exposing a light sensitive material

• US 5,539,568 A
• Filed: 06/07/1995
• Issued: 07/23/1996
• Est. Priority Date: 06/16/1994
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Brown, Jay M., Gustafson, Steven C., Palmer, Shane R., Lin, Tsen-Hwang
• Primary Examiner(s): Ben, Loha
• Application Number:
  US08/478,157
• Time in Patent Office: 412 Days
• Field of Search: 359/281, 359/285, 359/254, 359/263, 359/315, 359/318, 359/291, 359/294, 359/295, 359/245, 359/224, 359/226, 359/230, 385/37, 430/5, 430/311, 372/26, 372/27
• US Class Current: 359/285
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G03F 1/26 Phase shift masks [PSM]; PSM blanks; Preparation thereof
• CPC Class Codes: G03F 7/2002 with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
• CPC Class Codes: G03F 7/70191 Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like
• 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 7/70566 Polarisation control

Abstract

A phase shift illuminator (700) is comprised of a light source (704) and a phase modulator (716), typically a flexure beam micromirror array, which transversely modulates the incident light beam. When a flexure beam micromirror array is used as the phase modulator (716) a polarizing beam splitter (712) and a quarter-wave plate (714) are used to separate the incident and reflected light beams. The phase modulated light beam (720) from the optical illuminator may be used in optical lithography by passing the light beam through a lithography mask (724), typically after the light beam is phase modulated, and focusing the light beam onto a target wafer (726).

Claims

1. A method of exposing a light sensitive material, said method comprising the steps of:

transversely phase modulating a beam of light in response to at least one electrical control signal;

spatially modulating said beam of light; and

focusing said phase and spatially modulated beam of light onto said light sensitive material, wherein said step of transversely phase modulating maximizes a destructive interference among portions of said phase and spatially modulated beam of light.

2. The method of claim 1 wherein said step of transversely phase modulating said beam of light comprises reflecting said beam of light with a flexure beam micromirror device.

3. The method of claim 1 wherein said step of spatially modulating said beam of light comprises passing said beam of light through a lithography mask.

4. The method of claim 1 wherein said focusing step comprises focusing said phase and spatially modulated beam of light onto a photoresist.

5. The method of claim 1 further comprising the step of sweeping said focused beam of light across the surface of said light sensitive material, wherein said step of spatially modulating said beam of light further comprises varying the spatial modulation of said beam of light in concert with said sweeping step.

6. The method of claim 5 wherein said step of transversely phase modulating said beam of light further comprises varying the phase modulation of said beam of light in concert with said sweeping step.