US 5,302,477 A · Inverted phase-shifted reticle

Abstract

A phase-shifted reticle with patterns proximate each other having inverted phases for the features and phase-shifting elements, and methods of fabricating the reticle, are disclosed. In a preferred embodiment, the inverted reticle is used to form an array of closely spaced contact or via openings. For a first pattern on the reticle, the feature will be the 0.degree. phase and the phase-shifting rim surrounding that feature will be the 180.degree. phase. All patterns surrounding the first pattern have phase-shifting rims of the 0.degree. phase and features of the 180.degree. phase. In this way, each pattern can form below conventional resolution features in the resist. Additionally, there will not be exposure of the regions between the closely spaced features since radiation transmitted through the closely spaced phase-shifting rims of the two patterns is 180.degree. out of phase.

Claims21

Dependent claims

A reticle for use in patterning a radiation sensitive layer on a lithographic printer having a numerical aperture (NA), an image reduction factor (IRF) and an exposing radiation wavelength (.lambda.), comprising:

a first region, said first region transmitting at least a portion of radiation incident thereon;
a second region proximate said first region, said second region comprising a phase-shifting element for said first region, said second region transmitting at least a portion of radiation incident thereon, wherein radiation transmitted through said second region is phase shifted approximately 160-200 degrees relative to radiation transmitted through said first region;
a third region disposed within approximately 0.55 IRF *.lambda./NA of said second region, said third region transmitting at least a portion of radiation incident thereon, wherein radiation transmitted through said third region is phase shifted approximately 160-200 degrees relative to said second region;
and,
a fourth region proximate said third region, said fourth region transmitting at least a portion of radiation incident thereon, wherein said third region comprises a phase-shifting element for said fourth region, and wherein radiation transmitted through said fourth region is phase shifted approximately 160-200 degrees relative to said third region.

2 more elements

A method of patterning a radiation sensitive layer comprising the steps of:

providing a substrate having said radiation sensitive layer;
exposing said radiation sensitive layer on a lithographic printer having a numerical aperture (NA), an image reduction factor (IRF) and an exposing radiation wavelength (.lambda.), using a reticle comprising:
a first region, said first region transmitting at least a portion of radiation incident thereon;
a second region proximate said first region, said second region comprising a phase-shifting element for said first region, said second region transmitting at least a portion of radiation incident thereon, wherein radiation transmitted through said second region is phase shifted approximately 160-200 degrees relative to radiation transmitted through said first region;
a third region disposed within approximately 0.55 IRF *.lambda./NA of said second region, said third region transmitting at least a portion of radiation incident thereon, wherein radiation transmitted through said third region is phase shifted approximately 160-200 degrees relative to said second region;
and,
a fourth region proximate said third region, said fourth region transmitting at least a portion of radiation incident thereon, wherein said third region comprises a phase-shifting element for said fourth region, and wherein radiation transmitted through said fourth region is phase shifted approximately 160-200 degrees relative to said third region.

4 more elements

Dependencies are inferred from the claim text.

Inverted phase-shifted reticle

Life of this patent

Inverted phase-shifted reticle

Life of this patent

Abstract

Claims21