System and method for custom-polarized photolithography illumination

Abstract

In one embodiment, a system for custom-polarized photolithography illumination includes an illuminator operable to generate an illumination pattern of light, a polarizer unit operable to variably polarize the light, and a mask pattern defining photolithographic pattern features in two dimensions. The mask pattern is associated with a mask capable of transmitting at least a portion of the variably polarized light through the mask pattern.

Description

TECHNICAL FIELD OF THE INVENTION [0001] This invention relates generally to photolithography systems and more particularly to a system and method for custom-polarized photolithography illumination. BACKGROUND OF THE INVENTION [0002] Achieving increasingly smaller line resolutions in semiconductor photolithography requires exposure tool systems with increasingly larger numerical apertures. As the numerical aperture increases, light transmitted through the lens illuminates the semiconductor wafer at Brewster's angle, which prevents light polarized parallel to the plane of incidence from coupling to the photoresistive material on the wafer. Conventional photolithography systems use unpolarized, circularly polarized, or linearly polarized illumination. In the case of unpolarized or circularly polarized illumination, interference of electrical fields exacerbated by Brewster angle effects can lead to a significant reduction in contrast for the resulting photolithographic image, decreasing...

AI Technical Summary

Benefits of technology

"The present invention provides a system and method for custom-polarized photolithography illumination. The system includes an illuminator, a polarizer unit, and a mask pattern. The method involves generating an illumination pattern, varying the polarization of the light, and transmitting the light through a mask pattern. The invention allows for variable polarization of light specific to a desired illumination pattern, resulting in optimum line and space printing of a photolithographic image and smaller images than conventional techniques. The invention also allows for printing photolithographic images in two directions using a single mask during a single exposure to the variably polarized light."

Problems solved by technology

In the case of unpolarized or circularly polarized illumination, interference of electrical fields exacerbated by Brewster angle effects can lead to a significant reduction in contrast for the resulting photolithographic image, decreasing the resolution of the system.

In systems where light is linearly polarized, significant contrast loss may prevent geometry from being printable on the wafer.

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