193nm laser and inspection system

摘要

An improved solid-state laser for generating sub-200 nm light is described. This laser uses a fundamental wavelength between about 1030 nm and 1065 nm to generate the sub-200 nm light. The final frequency conversion stage of the laser creates the sub-200 nm light by mixing a wavelength of approximately 1109 nm with a wavelength of approximately 234 nm. By proper selection of non-linear media, such mixing can be achieved by nearly non-critical phase matching. This mixing results in high conversion efficiency, good stability, and high reliability.

主权项

1. An optical inspection system for inspecting a surface of a photomask, reticle, or semiconductor wafer for defects, the system comprising:
a light source for emitting an incident light beam, the light source including a frequency mixing stage for combining light at a wavelength of approximately 1109 nm with light at a wavelength of approximately 234 nm to generate light at a wavelength between 190 nm and 200 nm; an optical system including a plurality of optical components for directing the incident light beam to a surface of the photomask, reticle or semiconductor wafer; optics for collecting at least two channels of light reflected or transmitted from the photomask, reticle or semiconductor wafer, and relaying that light to a sensor; and a sensor that simultaneously detects the at least two channels of light, wherein the optics further comprises at least one electro-optic modulator to reduce a coherence of the light at a wavelength between 190 nm and 200 nm.