Inspection System Using 193nm Laser

摘要

Improved inspection systems utilize laser systems and associated techniques to generate an ultra-violet (UV) wavelength of approximately 193.368 nm from a fundamental vacuum wavelength near 1063.5 nm. Preferred embodiments separate out an unconsumed portion of an input wavelength to at least one stage and redirect that unconsumed portion for use in another stage. The improved laser systems and associated techniques result in less expensive, longer life lasers than those currently being used in the industry. These laser systems can be constructed with readily-available, relatively inexpensive components.

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 configured to emit an incident light beam along an optical axis, the light source including a fundamental laser for generating a fundamental frequency having a corresponding wavelength of approximately 1064 nm, an optical parametric (OP) module configured to down convert the fundamental frequency and to generate an OP output having a frequency approximately equal to a half harmonic of the fundamental frequency, a fifth harmonic generator module configured to generate a fifth harmonic frequency, and a frequency mixing module configured to receive and combine the fifth harmonic frequency and the OP output to generate a laser output with the approximately 193.368 nm wavelength light; an optical system disposed along the optical axis and including a plurality of optical components for directing the incident light beam to a surface of the photomask, reticle or semiconductor wafer, the optical system being configured to scan the surface; a transmitted light detector arrangement including transmitted light detectors, the transmitted light detectors being arranged for sensing a light intensity of transmitted light; and a reflected light detector arrangement including reflected light detectors, the reflected light detectors being arranged for sensing a light intensity of reflected light, wherein the fundamental laser comprises one of neodymium-doped yttrium aluminum garnate, neodymium-doped yttrium orthovanadate, and a neodymium-doped mixture of gadolinium vanadate and yttrium vanadate.