Inspection System Using 193nm Laser

An inspection system for inspecting a surface of a sample, the inspection system comprising:

• an illumination subsystem configured to produce a plurality of channels of light, each channel of light produced having differing characteristics from at least one other channel of light, the illumination subsystem including a light source configured to emit an incident light beam of approximately 193.368 nm wavelength, the light source including a fundamental laser configured to generate a fundamental frequency having a corresponding wavelength of approximately 1064 nm, a fifth harmonic generator module configured to use the fundamental frequency to generate a fifth harmonic frequency, an optical parametric (OP) module configured to down convert an unconsumed fundamental frequency of the fifth harmonic generator module and to generate an OP output having a frequency approximately equal to a half harmonic of the fundamental frequency, and a frequency mixing module configured to receive and combine the fifth harmonic frequency and the OP output to generate the incident light beam with the approximately 193.368 nm wavelength light;
• optics configured to receive the plurality of channels of light and combine the plurality of channels of light into a spatially separated combined light beam and direct the spatially separated combined light beam toward the sample;
• and
• a data acquisition subsystem comprising at least one detector configured to detect reflected light from the sample,
• wherein the data acquisition subsystem is configured to separate the reflected light into a plurality of received channels corresponding to the plurality of channels of light, and
• 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.

A catadioptric imaging system comprising:

• an ultraviolet (UV) light source configured to generate UV light having an approximately 193.368 nm wavelength light, the UV light source including a fundamental laser configured to generate a fundamental frequency having a corresponding wavelength of approximately 1064 nm, a second harmonic generator module configured to double the fundamental frequency and generate a second harmonic frequency, an optical parametric (OP) module configured to down convert a portion of the second harmonic frequency and to generate an OP signal of approximately 1.5ω and an OP idler at approximately 0.5ω, wherein ω is the fundamental frequency, a fourth harmonic module configured to double another portion of the second harmonic frequency of the OP module and generate a fourth harmonic frequency, and a frequency mixing module configured to combine the fourth harmonic frequency and the OP signal to generate the UV light having the corresponding wavelength of approximately 193.368 nm;
• adaptation optics;
• an objective including a catadioptric objective, a focusing lens group, and a zooming tube lens section;
• and
• a prism for directing the UV light along an optical axis at normal incidence to a surface of a sample and directing specular reflections from surface features of the sample as well as reflections from optical surfaces of the objective along an optical path to an imaging plane,
• wherein the fundamental laser comprises a neodymium doped mixture of gadolinium vanadate and yttrium vanadate.