Patent ID: 7554654

Claim:
An inspection system for inspecting a substrate, the inspection system comprising: a radiation beam source for producing a radiation beam, first optical elements for selectively diverting the radiation prior to the radiation beam impinging upon the substrate, the inspection system being in a scatterometer mode when the radiation beam is diverted in a first direction, and the inspection system being in an interferometer mode when the radiation beam is diverted in a second direction, second optical elements for receiving the radiation beam only when the inspection system is in scatterometer mode, and for directing and focusing the radiation beam onto the substrate at a non-perpendicular angle to a surface of the substrate, a first sensor for receiving the radiation beam as it is reflected from the substrate only when the inspection system is in scatterometer mode, and for making scatterometry measurements, third optical elements for receiving the radiation beam prior to the radiation beam impinging upon the substrate only when the inspection system is in interferometer mode, and for directing and focusing the radiation beam onto the substrate at a perpendicular angle to the surface of the substrate, fourth optical elements for diverting the radiation beam along two light paths when the inspection system is in interferometer mode, the second optical elements also for rejoining the two light paths after a first of the two light paths has reflected the radiation beam off of the substrate and a second of the two light paths has reflected the radiation beam off of a reference surface, and a second sensor for receiving the rejoined radiation beam when the inspection system is in interferometer mode, and for making interferometry measurements, where the first sensor and the second sensor are two separate sensors, and the first optical elements, the second optical elements, the third optical elements, and the fourth optical elements are all separate optical elements.