All-reflective optical systems for broadband wafer inspection

Abstract

All-reflective optical systems for broadband wafer inspection are provided. One system configured to inspect a wafer includes an optical subsystem. All light-directing components of the optical subsystem are reflective optical components except for one or more refractive optical components, which are located only in substantially collimated space. The refractive optical component(s) may include, for example, a refractive beamsplitter element that can be used to separate illumination and collection pupils. The optical subsystem may also include one or more reflective optical components located in substantially collimated space. The optical subsystem is configured for inspection of the wafer across a waveband of greater than 20 nm. In some embodiments, the optical subsystem is configured for inspection of the wafer at wavelengths less than and greater than 200 nm.

Dependencies are inferred from the claim text.