An air turbulence compensated interferometer: IC manufacturers´ metrology needs translated into system component requirements

Summary form only given. A new interferometric system has been developed, which is designed to meet the needs of high-end IC manufacturing in the immediate future. High-precision positional measurements during the lithographic exposures for IC manufacturing are critical to the ability to fabricate fine geometry circuits at high yield. The positional measurements are provided by high-performance interferometers, which are limited in performance principally by the turbulent air inside the lithographic exposure tool (a stepper). These turbulent-air-induced positional errors typically have a magnitude in the range of 10 to 100 nm. Our new system is a combination of the conventionally used HeNe-based interferometer system and a second colinear system based on second-harmonic interferometry (SHI).