Development of super-resolution optical inspection system for semiconductor defects using standing wave illumination shift

Semiconductor design rules and process windows continue to shrink, so we face many challenges in developing new processes such as 300mm wafer, copper line and low-k dielectrics. The challenges have become more difficult because we must solve problems on patterned and un-patterned wafers. The problems include physical defects, electrical defects, and even macro defects, which can ruin an entire wafer rather than just a die. The optics and electron beam have been mainly used for detecting of the critical defects, but both technologies have disadvantages. The optical inspection is generally not enough sensitive for defects at 100nm geometries and below, while the SEM inspection has low throughput because it takes long time in preparing a vacuum and scanning 300mm. In order to find a solution to these problems, we propose the novel optical inspecting method for the critical defects on the semiconductor wafer. It is expected that the inspection system’s resolution exceed the Rayleigh limit by the method. Additionally the method is optical one, so we can expect to develop high throughput inspection system. In the research, we developed the experimental equipment for the super-resolution optical inspection system. The system includes standing wave illumination shift with the piezoelectric actuator, dark-field imaging and super-resolution-post-processing of images. And then, as the fundamental verification of the super-resolution method, we performed basic experiments for scattered light detection from standard particles.