Diffraction-based overlay metrology from visible to infrared wavelengths using a single sensor

Background: Integrated circuits are fabricated layer by layer. It is crucial to their performance that these layers well aligned each other, and any undesired translation of a called overlay. Thus far, overlay measurements have been limited visible wavelengths, but the use materials opaque wavelengths necessitates using infrared light. Aim: We set out demonstrate an sensor based on digital holographic microscopy can perform such measurement at while maintaining functionality wavelengths. Approach: This was done constructing breadboard setup capable measuring ranging from 400 1100 nm. Results: Using setup, we demonstrated good linearity between applied amount measured amount. In addition, only sensitive structures top wafer. Measurements therefore unaffected fact Si transparent Conclusions: These results viability light, allowing more freedom in choice for integrated circuits.