Nanometer-level alignment to a substrate-embedded coordinate system

Abstract

The authors describe a method that uses infrared (IR) radiation to detect alignment on the nanometer level between grating marks on the front side of a template and a checkerboard-type mark on the back side of an IR-transparent, double-side-polished substrate. The mark can cover the entire substrate back side. No alignment marks are required on the front of the substrate. A back-side-specific mark is utilized with λ=1065nm illumination to detect alignment within σ=0.4nm.