Development of the half-angle divergence metrology applied to the inner-layer exposure facility for PCB industry

Abstract

According to the requirement of a precisely exposing process of PCB, how well you controlled the beam expanding and guaranteed the half-angle divergence in the PCB inner-layer exposing facility would be significant obviously. Shack-Hartmann (SH) wavefront sensor is a powerful and robust tool focusing on wave front sensing, meanwhile, which had a good performance even compared with interferometer or shearing interferometer so as to do highly accurate metrology applied to many other fields like position sensing and ocular optics. It’s also available about making sure of the beam quality of the exposing light module in the semiconductor industry. The paper claimed that we adopted an array-type sub-wavelength annular aperture (SAA) micro-structure (12x12) to build up a new wavefront sensing system instead of a conventional micro-lens array. The metrology resolution was limited by its feature size of the micro-lens array about several hundred micrometers. Our proposed design can achieve the specific characteristics of the long depth of focus and sub-wavelength focusing capability, so our prior device would be obviously more suitable for highly precise wavefront measurement.