DEPTH MEASUREMENT OF THROUGH SILICON VIA BY USING IR CONFOCAL MICROSCOPE
Authors: Deh-Ming Shyu, Wei-Te Hsu and Yi-Sha Ku Company: Industrial Technology Research Institute Date Published: 10/11/2010
IWLPC (Wafer-Level Packaging)
Abstract: Laser scanning confocal microscope (LSCM) offers the ability to control depth of field, and capability to collect serial optical sections from measurement samples. Thus, it can be used for the measurement of the through silicon via (TSV) depth. In our optical system, the infrared laser source illuminates the wafer from the bottom surface for backside measurement to penetrate a polished silicon surface. The wavelength of the infrared laser source used in LSCM is 1.31um. We developed a novel method to extract the bottom via profile by processing the infrared image of a bottom via. In the experiment, the widths of via are from 30um to 150um and the depths are around 100um. These targets are measured by the IR LSCM system and the results are verified by the cross-section scanning electron microscope (SEM) results.