Si(004) measurements of wafer curvature due to the stress introduced by PECVD/HDP SiN films in wafer fabrication

摘要

Thin film deposition process invariably introduces compressive or tensile stress in the films. The stress in a film causes the wafer to warp whose curvature is estimated in a wafer fab using optical reflectance technique. Alternatively, the wafer curvature can also be measured using the high resolution XRD (HRXRD) Si(004) rocking curves. In this paper, the HRXRD technique was employed to evaluate the stress in PECVD and HDP SiN films deposited on blanket Si wafers (prime-grade material) which were subjected to different Xe ion-implant energy conditions. It will be shown that stress-matching in PECVD and HDP SiN can be achieved by tuning Xe implant energy. From the change in the width of Si(004) peak, a qualitative assessment regarding the quality of single crystal Si lattice will be presented which is not possible to measure with optical reflectance methods.