A Novel Backside Process to Achieve 1-mil Thick Wafers at 6-inch Foundry

摘要

A manufacturable 1-mil backside process with high quality and high yield has been successfully developed and demonstrated at WIN Semiconductors' 6-inch foundry to accommodate customer's need. The key differences between the existing 4mil/2mil backside process and the newly developed 1-mil process are compared and discussed. Modified mount/demount and cleaning procedures to reduce the thermal shock are presented. It has been found that stress reduction of plated Au films with the plating condition optimization and the increase in Au thickness for supporting are effective in reducing the 1-mil wafer breakage rate. A selective plating process has also been implemented on the 1-mil wafer to ensure, a higher backside yield. Greater than 95% scribe and break yield has been achieved with excellent quality after optimization on the scribe and break process.