"Fear of cross contamination is a primary concern with using copper on wafers," says Paul Miller, VP and general manager of KPI's Silicon Wafer Division. "Kobe's wafer reclaim process uses a patented combination of chemical and mechanical steps to not only completely remove the copper from the copper wafers, but also to protect the non-copper wafers from contamination."
KPI's silicon wafer reclaim process provides several barriers to prevent copper cross contamination risk while also removing minimal silicon from the substrate, which translates into lower cost of ownership. Proprietary segregated chemical baths and precise reconditioning of all surfaces of the wafer are key elements that protect KPI's downstream processes from cross contamination. KPI has confirmed the process using copper wafers from several leading semiconductor customers. Analysis of reclaimed copper wafer surfaces show surface copper levels of less than 110atoms/cm2.
Competitive copper wafer reclaim processes are based on mechanical lapping or strictly chemical means. These have several downfalls. Mechanical lapping techniques remove twice as much silicon as KPI's process. They also do not address the edge of the wafer. Chemical processes are not good at controlling cross contamination since copper can dissolve and plate onto non-copper wafers without visible evidence.
Monitoring copper contamination on a wafer is difficult since the analysis is expensive and done on only a small percentage of the wafers. Thus, the best defense is a reclaim process designed with multiple barriers to cross contamination.
Founded in 1987, KPI is a subsidiary of Japan's Kobe Steel Ltd., and is a leading supplier of disk substrates for the hard disk drive industry with 450 employees. KPI branched into the silicon wafer reclaim market in 1993 to enter the semiconductor materials market. Company sales have grown to more than $100 million per year.
For more information, call Paul Miller at KPI at 510-487-3200.