Wafer thinning development continues

02/01/2002

FREMONT, CALIF. - The latest advance in the active area of wafer thinning was announced by ChipPAC. The packaging sub-contractor recently qualified the processes required to thin 300 mm wafers down to 150 microns. According to Marcos Karnezos, CTO at ChipPAC, the plan is to extend the capability further, so that 300 mm wafers can be thinned to 100 - 125 microns, matching the current capability with 200 mm wafers.

ChipPAC uses mechanical back-grinding and a new mechanical polishing step to thin the wafer. The polishing is done to relieve the stress created by the backgrinding, so that the residual stress that would cause a bow in the thin wafers is eliminated. These processes were chosen because they leverage equipment and infrastructure that already exist in the packaging industry. Processes that are more typical of wafer front-end processing, such as chemical polishing and plasma etching, are also candidates for wafer thinning, but they are currently less-common in packaging facilities.