Dicing of optical wafer level packages

The optical wafer level packaging, developed by Schott Advanced Packaging, consists of a Silicon wafer, comprising the optical sensors, which is bonded to a glass wafer in the very first process step to protect the sensors. The package utilizes a via through contact through the Silicon by contacting the bond pads of the image sensor from the backside. By this approach, a package for optical sensors that is manufactured has virtually the same lateral dimensions as the image sensor by itself (Leib and Topper, 2004) and (Viswanadam, et. al., 2005). As typical for any wafer level packaging application, the last step of the manufacturing flow is the singulation of the Si-Glass compound using a standard dicing saw for board assembly of the chips. Depending on the specific process flow of the SCHOTT opto package, the final dicing has to be performed either through a Si-glass compound, or only through the glass. Both approaches have their benefits and trade-offs under design and manufacturability point of view. This paper describes the effects of glass and silicon thickness and dicing speeds on dicing of glass-silicon bonded wafers without dicing streets. The study compares various glass and silicon thickness and cutting speeds and observing their impacts to sidewall cracks/chipping