Backside Chipping Improvement Study On Hybrid Bonding Process

The next generation of electronic devices such as micro-dimensional integration is playing a more and more important role and direct wafer bonding (fusion bonding and hybrid bonding of Cu/Dielectric damascene patterned surfaces) has been getting extra attention due to the capability of enhancing system performance. After bonding, two kinds of diamond abrasive processes, namely wafer backside grinding and edge trimming, are normally processed to realize significant Si thickness reduction. In edge trimming, due to the high rotation speed of diamond blade working at the wafer edge, the chipping and delamination at the wafer edge is easily suffered. According to the damage region caused by edge trimming, chipping can be defined as Front Side Chipping(FSC) and Back Side Chipping(BSC). In this paper, the mechanisms of the formation of BSC between fusion bonding and hybrid bonding is discussed. In addition, blade selection and trimming parameters optimization is investigated. The main parameters of blade include the abrasive grit size(Factor1), the resin adhesive(Factor2) and the proportion of chip pockets(Factor3). For the trimming parameters, feed speed of blade and cutting depth of wafer were detail investigated. The results indicated with a smaller abrasive size of diamond between 5-8μm, according to adjustment of cutting depth, better BSC performance can be achieved.