Wafer sawing process characterization for thin die (75micron) applications

The drive for package thickness reduction has created new processing challenges with regards to thin wafer handling. While back-grinding and die attach film (DAF) lamination are now established procedures, sawing DAF-laminated wafers with wafer thickness 3 mils and below is still a significant challenge. The need is for a suitable saw process that meets the following criteria: less than 1 mil wafer chipping, low cost and high throughput. This paper elaborates work that evaluated different saw parameters and their effects on wafer chipping. 8" wafers with varied die sizes and 2 in 1 DAF-dicing material sets were used during this evaluation. The work evaluated both single and dual pass saw processes. The effects of saw parameters-feed speed, RPM and blade types are also elucidated. The results show that for thin die a dual pass saw process gives better results than a conventional single pass process. Results also show that using non-optimized saw process parameters for a given DAF material set combination could adversely affect the yield consequent assembly processes like die attach and wirebond.