Development of high accuracy wafer thinning and pickup technology for thin wafer

We have evaluated accurate wafer thinning and picking up die technology around 10μm thickness. In order to achieve the thickness accuracy of 10±1μm, glass attachment accuracy is very important. TTV (Total thickness variation) was improved from 3.0μm to 1.4μm by using a high accuracy glass substrate and adjustment of glass attachment condition. Glass attachment condition improved a glass loading power, time and a size of the flatting disk which is a glass loading unit. For picking up the ultra thin dies, we have evaluated slide peel method. In order to verify the best overhang amount, which is the width between a die edge and a slider edge, the simulation and the analysis of the picking up action were performed. In the result of the simulation and the analysis, we judged overhang amount: 0.3mm was the best. We also evaluated 4 layer WOW grinding and dicing. Wafer TTV became 1.0 μm by using NCG (Non Contact Gauge) and auto TTV function. NCG could measure the thickness of grinding layer correctly without influence of the multi reflection from other layers. The targeted value TTV: 1.4μm was able to achieved. And we obtained the prospect of dicing 4 layers WOW. We selected a dicing blade consisting of #3000 diamond powder, and rotation speed of a blade was selected 60,000 rpm.