A warpage of wafer level bonding for CIS (CMOS Image Sensor) device using polymer adhesive

The polymer adhesive bonding technology using wafer-level technology was investigated to adhere silicon to glass wafer and it analyzed warpage caused in cemented wafer and the degree of intensity. We executed the wafer adhesion depending on temperature (130degC, 190degC), the pressure (5000 N, 8000 N), the height of the adhesive layer (10 mum, 20 mum) and the adhesive time (process time, the time for temperature rising) of each of the silicon and glass wafer. The warpage was measured using three-dimensional measuring equipment and the results were caused by the differences of CTE and the physical stress. It was also confirmed that the more the temperature of Si wafer, adhesive pressure and adhesive layer was lowered in order to improve the warpage results, the more warpage decreased, and that the adhesive time and temperature differences of glass wafer were relatively insufficient factors. To judge the degree of wafer adhesion, the shear intensity was tested and it showed that the higher the adhesive temperature of glass wafer was, the more degree of shear intensity it showed, and that the other conditions showed little effects. Also, in the center of the adhesive wafer where the warpage occurred showed that the more it was getting to the edge, the more shear intensity decreased, and that the stress related with the occurrence of warpage also had effects on the state of adhesion.