A Novel High Temperature Resistant Temporary Bonding Material for Ultra-thin Wafer Handling: Superior Room Temperature Bonding, Heat Curing and Mechanical De-bonding Performances

With the development of semiconductor end products toward miniaturization, digitization and intellectualization, the advancement of Moore’s Law is approaching its physical limit little by little. To resolve this issue, advanced packaging has been perceived as the optimal strategy, leading to an increasing performance requirement for temporary bonding material (TBM), such as sufficient thermal resistance, chemical resistance and lower TTV (total thickness variation) value. Herein, a new high temperature resistant TBM without any solvents incorporating is introduced and several measurements were performed on its curing behavior and properties. The curing reaction could be immediately initiated at a higher temperature over 100 ℃ confirmed by temperature scanning test and differential scanning calorimeter (DSC). Thus, to ensure enough curing can be obtained, the TBM was required to cure at 160 ℃ for 15 min. As expected, it exhibits excellent high temperature thermal stability by TGA test. More importantly, the TBM presented superior performances on TBDB process. The average film thickness is 18.33 μm and TTV value is just 0.13 μm. As the material is liquid and easy to flow, it can be well bonded at ambient temperature without any residual stress. After curing, thinning and chemical mechanical polishing (CMP) processes were conducted, the device wafer was able to be reduced to 70 μm. Then the ultrathin wafer bonding pair was treated by PVD at high temperature and high vacuum, the quality reliability was evaluated using scanning acoustic microscopy (SAM), and there was no void can be detected. Next, a room temperature mechanical de-bonding process was employed for the bonding pair and it can be successfully released without any damages on the device wafer. At last, a specific solvent was applied to clean the TBM by means of bathing. The cleaning effect was characterized by X-ray spectroscopy (EDS) and there was no residual can be observed by comparing to the blank glass wafer.