Wafer bonding for CMOS integration and packaging

The use of CMOS wafers imposes important limitations for W2W (Wafer-to-Wafer) or C2W (Chip-to-Wafer) bonding: low processing temperature (max. 400°C), no mobile ions and extreme cleanliness. Additional to substrates preparation a special focus is directed on cleaning and maintaining the wafers clean during processing. Special cleaning processes were adopted for CMOS-compatible applications. The main challenges raised by CMOS-compatible wafer bonding in terms of processing and process control were identified and process solutions will be presented illustrated with examples.