Chuan Seng, 1. Typically if you are doing a plasma assisted direct bond with Oxide wafers, you will need to consider a chemical clean (SC1/SC2) 2. From personal experience, best bond results come from Chem clean w/DI rinse -> Plasma activation -> DI megasonic clean -> bond initiation -> anneal 3. Typically the most critical aspect is exposure time. However, the type of plasma tool you are using will dictate the parameters needed. If you would like, we could run some samples for you using our SOI bonding equipment. Please contact me directly with questions. Best Regards, Brian Douglas Suss Microtec Inc. Applications Engineer - Bonders Phone: (802) 244 - 5181 x202 Fax: (802) 560 - 0001