Specific Process Knowledge/Wafer cleaning/IMEC

IMEC process for cleaning of wafers before fusion bonding:

Step	Process	Details	Comments	Comments
4.0	Pre bonding cleaning of Si wafers with cavities and SOI wafers with nitride		Use wafers with cavitys on and SOI wafers Takes 1½ hours Orient flat to minimize handling Preferable done just before bonding!	Get CLEAN box for wafers!!!
4.1	Piranha	Mixture: H2SO4:H2O2 (4:1) Temp: 80 degC Time: 5 min (en gul og en sort prik)	Clean tank (cleanroom 4) and make your own or make in dedicated glass. Pour up H2SO4 first, put wafers in carrier (USE this in steps4.1-4.6), add H2O2, wait 30 sec, dip wafers.	Maybe clean the tank the day before! Put into dedicated wet box for IMEC
4.2	Rinse	2 min rinse		Put into dedicated wet box for IMEC
4.3	IMEC	DI water:5% HF:isopropanol (100:10:1) Temp: 25 degC Time: 100 sec (to sorte prikker)	Clean tank (cleanroom 4) and make your own, it needs 2 bottles Bottle in service room 2 on the left, pump by Leica microscope in cleanroom 3	Bottle for mixing is in service room 2, use bHF pump from RCA fumehood! Put into dedicated wet box for IMEC
4.4	Rinse	2 min rinse
4.5	Piranha	Not nitride wafers! Mixture: H2SO4:H2O2 (4:1) Temp: 80 degC Time: 20 min	Reuse previous piranha Makes wafers hydrofilic	Put into dedicated wet box for IMEC
4.6	Rinse & spin dry	5 min rinse		Put into dedicated wet box for IMEC
4.7	Put wafers in new clean carrier box