Specific Process Knowledge/Bonding/Fusion bonding: Difference between revisions
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==Fusion Bonding== | ==Fusion Bonding== | ||
Fusion bonding is a relative weak bond between e.g. two clean Si wafers. It is absolutely necessary for the wafers to be very clean and to be annealed at | Fusion bonding is a relative weak bond between e.g. two clean Si wafers. It is absolutely necessary for the wafers to be very clean and to be annealed at 1000°C afterwards to avoid and minimize defects. Fusion bonding can be made as a Si to Si direct bonding or with SiO<math>_2</math> layers in between. It is also possible to use nitride in between but it should be close to 100% particle free. We have good experience with Sintef but unfortunately not with the old DANCHIP nitride furnace. | ||
Please be advised that it is notoriously difficult to use the EVG NIL bond aligner, due to its manual nature it is strongly advised to book extra time to do alignment. However alignment of ±2 microns is possible by very experienced users. The alignment marks (on the masks) are to be positioned at y=0 and x=±40mm for 4", for optimal result. It is possible to use both backside alignment and IR alignment however IR alignment is more accurate, since only one aligning is used. However it is very important to use dobbelt polished wafers to have enough IR light to see the patterns. | Please be advised that it is notoriously difficult to use the EVG NIL bond aligner, due to its manual nature it is strongly advised to book extra time to do alignment. However alignment of ±2 microns is possible by very experienced users. The alignment marks (on the masks) are to be positioned at y=0 and x=±40mm for 4", for optimal result. It is possible to use both backside alignment and IR alignment however IR alignment is more accurate, since only one aligning is used. However it is very important to use dobbelt polished wafers to have enough IR light to see the patterns. | ||