Vapour Injection is a system that delivers the vapour directly into the chamber for in-situ surfaces treatment, without exposing the wafers to atmosphere.
In direct bonding, water is important to initiate Hydrogen bonding that bridges the surfaces together. It is important to deliver the right amount of wafer – too much will create unwanted annealing voids and too little will prevent the initial bond from forming.
Vapour injection can be used in two different processes:
1. Water vapour - following the RAD activation for low temperature direct bonding (read more about RAD activation)
2. Acid vapour, used in metal bonding for metal oxide reduction.
Acid treatment can be used for metal oxide reduction and can increase the yield and decrease the required process temperature and bonding force.
Formic acid vapour can be used for Cu or In bonding. This in-situ chemistry is made possible by the large gap that can be maintained between the wafers during the pre-alignment stage, thus enabling access to the wafer surfaces. The in-situ alignment capability is then used to align and contact the wafers before the native oxide can regrow.
Did you know?
Our injection system allows delivery of a controlled amount of water needed for achieving an excellent bond strength but without compromising the bond quality.