37.2.2. Ex situ Alignment and Bonding
Precise in situ alignment in the bond chamber is not possible for bonding technologies requiring high contact force and high temperature for the wafer-bonding process.
Due to this, the two processes are separated in two steps (Figure 37.1). In this process separation, the flow is the following:
- Wafers are loaded to the wafer-to-wafer aligner (bond aligner).
- Wafers are aligned (manually or automatically) and mechanically fixed on a bond chuck. If controlled atmosphere is required at the bonding interface (inside devices) the two wafers are mechanically separated by spacers.
- Bond chuck is loaded to the bond chamber. The bond chamber can be evacuated down to high vacuum range and bonding ...