[mems-talk] Extreme wafer bow after eutectic Au-Si waferbonding

[P.E.M. Kuijpers]

Hi all,

In our project we use a Au-Si wafer-to-wafer bonding, which works quite
good. After bonding wafer bow was measured and we found a compressive bow
of 280µm!! of the total stack
Before bonding bow was also measured, Patterned Au wafer: 40µm, patterned
SOI wafer 30µm. Thickness Au wafer 380µm, thickness SOI wafer 540µm.
Bonding settings: heating up to 200°C, apply pressure 2000mbar, heating up
to 380°C, cooling down
Has anyone an idea how to overcome this problem??? Any kind of help would
be appreciated.

Regards,
Peter Kuijpers
Philips