Hello,

a pretreatment of the gold layer is recommended to have a better result.
This could be a activation with a Piranha solution to eliminate the organic
impurities. The native oxide on the silicon can hamper the bond, since it
has to be removed to.
To have a successful bond result it is necessary to have a good uniformity
of temperature and bond pressure of course.
At first evacuate the chamber and purge it. Then heat up to the melting
point 363 degree Celcius, wait at that temperature for 2min and bring the
substrates in contact and apply the pressure. Keep the pressure for at least
10min. Finally cool down with applying pressure.

Best Regards,
Volkan Cetin