Annealing

[MartChic]

a) Cleaning

Usually, samples are cleaned before annealing, is it necessary in this case ?

b) Process

• Ramp from RT 110 C, ramp rate of 1.5 C/min.
• Hold at 110 C for 12 hours.
• Ramp down to RT (can be faster than ramp up).

c) Location

Garret raised the possibility of annealing inside the bonder. Should we perform annealing in LMA oven or inside the bonding tool (to limit the risks associated with transportation)? Is annealing part of the FAT?

d) Interrogations

Can a difference between GaAs and SiO2 CTE (coefficient of thermal expansion) induce mechanical stress leading to cracks or delamination ? This phenomenon increases with the surface of bonding. Is it part of the FAT?

[MartChic]

Garrett Cole comments:

Usually, samples are cleaned before annealing, is it necessary in this case ?

There is no need to clean before anneal. In this case the maximum anneal temperature is ~110 °C.

Garret raised the possibility of annealing inside the bonder. Should we perform annealing in LMA oven or inside the bonding tool (to limit the risks associated with transportation)? Is annealing part of the FAT?

Either works. If it simplifies things, just anneal in an external oven. Van der Waals bond is more than sufficient to keep parts joined during handling.

Can a difference between GaAs and SiO2 CTE (coefficient of thermal expansion) induce mechanical stress leading to cracks or delamination ? This phenomenon increases with the surface of bonding. Is it part of the FAT?

Yes, but only if heated > 200 °C in my experience. Following the ramp process outlined above, this is fine.