Hi,
I have been dealing with gold surface roughening issue after I anneal my samples at 450C for 15 min in forming gas in an RTA furnace. Attached please find images showing a few areas after gold evaporation deposition and lift-off (left) and the same area after annealing (right). The gold thickness is roughly 250 nm, and is evaporated on top of a 25 nm Ti which itself is evaporated on a 80 nm TiN film. There was no vacuum break between Ti and gold evaporation. The substrate is silicon.
I suspect I'm seeing gold reflow; although RTA is done well below gold melting point.
Any thoughts and comments on what's happening and how to prevent it are highly welcomed.
Best,
Alireza
I don't have any experience with gold annealing. I suspect gold grain growth or recrystallization. Do you have any SEM or EBSD images?
The physical dimensions of the gold layer remain, thus the deposited layer does not reflow. What happens is that the gold crystals grow and the crystal structure is improved.
Hi Valentin, Thanks for raising the issue. The thing is, I have seen droplet looking bits n pieces of gold. Do you think it is possible that parts of the substrate become substantially hotter and thus gold actually melted?
- Badges
- Science topic
- Similar topics
- Comment