Hi all, do you know any method to improve the adhesion between the silicon substrate and the indium solder?
I am measuring the photocurrent from a device at a low temperature. The electrode is made of gold, on a Silicon substrate. I use indium soldering to connect the gold electrode with gold wire and connect it to the circuit. At room temp, the indium soldering sticks well to the gold electrode/Si substrate. The problem is when I cool down the temperature, the soldering always peels off from the Si substrate. I tried to solve this using silver paint, but it does not help. Do you know any method to overcome this issue?
Thank you very much
Dear Minh Pham,
See relevant information below:
https://physics.stackexchange.com/questions/207985/how-to-make-electrical-connection-to-silicon-wafer-for-testing
https://www.sciencedirect.com/topics/engineering/solder-bump
https://www.researchgate.net/publication/268291977_Evaluation_of_Thin_Film_Indium_Bonding_at_Wafer_Level
www.researchgate.net/publication/258297269_Low-temperature_thin-film_indium_bonding_for_reliable_wafer-level_hermetic_MEMS_packaging
You may want to deposit a patch of Ti, Cr, Al, Ta, Mo, or Nb to the substrate. Although Cr and Ti are the most commonly used to interface oxide substrates with metals like Au, any (1) layer of the metals that I listed above should work well. A stable bond is the result and you only need 5-10 nm of it deposited under the gold. Hope that helps.
Instead of soldering use sputtering process using other metal protecting outer surface/opening window..
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