All-

I've looked thru archives without many leads on this topic.

Can anyone recommend a supplier, or name a process, to form shallow
conically bored holes [120 deg included angle] in a .013  inch thick
sapphire [Al2O3] substrate, approx .50 inch by .50 inch in size?

Application is IR detector chips, 0.10 inch square, straddling these small
conterbored holes on a single sapphire substrate.

Info on fabricators, or university researchers, having insight to plausible
processes, would be greatly appreciated!

Thanks,

Michael Alderete
Sensors & Elec Products, Boeing Anaheim CA