Question about etching InAlAs/InGaAs - Alternative masking layers

Crystal Rose Kenney ckenney at
Sun Aug 17 15:40:22 PDT 2008

In my experiments I have an MBE stack of InAlAs and InGaAs materials. I need to etch down about 150nm and place contacts in those holes. I was initially planning on using photoresist as my mask layer, first by opening the areas to etch and then evaporating metal into the holes and doing liftoff. 

However, because of the high bias needed to etch InAlAs that doesn't look like a viable option. I do not wish to use two lithography steps of the same mask layer (karlsuss mask) because I am concerned about misalignment issues since I need good contact of metal on the sides of the contact holes. Are there other masking layers that could be used in this case? I need something that could stand a high bias (possibly using pquest) for etching and then use the same mask layer to evaporate metal and then have some way of removing said mask layer. 

I'm also open to suggestions for alternative processing steps. Thank you in advance for your help.

~Crystal Kenney

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