The In material etch process on the PQ is run hot. The chuck temp is set
to around 170C with the sample running near 200C. This is too hot for a
resist mask. You to use either an oxide or a nitride mask. The selectivity
to oxide is around 10:1.
Jim
On Sun, 17 Aug 2008, Crystal Rose Kenney wrote:
> 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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Jim McVittie, Ph.D. Senior Research Scientist
Allen Center for Integrated Systems Electrical Engineering
Stanford University jmcvittie@stanford.edu
Rm. 336, 330 Serra Mall Fax: (650) 723-4659
Stanford, CA 94305-4075 Tel: (650) 725-3640
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