Dear Nathan,

What equipment do you have access to, and what are you masking with?  Are
you etching completely through a 20-30 micron film, or only partially
through a thicker film (i.e. is your goal to completely remove the exposed
material or only etch part way)?

If you just need to etch glass isotropically, I would imagine that HF or
buffered oxide etchant should work just fine provided that your mask
material sticks around long enough.  I can't comment on HF or BOE's ability
to produce optical-quality surfaces, however.  You might try experimenting
with different mask materials/resists (Ed Sebesta recently sent out some
good information on positive vs. negative resists) if delamination is an
issue.  I would avoid gold hard masking though, as gold tends to adhere
poorly to glass surfaces.

Another thought: is there a post-etch treatment (maybe thermal annealing)
you can perform on your polycarbonate substrate to remove the optical
blurring?  Something of an analog to flame polishing glass?

Best regards,

Brian C. Stahl
Graduate Student Researcher
UCSB Materials Research Laboratory
brian.stahl@gmail.com / bstahl@mrl.ucsb.edu
Cell: (805) 748-5839
Office: MRL 3117A


On Tue, Nov 3, 2009 at 1:52 PM, Nathan McCorkle  wrote:

> I am currently working with lexan (polycarbonate) and am experiencing
> optical blurring when I use O2 plasma etch for too long, as well as
> warping. I have decreased power and time to alleviate this problem,
> but it takes many more runs to achieve the 20 - 30 micron etches that
> I desire.
>
> I asked an advisor about switching to glass, maybe a quartz or
> borosilicate, and he said that I would need a gold hard mask to get
> around having mask lift off during etch. I feel like there should be
> some way to get a nice isotropic etch with a glass, using the current
> lab equipment that we have.
>
> Any ideas?
>
> Nathan McCorkle