durusmail: mems-talk: Are there any 'safe' (non-hf) isotropic etches?
Are there any 'safe' (non-hf) isotropic etches?
2013-09-20
Nathan McCorkle
2013-09-20
David Casale
2013-09-20
Bill Moffat
2013-09-20
Nathan McCorkle
2013-09-24
Mike Whitson
2013-09-24
Mike Whitson
2013-09-23
André Bödecker
2013-09-24
Dave
2013-09-25
Mike Whitson
2013-09-25
Kirt Williams
2013-09-27
Nathan McCorkle
Are there any 'safe' (non-hf) isotropic etches?
Mike Whitson
2013-09-24
Do you have access to a XeF2 vapor etch system?  While I haven't personally
worked with it, the etch is fast, close to isotropic (pure chemical process, no
plasma), has very high selectivity of Si over photoresists, and a typical system
will handle containment and purge of the toxic gas rather than expose the user
to any risks of handling directly.  Might be worth considering for your
purposes?

Also, for patterning trenches with different etch processes in the same Si
layer, you might want to consider a reflowable trench fill coating to enable
multiple photo steps on the same layer.  I know Brewer makes things like that,
maybe MicroChem has a workable product as well?  (This is not a personal
endorsement of any product or vendor; I just happen to have seen their
advertising.)  Both companies can give you all kinds of suggestions if you call
their technical sales folks and discuss your process requirements.

http://www.brewerscience.com/gap-fill-systems
http://microchem.com/Appl-MEMs-Via.htm

Good luck,
Mike


On Sep 20, 2013, at 13:19, Nathan McCorkle  wrote:

> Bill, I actually posted the question, not David.
>
> This is for microfluidics. I'm trying to get curved AND square
> channels. It looks like I can't have these on the same layer, unless I
> use FIB maybe, but then that limits production rates in the future
> (when I'm not making just one device). The two channels are next to
> each other and positioned perpendicular, when the square channel is
> pressurized it cuts off flow in the curved channel.
>
> http://www.kni.caltech.edu/foundry/graphics/msl-ex2.gif
> http://www.stanford.edu/group/foundry/images/Microfluidic_valve_technology_cli
p_image011.jpg
>
> I'm going to use a DLP projector as a digital photomask, so inverting
> the color is a simply photoshop operation. What's the functional
> difference between positive and negative resist other than whether it
> inhibits or activates hardening? Do only positive resists have glass
> transition states?
>
>
> On Fri, Sep 20, 2013 at 9:16 AM, Bill Moffat
>  wrote:
>> David not clear on your question. If you are trying to create a resist
profile that has vertical lines image reversal can do this.  Using the flood
exposure it is possible to go from a negative resist angle of 22 degrees,
through vertical to a positive 22 degrees in controllable stages. Contact me at
YES for free trials.  Bill Moffat 925 373 8353.
>>
>> Sent from my iPad
>>
>> On Sep 20, 2013, at 7:22 AM, "Nathan McCorkle"  wrote:
>>
>>> I'm working on microfluidics and think I can use PDMS castings
>>> directly on my photoresist for square channels, but the resist looks
>>> like swiss-cheese up close when it's defocused to create a curved
>>> profile, so I think my only option is to pattern then isotropic etch,
>>> ash/wash away resist, then cast with PDMS.
>>>
>>> Seems that HF based solutions are my only google hits...I've used HF
>>> once or twice before and the local lab I plan on working in has HF
>>> already, but I remember being pretty wary of the HF. I occasionally
>>> bump or spill things, not /that/ often, but I'd rather play with safer
>>> chems if possible. I guess driving my car might be more dangerous
>>> statistically, but I feel there's a little more wiggle room in
>>> something like driving!
>>>
>>> Anyway, any recommendations would be great. I don't have any process
>>> setup yet so I'm flexible.
>>>
>>> --
>>> -Nathan
>>> _______________________________________________
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>> Hosted by the MEMS and Nanotechnology Exchange, the country's leading
>> provider of MEMS and Nanotechnology design and fabrication services.
>> Visit us at http://www.mems-exchange.org
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>
>
>
> --
> -Nathan
> _______________________________________________
> Hosted by the MEMS and Nanotechnology Exchange, the country's leading
> provider of MEMS and Nanotechnology design and fabrication services.
> Visit us at http://www.mems-exchange.org
>
> Want to advertise to this community?  See http://www.memsnet.org
>
> To unsubscribe:
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