Hello
The etch takes place with a silicon wafer suspended over the top surface of
an HNA bath. The bath consists of two chambers - the bottom of the HNA (Top)
chamber has an array of small holes from which N2 is introduced. N2 is
hooked into the bottom chamber and the flow is dependent on size of bath.
The object of the N2 is to agitate the HNA at a level to uniformly
introduce fresh HNA to the surface of the substrate and result in a uniform
etch. I have used this process with various HNA ratios for deep silicon
etch (up to 125 microns thindown) 50-100u with a NiCr mask(1000A)
and < 10 micron etch for 25u geometries with a nitride mask.
6-1-1 gives an average etch rate of ~12 1/2 microns/min.
I understand a controlled/cold etch bath also works well, but this is "cheap
& dirty" and works.
Liz
> From: "il-seok Son"
> Reply-To: mems-talk@memsnet.org
> Date: Sun, 17 Feb 2002 00:02:08 -0600
> To:
> Subject: Re: [mems-talk] ISOTROPIC Silicon etching
>
> Hi, Liz.
>
> Would explain how the bubble etch process is different to the conventional
> wet etching process?
>
> Thanks in advance.
>
> ----- Original Message -----
> From: "Liz Shelley"
> To:
> Sent: Friday, February 15, 2002 8:09 AM
> Subject: Re: [mems-talk] ISOTROPIC Silicon etching
>
>
>> Hello Avi
>> Do you have more details regarding your process?
>> agitation
>> Undercut profile/aspect ratio
>> etch rate
>> etc.,
>>
>> We use a bubble etch process (bleeding N2 through 6-1-1 HNA)
>> for 250u silicon SC180 &SC450 resist., but I'm always interested in
> other's
>> technique:success.
>> Liz
>>
>>> From: Avi.Laker@teccor.com
>>> Reply-To: mems-talk@memsnet.org
>>> Date: Thu, 14 Feb 2002 11:37:39 -0600
>>> To: mems-talk@memsnet.org
>>> Subject: [mems-talk] ISOTROPIC Silicon etching
>>>
>>> We routinely etch 50 to 75u silicon in production using a 2:1:1
>>> (Nitric,HF, Acetic) etch at
>>> 6'C with SC450 resist as the mask with or without underlying oxide. The
>>> resist is a negative
>>> tone resist made by Arch.
>>> The resist etch rate is 0.
>>>
>>> Contact me if you need further details.
>>>
>>> avi
>>>
>>> Avi Laker
>>> Teccor Electronics
>>> 972 756 8237 Office
>>> 214 439 6770 Pager
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>> _______________________________________________
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> _______________________________________________
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> Visit us at http://www.mems-exchange.org/