Patterning SU-8 for DRIE process

[D. Zhou]

Dear all,

I am trying to use SU-8 photoresist as the etch mask for the DRIE etch of
Si substrate ( ~5um (or above) thick resist is needed). Did anyone have any
experiences in this? What is the selectivity of the typical Bosh process
between SU-8 and Si? And how can I pattern it (typical recipe for UV
exposure and development)? I have not used SU-8 before and hope someone can
give me a hand. Many thanks.

Best wishes,
--
Xiang Zhou
PhD candidate
Semiconductor Physics Group
Cavendish Laboratory
University of Cambridge
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[Florian Herrault]

Hi Xiang,

I am surprised that your cleanroom allows you to use SU-8 as a mask for ICP
etching. SU-8 will dramatically contaminate your chamber. Why don't you use
thick negative resist ? Plus, it will be hard to remove your SU-8 etch mask
once your DRIE etch is done... I don't see any advantages to go for a SU-8
mask. Could you please give more information ?

typical recipes for SU-8 resist can be found on microchem.com

Regards,
Florian

Post by D. Zhou
Dear all,
I am trying to use SU-8 photoresist as the etch mask for the DRIE etch of
Si substrate ( ~5um (or above) thick resist is needed). Did anyone have any
experiences in this? What is the selectivity of the typical Bosh process
between SU-8 and Si? And how can I pattern it (typical recipe for UV
exposure and development)? I have not used SU-8 before and hope someone can
give me a hand. Many thanks.

--
Florian Herrault, PhD student
Georgia Institute of Technology
791 Atlantic Dr., Atlanta, GA 30332-0269
ph: 404-894-9909; fax: [phone]
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[D. Zhou]

Hi Florian,

Thanks very much for your message. Actually I know nothing about SU-8 at
all. The reason why I am considering SU-8 as a candidate for the DRIE mask
is that it could be thick. I tried S1828 (the thickest positive resist
available in our group) with low spin speed but still could not reach the
required thickness. Silcon dioxide is the perfect mask but our facility
broke down and will not be ready in September. According to your
suggestion, what negative resist can I use for this purpose? How thick can
it be? And how to pattern it?

Xiang

Post by Florian Herrault
Hi Xiang,
I am surprised that your cleanroom allows you to use SU-8 as a mask for ICP
etching. SU-8 will dramatically contaminate your chamber. Why don't you use
thick negative resist ? Plus, it will be hard to remove your SU-8 etch mask
once your DRIE etch is done... I don't see any advantages to go for a SU-8
mask. Could you please give more information ?

--
Da-xiang Zhou
PhD candidate
Semiconductor Physics Group
Cavendish Laboratory
University of Cambridge

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provider of MEMS and Nanotechnology design and fabrication services.
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[Brubaker Chad]

If positive resist is okay, and your only limitation is film thickness, there are several other candidates:

Rohm & Haas SPR220 (4.5 or 7.0)
AZ Electronic Materials AZ9260 or AZ9245

All of these materials can easily be coated in excess of 5 µm (for the thicker films, up to 65µm is possible in a single coat with specialized coating equipment).

If you need even thicker, there is AZ50XT from AZ Electronic Materials, and SIPR7123M20 from Shin Etsu.

Best Regards,
Chad Brubaker

EV Group invent * innovate * implement
Technology - Tel: [phone], Fax: [phone] e-mail: ***@EVGroup.com, www.EVGroup.com

-----Original Message-----
From: mems-talk-***@memsnet.org [mailto:mems-talk-***@memsnet.org] On Behalf Of D. Zhou
Sent: Monday, July 31, 2006 9:06 AM
To: General MEMS discussion
Subject: Re: [mems-talk] Patterning SU-8 for DRIE process

Hi Florian,

Thanks very much for your message. Actually I know nothing about SU-8 at
all. The reason why I am considering SU-8 as a candidate for the DRIE mask
is that it could be thick. I tried S1828 (the thickest positive resist
available in our group) with low spin speed but still could not reach the
required thickness. Silcon dioxide is the perfect mask but our facility
broke down and will not be ready in September. According to your
suggestion, what negative resist can I use for this purpose? How thick can
it be? And how to pattern it?
_______________________________________________
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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[Hongjun-ECE]

Xiang,

As Florian has said, SU8 is not a good masking material. Generally SU8 is
good for fabricating devices or molding masters, but not mask. If you want
to use negative resist, S5214 might be OK for you considering your Si
etching is only several microns (piece of cake for Bosch tube!).

Good luck,

Hongjun

------------------------------------
Hongjun Zeng, PhD
MEMS/Nano Scientist
Nanotechnology Core Facility
(NCF formerly MAL)
University of Illinois at Chicago
3064 ERF Building
842 W. Taylor St., Chicago, IL 60607
Tel. [phone], Fax: [phone]
------------------------------------



-----Original Message-----
From: mems-talk-***@memsnet.org [mailto:mems-talk-***@memsnet.org]
On Behalf Of D. Zhou
Sent: Monday, July 31, 2006 9:17 AM
To: MEMS_BBS
Subject: [mems-talk] Patterning SU-8 for DRIE process

Dear all,

I am trying to use SU-8 photoresist as the etch mask for the DRIE etch of
Si substrate ( ~5um (or above) thick resist is needed). Did anyone have any
experiences in this? What is the selectivity of the typical Bosh process
between SU-8 and Si? And how can I pattern it (typical recipe for UV
exposure and development)? I have not used SU-8 before and hope someone can
give me a hand. Many thanks.
_______________________________________________
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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[li cai]

Can anyone advise me where to buy 5' Si (100) wafers?

Thank you in advance.

Li
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