When you coat (spin?) 20-30um resist over 24um high 3D structures,
what does the resist profile look like? Do you have cross-section
photos? How about uniformity over the wafer area - any "speedboats"?

Greetings,
        Frank Berauer
        Senior R&D Engineer
        HP IJMS Singapore


-----Original Message-----
From: Onnop Srivannavit [mailto:[email protected]]
Sent: 2 October 2001 18:03
To: BERAUER,FRANK (HP-Singapore,ex7)
Subject: RE: [mems-talk] spin photoresist after releasing the structure


Hi

In my case, I have 3 level steps, 24, 100 microns and
thru hole. To reduce nonuniformity coating
1. I use thick PR (can get 20-30 microns) after 24
microns structure formed.
2. after I form 100 microns structure, I use backside
alingment to get thru hole wafers.

Your question is very interesting. If you don;t mind,
please share the results of  your questions you get.
Thanks,.

Onnop
PhD candidate.
University of Michigan
Ann Arbor, MI
48109

--- "BERAUER,FRANK (HP-Singapore,ex7)"
 wrote:
> Hi,
>
> In our experience, spin is not a good option on 3D
> structures
> due to non-uniform coating, and in the extreme case
> uncovered
> areas, in the "shadow" of a released structure
> (which we call
> "speedboats" due to the similarity in shape to the
> trace a fast
> boat leaves in water). Spray coating gives better
> results, but
> uniformity on 3D structures is still not good due to
> surface
> tension, which retracts resist from protruding
> corners and accu-
> mulates it in cavities. Spraying is also not
> suitable for thin
> layers (7-10um being the minimum).
> We are also working with electrophoretic resist
> (plating from
> a watery solution), which is completely uniform on
> all surfaces
> in all directions - but process and material
> compatibilities
> pose a different set of challenges.
> Our structures are big enough that damage due to
> spinning is
> not a problem.
> Hope this helps. Greetings from Singapore!
>
> Frank Berauer
> Senior R&D Engineer
> Hewlett-Packard IJMS Wafer Fab
>
>
> -----Original Message-----
> From: Yong Zhu [mailto:[email protected]]
> Sent: 27 September 2001 14:23
> To: [email protected]
> Subject: [mems-talk] spin photoresist after
> releasing the structure
>
>
> Hello, MEMS friends;
>
> Does anyone have experience to spin photoresist
> after releasing the
> structure, such as comb drive?
> I am wondering if the spin will damage the suspended
> device. I would like to
> get some idea before
> I make the design. Thank you.
>
> Yong
> _______________________________________________
> mems-talk mailing list
> [email protected]
> To unsubscribe or change your list options, use:
>
>
http://fab.mems-exchange.org/mailman/listinfo/mems-talk
> _______________________________________________
> mems-talk mailing list
> [email protected]
> To unsubscribe or change your list options, use:
>
http://fab.mems-exchange.org/mailman/listinfo/mems-talk
Listen to your Yahoo! Mail messages from any phone.
http://phone.yahoo.com