As suggested by Mr. Bill Moffat, spray it for longer period of time so that the
PI thickness is more than your feature depth, i.e. 1-5um. You can try to lower
the RPM for your spin coating to have higher thickness of PI.

  Best of luck.

Bill Moffat  wrote:
  Spray. Bill Moffat

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of kris
Sent: Thursday, June 29, 2006 5:21 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] Planar deposition of PI 2610

Hello All,

I am trying to deposit(spin) polyimide PI 2610 on the substrate that has
features ranging from 1 to 5um in depth. I am spinning PI2610 for the
planar deposition on the top of the etched features. I need 1um thick
ployimide.

After spinning the PI at 4000 r.p.m. for 30 seconds, i can see the PI
deposition as a conformal deposition rather than the planar deposition.
I can see that the etched pits were covered only by 1um Polyimide. I
want the features to be filled up completely. I dont want any crests or
troughs on the sample when i scan the profilometer over the features.

In short, can someone suggest me the procedure to get the planar
deposition of the PI2610 on the substrate that has different depth
features.