litho process for STS etch

Luan_Van at Luan_Van at
Wed Nov 14 10:52:19 PST 2001

Minor correction the problem statement.  The gray spot in the center and
somtimes near the edge of the wafer--of what I had assumed to be completely
etched resist--still has a thick layer of resist, but it has become
hardened due to the poor heat transfer.  It becomes gray, and I can see
under the microscope that that the resist has flowed and looks like strands
of bacteria.

Your suggestions are appreciated.


From: Luan Van/ETEC/APPLIED MATERIALS at AMAT on 11/14/2001 09:50 AM

To:   stsetch at at ETECEXCH
Subject:  litho process for STS etch

Dear users,

I'm currently having problems with my AZ9245 resist--coated in my company's
fab--about 17-20um thick getting etched completely within an hour.  I mount
my 200um wafer on a carrier wafer with about 2um of resist in between, and
bake it in a 120C oven for 3hr with a heavy object on top of it.

I want to etch 10um trenches that are 200um deep, which typically takes 3
hours on the STS etcher.  I hear that the SPR220-7 resist has a higher etch
resistance.  Does any one have this similar problem?  Can someone
recommend a process for me using the SPR220-7 resist (thickness, bake time,
exposure time, and development time)?  Also, how do you mount the carrier
wafer (resist thickness, bake time, any tricks)?

Thanks very much.

Luan Van
Process development engineer
Etec Systems, an AMAT Co.

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