Etching fused silica wafers in PQuest ECR etcher

Michael Wiemer mwiemer at
Mon Sep 12 17:13:09 PDT 2005

Are we etching Fused Silica in the chamber these days? As I remember the
gases needed for that were CF4 + other stuff (maybe O2, Ar).  I am worried
that the CF4 can polymerize in the chamber under the right circumstances
(particularly while developing a process).
Anybody have any thoughts on this? Jim McVittie perhaps?

-----Original Message-----
From: Nickolai Belov [mailto:nbelov at] 
Sent: Monday, September 12, 2005 4:01 PM
To: pquest at
Cc: Nickolai Belov
Subject: Etching fused silica wafers in PQuest ECR etcher

Dear PQuest user,


I would like to etch fused silica wafer at PQuest ECR etcher.

The wafer is 4" with SEMI standard flat. Wafer thickness is 500 um.


I consider two options of doing that:


Option 1 

Mount fused silica substrate on a silicon carrier wafer using small pieces
of Kapton tape and etch the fused silica wafer this way.

Kapton tape will not go under the clamps in the system and will not go to
the back side of the carrier wafer.


Option 2

Etch fused silica wafer without carrier wafer.


Concern with the first option is overall thickness of the stack (about 1
mm). Most likely this thickness is ok.


Concern with the second option is breakage of the fused silica wafer due to
clamping in the chamber.


I incline to the first option as it is safer.

Please, let me know if you have any relevant experience / recommendations.

If I don't have definite response then I'll try to find answer either in the
PQuest documentation or contacting the manufacturer.


With respect


Nickolai Belov


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