From mtang at stanford.edu  Fri Dec 10 16:43:43 2010
From: mtang at stanford.edu (Mary Tang)
Date: Fri, 10 Dec 2010 16:43:43 -0800
Subject: Lampoly update (it's up!)
Message-ID: <4D02C93F.5000504@stanford.edu>

Dear lampoly users:

The machine is conditionally up.  It tunes beautifully now, thanks to 
expert attention from Jim McVittie. A couple of issues to note, however:

1.  DC bias is lower than before.  Increasing RF power to the bottom 
electrode doesn't increase DC bias.  General etch qual results look 
good(see below); however, profile has not yet been confirmed with SEM.   
Please check before committing your critical wafers.

2.  Jim observes that HBr/O2 only (no chlorine) recipes, such as #25, do 
not tune quickly and even exhibit some plasma instability for 30 
seconds.  This is not a machine problem, but one of the chemistry.  Jim 
has shown that 10 seconds of a standard recipe 1 main etch (step 5) 
allows very fast tuning/stable plasma for HBr/O2 recipes.  This is 
something we should look into for people using these recipes.

3.  The receiver cassette wafer present sensor sometimes fails, 
particularly on some wafers with certain backside films.  This needs to 
be adjusted or replaced, but in the meantime, please make sure wafers 
unload into the receiver cassette -- watch your wafers!  If a wafer is 
not sensed, it can go back into the exit loadlock and back into the 
chamber.  This could result in damaged/broken wafers.


Etch rate results (resist on silicon, etched on Recipe 1):
Silicon etch depth = 3985A
%nonunifomity = 1.3%
Silicon to resist etch selectivity = 4.5X
Everyone:  please share your observations with lampoly etch users.
Thanks.

-- 
Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
(650)723-9980
mtang at stanford.edu
http://snf.stanford.edu