Thanks: RE: Etching small features in Si

Rohan D. Kekatpure rohank at
Thu Nov 4 09:31:02 PST 2004

Hi All,

Thank you very much for the suggestions/solutions on my question about 
etching narrow features in Si. Heres the summary of  the feed-back I got in 
last two days:

(1) LamPoly: This seems to be the machine of choice for most people. 
Specifically, I was suggested to use the HBR/O2 chemistry.

(2) P5000: This is an equally good etcher with a similar chemistry and 
people have got straight sidewalls upto 85degrees. But it may require a 
little more tuning than Lam.

(3) AMTEtcher: This is a via etcher and is capable of etching narrow 
features. But it suffers from poor selectivity to oxide hard-masks. Metals 
are allowed as stops but not as masks.

(4) Drytek: Mixed feedback. People were mainly concerned about undercutting.

(5) STS: Did not receive much feed back on this one except that the etch 
rate is very fast and that it produces scalloping along the sidewalls.

Many thanks again to all the lab-members who shared their inputs. It was 
indeed very helpful.


-----Original Message-----
From: Rohan D. Kekatpure [mailto:rohank at]
Sent: Tuesday, November 02, 2004 1:07 PM
To: labmembers at
Subject: Etching small features in Si

Hi all,

I am trying to etch ~ 200-250nm wide trenches in Silicon with an aspect
ratio of about 1:2 to 1:3. I have an oxide hard mask and it is not critical
that I stop perfectly on some material (eg., oxide etc). About 5 degrees
tilt in the sidewalls is also tolerable. I am looking for a first order
guess on what chemistry (Fluorine, Chlorine, SF6 etc) to use and which
instrument would be best suited for this purpose.

Thank you in advance!


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