[labnetwork] Si RIE etch

Wed Mar 8 13:36:46 EST 2017

That’s a good call by Bernard actually, just looking at your numbers again you are already working over 12% which is rather high for a CF4 process.

Best Regards,

Stuart

________________________________
Dr Stuart Pearce
Senior Process Engineer and Cleanroom Manager

华为技术有限公司 Huawei Technologies (UK) Co., Ltd
[cid:image001.jpg at 01D1B042.F1D20CA0]

Phone: +44 147 366 3153
Email: stuart.pearce at huawei.com<mailto:stuart.pearce at huawei.com?subject=Email%20Query>
Web:  http://www.huawei.com<http://www.huawei.com/>
Web:  http://www.ciphotonics.com

CIP Technologies is the trading name of The Centre for Integrated Photonics Ltd., a wholly owned subsidiary of Huawei Technologies (UK) Co., Ltd.
Registered Office: - Phoenix House, Adastral Park, Martlesham Heath, Ipswich, Suffolk IP5 3RE.
Registered in England no. 4905488
________________________________
本邮件及其附件含有华为公司的保密信息，仅限于发送给上面地址中列出的个人或群组。禁
止任何其他人以任何形式使用（包括但不限于全部或部分地泄露、复制、或散发）本邮件中
的信息。如果您错收了本邮件，请您立即电话或邮件通知发件人并删除本邮件！
This e-mail and its attachments contain confidential information from HUAWEI, which is intended only for the person or entity whose address is listed above. Any use of the information contained herein in any way (including, but not limited to, total or partial  disclosure, reproduction, or dissemination) by persons other than the intended recipient(s) is prohibited. If you receive this e-mail in error, please notify the sender by phone or email immediately and delete it!

From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Bernard Alamariu
Sent: 08 March 2017 13:39
To: Jugessur, Aju S <aju-jugessur at uiowa.edu>; labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] Si RIE etch

Hello,
CF4/O2 ratio is too high, I think.
I suggest to do a run without O2 first, just to check it.
Then try it with no more than 1-2% O2; however I see you are using very very low flow rate for O2
and making it even low you might reach the MFC accuracy limits. I suggest to increase accordingly
the CF4 flow rate to allow 1-2% O2 flow, and try to maintain the pressure value.

Some comments and suggestions:
The CF4 plasma etch was the first one used to etch SiO2, Si3N4 and Si more than 40 years ago.
The German LFE barrel reactor machine was one of them.
The main problem was its selectivity to Si, which was solved by adding H2 and He for safety reasons.
Then was the etch rate which was not stable; it was discovered that the O2 desorbed from the Quartz walls
was the culprit. The chamber process history counted.
Then it has been established that adding ~ 1-2% of Oxygen increases the etch rate and makes it
repeatable, while adding more than 3% quenches the the etch rate.
Practically an even higher etch rate was observed by using industrial O2 from a tank, which adds
more impurities!
The scientific explanation was based on the so named " Second Order Atomic Collision" phenomena.
The main etching specie is CF3- molecular ion.
Its plasma concentration is increased by adding some Oxygen which enhances its ionization rate, by
the second order atomic collision. The O2 is brought by RF plasma in a long lifetime metastable
energy state higher than the CF4 ionization energy; by inelastic collision O2 transfer this extra energy
to CF4 and increases its ionization rate.
The low O2 concentration acts like a ionization catalyzer. More O2 is an inhibitor.
There are old papers in the Journal of Physical Chemistry around 1973, etc.
Thanks, Bernard

On 3/7/17 1:14 PM, Jugessur, Aju S wrote:
Hi,

I have a user who is using the following Si etch recipe on our Oxford NGP80 etcher:

RF power: 100 W
Pressure: 100 mT
CF4 flow rate: 25 sccm
O2 flow rate: 3.1 sccm

The etch rate from the above parameters is ~ 0.15 microns/min.
The selectivity is 1:3.
 Can anyone suggest what parameters to tweak to increase the etch rate without causing too much substrate damage or roughness?

Thanks for your suggestions.

Regards
Aju

Aju Jugessur Ph.D.
Director, University of Iowa Microfabrication Facility
Professor (Adj.), Physics and Astronomy
OSTC, Iowa Advanced Technology Labs
University of Iowa

205 N. Madison St
Iowa City, IA 52242
319 -353-2342
aju-jugessur at uiowa.edu<mailto:aju-jugessur at uiowa.edu>
http://ostc.uiowa.edu/uimf

_______________________________________________

labnetwork mailing list

labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>

https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20170308/7205911d/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.jpg
Type: image/jpeg
Size: 2827 bytes
Desc: image002.jpg
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20170308/7205911d/attachment.jpg>