[labnetwork] Deep Reactive Ion Etch Problems

[Matthew Moneck]

Hi Pallavi,

What is the make and model of your DRIE?  Also, what is the mask you are using for the etch?

The grass is typically a result of micromasking that occurs when either the chamber needs to be conditioned (i.e. you have an abundance of polymer in the chamber) or when you have an etch mask that re-sputters onto the wafer surface.  If it is due to the chamber conditions, you will need to perform a cleaning followed by a conditioning process.  The vendor will typically have a recommended procedure.  There are other potential causes too, but the chamber conditions and/or re-sputtering are the two most common in my experience.

Best Regards,

Matt

--
Matthew T. Moneck, Ph.D
Executive Manager, Claire & John Bertucci Nanotechnology Laboratory
Electrical & Computer Engineering | Carnegie Mellon University
5000 Forbes Avenue, Pittsburgh, PA 15213-3890
Phone:  412-268-5430
ece.cmu.edu<http://www.ece.cmu.edu>
nanofab.ece.cmu.edu<http://www.nanofab.ece.cmu.edu>

From: labnetwork-bounces at mtl.mit.edu <labnetwork-bounces at mtl.mit.edu> On Behalf Of Pallavi Sharma
Sent: Monday, July 27, 2020 12:02 PM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] Deep Reactive Ion Etch Problems

Hello all,

I am having problem with anisotropic etching of silicon by Deep Reactive ion etch. Grass or black silicon is the issue all the time, attaching some of the SEM pictures of the sample. Every recipe I tried to fine tune result in grass formation, even as the process initiates in tool wafer surface starts to turn brown and ultimately black. I tried varying SF6 gas flow, Bias power, Substrate temperature but every time I see is highly dense grass with no clean surface.
Any help will be greatly appreciated.

Thank you,
Pallavi

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