[labnetwork] Piranha & HF no rinse protocols

[Olona, Leonard E.]

Greetings Errol,

Here at OU one of our main wet bench uses in the CR is wafer preparation for IV/VI MBE growth.   Shiraki Clean is the method of choice.  Its really just a fancy RCA clean with solvent metal cleaning in the beginning of the process.

As our other colleagues stated…  DI rinse is highly recommended post HF or any other type of acid dip.

And to take it a bit further,  the way the rinse is performed is very important.   One must stride to employ a steady stream of decent research grade DI.   A small trickle of low resistivity DI into a beaker just wont cut it.   If you can provide ~18Mohm with a high volume of flow- you will be set!     You really need to have the samples placed vertical in the boat or holder.   That way the DI rinse can do its thing in a uniform fashion.   I've seen folks submerge the samples horizontally which proved to be a poor way of rinse.  Bubbles propagate and get stuck in between the samples/wafers.

I have seen a weak flow of say ~2000ml / 4min  @10Mohm DI barely cut it when your looking for a nice sheeting action of the sample.   After boosting our DI system to provide an actual 17.86Mohm at gallons of flow per minute we now have excellent results in wafer preparation.

A QDR (quick dump rinse) is ideal,  but that system requires some serious infrastructure.  Simply stated.   A good strong rinse with the highest grade (18 Mohm) DI water is the best for results and safety.

I hope this helps!  Don’t forget your PPE!

-Len

Leonard E. Olona
University Cleanroom Manager
University of Oklahoma
110 West Boyd Street Rm 550
Norman, Oklahoma  73019
D: +1- 405 325-4374
C: +1- 405 630-9068
F: +1- 405 325-7066



From: "Errol V. Porter" <evporte at uark.edu<mailto:evporte at uark.edu>>
Date: Wednesday, February 26, 2014 4:43 PM
To: "labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>" <labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>>
Subject: [labnetwork] Piranha & HF no rinse protocols

Greetings,

I am trying to get a consensus and feedback from the group on a wet etch process using 1st H2SO4:H2O2 (1:1) and 2nd HF:H2O (10:1) where the water rinse is omitted. If this is an acceptable practice in some special circumstances, what safeguards to you put in place to protect the users.

Regards,

Errol Porter
University of Arkansas / HiDEC
700 W. Research Center Blvd
Fayetteville, AR 72701
Tel. (479) 575-2519
Mobile: (479) 236-0693
Fax (479) 575-2719
email: evporte at uark.edu<mailto:evporte at uark.edu>
http://www.hidec.uark.edu<http://www.hidec.uark.edu/>

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