Request to bring new chemicals Nickel Etchant TFG

Mary Tang mtang at
Thu Apr 2 17:03:10 PDT 2009

Hi Leo --

This should be OK to use.  Please do the following:

1.  When your chemical arrives, contact a staff member about getting a 
yellow label and a barcode label.  These should be filled out placed on 
the bottle.  The chemical should be stored in the Corrosives chemicals 
passthrough.  Please contact a staff member about getting access to 
store this.  (It should be stored in the personal chemicals area, 
outlined in red tape.)

2.  You should contact Uli about using the hot plate at wbgaas.  I 
believe there are new procedures. 

3.  Make sure to collect the waste and rinse water in a chemically 
compatible, appropriately labeled container for hazardous waste pickup.  
This should not be aspirated.

4.  When at some future date you no longer need the nickel etchant, 
please label for hazardous waste pickup.


Leo Yu wrote:
> Dear SpecMat Committee, 
> My name is Ching-Yang Yu and my CORAL Id is leoyu. 
> I am a EE graduate student at Stanford and work in the Yamamoto group.
> For GaAs-compatible Nickel etching, I would like to bring the Nickel Etchant TFG into the SNF fab. 
> The ingredients are Thiourea, CAS#62-56-6, Sodium N-Nitro Benzene Sulfonate, CAS#127-68-4, 
> and Sulfuric Acid, CAS#7664-93-9. 
> (More details can be found in the MSDS enclosed. )
> The main hazard class is CORROSIVE and the storage Group Identifier is F.
> The vendor is Transene Company, whose contact information is
> Danvers industrial park
> 10 Electronics Avenue
> Danvers, MA 01923
> Tel:978-777-7860   FAX:978-739-5640
> Their website is
> The reason for the request is to strip off Nickel from GaAs/AlGaAs layered structures. 
> Nickel is one of the best metal hardmask used in dry etching. 
> However, most of the Ni etchants available are not compatible with GaAs substrates.
> The Ni etchant developed by the Transene Company provides this compatibility.
> In my process a film of 50nm Ni is deposited using Innotec in SNF as a hardmask. 
> After dry-etching with PQuest in SNF, the Ni hardmask is then supposed to be stripped off by this new Ni etchant.
> The sample will be wet-etched in Ni etchant on 90 degrees hotplate for 60sec, and rinsed in DI water.
> This final step is done in wbgaas.
> The amount to bring in is 1 quart for storage. 
> The chemical will be directly put to use without mixing. 
> The EPA Hazardous waste number is D002 corrosive waste. 
> Regards, 
> Ching-Yang (Leo) Yu
> EE PhD student
> Ginzton Lab
> Stanford University

Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
mtang at

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