Request to bring new chemicals Nickel Etchant TFG

Leo Yu leoyu at
Thu Apr 2 16:55:38 PDT 2009

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. 


Ching-Yang (Leo) Yu
EE PhD student
Ginzton Lab
Stanford University
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