[labnetwork] Expired chemicals

[Fouad Karouta]

Hi all,

I agree with what is said so far.
We do tend to use resists a few months after expiry (also PMMA and ZEP).
We've seen negative resists (maN series from Micro-Resist) need replacement
hardly 1-2 months after expiry date. Solvents should be fine though we
usually consume son much that we never get to expiry date.
BOE should be fine to use after date as the NH4F should compensate for any
volatile HF.
H2O2 peroxide is unstable especially if mixed with other chemicals. Piranha
solution for instance should be used within 1-2 hours as H2O2 degrades in
acid presence. The same stands for III-V etchants like H3PO4:H2O2:H2O (or
H2SO4 instead of H3PO4). 

In general whenever you doubt about results then it is time to get new
chemicals.

Kind regards,
Fouad Karouta

*********************************
Facility Manager ANFF ACT Node
Research School of Physics and Engineering
Australian National University
ACT 0200, Canberra, Australia
Tel: + 61 2 6125 7174
Mob: + 61 451 046 412
Email: fouad.karouta at anu.edu.au


-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu]
On Behalf Of Morrison, Richard H., Jr.
Sent: Monday, 16 July 2012 8:28 PM
To: Matthieu Nannini, Dr.; labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] Expired chemicals

Hi Matthieu,

In general solvent materials are ok to use after the expiration date, we
leave it up to the engineer. Stuff like resist can be useable up to a year
after they expire. The risk that you run is that you will need to change
your exposure and development time. Then when you receive the new material
the parameters will change again.

Hydrogen peroxide will not be active after the expiration date, the H2 comes
out as a gas, that is why H2O2 has a vented cap. Be careful with H2O2 it
comes in 2 flavors, stabilized and un-stabilized. The stabilized has an
expiration date longer than the un-stabilized.

Other acids maybe ok to use after the date, but things like HF may change
concentration over time as the gas evolves out of the solution.

Rick




-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu]
On Behalf Of Matthieu Nannini, Dr.
Sent: Thursday, July 12, 2012 2:53 AM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] Expired chemcials

Dear colleagues,

What is your take on expired chemicals like:

- PMMA
- acids
- H2O2
- BOE
- TMAH
- LOR
- MIBK and solvents

Thanks

Matthieu

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