This is serious.

I would make an immediate inquiry to your safety department as to the
smell.

They should be able tell you what the smell is. You should avoid this
smell until you know what it is. I explain why later in my email.

I don't know why a HF etch would cause a smell with a phosphosilicate
glass. I have etch these type of deposited oxides for years and didn't
ever smell anything.

Did you mean to write a glass with deposited "phosphors" which would be
something else entirely.

Arsine has a garlic odor and phosphine has a rotting fish odor. Smells
are your own immediate personal warning system against toxic gases. You
should consider what type of smell you are smelling and check the
composition of the deposited film.

One dangerous feature of toxic gases is that they often deaden the sense
of smell to a gas. For example, Hydrogen sulphide H2S has the dangerous
property of deadening smell, so an individual smells less of it as its
concentration increases. Also, a chronic exposure might lead you to not
smell this gas contaminant.

Certain toxins will accumulate in your bones or tissues or other
components of your body. It might be a minor contamination but cumulated
exposure could have long term consequences and literally be with you for
a long time to come.

I am frankly shocked that the wafer handling isn't done in an
environment strongly ventilated so that you won't smell the wafers and
stored in nitrogren purge boxes when not being processed.

Smells in a semiconductor facility are not "normal," just an indication
of possible danger.

If your employer doesn't adequately inform and explain to you what is
the smell, you should consider other employment. An employer that is
sloppy on one safety procedure will be generally sloppy on all safety
procedures.

As a professional you have responsibility for safety.

Edward H. Sebesta

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of Nicolas Duarte
Sent: Friday, November 07, 2008 6:47 AM
To: General MEMS discussion
Subject: [mems-talk] Smelly Wafers

I just started a new job where, after an HF etch to remove phosphor
glass, the wafers have a pungent garlic smell to them.  I asked my
coworkers about this and they said it was "normal," but I have never
encountered a wafer that had a scent.  It has been my experience that
where there is smell there is a contaminant so I was wondering if anyone
know what the potential source of this smell may be.

Nicolas Duarte