Hi from Singapore,

I know of two suppliers: EV (Austria) and UTS (Ultratech, San Jose).
The UTS tool is a modified Leitz (Germany) microscope and costs a
lot more than EV (>200k US$).
There are two techniques to check alignment (or to align) between
front and backside. One is to use IR light to look through the
wafer, the other to look at both sides separately with visible
light and use a projection optics to bring the images together.
The UTS metrology tool uses IR (their stepper uses projection),
EV's metrology tool has a projection optics (their dual-side
aligner uses IR). I figured that it is a good idea to check
alignment done with one technique with a tool using the other.
IR is not usable on metallized wafers (metal is not transparent
to IR) and the accuracy is given by the parallax angular accuracy
of the IR beam. Projection optics is fairly complicated, accuracy
is given by the optical quality of all components plus how well
they are aligned to each other, but it can be used on all kinds
of substrates. IR tends to be more accurate.

Hope this helps.

Greetings,
        Frank Berauer
        Senior R&D Engineer
        HP IJMS Singapore


-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: 7 September 2001 00:39
To: [email protected]
Subject: [mems-talk] photolitho backside-alignment inspection tools


Does anyone knows of a supplier for visual inspection tools to check
photolitho backside alignment accuracy on 4/6" wafers. I know one supplier
of
such systems, Electronic Vision in Austria, but their tools are rather
expensive ($70,000). Any idea?

Joern

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Joern Koblitz
microFAB Bremen GmbH
Fahrenheitstr. 1
28359 Bremen, Germany
fon +49 (0) 421 2208 272
fax +49 (0) 421 2208 275
[email protected]
http://www.microfab.de
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