Subject: RE: Collecting silicon wafers

From: "Dave Wilson" <[email-masked]>
Date: Thu Mar 13 15:05:01 2003

> On Wed, 12 Mar 2003, Sridhar wrote:
> 
> An extremely new wafer can be valuable just by the ability to reverse
> newfangled engineering.
> 
> Peace...  Sridhar

Can't see this myself. Yes. I know it's theoretically possible (just) 
Modern chips are to all intents and purposes three dimensional objects. 
The real logic lies, out of sight below several layers of metal conductor. 
It's just this, incidentally, that makes them of limited interest to a 
collector. (There's not much to see on the surface anymore) 
So OK, you could probe them with X-rays or something like that or try
etching away the layers with acids. 
My own view is that this is just about as impossible a task as one can 
possibly imagine. After you've done all of this you'd have to reverse 
your way back to the masks (which, these days, are quite distinct from 
the geometries they produce on silicon. AND THEN you have to have a 
fabrication available to you that is capable of putting the whole thing 
back together again. Much easier just to steal the design database. 

The forward engineering is quite difficult enough. It's my own belief 
that reverse engineering is - practically speaking - intractable. 

If this really is so appealing to sinister governments etc. why not 
just reverse engineer the chip they bought legitimately, by mail order.  

> On Tue, 11 Mar 2003, Chandra Bajpai wrote:
> 
> > Before anyone goes in trying to cash in their wafers...I assume any
> > wafer that was not kept in a clean room environment is worthless.  The
> > couple of wafers I have finger prints so they definitely are worthless!

I'd respectfully suggest that the concept of value is not quite as 
straightforward as you suggest, Chandra. How much would your two wafers 
be worth if I were willing to buy them off you? Postage stamps are just 
about as 'worthless' as anyone could imagine, yet I'm regularly sent 
catalogues offering stamps at prices that amount to more than my annual 
salary.

---

From: "Eric Smith" <[email-masked]>
Date: Thu Mar 13 19:24:01 2003

> that reverse engineering is - practically speaking - intractable.

Actually not.  Certainly beyond the means of a hobbyist, but there
are companies that offer this service commercially.  The most well-known
is Chipworks, but there are several others.  They'll take a packaged part,
decap it, and peel it layer by layer.  They can provide you results in
various forms including physical design formats such GDS, schemtics,
netlists, or even HDL code.

It's not inexpensive.

This is what AMD did to get the Intel 386 logic design.  I don't know
if they did all the work in-house, or contracted some of it out to
specialists.  They were entitled under a cross-license agreement to
obtain the actual 386 design files from Intel, but Intel was trying to
renege on the agreement.  The court eventually ruled for AMD, but in the
mean time they completely reverse-engineered the 386 back to a register
transfer level design, then reimplemented the exact same logic, though
they improved it by making it static rather than dynamic.  Altogether,
this is the most amazing reverse-engineering feat I've ever heard of.

> just reverse engineer the chip they bought legitimately, by mail order.

Yes, that's how it's normally done.  AFAIK, there's little additional
knowledge to be gained from studying a complete wafer vs. an individual
die.