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Comment by newswasboring | Hacker News Reader

On a lighter note, this is actually a career threatening news for me. So much of my job is to figure out what to do with the end of the round wafer (partial dies), that I can't imagine what my whole department will do if we go for rectangular wafers :'). Made me realize how specific my engineering has been for the last 5 years.

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What do they do with the leftovers? I’m curious

I mean even if they do start using rectangular wafers for _some_ things, there is so much supply chain momentum in circular wafers that surely you have some fairly significant job security.

You're right. But, I work in lithography, and there are only positives for going to rectangular wafers. We will be able to clamp is better, I think acceleration stresses will be easier to manage, modeling will be easier because it will be per field exactly the same, and so on. Litho industry (which basically means ASML at this point) might jump on this.

But I'll reiterate I mean all this on a lighter note, don't think it will happen within my career :).

Edit: Didn't read the question you asked in the first sentence. The left over parts are usually just taken along in the process till the end and are scapped when we get to the cutting stage. The problems arise because the structures on the partial dies are not the same as the full dies in the middle of the wafer. This causes a bunch of weird stresses on the edge and in my small corner of engineering we optimize the fuck out of the edge dies so their stresses are less weird.

I'm facing an engineering problem that amounts to stresses accumulating on the edges of a layered substrate. Are there any references, process notes, books, or industry approaches that you could point me to? High level and/or general are OK.

Lithography takes a more abstract approach to it, we are not actually calculating stresses, we have pretty powerful sensors which measure the wafer surfaces and then my department models the surface.

Lithography lives in the thin film approximation anyway. Timiosheko is a good reference. There are papers from Barnett or Nix that are very nice, but edges will probably end up a fem solver domain.

Handbook of Thin Film Deposition (Seshan)

> What do they do with the leftovers?

Gather them up into a ball, then flatten them into a new wafer using a rolling pin.

Fold it over a few times and you get a croisSiant.

> What do they do with the leftovers?

They keep fine in the fridge for a few days and are still pretty good reheated with a little Tabasco sauce

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