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I just bought a silicon wafer off of eBay to decorate my office. The seller didn't tell/know, but I'm dead curious as to what this wafer is. Could anyone help me identify which chips should have been built out of it?

Full picture

Here's a picture of the entire 12" wafer.

Full size picture

Poor man's macro

Here's a zoomed-in picture of the lighter rectangles that are scattered over this wafer. I took it using a super cheap magnifying glass.

macro

Another poor man's macro

Here's another angle trying to show both the light and dark rectangles. Unfortunately I only have a smallish magnifying glass so I can't see any better.

another macro

Extra info

  • This is a 300 mm wafer
  • I couldn't find any marking on the front side
  • The backside has a serial number (K444R215WFB3) and a QR code that's so small I couldn't decipher it.
  • The dark rectangles probably have something drawn in them, but it's impossible to see it even with a magnifying glass.
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  • \$\begingroup\$ Are there no other markings of any kind, on either side? \$\endgroup\$ – BeB00 Aug 26 '20 at 19:06
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    \$\begingroup\$ Smells like it has excess faults for some large BGA \$\endgroup\$ – Tony Stewart EE75 Aug 26 '20 at 19:09
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    \$\begingroup\$ An image of one of the dark rectangles is likely to be more helpful than one of the light rectangles. Best if you can get enough magnification to see any metal layer markings. \$\endgroup\$ – The Photon Aug 26 '20 at 19:26
  • \$\begingroup\$ Get it under strong enough magnification and you may find a copyright or brand marking on it. But it'd be super-small. Basically, if you can see individual transistors -- start looking for human-readable markings. \$\endgroup\$ – TimWescott Aug 26 '20 at 20:32
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The light rectangles are for wafer characterization test. The dark ICs are the actual chips.

As to what those chips are, they appear to be some kind of memory, perhaps DRAM.

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  • \$\begingroup\$ Interesting, thanks! How do you know this is some memory? Also, how could I try and find more about what kind of memory this is? \$\endgroup\$ – Romain Aug 26 '20 at 20:05
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    \$\begingroup\$ The regular block structure is typical of memories. The sense amps are the strip down the middle of the chip. I'm guessing DRAM, but it could also be flash. Hard to tell without further magnification. \$\endgroup\$ – hacktastical Aug 26 '20 at 20:07
  • \$\begingroup\$ Expanding on what @hacktastical has said and for the OP's benefit, in the bottom photo the lighter-coloured area comprises test patterns. Below that, and the same size, is an actual chip, comprising a strip of sense amplifiers etc. along the middle, eight storage areas (four above the amps and four below), and light-coloured connection pads for bonding wires on three sides. Or something like that :-) The detail in the grey area is likely to be substantially smaller than 1um (millionth of a meter), so won't be resolvable using a hand lens or ordinary camera. \$\endgroup\$ – Mark Morgan Lloyd Jan 26 at 18:06

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