Caplio R2
ƒ/5.4
4.6 mm
1/290
100
Puzzle Series: What is this, or what do you want it to be? (special bonus for explaining why it looks this way)
13 responses to “What’s That? (51)”
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I think jogales is close. It is a film used to project light onto silicon wafer blank using a light sensitive etching process. The reason you see a rainbow effect is because the lines in the circuits are so close, they effectively turn the film into a diffraction grating.
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Trees Glass
Trees Circuit
Film CircuitsTrees seen through a glass film pattern for circuit boards?
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DOH! Hmmm… not film… more than two nouns…
Maybe I should go with the wafer. Not blank, but a finished product (aside from being cut into individual IC’s). As davesag said, reflected light on the surface of a platter of wafers would give the impression of a mirror with squares, where the circuits are. The rainbow effect is from the etchings on the surface, working as a diffraction grating.
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Bingo Rocketeer! Back when I was a student, Gordon Moore visited class and let me keep an 8” wafer of Pentiums:
Yes, the rainbow of colors come from the circuit areas. In regular arrays, like a memory block or register file, we mght be seeing diffraction grating effects. Some of the colors probably come from thin-film interference. At HP, we used to design elaborate “logos” on chip where the colors depended on the thickness of the SiO2 layer (aka silicon dioxide or silica). I used a Devo plant pot hat with the motto "Oh no, it’s Stevo."
Tak is also right; the photo is flipped upside down to reorient the reflection of the trees.
The near perfect reflection of the grid between the chips is fascinating. Here’s what I think is going on. The chip’s active area (the gold squares) has a final processing step called a passivation layer. This is a glassy layer of a material like silica that protects the underlying circuitry. It in not deposited over the bond pads that ring each chip (so the wirebonder can make a good electrical contact with each pad).
Silicon and Silicon Dioxide have very a different refractive index (Silicon is 3.9 vs SiO2 and glass at 1.5). So, I think we are beyond the critical angle for a total reflection of light from air to silicon, but in the regime for a partial reflection of light from air to glass. So we get a partial image of what’s under the glassy thin film, and elsewhere, we have a great mirror.
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Great puzzle, Steve!
I find it ironic that your investment ventures are helping pave the way to get around Moore’s Law.
I’d love to see some of your chips and especially the "Oh no, it’s Stevo" part. HP produced seven of your designs, didn’t they? What did the chips do that you designed? Were they all communications related?
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I wish I still had those layout files. I had poster sized printouts, but you know how it goes when the spouse decides to clean house… Somewhere along the way, they got tossed.
The chips were a variety of amplifiers and QPSK modulators (used the RF block of cell phones, and sometimes missile guidance systems). We were hand crafting multi-fingered bipolar transistors for ECL circuits in a high fT silicon process.
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cool. i was thinking of a spinning cd or dvd but could not account for the regular shape of the gaps. also what confused me was the lack of motion blur on the edges of the squares, compared to the content of the squares. the lack of motion blur on the reflected trees eliminated by initial impression which was a shot through something from a moving car. neat puzzle. thanks.
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