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what metal are cmos chips made out of?

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#1 Mark Jones

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Posted 16 July 2019 - 00:31

What is the metallic surface of the CMOS chip made of? Dupont wants to know if it is copper or aluminum? they have 3 different photo resist chemicals that can strip the bayer layer and want to recommend the best one.

Dupont told me the tiny human hair like wires should be aluminum for best results. I highly doubt they are aluminum

i googled it, but all I found out is it is a semiconductor
Peace, Mark Jones, Charlotte, NC, UV amateur photographer.

#2 enricosavazzi

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Posted 16 July 2019 - 04:44

The chip itself is usually made of silicon substrate (with intentional trace impurities), but the conducting traces can be made of copper or aluminium. The surface of the silicon substrate is "glassivated", i.e. converted to a silicon dioxide layer, as a final step to make it resistant to corrosion by air and humidity. I found the following information, but with no references:

"Gold is rarely used inside ICs since it has worse conductivity than copper and is horribly more expensive. Silver has the highest room-temperature conductivity among pure metals.

Aluminum was used inside ICs until ~1999 due to being one of the easiest metals to work with but it was becoming a performance bottleneck due to relatively low conductivity which is why research into ways of preventing copper from diffusing or oxidizing during IC processing and operation became a major focus. After Intel and IBM figured out how to use copper on silicon, copper quickly became the most commonly used metal in mass-produced VLSI ICs and still is to this day.

Since silver is much more expensive than copper, I doubt we will see silver used in mass-produced ICs. The performance gains are unlikely to justify the 50X more expensive metal and massive R&D investments."

I guess what Dupont wants to know is whether the conducting traces on the uppermost layer of the chip are copper or aluminium because the resist stripper must be formulated not to corrode either metal, and it would be difficult to formulate an effective stripper that is gentle on both metals.

Edited by enricosavazzi, 16 July 2019 - 04:50.

-- Enrico Savazzi

#3 dabateman

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Posted 16 July 2019 - 04:47

Sony A6000 and earlier.
Nikon D800 and earlier.
Fuji 16Mpixels cameras, not the newer ones.
Most Canon DSLRs all used Aluminum under wiring.
I can't find my source, but thats from my old notes when contacting various people for monochrome conversion.

Once I found out about the ZWO 1600MM, I stopped diving into the monochrome conversion idea. If that camera comes down in price, I might get it. From Cloudy Nights, it seemed to out perform most converted cameras since it has the microlenses intact. Also it doesn't have any anti-reflective coating on the sensor coverglass.