I'm self-studying computer architecture and digital logic design and have a question regarding integrated circuits. When you examine a chip up close, such as through a scanning electron microscope, you see a layered, criss-crossing network. Would these be what my book refers to as "supply rails?" They have diagrammatic illustrations but I'm not sure it's the same thing.
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\$\begingroup\$ Pretty much all the on-chip wiring answers that description, not just the supply rails. Impossible to say more without a better description, and pictures. \$\endgroup\$– user16324Commented Aug 19, 2017 at 22:14
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\$\begingroup\$ Post a picture of what you are talking about. \$\endgroup\$– JRECommented Aug 19, 2017 at 22:15
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\$\begingroup\$ I'd call it multilayer metallization (but that includes not only the wiring, but any other structures made from the deposited metal atop the chip). \$\endgroup\$– Whit3rdCommented Aug 20, 2017 at 4:46
3 Answers
Those are interconnects. They connect the various components diffused into the substrate.
What you are seeing are the metal layers that are used to interconnect the various components on the IC die to perform the function required. Older or simpler chips use aluminum for this, while some new, complex ICs (such as modern CPUs) use copper instead.
The Rails are the wide regions, with small fingers reaching out to Source of PFET for +2.5v rails, and small fingers reaching out to Source of NFET for GND.