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Jul 01, 2023

A Node by Any Other Name: Transistor Size & Moore’s Law

Member-only story Matt Traverso Follow Predict -- 1 Share If you follow semiconductor news, you have probably heard about TSMC and Samsung producing 3 nm chips. You probably also know that these chips

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Matt Traverso

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If you follow semiconductor news, you have probably heard about TSMC and Samsung producing 3 nm chips. You probably also know that these chips are made of transistors which consist of features including gates, channels, sources, and drains. Metal contacts electrically join the transistors together through interconnects (wires) placed above them.

You may remember from chemistry class that the diameter of a Si atom is about 2.1 Å (0.21 nm). With a little math, you realized that a transistor must be no more than 15 atoms long and thought “This is amazing! How can we make these things so small?”

The answer is that we can’t. Transistors are not really that small.

The term “3 nm” doesn’t accurately represent the actual size of a transistor. Process nodes still several generations away have a minimum feature size of 13 nm (see below). I would expect that the length of a complete transistor would be at least three times this size, if not longer.

Realistically, transistors won’t reach a length of 3 nm in the next 20 years, regardless of any metric. The term “3nm” is primarily a marketing gimmick used by manufacturers to indicate that their new semiconductors are superior to previous ones.

This is an overview of how node names have evolved but continue to reflect some interpretations of Moore’s Law despite values that are increasingly untethered from physical dimensions and provides advice on how to interpret marketing hype when shopping for new processors.