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Back to What will computer chips look like in 2045?, with Chris Auth & Kevin Fischer.

Why Can't Logic Chips Stack Like Memory?

Chris Auth says logic chips cannot stack like memory because logic uses more power and the heat has no clear way out.

Chips pair N-type and P-type transistors, built side by side today. Stacking one on top of the other, a CFET, or complementary field-effect transistor, would fit twice as many transistors in the same area. Every extra layer adds manufacturing steps, cost, and heat. Stacks of DRAM that make high-bandwidth memory, and 3D NAND, do not transfer to logic for that reason.

Three things limit compute: how fast the device can switch, how much power the switch takes, and how the heat from that switch gets out. Those three limits were already being written about 20 years ago. Thermal tools for these 3D devices are still early, and heat will keep limiting how far the stack can go.

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What will computer chips look like in 2045? ·

Dwarkesh Podcast

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