Today’s advanced logic chips have as many as 20 layers of metal that support two types of wires – thin signal wires that switch transistors on and

Beyond Backside Power: Scaling Chips to 2nm and Beyond Also Requires Frontside Wiring Innovations

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2024-10-19 01:30:08

Today’s advanced logic chips have as many as 20 layers of metal that support two types of wires – thin signal wires that switch transistors on and off, and thicker power wires that deliver the current that flows when the transistor is switched on. In the near future, all of the world’s leading chipmakers plan to move the power lines to the backside of the wafer, which promises to reduce wiring complexity, free up space for more transistors, and improve chip performance and power efficiency.

Yet despite the tremendous benefits expected with backside power, we must not forget that we need to address wiring challenges on the front side of the wafer if we hope to scale transistors to 2nm and beyond.

Advances in patterning are making it possible to print ever-smaller transistor features on a chip. But as chipmakers continue to shrink transistors with each generation, they must also shrink the wiring. While it may seem counterintuitive, smaller is not actually better when it comes to wiring.

First, physics dictates that as wires get thinner, electrical resistance increases. Second, as wires get closer together, and the insulating dielectric material between the wires decreases, capacitance and electrical crosstalk increases, resulting in signal delays and distortion. The net effect of these wiring scaling issues is slower and more power-hungry chips.