Digging Trenches on Silicon Chips

If you look at a processor, or any other big piece of silicon, on a circuit board you'll see that it's normally surrounded by passives. Most of these passives will be capacitors. In the future you'll see this a lot less as we might be able to integrate them directly on-chip.

Silicon chips are built using transistors combined with other electrical components like resistors, diodes, inductors, and capacitors. Those are all wired together to make sure that they transform the inputs in the way we expect. The "logic" in the chip is built from individual components.

However today's on chip capacitors typically take a lot of area in the silicon die, making them expensive, which is why you typically see capacitors beside the chip on a lot of circuitboards. However adding components to a PCB also adds cost to the bill of materials, and complicates assembly. It also makes the PCB much bigger than it would otherwise be, and more power hungry. Integrating capacitors directly on chip minimises energy losses.

A new paper recently published in the journal Nature from scientists at Lawrence Berkeley National Laboratory and UC Berkeley shows some significant advances in on-chip microcapactiors.

Engineered using thin films of hafnium oxide and zirconium oxide to achieve a negative capacitance effect. Integrated into three-dimensional microcapacitor structures, growing the precisely layered films in deep trenches cut into silicon, they achieve record breaking energy and power densities.

The discovery could lead directly to smaller physical devices as some of the existing passives can be moved off the PCB and directly onto the chip, making PCBs smaller. The resulting hardware would also be more energy efficient, which in battery-powered devices could lead to longer battery life for your internet of things devices.