A group of engineers at the University of Michigan have stacked the second layer of transistors straight atop a state-of-the-art silicon chip.
They say that their design may remove the need for a second chip that converts from high to low voltage signals, which currently stands between the low-voltage processing chips and the upper-voltage user interfaces.
Moore’s Law holds that computing power per greenback doubles roughly every two years. As silicon transistors have contracted in size to become more affordable and power-efficient, the voltages at which they operate have also fallen.
Increased voltages would harm the more and more small transistors. Because of this, state-of-the-art processing chips aren’t appropriate with higher-voltage user interface elements, comparable to touchpads and display drivers. These have to run at larger voltages to avoid results comparable to false contact signals or too-low brightness settings.
Because the second layer of transistors can deal with higher voltages, they primarily give each silicon transistor its interpreter for speaking to the outside world. This will get across the current trade-off of utilizing state-of-the-art processors with an extra chip to transform signals between the processor and interface units—or using a lower-grade processor that runs at a higher voltage.
Peterson’s crew managed this by using a special kind of semiconductor, called an amorphous metal oxide. To use this semiconductor layer to the silicon chip without damaging it, they lined the chip with a solution containing zinc and tin and spun it to create an excellent cover.
They baked the chip briefly to dry it. They repeated this procedure to make a layer of zinc-tin-oxide about 75 nanometers thick—about one-thousandth the thickness of a human hair. During a final bake, the metals bonded to oxygen in the setting, creating a layer of zinc-tin-oxide.