What Is a Gate-all-around Transistor?

Dwarkesh Patel says a gate-all-around transistor slices the silicon channel into thin ribbons and wraps the gate completely around each ribbon, so the gate can stop current from leaking when the switch is off.

A transistor is a switch. A positive voltage on the gate pulls electrons into a channel between the source and the drain, and a thin insulator keeps them off the gate. Remove the voltage and the channel disappears. As transistors shrank, current could still leak when the switch was off. The planar MOS transistor, demonstrated in 1960, touches the channel only from the top. A FinFET squeezes it into a vertical fin so the gate controls three sides. Gate-all-around also covers the bottom.

Building the floating ribbons means sandwiching them in a temporary placeholder, because the real gate materials would not survive later processing that includes baking at around 1000 degrees Celsius. After those hot steps, chip makers etch away the placeholder, leave each ribbon suspended, coat it with a high-k insulator so the gate pulls more strongly, and then add the gate metal. FinFET was demonstrated in a lab in 1989 and reached volume production at Intel in 2011. A gate-all-around transistor had been demonstrated a year earlier, in 1988, but Samsung did not begin producing those chips until 2022.