US Patent 12094937 Stacked field effect transistor devices with replacement gate

A stacked field effect transistor device is provided. The stacked field effect transistor device includes a lower semiconductor channel segment between a first pair of source/drains, and an upper semiconductor channel segment between a second pair of source/drains. The stacked device further includes a gate dielectric layer on the upper and lower semiconductor channel segments, and a first work function material layer on the gate dielectric layer on the lower semiconductor channel segment. The stacked device further includes a first conductive gate fill on the first work function material layer, and a replacement work function material layer on the gate dielectric layer on the upper semiconductor channel segment and the first conductive gate fill, wherein the replacement work function material layer is a different work function material from the first work function material layer. The device further includes a replacement conductive gate fill on the replacement work function material layer.