Semiconductor structure having stacked gates and method of manufacture thereof

Abstract

Aspects of the present disclosure provide a method, which includes providing a semiconductor structure including a first lower semiconductor device and a first upper semiconductor device stacked vertically over the first lower semiconductor device. The first lower semiconductor device has one or more first lower channels. The first upper semiconductor device has one or more first upper channels. First work function metal (WFM) can cover the first lower channels and the first upper channels. The method can also include recessing the first WFM to uncover the first upper channels of the first upper semiconductor device, depositing a monolayer on uncovered dielectric surfaces of the semiconductor structure, depositing isolation dielectric on the first WFM of the first lower semiconductor device, and depositing second WFM to cover the first upper channels of the first upper semiconductor device. The isolation dielectric isolates the first lower semiconductor device from the first upper semiconductor device.