US Patent 11069684 Stacked field effect transistors with reduced coupling effect

A semiconductor structure includes a first field-effect transistor disposed on a substrate. The first field-effect transistor includes a first metal gate, and a first source/drain region. A second field-effect transistor is vertically stacked above the first field-effect transistor. The second field-effect transistor includes a second metal gate, and a second source/drain region. The first metal gate and the second metal gate are vertically aligned and configured with an air gap disposed therebetween. The first source/drain region and the second source/drain region are vertically aligned and configured with another air gap disposed therebetween.