Placeholder profile for backside self-aligned contact

Abstract

Backside self-aligned contact designs using a replacement contact process with unique placeholder profile are provided. In one aspect, a semiconductor device includes: a field-effect transistor(s) on a frontside of the device; backside power rails on a backside of the device; a backside source/drain region contact connecting a given one of the backside power rails to a source/drain region of the field-effect transistor(s), and a dielectric placeholder(s) between the given backside power rail and another source/drain region of the field-effect transistor(s), where a first end of the dielectric placeholder(s) having a width Wdirectly contacts the given backside power rail, a second end of the dielectric placeholder(s) having a width Wdirectly contacts the other source/drain region, where W>W. The field-effect transistor(s) can include a stack of active layers with bottom dielectric isolation, and a gate-all-around configuration. A method of fabricating the present semiconductor devices is also provided.