US Patent 11393910 Semiconductor device and formation method thereof

A semiconductor device includes a fin structure, a source/drain region, a first inter-layer dielectric (ILD) layer, a first contact plug, and a second contact plug. The fin structure extends above a substrate. The source/drain region is in the fin structure. The first ILD layer is over the source/drain region. The first contact plug extends through the first ILD layer to a silicide region of the source/drain region. The second contact plug is over the first contact plug. The first contact plug has a protruding portion extending above the first ILD layer and laterally surrounding a lower part of the second contact plug.