Seal ring for semiconductor device

Abstract

A method includes providing a structure having a substrate and first and second semiconductor layers alternately stacked one over another above the substrate, etching the first and the second semiconductor layers to form a first continuous ring in a seal ring region of the structure, and forming an isolation structure adjacent the first continuous ring in the seal ring region. The method further includes forming a dummy gate structure that is disposed directly above the first continuous ring and completely within a boundary of the first continuous ring from a top view, growing first and second epitaxial features sandwiching the dummy gate structure, removing the dummy gate structure, resulting in a gate trench that exposes a topmost layer of the first semiconductor layers and does not expose side surfaces of the first and second semiconductor layers, and depositing a gate structure in the gate trench.