Extended side contacts for transistors and methods forming same

Abstract

A method includes forming a source/drain region for a transistor, forming a first inter-layer dielectric over the source/drain region, and forming a lower source/drain contact plug over and electrically coupling to the source/drain region. The lower source/drain contact plug extends into the first inter-layer dielectric. The method further includes depositing an etch stop layer over the first inter-layer dielectric and the lower source/drain contact plug, depositing a second inter-layer dielectric over the etch stop layer, and performing an etching process to etch the second inter-layer dielectric, the etch stop layer, and an upper portion of the first inter-layer dielectric to form an opening, with a top surface and a sidewall of the lower source/drain contact plug being exposed to the opening, and forming an upper source/drain contact plug in the opening.