A New Tungsten Gate Metal Oxide Semiconductor Capacitor Using a Chemical Vapor Deposition Process

Abstract

A new process for tungsten gate metal oxide semiconductor (MOS) capacitors has been developed using chemical vapor deposition (CVD) of tungsten on a thin poly‐Si layer of appropriate thickness. The poly‐Si acts as a sacrificial layer and is consumed during the CVD of tungsten (W). This process yields a nearly pure W metal gate after reduction of at 300°C. Compared with sputtered tungsten films, the CVD tungsten film has lower resistivity and lower intrinsic film stress. In addition, the CVD tungsten metal gate MOS capacitor has a lower interface state density (Dit) and a higher charge‐to‐breakdown (Qbd), than sputter‐deposited tungsten gate MOS capacitors.