Advanced oxynitride gate dielectrics for CMOS applications

A most preferable candidate of gate dielectrics in advanced CMOS to satisfy the requirement of an ITRS roadmap is still SiON, especially for high-performance and low-power devices. To advance the efficiency of SiON gate dielectrics, the keyword is N-rich. A high nitrogen concentration leads to low leakage current and high immunity to impurity penetration. However, in N-rich SiON, the mobility degradation and NBTI enhancement due to fixed charges formed by incorporated nitrogen atoms near the interface are problems. To solve these problems, we developed a SiN gate dielectric with an oxygen-enriched interface (OI-SiN). A process in which oxygen atoms are incorporated after forming SiN provides enhanced nitrogen concentration and an oxygen-enriched interface while simultaneously suppressing fixed charges, even in dielectrics having sub-nm EOT. This OI-SiN has good immunity against impurity penetration and provides superior device performance compared to the conventional SiON. Furthermore, the OI-SiN was much effective as an interfacial layer of high-K gate stack to solve problems in high-K gate dielectric.