High-Quality Deposited Gate Oxide MOSFET’s and the Importance of Surface Preparation

The fabrication and electrical characteristics of MOSFET’s incorporating thin gate oxides deposited by a modified plasma-enhanced chemical-vapor-deposition (PECVD) process are reported. The gate oxide deposition and all subsequent steps were carried out at or below 400°C. These results represent the first demonstration of near thermal gate oxide quality MOSFET’s fabricated using a low-temperature PECVD gate oxide process without requiring a high-temperature anneal. The ultimate performance of the deposited oxide devices is shown to be critically dependent on the degree of process induced microroughness of the starting silicon surface. Low-temperature effective mobility measurements are used to compare inversion-layer scattering mechanisms in these devices. © 1989 IEEE