Growth and properties of fluorinated plasma oxide for Si MOSFET devices

Abstract

Plasma oxidation is a potentially attractive technique for growth of silicon dioxide at low temperatures for Si MOSFET devices and for thin film transistor (TFT) devices. It avoids the use of H containing materials as precursors and therefore, can be more stable. In this paper, we report on the growth, electronic properties and stability of plasma oxidized SiO2 films grown in an electron cyclotron (ECR) plasma reactor. The films were grown using either oxygen or oxygen with small amount of fluorine. We show that negative ions play a major role in the growth of oxide films. MOSFET devices that use films grown using plasma oxidation with oxygen alone show higher interface defect densities and much poorer stability than films grown using dry thermal oxides. When fluorine is added to oxygen, the plasma oxidized films grow at a higher rate and the interface density is reduced to the range typical of dry thermal oxides. The MOSFET devices made using the fluorinated oxide films grown at low temperatures perform as well and are almost as stable against hot electron degradation as devices grown using dry thermal oxide at much higher temperatures.