Effect of adding HCl to the oxidizing ambient on characteristics of metal-oxide-semiconductor capicitors

Abstract

Electrical properties of HCl oxide and dry oxide are investigated and compared. Surface state density near midgap is independent of HCl content added in the oxidizing ambient. The excellent performance of metal-oxide-semiconductors using HCl oxide is attributed to the cleaning effect of HCl, and not to the chlorine incorporated in the oxide. Incorporated chlorine causes a positive charge in the oxide and creates a surface state near the conduction-band edge. The amount of positive charge is less than that of incorporated Cl by several orders of magnitude, and the major portion of Cl is in a neutral charge state. A negative charge arises near the metal/SiO2 interface, and for thin oxide, surface state density near midgap is increased.