Sacrificial Deuterium Passivation for Improved Interface Engineering in Gate Stack Processing

The high reactivity of the free silicon surface and its consequence: the "omnipresent" native silicon oxide hinder the interface engineering in many processing steps of IC technology on the atomic level. Methods known to eliminate the native oxide need in most cases vacuum processing. They frequently deteriorate the atomic flatness of the silicon. Hydrogen passivation by a proper DHF (diluted HF) treatment removes the native silicon oxide without roughening the surface while simultaneously maintaining a "quasi oxide free" surface in a neutral or vacuum ambient for short time. Under such circumstances the last thermal desorption peak of hydrogen is activated at around 480-500degC where the free silicon surface suddenly becomes extremely reactive. In this study we show that deuterium passivation is a promising technology. Due to the fact that deuterium adsorbs more strongly on a Si surface than hydrogen even at room temperature, deuterium passivation does not need vacuum processing and it ensures a robust process flow.