Atomic layer deposition of carbon doped silicon oxide by precursor design and process tuning

Abstract

Different precursors for atomic layer deposition of carbon doped silicon oxide have been investigated. The impact of precursor reactivity, the number of silicon-carbon bonds in the precursor, oxidant concentration and dosing time, and deposition temperature on deposited film's carbon content are discussed. It is found that substituting the Si-H by Si-CH3 reduces precursor reactivity and decreases film growth per cycle (GPC). At temperatures higher than 225 °C, all the precursors could deposit a silicon oxide films with reasonable GPC but with very little carbon in the film (<1 at. % by X-ray photoelectron spectroscopy). At temperatures, lower than 150 °C, precursors with two or three Si-CH3 groups, e.g., dimethylaminotrimethylsilane and dimethylaminodimethylsilane, and bis(dimethylamino)dimethylsilane have almost no deposition of silicon oxide film (GPC < 0.1 Å/cycle), while the monoaminosilane precursor with only one Si-CH3, e.g., di-iso-propylaminomethylsilane, could deposit silicon oxide film with relatively high GPC and high carbon content (1–8 at. %). The bisaminosilane precursor with one Si-CH3 bis(dimethylamino)methylsilane (BDMAMS) shows decreased carbon doping compare to DIPAMS. In addition, the ozone concentration affects the film deposition. The lower ozone concentration and shorter ozone dosing time result in lower GPC, higher carbon doping and lower film wet etch rate.