Microwave plasma oxidation of silicon

Plasma-assisted oxidation, anodization, and nitridation of silicon

“…This result is in opposition to the previously discussed microwave studies, and suggests that growth is controlled by field-assisted ionic conduction (negatively charged oxygen species) rather than by diffusion (parabolic relationship). It is likely that such discrepancies are due to higher current densities in Reference [15] than in References [9][10][11][12][13][14], where the area of current flow is not defined by physical restrictions. Thus, at (intentional or unintentional) low current densities, where growth rates are more controlled by temperature than by current, parabolic or linear-parabolic kinetics may dominate (e.g., Reference [14]), and activation energies are therefore higher (0.31 eV for parabolic region) than for currentcontrolled growth (0.06 eV for ohmic region [15]).…”

“…It is likely that such discrepancies are due to higher current densities in Reference [15] than in References [9][10][11][12][13][14], where the area of current flow is not defined by physical restrictions. Thus, at (intentional or unintentional) low current densities, where growth rates are more controlled by temperature than by current, parabolic or linear-parabolic kinetics may dominate (e.g., Reference [14]), and activation energies are therefore higher (0.31 eV for parabolic region) than for currentcontrolled growth (0.06 eV for ohmic region [15]). Chlorine addition also improved oxide electrical properties; after a post-metallization forming-gas anneal, the effective charge level was -5 X lO'" cm"^ with a mobile charge density of -2 X 10'° cm"' and a MBDF of 10 MV/cm [14].…”

“…Isotopic labeling studies using O plasma oxidation of an existing thermally grown SiO, film on silicon indicated that without anodization current, only the surface layer of oxide was enriched in O; when plasma anodization was performed, ' O was detected at the SiO^ surface and at the Si-SiO, interface [15]. A linear dependence of growth rate on current was noted, while no difference in growth rates between (100) and (111) silicon was observed [15].…”

“…Chlorine addition also improved oxide electrical properties; after a post-metallization forming-gas anneal, the effective charge level was -5 X lO'" cm"^ with a mobile charge density of -2 X 10'° cm"' and a MBDF of 10 MV/cm [14]. Isotopic labeling studies using O plasma oxidation of an existing thermally grown SiO, film on silicon indicated that without anodization current, only the surface layer of oxide was enriched in O; when plasma anodization was performed, ' O was detected at the SiO^ surface and at the Si-SiO, interface [15]. A linear dependence of growth rate on current was noted, while no difference in growth rates between (100) and (111) silicon was observed [15].…”

“…Using a reactor design similar to that shown in Figure 1, but configured so that the anodization current was essentially confined with a quartz tube to a specific substrate surface area, silicon oxidation was performed at ~55 mTorr O,, -10 mA/cm , and a substrate temperature of ~400°C [15]. A constant growth rate of -1.4 nm/min was observed up to four hours (-350 nm) oxidation time ( Figure 2).…”