Self-limiting and pattern dependent oxidation of silicon dots fabricated on silicon-on-insulator material

Abstract

We present a systematic investigation of the oxidation properties of Si dots fabricated on a silicon-on-insulator ͑SOI͒ wafer. Dots with diameters varying from 9 to 81 nm were structured on a SOI wafer. These dots were oxidized in a dry oxygen atmosphere at 700, 850, and 1000°C. The resulting structures were investigated using a side view transmission electron microscopy ͑TEM͒ technique in combination with energy filtered TEM. The dimensions of the residual Si and the grown SiO 2 were then extracted from the micrographs and analyzed. The oxidation appears to be retarded as compared to the well-known planar oxidation. At 700 and 850°C a self-limiting effect is observed as well as a clear pattern dependent oxidation at 850 and 1000°C. We attribute these effects to stress buildup in the oxide. The critical stress, causing the self-limiting effect, is calculated using a model that considers the decrease of the reaction rate with increasing stress perpendicular to the Si surface.

Effects of thermal oxidation on the photoluminescence properties of porous silicon

“…Similar results are also observed by several authors [22,23]. The high reactivity of PSi for oxidation may arise from peculiar internal strain induced in nanostructured substances [26,27].…”

Crystallization of Amorphous SiO2 Microtubes Catalyzed by Lithium

“…[22] The presence of a concave curvature as in macroporous Si results in a pronounced retardation of the oxide growth with respect to planar oxidation. [21,[23][24][25][26][27] Kao et al attributed this phenomenon to viscous stress in the oxide layers associated with nonuniform mechanical deformation. [24] Whereas in planar systems only stress components parallel to the Si/SiO 2 interface exist in the newly formed SiO 2 layer, stress normal to the Si/SiO 2 interface also occurs in concave systems.…”

Retardation in the Oxidation Rate of Nanocrystalline Silicon Quantum Dots

“…These things are physically reasonable since the normal stress is low at high oxidation rate, and gradually increases as the Figure. 4 The structure of nc-Si used in the oxidation model. Figure.…”

“…Using very-high-frequency (VHF) plasma decomposition of SiH 4 and pulsed gas technique, we have successfully prepared nanocrystalline silicon (nc-Si) quantum dots with an average diameter of 8 nm and dispersion of 1 nm [1], [2]. Recently, it is reported that the oxidation rate of lithographically patterned Si columns (Si nanocolumns) is retarded by the stress induced near Si/oxide interface [3], [4]. Moreover, in Si nanocolumns, the self-limiting effect of oxidation is observed.…”