A study of trenched capacitor structures

Abstract

Trenched structures have been fabricated using a highlsanisotropic low ion energy bombardment etching technique and evaluated using their CV characteristics. It is shown that the structure can be modeled by two capacitors in parallel, one for the bottom and the other for the sidewall. Obtained results indicate that the crystal orientation of the side and bottom surfaces of the trench determine the value of N,, fixed charge, and oxide thickness, especially in the thin range. Orientation-dependent oxidation rates account for the different oxide thicknesses on the sides and bottoms of the trenches. Both the value of N, and the oxide thickness on each wall determine the flat-band voltage V,, of the corresponding capacitors so that the overall capacitance behavior is given by the relative importance of the side and bottom components. A lower value of 1%) than previously reported is found with the etching technique used. It is also shown that an improvement of N, can be obtained by aligning the trench sidewall along the (100) plane.

Kinetics of Initial Lithiation of Crystalline Silicon Electrodes of Lithium-Ion Batteries

“…Surfaces of silicon in various crystallographic orientations have drastically different atomic structures, which can readily result in different rates of reaction on these different surfaces. For instance, such anisotropy has been observed in the rate of thermal oxidation of silicon of various crystal orientations. , Thus, we believe that the reaction at the a-Li η Si/c-Si interface must contribute to the observed relationship between current density and potential as shown in Figure .…”

“…For instance, such anisotropy has been observed in the rate of thermal oxidation of silicon of various crystal orientations. 40,41 Thus, we believe that the reaction at the a-Li η Si/c-Si interface must contribute to the observed relationship between current density and potential as shown in Figure 2.…”

A High Resolution Electron Microscopy Study of the Fine Structure in a Trench Capacitor

“…Increasingly thinner oxides are being used for device applications, and so clearly the integrity and uniformity of the oxide layer is a critical issue. It is well established that thickness variations occur at curved surfaces of trenches [e.g., at the top and bottom corners (2,3)] and that the crystallographic dependence of silicon oxidation rate can introduce oxides of different thickness on the various crystallographic faces (2)(3)(4)(5). Very thin oxides themselves, grown at low temperatures, show sufficiently large -1 nm silicon protrusions at the singlecrystal Si-SiO2 interface that breakdown characteristics can be influenced (6).…”

Conformal Two‐Dimensional SiO2 Layers on Silicon Grown by Low Temperature Corona Discharge

“…Two-dimensional effects in silicon oxidation have become increasingly important as integrated circuit device geometries have become smaller. GreatlY reduced oxide growth rates have been observed at the corners of both Si trenches and polysilicon (1)(2)(3)(4)(5)(6). The very high stresses in the oxide at such corners can create oxide defects that introduce serious device limitations because the leakage current and breakdown voltage of the oxide layers are compromised (6,7).…”

“…Recently, better understanding of two-dimensional oxidation has been sought (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). Kao et al (14) performed extensive experimental studies to determine oxide thickness retardation for concave and convex structures as a function of radius of curvature and temperature for both wet and dry oxidations.…”