Influence of curvature on impurity gettering by nanocavities in Si

Abstract

Competition for Au gettering in Si between two cavity layers of different diameter (34 and 12 nm) is examined. Au is initially contained in the large cavity layer made by He implantation. Transport of Au towards the second, small diameter cavity layer is measured by ion scattering. The true surface in both layers is determined by electron microscopy. Small cavities are found to be four times more efficient gettering sites than large cavities for the same amount of internal surface. This difference is explained by a simple model based on curvature thermodynamics, faceting, and surface reconstruction.

Nanocavities in He implanted InP

“…Data for cavities in Si implanted with He ϭ1ϫ10 17 cm Ϫ2 at 100 keV and vacuum annealed for 1 h are shown for comparison. 20,21 The temperature is normalized to the respective melting temperatures T m ͑1333 K for InP and 1687 K for Si͒ to provide an approximate scaling for defect concentrations and diffusivities in these materials. The comparison is not perfect since for these conditions, cavities in Si have reached equilibrium at this temperature while this is not the case for InP but it nevertheless provides insights into the formation mechanisms in InP.…”

Impact of Hydrogen Plasma Treatment on Gettering by He Implantation-Induced Cavities in Silicon

“…The implantation of He at 160 keV for a dose of 5x10 16 He + /cm 2 followed by an annealing at 800°C for 1 hour creates a well-defined cavity band at a depth of 0.85 µm from the surface. The corresponding cavity bandwidth is 150 nm.…”

“…A reduction of the cavity bandwidth is also observed; from 150 without H-treatment to 100 nm with hydrogen. Low-doped wafers were implanted with helium (5x10 16 He per cm 2 at 160 keV). First, the possible in-diffusion of H [11] can impact the cavity evolution as already demonstrated in the case of wafer splitting/bonding techniques [13,14].…”

“…Helium implantation was performed at room temperature at an energy of 160 keV and a dose of 5x10 16 He + /cm 2 . Helium implantation was performed at room temperature at an energy of 160 keV and a dose of 5x10 16 He + /cm 2 .…”

Roles of Impurities and Implantation Depth on He+- Cavity Shape in Silicon

“…Depending on both the experimental conditions and the nature of the impurity (interstitial, hybrid, forming silicides or not), the atoms are supposed to be trapped at cavity either as a fraction of a chemisorbed-layer [23], up to a monolayer (which is too thin to be detected by microscopic studies) or as a three dimensional structure [24]. Moreover, the gettering efficiency of the cavities was found to be dependent of the cavity radius [25]. However, the chemisorption hypothesis [23] was never confirmed by direct microscopic observation.…”