The desorption behaviour of implanted noble gases at low energy on silicon surfaces

Abstract

Under UHV conditions, clean crystalline Si(lll) surfaces have been bombarded mass-selectively at room temperature with noble gas ions, Ne +, Ar +, Kr +, at normal incidence. By means of stepwise heating up to 1050 K the activation energies and desorbed doses of the noble gases have been straight forwardly determined as a function of temperature and bombardment dose. Firstly a short review of the kinetics of desorbed adsorbates is given and compared with a simple model for the desorption of particles embedded in a surface layer. This shows that the rate constant u in the latter case is orders of magnitude lower and are in agreement with obtained experimental values. From the obtained activation energies we have concluded that these values have to be explained by the silicon properties and that the influence of the noble gas is of second-order importance. The present method enables the simultaneous measurement of both the ellipsometric and desorption spectra during stepwise heating of the sample.

Random and ordered defects on ion-bombarded Si(100)-(2×1) surfaces

“…However, previous ellipsometry studies of desorption of implanted Ar from Si surfaces [3] show that desorption takes place at temperatures as low as 400°C, reaching a maximum at 600°C. Complete desorption is achieved at 800 ""C and the Si surface returns to its original state [4].…”

Deformation and Restoration of Shape in Microelectromechanical System Membrane

“…This value is larger than the activation energy of desorption for physisorption, and smaller than that of desorption for noble gases implanted with an acceleration voltage of kV-order. 14,15 This might suggest that the low-energy implantation of Ar occurs at the outermost atomic surface layer of Si during Ar plasma exposure for the removal of oxidized surface by ICP-RIE. …”

The interpretation of ellipsometric measurements of ion bombardment of noble gases on semiconductor surfaces

“…A minicomputer system has been constructed with automatically controls the ellipsometer and data acquisition [4]. Initially the ellipsometer was calibrated [5] and alligned (angle of incidence 70.25"). Every ellipsometric measurement (A, 4) was preceded by an offset measurement at each analyser setting, since during each desorption the silicon sample is heated up to 8OO"C, resulting in the optical measurements being disturbed by the partially polarised light emitted from the sample.…”