ARGON INCORPORATION IN SI(100) BY ION-BOMBARDMENT AT 15-100 EV

Argon incorporation in Si (100) by low energy ion bombardment has been studied by polar angle dependent x-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. The bombardment was performed at 15, 20, and 100 eV in an ultrahigh vacuum chamber where a mass-sep arated argon ion beam with an energy spread of less than 1 eV was dire cted to the target. Both the argon penetration depth and incorporation probability were found to increase with bombardment energy. With a fl uence of 2 X 10(17)/cm2, most of the incorporated argon was located wi thin 20 angstrom of the target surface for the 100 eV bombardment and within 10 angstrom for the 15 eV bombardment. In all cases, the argon depth distribution reached a maximum and then declined. At this fluenc e, the incorporation probabilities were 0.0015 and 0.0004 for the 100 and 15 eV bombardment, respectively. When the amount of incorporated a rgon was measured as a function of fluence, it increased with fluence at low fluences, reached a quasisaturation at about 1 X 10(16)/cm2, bu t became fluence dependent again above 1 X 10(18)/cm2. The retained ar gon was stable at room temperature but showed at least two stages of t hermal desorption in the temperature range 25-500-degrees-C.