Characterization of GeSi layers formed by high dose Ge implantation into Si

Abstract

High dose Ge implantation into p-type <100> Si wafers at 150 keV has been performed at doses of 3.6 × 10 16, 6.7 × 10 16 and 9.0 × 10 16 cm −2. The Ge distribution and the crystal quality of the implanted layer before and after annealing at various temperatures have been studied by RBS and channeling experiments. It is found for the medium and high dose samples before annealing, more than 90% of the Ge atoms are interstitial sites and after annealing at 1000°C, more than 50% of the Ge atoms have become substitutional. The situation is better for the low dose sample where less than 70% of the Ge atoms are in interstitial sites before annealing and about 80% of them become substitutional after annealing at 1000°C. The ESR spectra of these samples are of Lorentzian shape with a g-value of about 2.007 and a spin density of about 6 × 10 16 cm −3. The ESR signals of these samples have been inferred to be mainly due to Si-dangling bonds in the GeSi alloy layer and can be eliminated by annealing at 1000°C for 2 min. Electrical characterization of the GeSi layer by spreading resistance profiling technique shows that the implantation damage has been extanded deep into the substrate before annealing. After annealing at 1000°C, these defects are removed but the spreading resistance of the surface GeSi layer is found to remain higher than that of the substrate.