Oxygen Bubble Formation and Transformation During High-Dose Oxygen Implantation and Annealing of Silicon

Abstract

The formation of bubbles during high dose implantation of oxygen into silicon, and the subsequent transformation of the bubbles during annealing, were studied with transmission electron microscopy (TEM). There was a threshold for bubble formation at a minimum dose of 0.3 × 10¹⁸ oxygen/cm² and a lower temperature of 550°C. As dose increased the bubbles grew larger and the bubble trails lengthened. However, increasing beam current by a factor of 10 or increasing temperature to 700°C did not affect bubble formation. Bubble evolution during intermediate temperature annealing was also studied using TEM techniques. For 2 hour anneals between 1000 and 1100°C the oxygen bubbles transform into SiO₂ particles by first forming a “shell” of SiO₂, which then facets, grows inward, and finally completely transforms the bubble into an oxide particle. At temperatures greater than 1100°C the oxide particles dissolve by outdiffusion of the oxygen to the wafer surface.