Formation of silicon islands on a silicon on insulator substrate upon thermal annealing

Starting from silicon on insulator substrates, we show that a thermal treat ment (in the 600-900 degrees C range) induces the creation of silicon islan ds. To characterize the island formation as well as the initial silicon lay er thickness, we use in situ Auger electron spectroscopy analysis in an ult rahigh vacuum chamber. The island size and density are studied with an ex s itu atomic force microscope. We show that the formation temperature of the islands increases from 575 to 875 degrees C as the initial silicon layer th ickness increases from 1 to 19 nm. For the 1 nm thickness, the minimum isla nd size is reached (semispherical shape with a 16 nm diameter). The phenome na involved in the island formation are discussed and the study of the vari ations of the calculated stress tensor (IMPACT software) as a function of t he thermal treatment explain the behavior of the top silicon layer. (C) 200 0 American Institute of Physics. [S0003-6951(00)02421-9].