New Developments in the Defect Structure of Implanted Furnace-Annealed Silicon on Sapphire

Abstract

ABSTRACTThe structural defect properties of silicon on sapphire (SOS) are investigated with transmission electron microscopy and Rutherford backscattering. The results for as-grown SOS films are compared with SOS films which have been implanted with 1016 Si+ ions cm− 2 at an energy of 170 keV and annealed at 600°C (1 h) and 1000°C (18 h). The regrowth proceeds from the silicon surface even though it is noncrystalline as determined by reflection high energy electron diffraction. The structural defects consist of stacking faults, microtwins and dislocations. The stacking faults and microtwins show a dramatic reduction with processing. The nature of the structural defects at the interface after implantation and annealing is reported here for the first time. It is different from the bulk of the silicon film and consists of a layer of dislocation loops of various sizes and short dislocation lines which follow the interface and curve upwards. This behavior is analogous with the secondary defects generated in self-implanted bulk silicon. Suggestions, based on results from bulk silicon implantation, are made for optimizing the ion implantation furnace annealing process.