DEFECT REDUCTION IN SIMOX WAFERS

CREATION OF BURIED INSULATING LAYERS IN SILICON WAFERS BY HIGH DOSE OXYGEN IMPLANTATION (SIMOX) HAS GAINED SIGNIFICANT ATTENTION IN THE LAST TWO YEARS. THE SIMOX TECHNOLOGY IS POSITIONED TO BE A PRIME CONTENDER IN THE SILICON-ON-INSULATOR (SOI) ARENA MAINLY BECAUSE OF THE INHERENT RELIABILITY/REPRODUCIBILITY OF THE ION IMPLANTATION TECHNOLOGY. ONE OBSTACLE TO BROADER USE OF THE SIMOX MATERIAL IS THE HIGH DENSITY OF DISLOCATIONS THAT APPEARS IN THE TOP-LAYERSILICON FOLLOWING THE HIGH TEMPERATURE ANNEALING REQUIRED FOR THE PROCESS. THE DISLOCATIONS ARE PARTICULARLY HARMFUL IN THE FABRICATION OF BIPOLAR DEVICES ON SIMOX MATERIAL. SPIRE CORPORATION HAS CONTRIBUTED SIGNIFICANTLY TO THE DEVELOPMENT OF SIMOX TECHNOLOGY AND IS PERFORMING ONGOING RESEARCH IN THIS FIELD. SPIRE PROPOSES TO PERFORM SECONDARY ION IMPLANTATION OF SPECIES SUCH AS GE INTO THE SIMOX WAFERS FOR REMOVING THE DISLOCATIONS CREATED BY THE HIGH TEMPERATURE ANNEAL. PRELIMINARY RESULTS INDICATE THAT LOW DOSES OF GE IN THE TOP-LAYER-SILICON CAUSE AMORPHIZATION AND CREATED STRESS FIELDS. SUBSEQUENT ANNEALING OF THE WAFERS HAS RESULTED IN DISLOCATION DENSITIES BELOW THE DETECTABLE LIMIT OF THE X-TEM OR PLANE VIEW TEM METHODS.