LOW COST IMPROVED SIMOX MATERIAL BY HIGH-CURRENT-DENSITY HIGH TEMPERATURE IMPLANTATION

SPIRE HAS RECENTLY DEMONSTRATED THAT SIMOX WAFERS OF SUFFICIENTLY HIGH QUALITY AND LOW DEFECT DENSITY TO SUPPORT BIPOLAR DEVICE APPLICATIONS CAN BE PRODUCED. TO ACHIEVE SUPERIOR QUALITY, HOWEVER, PRESENTLY REQUIRES PRODUCTION METHODS WHICH RESULT IN RELATIVELY HIGH COST. A RESEARCH PROGRAM IS PROPOSED WHICH WILL ESTABLISH THE FOUNDATION FOR LOWER COST, HIGHER THROUGHPUT PRODUCTION ALTERNATIVES WHICH PRESERVE BIPOLAR QUALITY. THE STANDARD IMPLANTATION PROCESS RESULTS IN SIMOX MATERIAL WITH DEFECT DENSITIES OF ABOUT 10(9)/CM(2); IT IS KNOWN THAT SIMOX WITH LOWER DEFECT DENSITIES CAN BE PRODUCED USING IMPLANTATION TEMPERATURES OF 600 DEG C TO 700 DEG C. TO UTILIZE THE MAXIMUM POWER OF A HIGH CURRENT IMPLANTER SUCH AS AN NV-200, SPIRE HAS STUDIED FABRICATION OF SIMOX AT MUCH HIGHER IMPLANTATION TEMPERATURES: 900 DEG C TO 1000 DEG C (CURRENT DENSITY OF ABOUT 60 MICROAMPERES/CM(2)). RESULTS INDICATE THAT, TO FORM BURIED LAYERS WITH SUCH HIGH BEAM CURRENT, AN INITIAL LOWER TEMPERATURE IMPLANTATION (LOWER DOSE RATE) IS REQUIRED TO PRODUCE SIO(2) PRECIPITATES OR "SEEDS". PHASE I PROPOSES TO FURTHER INVESTIGATE THIS TWO STEP PROCESS BY 1. IMPLANTING A SMALL FRACTION OF THE TOTAL OXYGEN DOSE (ABOUT 1%) AT LOW TEMPERATURE TO GENERATE A FINE DISPERSION OF SIO(2) PRECIPITATES, FOLLOWED BY (2) IMPLANTATION OF THE OXYGEN BALANCE AT 750 DEG C-850 DEG C.