HIGH PRESSURE FLOAT ZONE GROWTH OF TIC

TITANIUM CARBIDE (TIC) IS THE IDEAL SUBSTRATE FOR SINGLE CRYSTAL EPITAXIAL GROWTH OF B-SILICON CARBIDE. THE TITANIUM CARBIDE CRYSTALS NOW AVAILABLE ARE LACKING IN BOTH SIZE AND QUALITY FOR THIS APPLICATION. IT IS BELIEVED THAT BY IMPROVING UPON THE HIGH PRESSURE FLOAT ZONE CRYSTAL GROWTH METHOD NOW USED FOR TIC CRYSTAL GROWTH, BOTH THE QUALITY AND SIZE REQUIREMENTS CAN BE MET. THE PRIMARY EFFORT IN THE PHASE I PROGRAM WILL BE TO REDUCE ALL IMPURITIES IN THE FLOAT ZONE CHAMBER, ESPECIALLY THOSE ORIGINATING FROM THE TIC FEED RODS AND THE PRESSURIZED INERT COVER GAS. IMPURITIES WITHIN THE FEED ROD CAN CAUSE DISLOCATIONS OR NUCLEATE NEW CRYSTALS, LIMITING THE SIZE OF THE SINGLE CRYSTAL BEING GROWN. THESE WILL BE REDUCED BY USING HIGH PURITY POWDERS IN THE MANUFACTURE OF THE FEED RODS. IMPURITIES IN THE PRESSURIZED INERT COVER GAS CAN CAUSE ARCING BETWEEN THE RF COIL AND THE WORKPIECE, IN ADDITION TO CONTAMINATING THE FEED ROD. THESE WILL BE REDUCED BY USING PROPRIETARY GAS PURIFICATION TECHNOLOGY. A COMPUTER SIMULATION RUN WILL ALSO BE DONE IN PHASE I. THIS PHASE I PROGRAM WILL RESULT IN THE GROWTH OF HIGH PURITY 3/4 IN. SINGLE CRYSTAL TIC. THE PHASE II PROGRAM WILL RESULT IN SCALE-UP TO 2 IN DIAMETER SINGLE CRYSTALS.