LOW DEFECT DENSITY SELF-INTERSTITIAL DOMINATED SILICON

THE PRESENT INVENTION RELATES TO SINGLE CRYSTAL SILICON, IN INGOT (10) OR WAFER FORM, WHICH CONTAINS AN AXIALLY SYMMETRIC REGION (6) WHICH IS FREE OF AGGLOMERATED INTRINSIC POINT DEFECTS,AND A PROCESS FOR THE PREPARATION THEREOF. THE PROCESS FOR GROWING THE SINGLE CRYSTAL SILICON INGOT (10) COMPRISES CONTROLLING (I) A GROWTH VELOCITY, V, (II) AN AVERAGE AXIAL TEMPERATURE GRADIENT, G₀, DURING THE GROWTH OF A CONSTANT DIAMETER PORTION OF THE CRYSTAL OVER A TEMPERATURE RANGE FROM SOLIDIFICATION TO A TEMPERATURE OF NO LESS THAN ABOUT 1,325°C, AND (III) A COOLING RATE OF THE CRYSTAL FROM A SOLIDIFICATION TEMPERATURE TO ABOUT 1,050°C, IN ORDER TO CAUSE THE FORMATION OF AN AXIALLY SYMMETRICAL SEGMENT (6) WHICH IS SUBSTANTIALLY FREE OF AGGLOMERATED INTRINSIC POINT DEFECTS. THIS AXIALLY SYMMETRIC REGION (6) EXTENDS INWARDLY FROM THE CIRCUMFERENTIAL EDGE (20) OF THE INGOT, HAS A WIDTH AS MEASURED FROM THE CIRCUMFERENTIAL EDGE RADIALLY TOWARD THE CENTRAL AXIS (12) OF THE INGOT WHICH IS AT LEAST ABOUT THREE-TENTHS THE LENGTH OF THE RADIUS (4) OF THE INGOT, AND HAS A LENGTH (24) AS MEASURED ALONG THE CENTRAL AXIS OF AT LEAST ABOUT TWO-TENTHS THE LENGTH OF THE CONSTANT DIAMETER PORTION OF THE INGOT. (FIG.8)