PROCESS FOR PREPARING DEFECT FREE SILICON CRYSTALS WHICH ALLOWS FOR VARIABILITY IN PROCESS CONDITIONS

摘要

A PROCESS FOR GROWING A SINGLE CRYSTAL SILICON INGOT HAVING AN AXIALLY AYMMETRIC REGION SUBSTANTIALLY FREE OF AGGLOMERATED INTRINSIC POINT DEFECTS. THE INGOT IS GROWN GENERALLY IN ACCORDANCE WITH THE CZOCHRALSKI METHOD; HOWEVER, THE MANNER BY WHICH THE INGOT IS COOLED FROM THE TEMPERATURE OF SOLIDIFICATION TO A TEMPERATURE WHICH IS IN EXCESS OF ABOUT 900°C IS CONTROLLED TO ALLOW FOR THE DIFFUSION OF INTRINSIC POINT DEFECTS, SUCH THAT AGGLOMETRIC REGION. ACCORDINGLY, THE RATIO V/G IS ALLOWED TO VARY AXIALLY WITHIN THIS REGION, DUE TO CHANGES IN V OR G0, BETWEEN A MINIMUM AND MAXIMUM VALUE BY AT L EAST 5