Method for the crucible-free floating zone pulling of semiconductor rods and an induction heating coil therefor

US4851628A · kind A · utility

Assignee

• Wacker-Chemitronic Gesellschaft fur Elektronik Grundstoffe mbH · DE

Inventors

• Wilfried Ammon · Burghausen, DE
• Wolfgang Hensel · Langenfeld, DE
• Heinz Klinger · Altötting, DE

Key dates

• Filing date: Dec 8, 1988
• Grant date: Jul 25, 1989
• Expiry date: Dec 8, 2008

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T117/1084
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

A method for pulling silicon semiconductor rods, in particular having diaers of 10cm and over. The current methods of crucible-free float zoning or float zone pulling can be markedly improved if the molten cap like zone which develops is forced inwardly in the growth process. This is accomplished with the aid of electromagnetic forces in an annular zone situated opposite the coil slot. The electromagnetic forces can be achieved by using induction heating coils whose coil surface facing the molten cap is provided with annular segments whose thickness increases from their inner periphery ouotwardly and which are disposed opposite the coil slot above the peripheral region of the molten cap.