Apparatus for controlling the oxygen content in silicon wafers heavily doped with antimony or arsenic

A crystal puller apparatus having a purge system for use in removing vapors and particulate generated during the production of a single crystal silicon rod having a radius and which is pulled from a silicon melt in accordance with the Czochralski method, the crystal puller apparatus comprising:

• a shell enclosing a volume including a crystal growth chamber, the shell being capable of substantially maintaining an atmosphere therein;
• a crucible for containing the silicon melt, the crucible having a central axis and being mounted for rotation about the central axis within the crystal growth chamber;
• a heater for heating the crucible and melt contained therein;
• a crystal pulling mechanism including a seed crystal pull cable connected to a supporting structure capable of raising a seed crystal for pulling the single crystal rod from the melt;
• a purge system comprising a purge gas delivery structure positioned within the crystal puller apparatus shell for delivering high velocity gas in a stream directed generally downwardly at a location spaced a distance greater than the radius of the silicon rod radially outwardly from the central axis of the crucible, whereby the stream of high velocity gas can create a region of low pressure relative to the pressure above the center of the crucible whereby vapors and particulate are aspirated radially outwardly from the surface of the silicon rod and away from above the center of the crucible toward the stream of gas;
• exhaust ports in the shell for passage of purge gas and vapors and particulate entrained therein out of the shell;
• and
• a view port through the shell for viewing the crystal pulling chamber, the view port including a transparent window sealingly mounted in the port, and baffling including a plurality of thin baffles mounted generally in a face-to-face relation adjacent to the view port, the spacing between adjacent baffles being selected to stagnate gases from the atmosphere above the crucible while permitting viewing through the baffles into the crystal pulling chamber thereby to protect the view port window from deposits of material from the atmosphere.

A crystal puller apparatus having a purge system for use in removing vapors and particulate generated during the production of a single crystal silicon rod which is pulled from a silicon melt, the crystal puller apparatus comprising:

• a shell enclosing a volume including a crystal growth chamber, the shell being capable of substantially maintaining an atmosphere therein;
• a crucible for containing the silicon melt, said crucible having an outer perimeter;
• a heater for heating the crucible and melt contained therein;
• a crystal pulling mechanism including a seed crystal pull cable connected to a supporting structure capable of raising a seed crystal for pulling the single crystal rod from the melt;
• a purge system comprising at least one purge gas first outlet positioned within the crystal puller apparatus shell for delivering high velocity gas in a first stream into the volume, said first outlet being positioned above the crucible and being directed generally downwardly and outwardly of the crucible outer perimeter, said first outlet being positioned radially outwardly of the crucible outer perimeter;
• and
• at least one exhaust port in the shell for passage of purge gas, vapors and particulate entrained therein out of the crystal growth chamber.