Continuous replenishment of molten semiconductor in a Czochralski-process, single-crystal-growing furnace

Apparatus for producing solid crystals from a melted material comprising:

• A. a drawing crucible for containing a melt of said material from which a solidifying crystal is drawn;
• B. crystal drawing means to progressively draw a solidifying crystal from melt contained in said drawing crucible;
• C. heater means surrounding said drawing crucible for applying the thermal energy to said melt required to permit formation of said solidifying crystal;
• D. means to rotate said drawing crucible relative to said heater during the drawing of a solidifying crystal from melt contained therein;
• E. a melt replenishment crucible separate from but adjacent to said drawing crucible, containing melt for replenishing melt in said drawing crucible;
• F. heater surrounding said replenishment crucible for forming and maintaining a melt of said material in said replenishment crucible;
• G. a siphon tube providing fluid communication between said drawing and melt replenishment crucibles, said tube having its opposite ends respectively immersed within the melt contained in said replenishment crucible and within the melt contained in said drawing crucible;
• H. means to initiate flow of melted material through said siphon tube;
• I. level sensing means to sense the level of said melted material in one of said crucibles and generate an electrical signal indicative of said sensed level;
• and
• J. level control means responsive to said sensed level for automatically controlling the level of melt in said drawing crucible, said level control means including a lift mechanism connected to said replenishment crucible for changing the elevation of the same relative to said drawing crucible and thereby cause automatic flow of melt material between said replenishment and drawing crucibles through said siphon tube to control the melt level in the drawing crucible.