Western Electric Company, Inc.

Bell Telephone Laboratories

Raymond E Reusser

Robert J Lavigna

Tze Yao Chu

Yogesh Jaluria

George Williams

Charles Walter Pearce

Lewis Emanuel Katz

David W Hill

Specially selected particles 32 of an irregularly shaped material are almost completely melted in a heated crucible 22. Then while a small upper portion of the material 32 is still partially solid, additional but smaller particles 38 of a material are added thereon. Another method also starts with the specially selected particles 32 of a material which are completely melted in the heated crucible 22. Then the top surface of the liquid is partially frozen into a structural layer 36 to receive the addition of the smaller particles 38. Both techniques substantially prevent extremely hot liquid which is dangerously reactive from being scattered outside the crucible 22 when additional material 38 is added therein. Finally the entire contents of the crucible 22 are melted and a single-crystalline ingot 48 is grown from a melt 34.

Growing crystals from a melt by controlling additions of material thereto

In Czochralski crystal growing operations, particularly those involving growth of silicon crystals, projecting formations of silicon monoxide, which sometimes form on the surface of the melt-containing crucible just above the surface of the melt, are avoided by perturbing the formation conditions at the region of probable formation. Such perturbations may include increasing the temperature of the crucible at the region of probable formation. The increase in temperature may be provided by including an aperture in the housing which surrounds and supports the crucible to enable locally greater radiative heating of the crucible in the region of probable formation. Other expedients for locally increasing the temperature of the crucible include, without limitation, selective frosting and other techniques for locally changing the emissivity characteristics of the crucible and/or the surrounding material.

Method for avoiding undesirable deposits in crystal growing operations

In Czochralski crystal growing operations, particularly those involving growth of silicon crystals, projecting formations of silicon monoxide sometimes form on the surface of the melt-containing crucible just above the initial level of the melt. These formations are avoided by perturbing chemical formation conditions at the region of probable formation. Such perturbations may be provided by a tube through which either a positive pressure of a gas, such as argon, is directed toward the region of probable formation or through which a negative pressure may be applied to perturb the formation conditions.

Method and apparatus for avoiding undesirable deposits in crystal

To improve the control over resistivity of grown single crystalline ingots, to reduce the turn-around time between growth of successive ingots in a particular crystal grower and to enable recycling of otherwise junk material, a sample of a molten material (the 'melt') from which the ingot is to be grown is withdrawn from the crystal grower, cooled, and analyzed. Based on the analysis, controlled additional amounts of the material and/or a dopant impurity are added directly to the melt to restore it to a desired chemical composition. Thus, avoidable is costly and time-consuming cooling of the melt and restarting the system with a completely new charge of material and impurity, and achievable is uniformity of resistivity among the successively grown ingots. Preferably the sample is withdrawn from the melt into a quartz tube which is inserted into the system through a port. The sample is rapidly cooled and solidified and inserted into a waveguide system where a microwave absorption measurement provides a number which is readily converted into resistivity of the sample, and then, into doping level of the melt.

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Bethlehem, PA, United States of America

Raymond E Reusser