Single-crystal – oriented-crystal – and epitaxy growth processes; – Apparatus
Reexamination Certificate
1998-12-01
2001-01-09
Utech, Benjamin L. (Department: 1765)
Single-crystal, oriented-crystal, and epitaxy growth processes;
Apparatus
C117S204000, C117S217000
Reexamination Certificate
active
06171395
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a process for melting semiconductor material in a crucible that is located in a container. The invention also relates to a heating device that is suitable for carrying out the process.
The process is preferably used for the production of single crystals using the Czochralski method. In order for it to be possible for a single crystal to be pulled from a melt using this method, it is first necessary to melt the semiconductor material, which is customarily placed in a silicon crucible. The energy needed for this step is usually applied by a fixed heating device which is arranged around the crucible.
During the melting procedure, the crucible is exposed to a high temperature. As a result, so-called pitting corrosion of the crucible material takes place. This leads to the production of particles which may subsequently make it impossible to grow the single crystal without dislocations. The temperature at the crucible wall, as well as the melting time, should therefore be minimised.
SUMMARY OF THE INVENTION
The invention relates to a process for melting semiconductor material in a crucible which is located in a container and is enclosed by a fixed heating device. In this case, the heater of a displaceable heating device is lowered from a lock chamber above the container through an open shut-off valve into the container in the direction of the semiconductor material. In addition, the semiconductor material is melted using the fixed heating device and the lowered heater, and the heater is raised back out of the container into the lock chamber after the semiconductor material has been melted.
The invention also relates to a heating device which is suitable for carrying out the process. A heating device is proposed which is displaceable and comprises a heater which can be lowered from a lock chamber above the container. Next, the heater is lowered through an open shut-off valve into the container in the direction of the semiconductor material, and raised back into the lock chamber.
The invention permits rapid melting of the semiconductor material starting from the center of the semiconductor material charge. The crucible material is protected since a substantial proportion of the required energy is not introduced through the crucible wall. Furthermore, the process does not have any effect on the procedure involved in the actual crystal production, so that tried and tested pull conditions can be kept unchanged.
One object of the invention is to provide a moveable heating device for melting semiconductor material.
Another object of the invention is to provide a heating device to carry out the Czochralski system for forming single crystals from a semiconductor material.
Another object of the invention is to provide a heating device for melting semiconductor material that is simple in design, inexpensive to manufacture, and easy to operate.
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Ammon Wilfried Von
Fuchs Paul
Tomzig Erich
Collard & Roe P.C.
Perez Vanessa
Utech Benjamin L.
Wacker Siltronic Gesellschaft f{umlaut over (u)}r Halbleitermate
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