Device for growing single crystals

 

(57) Abstract:

The invention relates to methods of obtaining crystals by the Czochralski method using recharge melt the source material. Provides increased output dislocation crystals and reduce energy consumption. The device contains a camera of the growth crucible to melt with the spacer, heater and a means of feeding the melt. The heater has a protrusion in the form of a ring located above the melt. The heat transfer to the melt in the feed area of the granules is direct radiation. This increases the symmetry of the temperature field in the melt. 1 C.p. f-crystals, 1 Il.

The alleged invention relates to technologies for semiconductors single crystals by Czochralski method.

A device for manufacturing a silicon single crystal containing a growing chamber, a crucible for melting, which is the spacer ring, heater, and system heat shields (see the application of EPO, N 0390503, MKI C 30 B 15/12, 1990.)

In the known device in the zone of introduction of the feed material (outside spacers) significantly reduced the temperature of the melt, because the granules rasped crystals with dislocation structure.

This heat pellet is an indirect radiation from the radial heater, which requires substantial energy consumption. In addition, the presence of horizontal screen with a hole whose diameter commensurate with the diameter of the crystal reduces the radiation from the melt surface, however, this reduces the axial temperature gradient, and hence the growth rate of the crystal, which reduces the performance of the device.

A device for growing single crystals, including the growing chamber, a crucible for the melt located therein a spacer ring mounted on thermal screen installed coaxially to the crystal, thermal insulation system, and means for supplying granular material in the melt (see U.S. patent N 1936949, IPC C 30 B 15/12, 1990).

This device is the closest proposed and accepted by the authors for the prototype.

The device prototype resolved the heat sink issue from the melt surface in the zone of crystal growth due to the introduction of a heat shield mounted coaxially to the growing crystal.

However, he has all the disadvantages of similar, related to the asymmetry of thermal field generated in the area Panie high crucible requires additional power consumption for heating the top.

The essence of the proposal is that in the device for growing single crystals, including the growing chamber, a crucible for melting, which is the spacer ring mounted on thermal screen installed coaxially to the crystal, a heater, a thermal insulation system, and means for supplying feed material to the melt, the upper part of the heater is provided with a horizontal ledge in the form of a ring placed over the melt, the inner diameter of the ring is 0.6 0.9 diameter of the crucible, and a thickness of 0,6 - 1,0 thickness of the heater. The ring may have a variable width and thickness.

In the proposed device the annular ledge of the heater is located above the melt, allows direct radiation to transfer heat to the melt surface located on the outer side of the barrier ring, which leads to the reduction of energy consumption for melting of the granules and increases the symmetry of the temperature field in the melt. In addition, to ensure the symmetry of the temperature field in the area of introduction of pellet feed material melt a few heated by increasing the temperature on the ledge of the heater. This is achieved by changing the resistance around the circumference of the ledge, nab the RA ring and the diameter of the crucible, the thickness of the rings and the thickness of the heater is obtained experimentally. When the inner diameter of the ring < 0.6 diameter of the crucible is impossible to install the heat shield around the growing crystal used to create a temperature gradient required for crystal growth. When the inner diameter of the ring greater than 0.9 diameter of the crucible, it has almost no influence on the surface temperature of the melt, i.e. is not overheating. When the thickness of the ledge, the lesser of 0.6 thickness of the heater overheating occurs the periphery of the melt crucible, reduced axial temperature gradient, and hence the growth rate of the crystal, which, in turn, reduces the performance of the installation. When the thickness of the ledge, greater 1,0 thickness of the heater, reducing the efficiency of the heating of the melt, resulting in the occurrence of thermal asymmetry in the melt and reducing dislocation crystals. Thus, the proposed device provides higher output dislocation crystals by increasing the symmetry of the temperature field and the reduction of energy consumption.

The drawing shows a diagram of an apparatus for growing single crystals.

The device is part of the ring 4, which divides the volume of the melt on the inner part 5 of the growth zone and the outer part 6 - the recharge zone. Spacer ring 1 is made of quartz and is fixed on thermal screen 7 installed coaxially to the growing crystal 8. The crucible 2 is placed in the cavity of the heater 9, having a horizontal ledge 10 in the form of a ring located on the outer part 6 of the melt. The device also has a thermal insulation system 11 and the tool feeding of the melt 12.

The device operates as follows.

The source material is loaded into the crucible 2, then seal and vacuum growth chamber 1 includes a heater 9 and melted the download. After this, put a seed crystal in the melt and are growing a single crystal while maintaining a constant melt level throughout the crystal growth process by filing in the melt granules feed material. In this case, due to the protrusion 10 of the heater 9, the heat transfer to the outer part of the melt is direct radiation. To ensure the symmetry of the temperature field on the ledge 10 of the heater 9 through the selection of its resistance creates a higher temperature than the heater, small overheating of the melt to the melting of the proposed device were obtained silicon single crystals with a diameter of 125 mm and a length of 1.2 m While the yield on crystals brand EFC-4,5 amounted to 60% which is approximately twice the output of similar crystals obtained on the device prototype, and specific energy consumption in half.

1. Device for growing single crystals, including the growing chamber, a crucible for melting, which is the spacer ring mounted on thermal screen installed coaxially to the crystal, a heater, a thermal insulation system and means for supplying feed material in the crucible, characterized in that the upper part of the heater is provided with a horizontal ledge in the form of a ring placed over the melt, the inner diameter of the ring is 0.6 0.9 diameter of the crucible, and the thickness of 0,6 1,0 thickness of the heater.

2. The device under item 1, characterized in that the ring has a variable width and thickness.

 

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