Device for growing single crystals from melt

 

The invention relates to devices for growing shaped single crystals from the melt to the seed crystal, such as sapphire, methods Czochralski, kyropoulos. The device includes a cylindrical chamber with a lid, the crucible to melt structurally mounted on the rod can move, the camera performed and two with the mechanism of the vertical transfer sections; thermal unit, installed between the upper and lower sections of the camera, made in the form of a hollow water-cooled cylinder placed inside the heater collected from the U-shaped slats, bent in the shape of the crucible, and a closed annular water-cooled current leads, a cylinder mounted on the secondary shaft, located on the outer surface of the cylinder and provided with a mechanism for moving the cylinder vertically and around the rod, the inner side of the cylinder in the lower part thereof is made with the tabs, which are insulators, the current leads are made with holes, in which are secured the free ends of the slats and curved U-shaped ends of the slats mounted on the centering their ring; the current leads are installed on insulators, centering the heater and the findings organization and maintenance of a constancy of form radial isotherms with different geometry along the entire length of the grown single crystal, reduction of structural defects in the crystal due to the process of growing with minimal temperature gradients, ease of use and ergonomics. 1 s and 5 C. p. F.-ly, 3 ill.

The invention relates to a device for growing single crystals from the melt to the seed crystal and can be used in the technology of growing crystals, such as sapphire, methods Czochralski, kyropoulos.

The technical problem solved by the invention is a device for growing single crystals from melt, allowing you to grow volumetric shaped crystals in a uniform thermal field and providing a simplified design thermal unit and the operation of the heater, as well as the stability regimes of growing bulk single crystals of various types and size and increase the structural perfection of the crystals.

A device for growing monocrystalline ribbons sapphire, which includes a camera located inside the crucible, thermal unit, the shaper, structurally mounted on a rod.

Thermal unit made in the form of cylindrical graphite heater, the inner surface of lframe. The crucible is mounted on a pedestal and placed inside a graphite heater. Screens placed above the crucible. (See A. C. the USSR 1213781, publ. 23.04.1991, With 30 In 15/34).

The device has the following disadvantages.

The material of the heater - graphite with a deposited layer of silicon carbide, chemically reacts with corrosive oxides of aluminum at high temperatures, which dramatically reduces the life of the heater and pollutes the carbon of the growing crystal. The heater cannot be repaired in the event of a breakdown, thermal unit cannot provide a rectangular radial isotherms necessary to obtain high-quality surround shaped single crystals.

A device for growing shaped crystals of refractory compounds, including the camera, the crucible is installed in it by the shaper and thermal unit, containing situated coaxially to the crucible with a gap of a graphite heater in the form of a Cup with a front opening at the level of the end face of the shaper and with the increasing cross section of the hole towards the bottom, and the screen in the form of a hollow cylinder mounted above the crucible with tie rods attached to the upper block insulation. The heater is connected to the current source. (See auth. St. Scrollsawing for growing high-quality bulk single crystals.

A device for growing bulk single crystals, including the camera, two melting heater and the double-crucible. In the upper section of the melted source material using one heater located around the upper section of the crucible, and the cultivation is carried out on the lower section of the crucible using a different heater installed under the bottom section of the crucible. (See auth. St. 661966, publ. 30.03.80, WITH 30 IN 15/02).

The unit is adopted for the prototype.

The device cannot be used for growing shaped bulk single crystals because of the impossibility of creating in the radial melt isotherm rectangular forms.

The technical result of the claimed invention is the ability to create and maintain constancy of forms radial isotherms with different geometry along the entire length of the grown single crystal, the reduction of structural defects in the crystal due to the process of growing with minimal temperature gradients, ease of operation and ergonomics.

The technical result is achieved in that a device for growing single crystals from the melt to the seed crystal, comprising a cylindrical chamber with a lid, heat the site, TIG the EPA made two and a mechanism for vertical movement of the sections, thermal unit is installed between the upper and lower sections of the camera and is made in the form of a hollow water-cooled cylinder placed inside the heater collected from the U-shaped slats, bent in the shape of the crucible, and a closed annular water-cooled current leads, a cylinder mounted on the secondary shaft, located on the outer surface of the cylinder and provided with a mechanism for moving the cylinder vertically and around the rod, the inner side of the cylinder in the lower part thereof is made with the tabs, which are insulators, the current leads are made with holes, in which are secured the free ends of the lamellas, while curved U-shaped ends of the slats mounted on the centering their ring, the current leads are installed on insulators, centering the heater, and the findings of the current leads are located on the lateral surface of the cylinder in different horizontal planes. The current one relative to another are coaxial or one above the other.

The slats are made of the same length and configuration, the number of lamellae in the heater and hole current in multiples of 12. To create a radial isotherms rectangular or other polygonal forms lamellae are collected in section, whose length and location of the sections of the camera.

Centering lamella ring is not involved in the electric circuit.

The essence of the claimed device is a new design thermal unit in which all the elements, namely the heater, the current leads, insulators, current terminals originally made, compactly arranged relative to each other and represent a single whole.

This design thermal unit has a number of advantages.

The heater is assembled from strips, mounted on the closed annular current and centring ring at the same time performs the function of a thermal shaper and has the ability to change the shape of the radial isotherms and to determine the profile shape of the grown crystals. To create a shaped isotherms for growing single crystals of cubic and hexagonal lattices with natural cut the total number of lamellae in the heater is a multiple of the number of faces of a single crystal and a multiple of 12. The heater is simple in operation, can be easily assembled and dismantled in accordance with the task of changing the geometry of the profile of the single crystal, so that changing forms radial isotherm is achieved by removing or adding the desired number of slats.

Hollow water-cooled cylinder with slats heater, and also creates a symmetric thermal field relative to the vertical axis of the camera by centering heater as by insulators based on internal projections of the cylinder, and due to the possibility of horizontal movement of the slats of the heater in the holes of the ring current.

In addition, the execution of the cylinder with the possibility of vertical movement and movement about the axis of the shaft on which the cylinder is fixed, provides easy access to the heater and the replacement of elements of thermal node.

In General, thermal unit design significantly increases the period of its operation, ergonomic and does not require the consumption of expensive graphite, not subject to recovery.

The device schematically depicted in Fig.1.

The device includes upper 1 and lower 2 sections cameras, made with a mechanism for moving in the vertical direction (not shown), with cover 3, strukturdaten 4, the crucible 5, mounted in the lower section of the 2 cameras, the top rod 6 for fastening structurally 4, the lower rod 7 for mounting the crucible 5. The rods 6 and 7 is designed for rotation and vertical movement. Between the upper section 1 and the lower section 2 of the camera is set to heat the UGA is in the form of a crucible U-shaped slats 10, and closed annular water-cooled current leads 11, 12. The current leads 11, 12 are located one above the other (not shown) or coaxial and have holes 13, in which is fixed the upper ends of the U-shaped slats 10. The lower bent U-shaped ends of the slats 10 are fixed ring 14, is not involved in the electric circuit of the heater 9.

The cylinder 8 is fixed on the secondary shaft 15, which is located on the outer side of the cylinder 8 and is equipped with a mechanism for moving it (not shown) vertically and around the rod 15. On the inner surface of the hollow cylinder 8, in the lower part thereof, the protrusions 16.

The current leads 11, 12 mounted on the protrusions 16 in the insulator 17, which center the current leads 11, 12 and the heater 9 additionally has the possibility of alignment with respect to its vertical axis by a displacement of the free ends of the U-shaped sipes in the holes 13.

On the lateral surface of the cylinder 8 in different horizontal planes placed conclusions 18, 19 current leads 11, 12. The crucible 5 mounted on the lower rod 7 inside the heater 9.

Device for growing single crystals from the melt to the seed crystal is as follows.

Collect thermal unit. For this purpose water-cooled cylinder 8, zakreplyaya centering on the insulators 17 water-cooled current leads 11, 12.

For growing shaped bulk single crystals, for example, rectangular shapes into the holes 13 of the ring current leads 11, 12 set curved shape of the crucible U-shaped slats 10, collected in the section (Fig.3), the width of which corresponds to the lengths of the sides of the given rectangle. The upper ends of the slats 10 are fixed in the holes 13 of the current leads 11, 12, and the lower U-shaped curved ends of the centring ring 14 that is not part of the electrical circuit of the heater 9.

Such thermal unit deploying in the opposite direction on the 90ocombine with a vertical axis of the chamber and hermetically connected to the bottom sections 2 melting chamber, place the crucible 5 with charge 20 inside the heater 9 to the lower rod 7. On the top rod 6 set the seed crystal in the form of a 4-facet prism, one of the side faces which are oriented in accordance with sections slats 10, creating a rectangular radial isotherm for crystal growth of a rectangular shape with a natural cut.

The upper section of the melting chamber 1 is hermetically connected to thermal node, a heater 9 and carry out the process of growing single crystals by the Czochralski obtaining crystals pramool the ina which corresponds to the lengths of the triangle (hexagon).

Were grown single crystals of sapphire triangular and rectangular shape with a length of 200 mm

The deviation in the transverse dimensions did not exceed(1-2) mm on the side.

The device allows to obtain the following positive effects.

1. The possibility of growing volume shaped single crystals with natural faceted triangular (hexagonal), rectangular forms, depending on the directions of growth and structural properties of as-grown single crystal.

2. To increase the perfection of the structure and to ensure uniformity in size along the length of the single crystal.

Claims

1. Device for growing single crystals from the melt to the seed crystal, comprising a cylindrical chamber with a lid, heat the node, the crucible to melt structurally mounted on the shaft for rotation, characterized in that the chamber is two and the mechanism of vertical movement of the sections, thermal unit is installed between the upper and lower sections of the camera and is made in the form of a hollow water-cooled cylinder placed inside the heater collected from the curved shape of the crucible U-shaped blades, nom on the outer surface of the cylinder and provided with a mechanism for moving the cylinder vertically and around the rod, the inner side of the cylinder in the lower part thereof is made with the tabs, which are insulators, the current leads are made with holes, in which are secured the free ends of the blades, and U-shaped curved ends of the slats mounted on the centering their ring, the current leads are installed on insulators, centering the heater, and the findings of the current leads are located on the lateral surface of the cylinder in different horizontal planes.

2. The device under item 1, characterized in that the current leads are coaxial or one above the other.

3. Device according to any one of paragraphs.1 and 2, characterized in that the slats are made of the same length and configuration.

4. Device according to any one of paragraphs.1-3, characterized in that the number of lamellae in the heater and hole current in multiples of 12.

5. Device according to any one of paragraphs.1-4, characterized in that for radial isotherms polygonal forms lamellae are collected in section, whose length and location correspond to the sides of the polygon.

6. Device according to any one of paragraphs.1-5, characterized in that the diameter of the hollow cylinder is equal to the diameters of the sections of the camera.

 

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