JPH02255590A - Granular silicon supplying device - Google Patents

Abstract

PURPOSE:To supply a fixed amt. of silicon stably over a long period of time in a Czochralski process by providing a rotor having many radial valves, rotating this rotor and supplying the silicon particles from a hopper. CONSTITUTION:This granular silicon supplying device is provided in a continuous Czochralski pulling up device and is formed of the rotor 13 provided in a box body 11 which can be substd. with a reduced pressure inert gaseous atmosphere and a storage hopper 12 provided in the upper part of the rotor 13, etc. The rotor 13 has continuously the many radial valves which are perpendicular, in the opening direction, to the revolving shaft 14 in the outer peripheral part of the rotating body the revolving shaft 14 of which is horizontal. The above-mentioned hopper 12 supplies the stored silicon particles 25 from a discharge port opened in the lower part to the rotor 13 side. The particles 25 deposit on the rotor 13 and the supply of the particles 25 is stopped at the time of stopping the rotation of the rotor 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a granular silicon raw material supply device for supplying silicon raw material particles into a crucible in a silicon single crystal pulling device.

[Prior Art] In a silicon single crystal pulling apparatus using the Czochralski method, an operating method for continuously pulling a silicon single crystal while supplying granular raw materials into a crucible has been known. In this case, as a device for supplying the granular silicon raw material, it is easy to consider a vibrating feeder because of its simple structure for boat fishing. A vibrating feeder is a device that supplies granular silicon raw material onto a vibrating plate, and controls the supply amount by controlling the vibration amplitude or frequency of the plate.

For example, Japanese Patent Publication No. 61-17537 proposes a type of vibratory feeder.

A rotary valve can be considered as another supply device. Figure 2 is a cross-sectional explanatory diagram of a rotary valve, in which (1) is the rotor, (la) is the shaft, and (i
b) is a feather. (2) is a case, and (3) is a powder storage hopper. This rotary valve consists of a rotor (1
) is rotated in the case (2), and the powder discharged from the upper powder storage hopper (3) is received into the space between the blade (la) and the case (2). (2
) is discharged sequentially from the bottom.

[Problems to be Solved by the Invention] The feed rate with a vibratory feeder is greatly influenced by the dimensions of the granular silicon raw material. That is, the larger the particle size, the greater the amount supplied, and vice versa, if the particle size is small. It is difficult to completely mix raw material grains, and segregation of large or small grains is unavoidable. That is, in a vibratory feeder, fluctuations in the feed amount due to segregation in the size of the feed amount are unavoidable. This variation immediately results in a variation in the thermal environment of the single crystal growth furnace, so
There is a problem in that it is extremely unfavorable in terms of single crystal growth.

On the other hand, in rotary valves, when the powder received in the space between the blades and the case moves through the case due to the rotation of the rotor, the inner surface of the case is worn out due to friction between the powder and the inner surface of the case. Since impurities are mixed into the powder particles, this poses a problem as a raw material supply device to a silicon single crystal pulling device. Furthermore, when supplying particulate matter, there is a problem that particles get caught between the rotor blades and the case.

As a supply device for particulate matter, there is an anti-encroachment rotary valve for particles that prevents entrapment by preventing the valve-shaped space of the rotor from becoming full.

FIG. 3 is an explanatory cross-sectional view of the same, and although the blades (lb) have a special shape as shown in the figure to prevent particles from getting caught, there is a problem that the structure becomes complicated.

[Means for Solving the Problems] A supply device for granular silicon raw material according to the present invention has a box body that can be replaced with a reduced pressure inert gas atmosphere, and a rotating shaft having a horizontal axis on the outer periphery of the rotating body, the opening direction of which is parallel to the rotating axis. It has a rotor in which a large number of vertical and radial squares are continuously provided, and a storage hopper that is provided at the top of the rotor and supplies the stored silicon particles to the rotor side from an outlet opening at the bottom.

The rotor and the storage hopper are arranged so that when the rotor stops rotating, the silicon particles discharged from the storage hopper are deposited on the rotor and the supply of silicon particles is stopped.

[Function] In this invention, the granular silicon raw material discharged from the lower discharge port of the storage hopper is received in the valve-shaped space of the rotor, and is moved and moved together with the cell by the rotation of the rotor.
The granular silicon raw material is discharged and supplied into the crucible in an amount corresponding to the rotational speed of the rotor. When the rotor is stopped, the granular silicon raw material discharged from the lower discharge port of the storage hopper is deposited on the rotor due to the angle of repose of the particles, and the supply of the granular silicon raw material into the crucible is stopped.

In this invention, the factors that influence the supply amount are the size of the cell, the gap length between the cell and the storage hopper, and the rotational speed of the rotor. Since this is performed by controlling the rotational speed of the rotor, the supply amount can be controlled with high precision.

[Embodiment] FIG. 1 is a sectional view of a granular silicon supply device according to an embodiment of the present invention. A box body (11) communicating with the chamber via a gate valve (21) is provided on the top of the chamber lid (22) of the silicon single crystal pulling apparatus, and the box body (11)
The inside of the box (11) can be replaced with a reduced pressure inert gas atmosphere like the inside of the chamber, and the top of the box (11) is provided with a lid plate (18) for opening and closing when replenishing the silicon particles (25). It is bolted to the box body (11) and sealed with an O-ring (19).

Inside the box (11), there is a storage hopper (25) for temporarily storing silicon particles (25) and discharging it from the outlet at the bottom.
12), the storage hopper holder that holds the hopper is a stand (1
6), a rotor (13) having a horizontal rotation axis (14) and a large number of consecutive radial squares with opening directions perpendicular to the rotation axis on the outer periphery; a funnel-shaped guide tube A (15); The guide tube holder is provided with a stand (17) and a chamber lid (22).
) has a gate valve (21) and silicon particles (
A funnel-shaped guide tube B (23) is provided to guide the crucible (25) into the crucible.

Next, the operation will be explained. The silicon particles (25) filled in the storage hopper (12) are continuously discharged from the lower discharge port of the hopper, and are transferred to the rotor (1) located directly below the discharge port.
3) is filled in the valve-shaped space on the outer periphery.

The filled silicon particles move together with the cell due to the rotation of the rotor (13), and eventually fall downward from the cell space due to gravity, forming funnel-shaped guide tubes A (15) and B.
(21) into a crucible (not shown).

In this case, the discharge amount of silicon particles (25), that is, the amount of silicon particles (25) supplied into the crucible is the rotor (
Since it is determined by the moving speed of the silicon particles filled in the valve-shaped space on the outer periphery of ta>, the supply amount can be controlled by arbitrarily adjusting the rotation speed of the rotor (13).

When the rotation of the rotor (13) is stopped, the particles discharged from the storage hopper (12) are transferred to the rotor (13).
The silicon particles are deposited on top in a conical shape with a specific angle of repose, and the supply of silicon particles into the crucible is stopped.

In the granular silicon raw material supply device according to this embodiment, unlike the conventional diaphragm feeder, the supply amount is not affected by the grain size of the raw material, so it greatly contributes to stabilizing single crystal growth. Furthermore, since there is no case like a rotary valve, the structure is not only simple, but also prevents impurities from getting into the particles due to wear of the case due to friction between the case and the rotor. It can also solve the problem of getting stuck.

In addition, in this embodiment, a storage hopper (12), a rotor (13), a funnel-shaped guide tube (15), (23)
If the portion in contact with the silicon particles (25) is made of quartz, silicon, or Teflon, it is possible to prevent impurities from entering the crucible when supplying the silicon particles into the crucible.

[Effects of the Invention] As described above, according to the present invention, in a continuous Czochralski method pulling device for silicon single crystals, a large number of radial openings, the opening direction of which is perpendicular to the rotation axis, is provided on the outer circumference of the rotating body whose rotation axis is horizontal. By rotating this rotor, the silicon particles from the storage hopper are supplied to the crucible, so the device can be realized with a simple structure, and furthermore, the granular silicon raw material is not contaminated. It is possible to stably and continuously supply a fixed amount without
Stable, long-term continuous operation is possible.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional explanatory view of a granular silicon supply device according to an embodiment of the present invention, and FIGS. 2 and 3 are cross-sectional explanatory views of a conventional rotary valve. In the figure, (12) is a storage hopper, and (13) is a rotor. Agent Patent Attorney Muneharu Sasaki Procedural Amendment (Voluntary) 1: Rotor 19995

Claims (1)

[Scope of Claims] A continuous Czochralski method pulling device for silicon single crystals that grows single crystals while supplying silicon raw material particles into a crucible, which is provided in a box that can be replaced with a reduced pressure inert gas atmosphere,
A rotor that continuously has a large number of squares with opening directions perpendicular to the rotation axis and radial on the outer periphery of a rotating body whose rotation axis is horizontal; and a storage hopper that supplies the silicon particles from the discharge port to the rotor side, and when the rotor stops rotating, the silicon particles discharged from the storage hopper are deposited on the rotor, and the supply of silicon particles is stopped. and a granular silicon supply device, characterized in that the supply amount of silicon particles is controlled by arranging the storage hopper and controlling the rotational speed of the ter.