JPH0479972B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to high purity silicon;
In detail, in fluidized bed coating equipment, seeds
The present invention relates to the production of small silicon particles that can be used as

Methods have been proposed to advance the species from a container to a target in a second container by means of a stream of inert gas. This proposal is inadequate because the target degrades before significant amounts of seed particles are generated. No suitable method of maintaining target integrity and purity of silicon feed particles and seed particles has ever been proposed. It is also often necessary to provide a method for separating seed particles from unbroken feed particles and powders that are too small to be utilized as seeds.

The present invention is a granular bed chemical vapor phase reaction method (CVD method).
The aim is to produce silicon particles suitable for use as seeds in the field of manufacturing and other seed particle applications. In accordance with the present invention, seeds are obtained by a gun-target apparatus and method in which silicon feed particles are accelerated and propelled toward a silicon target within a target chamber, the feed particles are crushed or fragmented into seed particles, and Seed particles are extracted and used. Also, in accordance with the present invention, the silicon target is movable and is moved intermittently so that approaching streams of feed particles impinge on different portions of the target.

The drawings illustrate a preferred embodiment of impinging silicon feed particles onto a movable silicon target within a target chamber to create silicon seed particles.

In accordance with a preferred embodiment of the present invention, there is provided a gun-target apparatus for producing silicon seed particles from silicon feed particles larger than the silicon seed particles, the apparatus comprising a feed particle distribution vessel, a target chamber, a gun-target apparatus for producing silicon seed particles from silicon feed particles that are larger than the silicon seed particles; a silicon target placed in the chamber, a target moving device for moving the target within the chamber, a feed particle stream for propelling the feed particle stream to the target and fragmenting the feed particles, and optionally for fragmenting a portion of the silicon target. It consists of an accelerator and a seed particle receptor that accumulates seed particles.

In accordance with the invention, other preferred embodiments include: (a) a feed particle storage vessel for dispensing silicon feed particles; (b) a feed particle storage vessel for receiving silicon feed particles dispensed from said storage vessel and for accelerating said particles; a feed particle accelerator comprising a source of inert gas directed into a gas jet stream located therein; (c) a target chamber in fluid communication with the jet stream so as to propel the silicon feed particles into the target chamber; (d) a movable silicon target disposed within the target chamber such that the silicon feed particles propelled into the target chamber impinge on the silicon target and fragment into seed particles; (e) supply from a jet stream; (f) a seed particle receiver located below the target chamber for accumulating the seed particles produced by impinging the target with the feed particles; A silicon species generator is provided comprising a container.

The present invention further provides a method for producing silicon seed particles, comprising: (a) dispensing silicon feed particles from a feed particle vessel into a flow of inert gas moving at a sufficient velocity to form a silicon seed particle in the vessel; (b) directing the inert gas stream to a target chamber having a movable silicon target and causing the stream-borne feed particles to impinge on the movable silicon target, thus Split the feed particles, 88-400
forming micron seed particles; (c) periodically moving the silicon target to cause feed particles of the air stream to impinge on different portions of the silicon target; and (d) collecting the silicon seed particles. A method is provided comprising steps.

According to the present invention, silicon supply particles of any size can be used to impinge on a silicon target to form smaller seed particles.
A preferred embodiment of the invention uses feed particles having an average diameter of 400 microns to about 2000 microns.
The feed particles are delivered to a feed particle container, which container may have means for controlling the dispensing rate of the feed particles. The outlet of the feed particle container can be dimensioned to allow silicon feed particles to flow at a reasonable distribution rate for subsequent acceleration and propulsion to a silicon target. The feed particle container is preferably lined with or made of a pure material such as quartz, silicon carbide, sialon or silicon. The container may be maintained under slight pressure or covered with an inert gas such as nitrogen gas or a noble gas such as argon.

In one embodiment, a needle valve device is installed in the feed particle container to intermittently and controllably open and close a small orifice in the bottom of the feed particle container with a needle passing from the bottom of the container to the top of the container. Good too. The needle valve, when sealed at the top of the container, can also move up and down to open and close a small orifice in the bottom of the container to controllably and intermittently dispense silicon feed particles from the container.

The entire supply particle container may be surrounded by a protective case. The enclosure preferably has a glass viewing window with a bottom made of a transparent material such as quartz to allow viewing of the bottom of the feed particle container. In this way, the distribution of silicon feed particles can be easily controlled visually to provide the appropriate particle flow rate and maintain proper delivery of the feed particles. Also preferably, the feed particles are distributed using a fluidizing gas and the feed particles may be delivered from a feed particle container. In this aspect of the invention, the feed particle container preferably includes a gas-tight valve and a repose valve that allows for a method of distributing and accelerating the silicon feed particles toward the silicon target in a contaminating manner.
The angle of the valve is attached.
The angle of the repose valve may be used to supply feed particles to the dispensing vessel.

Once the silicon feed particles are dispensed from the silicon feed particle container, they are accelerated towards the silicon target. A preferred means of accelerating particles to eliminate propelling them toward a silicon target is to
The method is to use a gas stream or jet that is supplied in a clean tube or otherwise and receives the particles to be dispensed from a supply particle container. Preferably, an inert gas such as nitrogen or a noble gas, preferably argon, is used as the gas stream or gas jet to accelerate and propel the silicon feed particles. It is desirable to control the gas jet that propels the silicon feed particles to the silicon target with a quartz or other contamination-free tube. Silicon tubing is highly preferred.

The gas jet or tube or other device used to flow the gas stream is preferably connected in a hermetically sealed manner to a silicon target, including a silicon target that is impinged by the propelled silicon feed particles. It should be understood that the entire method and apparatus of the present invention may be practiced in a manner that prevents contamination of the silicon feed particles and the silicon seed particles produced therefrom. The particles are preferably of very high purity, especially for electronic silicon applications. Preferably, the gas stream accelerating the feed particles should be delivered in high purity silicon tubing.

The silicon target chamber may be lined with silicon or silicon carbide, or may be lined with quartz or other
It is made of a material that does not cause impurity contamination, so that the silicon supply particles that are accelerated into the silicon supply particles and the seed particles that are generated when the supply particles are split do not cause impurity contamination. The seed particles may then be used in a fluidized bed process to produce additional product silicon particles. The silicon target chamber is preferably further encased in a protective, rigid material, such as steel, and preferably lined with pure silicon.

In a preferred embodiment, the gas flow or jet to the silicon target chamber is exhausted from the top of the target chamber. This gas discharge from the silicon target chamber loads the silicon seed particles with smaller silicon particles, removes such small particles (usually thought of as "dust") from the silicon target chamber, and removes the seed particles and the uncrushed supply. The velocity is such that it separates from the particles, and the chamber may be designed to do so. Unfractured feed particles and large particles fragmented from the silicon target in the silicon target chamber may be redirected to the feed particle container.

The receiver or vessel in which the formed silicon seed particles are stored is located below the target chamber or at another location such that the formed silicon seed particles are directed toward the receiver. Seed particles may be stored for fluidized bed or other uses.

It should be understood that the seed particles may be produced by crushing or splitting the silicon supply particles. They may also be produced by splitting or pitting a silicon target placed within a silicon target chamber.

It should also be recognized that while some of the seed particles may be larger than some feed particles, the average feed particle has a larger volume and a larger average diameter. Overlapping size ranges of seed particles and feed particles predict that the separation technique will not be 100% efficient. Thus, a small fraction of the feed particles are "small" (300-400
A small fraction of the seed particles obtained as a product may be "large" (also 300-400 microns).

According to the invention, the silicon target is movable within the target chamber, preferably by means outside the chamber. A preferred embodiment of the method for moving a silicon target is shown in the following description and drawings. Another method of moving the target is to use a relatively brittle, long target that can be continuously pushed in the direction of the gas jet so that when the silicon target wears out, other new silicon targets are available for bombardment with the feed particles. The first step is to provide a silicon target. However, this method requires that the perforated surface of the target be periodically cut away to expose a new target surface. The silicon target is
Preferably, the target is connected to a rod or other means extending outside the chamber, while the silicon can also be glued to a magnetic material mounted inside the chamber so that the target can be rotated or moved by the magnetic material.

A better understanding of the invention will be gained by reading the following description in conjunction with the drawings.

With reference to the drawings, a silicon feed particle container apparatus 10 will be described. Apparatus 10 includes a feed particle quartz supply bottle 12 preferably made of a non-contaminated material such as quartz. For the particular device described here, the quartz supply bottle 12 has a 95 mm outside diameter with a lower, smaller, 54 mm outside diameter neck 13 attached directly to a bottom 12 mm outside diameter tube 15. You can drink it in a bottle. The quartz supply bottle 12 has a 4 inch diameter 3/16 stainless steel shell 14 molded with a sight glass portion 16 that mounts a sight glass 18 for viewing the dispensing of silicon supply particles from the quartz supply bottle 12. , is surrounded. The needle valve device 20 may be sealingly placed from the top of the quartz bottle 12 to the bottom of it where the orifice is located, with the beveled tip 22 of the needle valve 20 sealingly aligned with the orifice and with the needle valve on the bottom side. When in position , no silicon feed particles are dispensed from the quartz feed bottle 12. Therefore, by slightly lifting the needle valve, the silicon feed particles can be distributed into the gas jet coming from the bottom of the quartz tube 12. A needle valve device is optional and may be omitted as a suitably sized orifice is sufficient to easily dispense the particles. The entire silicon feed particle container apparatus 12 may be kept under nitrogen or other inert gas.

The gas stream or jet is supplied from a pressurized source 24 through a 0.03 micron filter and meter 26 and from 3/8 inch stainless steel tubing 27 and then wrapped in stainless steel tubing 30 of quartz or preferably silicon particles. 28. Pipe 28 has an inner diameter of 8 mm and an outer diameter of 12 mm.
and approximately 183/16 inches long. Approximately 171/16 inches from the downstream end is a hole corresponding to the bottom tube 15 of the supply bottle 12. The length of the tube must be adequate to provide particle velocities that will result in particle impact and fragmentation of the target. The fluid connection between the quartz supply bottle 12 and the quartz tube 28 is provided by a silicon support 3 that supports the tube 28 on which the supply bottle 12 rests.
3 may be supported. The upper half of the support body 33 is "U"
A single-crystal silicon tube with an outside diameter of 1 inch and an inside diameter of 1/2 inch, cut into a shaped saddle. The outlet end of the tube 27 has an outer diameter of 1 inch, an upstream inner diameter of 3/8 inch,
and a downstream polytetrafluoroethylene concentric piece 32 having an outside diameter of 1/2 inch;
It supports the particle jet and ensures concentricity of the stainless steel tube 27 and quartz tube 28.

The gas jet with the feed particles is then placed on a 6 inch diameter Schedule 5 304.
304) To a target chamber apparatus 34 consisting of a target chamber 36 having a stainless steel shell 38. Room 3
6 is preferably made of a silicon lining 37. Silicon lining prevents contact between steel and product. (Iron is a bad impurity). Preferably, the lining has a length
It is a 36 inch, 135 mm inner diameter, 147 mm outer diameter tube with two 23/8 inch holes drilled into opposing T-pieces. A fabric strip is wrapped around the lining to cushion it and center it within the shell 38. A silicon top plate 39 may be made to match and bonded to a quartz riser plate 41 formed within shell 38. Shell 38 sealingly receives quartz or silicon tube 28 .
It has a T-shaped or extension 40 formed from a 1/2 inch 316 stainless steel three point fastener.

The quartz tube 28 has a silicon particle jet shield 42 placed around its end to prevent silicon particles from returning to the stainless steel portion of the tube 28 or shell 38, thereby preventing contamination and breakage. do. silicon supply particles to target 4
Accelerate toward a 2 inch thick, single crystal, 31/4 inch silicon target disk 44, which fractures, perforates and splits according to the exact properties of the silicon forming the target disk 44. As long as suitable silicon is used to form the target, there is no problem of contamination of the seed particles that are produced or the additional feed particles that are produced and recycled.

A silicon target 44 is mounted on a target support and rotating rod 46 and is non-concentric with the gas and silicon feed particle streams coming from the quartz or silicon tube 28. Such a silicon target 4
4. Target support and 1/4 inch rotating rod 46
In mounting, the target is thereby rotated, exposing new portions of the silicon target 44 to the incoming particles intermittently, allowing collisions to occur at new surfaces. A silicon disk rod protector 48 is attached to the target support and rotation rod 46 so as not to expose the rod to the interior of the chamber 36.
Prevents impurities from being mixed into the generated seed particles.

The steel shell 38 accommodates a target support and rotation rod 46 and a silicon disc rod protection 48 by means of a second extension 50.

The silicon seed particles fall through an opening in the bottom of target chamber 36 and then through an opening in the bottom of steel shell 38 into receiver 56. The receiver may optionally be protected with an inert gas blanket to protect the integrity and purity of the resulting seed particles. The gas flow entering from tube 28 passes through opening 58 in the top of target chamber 36 and exits through opening 60 in the top of the steel shell.

A steel annular liner support 57 is installed below the silicon target chamber 36 as a support. A quartz plate (with drain hole) 53 is supported on a support 57, and a silicon disk 52 prevents impurities from being mixed into the seed particles falling from the target 44.

Quartz tube 28 and needle valve 20 are preferably sealed with O-rings 43 and 21 as shown. Furthermore, the target chamber 36 and the steel shell 38
The size and shape of the particles are such that the exhaust gas flow is sufficient to carry at least a portion of the silicon dust particles, which are dust-like particles that are smaller than the seed particles and that are likely to ride on the exhaust gas at the designed gas flow rate. It can be made into This allows easy separation of silicon dust from seed particles and uncrushed feed particles. A filter device 62 can be installed as shown to accumulate dust if desired.

Since the primary use of the silicon seed particles produced by the apparatus and method of the invention is as a seed for a fluidized bed process to produce electronic grade silicon, preferred embodiments of the invention include This includes forming all contacting surfaces of the device used from materials that do not contaminate the silicon seed particles with impurities known to affect electronic properties. These impurities include iron, arsenic, carbon, phosphorous, aluminum and the like.

Although the apparatus and method of the present invention can be used to handle a wide range of particles, both feed particles and generated seed particles, it can also be used to handle feed particles of any size to distribute the appropriate gas flow rate into the gas stream. Although a practical range for particles of the above average diameter is a velocity of 400 to 1200 ft/sec. The preferred range is 600/800 ft/sec.
Gas flow rate should be evaluated as it affects the amount of silicon loss due to dust formation.

Using the movable silicon target device described above,
By rotating the silicon target intermittently or preferably constantly, approximately eight times as much work time and usage can be obtained from the target as when the target remains in one place.
Instead, a very long silicon target is pushed in the direction of the incoming jet flow intermittently by a sliding rod as the surface of the target is scraped or perforated by the incoming feed particles. In this method, the perforated surface of the target is intermittently scraped away to reveal a new surface. Therefore, it can be considered preferable to utilize highly pure silicon metal as a target. In some situations, it may be preferable to utilize single crystal materials as single crystals may tend to be more brittle than polycrystalline or amorphous silicon.

By operating the above equipment, the average diameter is 500-1400
Suitable seed particles were made from feed particles of various sizes in the micron range. Heavy particles that are not small enough to serve as seed particles of the desired size can be collected into a feed particle container and the product powder can be disposed of or collected for other uses. Typical product powders produced in the above equipment have an average diameter of less than about 88 microns and a maximum diameter of no more than about 150 microns.

60 to 80 using the method and apparatus of the above invention.
It was possible to achieve yields of particles of suitable diameter for use in a fluidized bed in the range of . This is a significant advantage compared to conventional grinders, which tend to contaminate the silicon and also produce a very high proportion of dust, producing only about 30% particles suitable for seed use.

Example In the device shown in the drawing, the diameter is 1190~
1400 micron high purity silicon feed pellets (approx.
2.0Kg) is supplied from the particle container into the horizontal quartz tube.
Feed to 0 grade nitrogen moving at a speed of 780 ft/sec,
It was fired into a silicon-lined target chamber and collided with a block of high-purity silicon. The silicon target was rotatable and the incoming air stream could be directed to a new portion of the silicon target's surface that was significantly larger than the cross-sectional area of the air stream containing the silicon feed particles. Silicon feed particles of 1190-1400 microns were bombarded with a silicon target, and some sorting was performed to determine the efficiency of producing seeds of various sizes. It had three separate operations. The first time, the average particle diameter was
Approximately 10 different particles, ranging from 210 to 500 microns, were produced for each charge of each feed particle. Approximately 12.3 particles ranging in feed particle size from 210 microns were produced per particle loaded into the device. Dust from the process was discarded in both cases. The second time, approximately 8.3 particles from 210 to 500 microns were produced per particle charge, and 10.4 particles from 210 microns to the feed particle size were produced per particle charge to the device. For the third time, the corresponding numbers were 7.6 particles and 9.7 particles, respectively. For a total of three runs, approximately 35.6 particles ranging in diameter from 106 microns to the size of the feed particles were produced per particle charge to the apparatus. Apparatus such as that shown in the figures and description above has been successfully used in a number of runs to produce species suitable for use in fluidized bed chemical vapor processes.

The invention is not limited to the above particle description or drawings. Having described the process and apparatus of the invention, variations may be made in the specific methods and apparatus described without departing from the true scope and true spirit of the invention.

[Brief explanation of the drawing]

The drawings illustrate aspects of the invention.

Claims (1)

Claims: 1. A gun-target apparatus for producing silicon seed particles from silicon feed particles larger than the silicon seed particles, comprising: a feed particle distribution vessel; a target chamber; a target chamber larger than the seed particles; a movable target in the form of a disc located at the target; feed particle acceleration means comprising a flow of inert gas for propelling the feed particles to the target and disrupting the feed particles, thereby producing the seed particles; a target moving means for rotationally moving within the target chamber non-concentrically and exposing new portions of the target to the feed particle stream as it moves; and a seed particle receptor for accumulating seed particles. The device consists of: 2. The apparatus of claim 1, wherein the feed particle container further comprises means for causing the feed particles to pass at a controlled rate into the gas jet. 3. The apparatus according to claim 1, further comprising means for removing silicon dust smaller than the seed particles from the seed particles. 4. The apparatus of claim 3, wherein said means for removing silicon dust consists of a gas flow in said target chamber of sufficient velocity to entrain said silicon dust but not said seed particles. . 5. A method for producing silicon seed particles, the method comprising:
dispensing silicon feed particles of ~2000 microns from a feed particle container into a flow of inert gas moving at sufficient velocity to accelerate and propel the feed particles from the container; impinging feed particles carried by the gas stream against the movable silicon target, thereby disrupting the feed particles and producing seed particles between 88 and 400 microns; The method comprises the steps of: moving a silicon target so that the feed particles in the gas stream impinge on different locations on the silicon target; and collecting the silicon seed particles. 6. The method of claim 5, wherein the target chamber is lined with a silicon-free material to maintain the purity of the silicon species. 7. Separating the silicon seed particles from larger silicon particles, including feed particles that did not fragment upon collision with the silicon target and larger silicon particles that fragmented from the silicon target, and separating the larger silicon particles from the feed particles. 6. The method according to claim 5, wherein the material is collected into a container. 8. Discharging the inert gas stream from the target chamber with at least a portion of the silicon dust particles smaller than the seed particles, thereby separating the portion of the dust particles from the seed particles. The method described in Section 5.