JPH0246049Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a molten silicon supply device used for manufacturing polycrystalline silicon wafers used in solar cells and other photoelectronic conversion elements.

[Prior Art] Polycrystalline silicon wafers have conventionally been manufactured by various methods, and the most common method is to first cast an ingot of a predetermined shape from a silicon base material and then slice it into wafers. However, this not only requires a lot of time for slicing, but also causes about 50% of the ingot to be lost during slicing, making the product expensive and making mass production impossible. It is possible.

Therefore, the ribbon method and the casting method (casting method) have already been implemented as methods that do not involve slicing, but they have the disadvantage of not being able to obtain large solar cell materials, and in addition, the casting method has the disadvantage that silicon crystal grains are Since the crystal grains are extremely fine and large crystal grains cannot be obtained, the photoelectric conversion rate of the solar cell obtained using the wafer is also extremely poor at 2 to 3%.

Therefore, the present applicant has already developed a method for manufacturing polycrystalline silicon wafers that can improve the defects of the above methods, by melting a silicon base material, and using this melt in a rotating state that is made of quartz or carbon. A method in which a thin layer of melt with a desired expanded diameter is layered by dripping onto a certain production plate, effectively utilizing centrifugal force, and this is peeled off from the production plate after solidification (hereinafter referred to as the spin method) ) was proposed.

The present invention relates to an unprecedented molten silicon supply device created to supply an appropriate amount of molten silicon to a rotating production plate during the production of polycrystalline silicon wafers using this new spin method.

[Problems to be solved by the invention] In carrying out the above spin method, the silicon raw material is melted in a desired inert atmosphere such as argon,
This molten silicon must be supplied to a rotating production tray, but when supplying silicon raw materials one after another into an inert atmosphere, it is a simple operation and prevents outside air from entering the atmosphere. In addition, the crucible tilting operation for supplying the molten silicon to the production dish can be performed easily from the outside without damaging the atmosphere. The purpose is to get it.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention has a method in which the silicon raw material supplied from the raw material supply port is stored in a crucible and melted in a desired inert gas atmosphere inside the furnace body. , which is used for manufacturing silicon wafers by dropping an appropriate amount of the molten silicon onto a rotating manufacturing plate,
The inert gas can be freely introduced into a supply space which can be freely isolated from the furnace body by a gate valve, and the raw material supply port is provided so as to be freely openable and closable;
The lower end of the elevator rod, which is airtightly penetrated so that it can be raised and lowered into the furnace body from the cavity, receives the silicon raw material supplied from the raw material supply port in the supply cavity, and also disassembles it at a predetermined lowering position. a raw material introduction section comprising a raw material cup into which the silicon raw material falls into the crucible after the receiving state is released; a crucible that receives the silicon raw material; a heater that heats and melts the silicon raw material; A pivot mechanism in which the crucible can be freely rolled by pulling up the tension of the operating cable connecting the rod and the crucible by the upward movement of the rod, and a silicon base material melt is flowed down by the rolling, and this is manufactured. The present invention provides a molten silicon supply device comprising a base material supply section equipped with a funnel for dripping the silicon into a dish.

[Operation] By opening and closing the gate valve, raw silicon can be supplied to the supply space in a state isolated from the furnace body, and since argon etc. can be separately supplied to the space, argon can be supplied to the entire furnace body. , it is no longer necessary to carry out operations every time raw material silicon is supplied.
In addition, the crucible can be operated reliably by hand or power, and because of the presence of the funnel that receives the silicon melt, even if the crucible moves rapidly, the silicon melt can be accurately supplied to the production pan, preventing any contamination. No serious leakage occurs.

[Example] Next, the present invention will be explained with reference to an illustrated example. A is a molten silicon supply device used for manufacturing polycrystalline silicon wafers, and as described later, it is used to supply silicon raw material to a crucible. Raw material introduction part 1
and a base material melt supply unit 2 that drips the base material melt onto a production plate that molds polycrystalline silicon wafers after heating and melting the raw materials in the crucible. It is made of quartz SiO ₂ or carbon C, which has little reactivity with other materials and can withstand high temperatures.

The raw material introduction section 1 is a hollow cylindrical body 11 erected in the center of the upper surface of a furnace body 3, which will be described in detail later, and has a hollow cylindrical raw material supply port 12 protruding from the upper side wall thereof. An opening/closing lid 13 is provided at the end so that it can be opened and closed, and a cylindrical body 1 is provided below the supply port 12.
A gate valve 14 is provided to block and close the cylinder 1 in a direction perpendicular to the axis, and an elevating rod 15 is inserted into the axial position of the cylinder 11 so that the upper end of the rod 15 touches the upper end of the cylinder 11. It penetrates the lid 16 to be closed and protrudes outward, and the O-rings 16', 1 of the lid 16
6', the lifting rod 15 can be raised and lowered manually or by power (not shown).

Further, a raw material cup 17 is provided at the lower end of the lifting rod 15 protruding into the furnace body 3 to receive the silicon raw material supplied from the raw material supply port 12 and supply it to the crucible as described later. There is.

The raw material cup 17 is fixed to the lower end of the lifting rod 15 and has a tapered top surface that descends toward the outside. A horizontal partition plate 2 is provided on the furnace body 3, and consists of a hollow cylindrical storage body 19 with a flange 19a projecting outward.
When the raw material cup 17 is fitted into the opening 20a, the flange 19a is inserted into the opening 20a.
It is configured to be locked to the peripheral edge of 0a.

Further, the upper side wall of the cylinder 11, that is, the supply space 11' defined by the gate valve 14, has on-off valves 21 and 22, respectively, a gas supply pipe 23 for supplying an inert gas such as argon, and a vacuum exhaust pipe 2
4 is provided.

Next, in the base material melt supply section 2, a funnel 31 is fixed to approximately the center of the furnace body 3 via a support 32,
A crucible 33 is pivotally supported above the funnel 31 and below the raw material cup 17 by pivot pins 35 of support columns 34, 34 erected on the funnel 31 so as to be rotatable up and down. It's summery.

The funnel 31 has a tapered receiving opening 31a formed therein, and a small-diameter outflow opening 31b connected to the lower end of the receiving opening 31a.

Furthermore, a supporting cylinder 36 is provided in the furnace body 3 in parallel with the cylinder 11, and an operating rod 37 is provided at the axis of the cylinder 36 so as to be able to move up and down.
The upper end of the operating rod 37 protrudes upward through the O-ring 36' so that it can slide freely through the O-ring 36', and the lower end of the operating rod 37 protrudes into the furnace body 3. A manipulation cable 38 such as a carbon fiber thread is connected between the two.

Further, 39 indicates the crucible 33 and the funnel 3 in the furnace body 3.
The crucible 33 is a heater provided at a predetermined interval around the outer periphery of the crucible 33, and heats and melts the silicon raw material in the crucible 33.

Here, 40 is a heater provided near the bottom of the funnel 31 to maintain the molten state of the silicon base material melt in the funnel 31, and 41 is a heater that maintains the molten state of the silicon base material melt in the crucible 33. A see-through window 42 that can see through the inside of the furnace body 3 is located in the outer vessel 43 of the furnace body 3 made of stainless steel or the like.
A heat-resistant wall made of carbon or the like is shown adjacent to this.

Reference numeral 4 denotes a turntable installed directly below the funnel 31, which rotates the production plate 5 placed on the upper surface at a required speed, and rotates the inflow passage of the upper plate 6 constituting the production plate 5. The silicon base material melt is injected from the port 6a, and 7 in the figure indicates the lower plate of the manufacturing plate 5, which is fastened to the upper plate 6 in an overlapping state by screws (not shown), and both plates are A plurality of cavities 8, 8, . . . are formed between 6 and 7, into which the silicon base material melt flows by rotation centrifugal force,
A product is obtained by solidifying the melt that has flowed here.

Next, in order to melt the silicon raw material using the molten silicon supply device A according to the above embodiment and supply it to the production tray 5, first, the lifting rod 15 is moved so that the raw material cup 17 is at the position of the raw material supply port 12. Let it rise until it comes.

Next, the gate valve 14 is closed and the supply space 1 is closed.
After closing 1', open the same opening 12 and insert the raw material cup 17.
A silicon raw material is introduced into the container, and the supply port 12 is closed with an opening/closing lid 13.

Next, open the on-off valve 22 to open the vacuum exhaust pipe 2.
After evacuating the space 11' through 4, the on-off valve 22 is closed, and then the on-off valve 21 is opened to introduce argon gas into the cylinder 11 above the gate valve 14 through the gas supply pipe 23. do.

Next, after opening the gate valve 14, when the elevator rod 15 is lowered, the flange 19a of the body 19 comes to the opening 20a of the horizontal partition plate 20 and is locked to the peripheral edge thereof. After that, the bottom cover 18 lowers with the body 19 placed thereon, so that the silicon raw material in the raw material cup 17 falls into the crucible 33 below, where it is heated and melted by the heater 39 at about 1400°C. It becomes a silicon base material melt.

Next, when the operating rod 37 is raised manually or by an automatic lifting device (not shown), the operating rope 37 is raised.
8 is pulled up under tension, the crucible 33 rolls around the pivot pin 35, and the silicon base material melt flows into the funnel 31.

At this time, the silicon base material melt that has flowed into the receiving port 31a is transferred from the outflow port 31b to the inflow port 6 of the production tray 5.
It drips into a.

Then, the silicon base material melt that has flowed into the manufacturing pan 5 is flowed in the direction of diameter expansion by the centrifugal force of the manufacturing pan 5, which is rotated by the rotation of the turntable 4, and the melt is thinned by the melt. Since the layers are formed within the cavities 8, 8, . . . , a polycrystalline silicon wafer can be manufactured by solidifying the layers.

[Effect of the invention] Lifting and lowering of the lifting rod 15 and operating rod 37 and gate valve 1
4. By simple operations such as opening and closing the on-off valves 21 and 22, silicon raw material corresponding to the amount of silicon base material melt supplied to the production tray 5 can be continuously supplied, so that polycrystalline silicon wafers can be continuously produced. This makes it possible to manufacture the product and is suitable for mass production.

In addition, the gate valve 14 and valve operation make it possible to supply raw material silicon while keeping the inside of the furnace body 3 in an inert state with an inert gas such as argon gas during silicon wafer production. It greatly contributes to the improvement of sexuality.

[Brief explanation of the drawing]

The figure is a longitudinal sectional front view showing an example of a molten silicon supply device according to the present invention. 1... Raw material introduction section, 2... Base material melt supply section, 3
... Furnace body, 5 ... Production plate, 11' ... Supply space,
12... Raw material supply port, 14... Gate valve, 15...
Lifting rod, 17... Raw material cup, 23... Gas supply pipe, 31... Funnel, 33... Crucible, 37... Operating rod, 38... Operating cable, 39... Heater.

Claims (1)

[Scope of utility model registration request] In a desired inert gas atmosphere inside the furnace, the silicon raw material supplied from the raw material supply port is stored in a crucible and melted, and an appropriate amount of the molten silicon is dropped onto a rotating production plate to produce silicon wafers. The inert gas can be freely introduced into the supply cavity which can be freely isolated from the furnace body by a gate valve, and the raw material supply port is installed so that it can be freely opened and closed. The lower end of the lifting rod, which is airtightly inserted into the body so that it can be moved up and down, has a supply cavity and receives the silicon raw material supplied from the raw material supply port, and is dissociated at a predetermined lowering position. A raw material introduction part comprising a raw material cup into which the silicon raw material falls into the crucible after the receiving state is released, a crucible that receives the silicon raw material, a heater that heats and melts the silicon raw material, and a rising movement of the operating rod. A pivot mechanism that allows the crucible to roll freely by pulling up the tension of the operating cable connecting the rod and the crucible, and the rolling causes the silicon base material melt to flow down and supply it dropwise to the production tray. A molten silicon supply device comprising a base material melt supply section equipped with a funnel.