JPS593096A - Device for producing belt-like silicon crystal - Google Patents

Abstract

PURPOSE:To enable mass production of a titled crystal without degrading quality in a device which brings a seed crystal into contact with the Si melt in a crucible in a heating furnace through the slit of a die and pulling the same by providing an introducing pipe for a raw material which penetrates through a specific heating plate for melt. CONSTITUTION:A capillary die 13 contacts with the Si melt 11 in a quartz crucible 12 in a resistance heating furnace, then the melt 11 ascends the die slit by capillarity. A seed crystal is brought into contact with said melt and the seed crystal is pulled upward whereby a belt-like Si crystal 16 is obtd. Here, a graphite heating plate 18 for melt is provided in contact with the top end in one longitudinal end part of the crucible 12. The plate 18 covers the melt 11 locally, is overhung so as to cover a heater 19 in proximity thereto, and heats the melt 11 by receiving the heat of the heater 19. An introducing pipe 17 for a solid material is connected to the through-hole in the central part of the plate 18, and a small lumped raw material of polycrystalline Si is supplied continuously through the pipe 17 as much as by the amt. corresponding to the rate of growth. The temp. drop of the melt 11 and the scattering of the melt 11 to the outside of the crucible are thus prevented, and the continuous growth of the product having high quality is made possible.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to an apparatus for manufacturing band-shaped silicon crystals.

[Technical background of the invention and its problems]

Since the band-shaped silicon crystal is in the form of a thin plate, it is different from the ingot-shaped single silicon crystal obtained by the chip-shaped Ralski method, and can be used as a substrate for a semiconductor solar cell in its obtained shape. Therefore, it has the great feature that, for example, silicon crystal obtained by the Zychralski method can be used as a substrate for a semiconductor solar cell at a low cost.

A cross-sectional view of the configuration inside a resistance heating furnace for growing band-shaped silicon crystals will be explained with reference to FIG. This figure 1 shows the quartz glass melt containing the silicon melt 11. A capillary die 13 (hereinafter simply referred to as die) having a slit (gap) made of carmen at 12 is inserted into the crucible 1 with its long side
2 is shown installed parallel to the long side direction.

The tips of the dies 13 are sharp and processed into a knife shape, and these dies 13 are strongly fixed to a heat shield plate 14. This heat shield plate 14 serves to weaken the thermal radiation of the melt 11 from reaching the tip of the die 13, and has a window that exposes the die ISO tip. The crucible 12 is inserted into a crucible holder 15 made of carmen.A pair of plate-shaped heaters (not shown) are provided on the outside of the crucible holder 16. This heater is installed parallel to the longitudinal direction of the die 13 and crucible holder 16.

Polycrystalline silicon is placed in the quartz crucible 12 of the growth apparatus configured as described above, and the temperature of the crucible is raised to about 1500°C. Then, polycrystalline silicon becomes silicon melt 11
Then, this silicon melt 11 rises to the tip of the die 13 due to capillary action. By bringing a seed crystal (not shown) into contact with the rising silicon melt 11 from above and then gradually pulling it up, it is possible to grow a band-shaped silicon crystal 16.

With the above-mentioned growth apparatus, it was impossible to obtain band-shaped crystals in an amount greater than the amount of melt stored in the crucible. In order to grow a large amount of band-shaped crystals, either increase the Ruth I capacity and input a large amount of raw material from the beginning, or leave the Ruth I capacity small and use the amount that is extracted as band-shaped crystals. It is conceivable to adopt either method of growing while supplying raw materials. The former method of increasing the crucible capacity is technically possible. As the capacity of the furnace increases, the question arises as to whether the entire furnace, including the heater, should be made larger. However, increasing the size would not only increase the manufacturing cost of the device, electricity consumption, inert gas consumption, cooling water, etc., but also go against the purpose of manufacturing solar cell substrates at low cost when considering the operating rate. is well predicted. Furthermore, it is not preferable to leave the raw material in a molten state for a long time from the viewpoint of the quality of the band-shaped crystals. 1. Ruth in contact with the melt? It is inevitable that the quality of the band-shaped crystal will deteriorate because impurity elements are dissolved and mixed in from the furnace and the die, and impurity elements from the furnace materials are mixed in through the atmospheric gas. On the other hand, the method of supplying raw materials during growth involves technical problems that must be solved.

For example, if a solid raw material is introduced into the melt using a raw material introduction pipe during growth, heat is required to melt the raw material, resulting in a decrease in the temperature of the melt. In fact, when we conducted an experiment in which we continuously fed in an amount of solid raw material equivalent to the amount of growth (approximately 3 f per minute), it took several seconds for the raw material to melt, and the solid raw material in the die It was confirmed that the temperature on the inlet pipe side decreased somewhat. Specifically, this phenomenon appeared as a phenomenon in which band-shaped crystals began to thicken toward the solid raw material introduction tube and sometimes stuck to the die, stopping crystal growth. Furthermore, in this method, a part of the supplied raw material or the melt may splash out of the crucible and adhere to the crucible holder or heater.

[Purpose of the invention]

The present invention is based on the above findings, and aims to provide a manufacturing apparatus that corrects the drawbacks of conventional band-shaped silicon crystal manufacturing apparatuses and can mass-produce band-shaped silicon crystals without degrading quality.

[Summary of the invention]

In the present invention, a melt heating plate having a +'4 structure is installed, which contacts the top of the melt to locally cover the silicon melt, and approaches the heater to cover the heater, and the melt heating plate is installed to cover the heater. ξ, which is equipped with an all-in-one raw material introduction pipe.

〔Effect of the invention〕

According to the present invention, it is possible to suppress the drop in liquid temperature that occurs when solid raw materials are directly charged into the crucible from outside the furnace.

That is, since the raw material introduction pipe is provided through the heating plate that heats the melt by receiving heat from the heater, the solid raw material introduced can be melted quickly, and the temperature of the melt is almost never lowered. There is no.

Further, according to the present invention, when the solid raw material is introduced through the solid raw material introduction pipe, the raw material and the melt are splashed by the melt heating plate, and the melt is melted. Prevents it from flying out.

(7E) The present invention enables continuous growth of high quality band-shaped silicon crystals.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 is a longitudinal sectional view taken along the longitudinal force and direction of the belt-shaped silicon crystal manufacturing apparatus i of the present invention, and FIG. 3 is a longitudinal sectional view taken along the line A-A' in FIG. 1, which is perpendicular to this. Figure 4 is a plan view of the main parts. The silicon melt 11 is put into a quartz crucible 12 (6J), the die 13 is in contact with the melt, the melt rises through the die and slit by capillary action, and solidifies at the upper end of the die. As a result, a band-shaped silicon crystal 16 is formed.

The quartz crucible 12 is supported by a crucible holder 15, and the die 13 is fixed to a heat shield plate 14. A pair of heaters 19 (1
9n, 19b) are provided. These basic configurations are the same as the conventional devices. The difference from conventional equipment is that:
A melt heating plate 18 made of graphite is installed in contact with the upper end of one longitudinal end of the crucible 12. As is clear from FIGS. 3 and 4, this heating plate 18 locally covers the liquid 11 and extends to the outside of the crucible holder 15 so as to cover the heater 19.
The melt 11 is heated by receiving heat from the heater 9. A through hole is formed in the center of the heating plate 18, and the solid raw material introduction pipe 17 is connected to this through hole. This introduction pipe 12 has a diameter of 0.3 to 2. Ottam a=
The raw material inlet is narrow enough to pass through the bulk solid raw material, and is located outside a chamber (not shown) that covers the outside of the furnace.

As a result of growth while continuously supplying crystalline silicon raw material in an amount corresponding to the growth amount through the raw material introduction pipe 11, a band-shaped silicon crystal of about 7 m could be obtained. In this case, no shift of the band-shaped crystals toward the melt heating plate 18 side was observed;
In addition, the raw material and melt did not splash out of the tube.

Since the raw material introduction pipe 17 was thin, outside air was not drawn into the furnace.

According to the apparatus of this embodiment, it is also possible to perform continuous growth as long as there is no time restriction or as long as the life of the die continues. Ruth is one of the reasons why the yield of crystal growth is improved in this example. There may be no fluctuations in the melt level within.

If raw materials are not supplied during growth, the liquid level will gradually drop and the temperature at the upper end of the die will gradually rise.
It was necessary to lower the temperature of the system. However, in the device of this embodiment, this is not necessary, and it becomes easy to maintain constant conditions. Further, in the conventional apparatus, the resistivity of the band-shaped crystal showed a tendency to gradually decrease, but the resistivity of the band-shaped crystal grown in the apparatus of this embodiment almost always showed a constant value. Is it true that the melt is not produced in conventional equipment? The time spent in the tumbler furnace is different from the one that crystallized after 1, and the one that crystallized later.This is probably because the concentration of impurity elements increases as the time passes. .

As described above, the device of this embodiment can produce band-shaped crystals of good quality.
This can be said to meet the objective of lowering the price of solar cell substrates through production.

Note that the present invention is not limited to the above embodiments. The melt heating plate may be made of a material other than graphite that is heat-resistant and inert to silicon vapor, such as silicon carbide, silicon nitride, and sialon. It is also conceivable to place melt heating plates on both sides of the die in the longitudinal direction and to introduce raw materials on both sides. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view taken along the longitudinal direction of a conventional belt-shaped/reconcrystal crystal manufacturing apparatus, and FIG. Front view, 3rd
The figure is a longitudinal sectional view taken along the line A--A in FIG. 1 along a direction perpendicular to this, and FIG. 4 is a plan view of the main parts. 11... Silicon m liquid, IS... Quartz crucible, 13
...Capillary die, 17...Solid raw material introduction '9
．． 18... Melt heating plate, 19l, 19b... Heater, Applicant's agent, patent attorney Takehiko Suzue, Figure 1, Figure 2, 476 Figure 3, Figure 4

Claims (1)

[Claims] Luxury containing silicon melt in a resistance heating furnace and pickpocket,
In an apparatus for pulling a band-shaped silicon crystal by disposing a capillary die having a capillary die, bringing the seed crystal into contact with the melt rising through the slit and the slit, and pulling up the seed crystal, the upper end of the crucible is A melt heating plate having a structure that covers the silicon melt locally in contact with the heater and covering the heater is installed close to the heater, and a solid raw material introduction pipe is provided that penetrates this melt heating plate. A device for producing band-shaped silicon crystals.