KR101111408B1 - Apparatus for manufacturing silicon thin plate using inert gas blowing - Google Patents

Abstract

Disclosed are a method and apparatus for manufacturing a silicon thin plate using an inert gas blowing which can contribute to the improvement of the surface quality of a substrate to be produced while improving the productivity of the silicon thin plate production using the continuous casting method.
Silicon thin plate manufacturing apparatus using an inert gas blowing according to the present invention comprises a silicon raw material input unit is supplied with a silicon raw material; A silicon melter for melting the supplied silicon raw material to form a silicon melt; A silicon molten metal storage unit configured to receive and store the molten silicon, and then discharge the molten silicon into a melt having a predetermined thickness; A transfer unit for transferring the discharged silicon melt; And a cooling unit cooling the transferred silicon melt, wherein the cooling unit controls the surface shape of the silicon melt while cooling the silicon melt in an inert gas blowing manner.

Description

Silicon thin plate manufacturing apparatus using inert gas blowing {APPARATUS FOR MANUFACTURING SILICON THIN PLATE USING INERT GAS BLOWING}

The present invention relates to a technology for manufacturing a silicon thin plate to which continuous casting is applied, and more particularly to manufacturing a thin silicon sheet using inert gas blowing, which may contribute to the improvement of the surface quality of the silicon thin plate to be manufactured. A method and apparatus therefor.

Silicon substrates, a key component of silicon solar cells, account for about 28% of solar cell module prices.

Generally, a silicon substrate for a solar cell is manufactured by melting a silicon, solidifying the molten silicon to produce a single crystal silicon ingot or a polycrystalline silicon block, and then cutting through several cutting processes.

In the case of the silicon substrate manufacturing method, the silicon raw material loss is generated 40-50% by the cutting process, which is the main cause of the increase in manufacturing cost.

In order to fundamentally eliminate such cutting loss, a technique for producing a silicon substrate directly from the molten metal has been developed.

Direct manufacturing technology of silicon substrate is divided into vertical growth method and horizontal growth method. The vertical growth method is already in mass production, but the growth rate is slow. On the other hand, despite the high growth rate, the horizontal growth method has not been mass produced.

In the case of the conventional horizontal growth method for direct silicon production, there is typically a ribbon growth on substrate (RGS) method. However, the RGS method controls the solidification inside the molten silicon storage container and has the following problems because the shape is controlled by using a blade.

First, in the case of the RGS method, the solidification is controlled inside the molten silicon storage container. In order to cause the solidification inside the container, the solidification time must be controlled to less than a millisecond (msec). If only a small amount of solidification time is passed, the solidified substrate may be caught in the blade, and the device itself may be damaged.

In addition, in order to uniformly solidify, the temperature of the silicon melt must be uniformly controlled over the entire substrate area. However, it is very difficult to uniformly control the temperature of the molten silicon melt.

In the case of the RGS method, a blade is used to control the shape of the substrate. In this case, there is a high probability that the blade is broken, and mechanical contact between the blade and the silicon substrate has a high possibility of causing contamination of the substrate.

Disclosure of Invention An object of the present invention is to manufacture a silicon thin plate directly from a molten silicon by using continuous casting, but to provide a method and apparatus for manufacturing a silicon thin plate using an inert gas blowing that can improve the surface quality of the silicon thin plate produced. It is.

Another object of the present invention is to provide a solar cell substrate having excellent surface quality using an inert gas blowing.

Silicon thin plate manufacturing method using the inert gas blowing in accordance with the present invention for achieving the above object is to produce a silicon thin plate using a continuous casting method, by controlling the surface shape by blowing an inert gas to the silicon thin plate to be manufactured Characterized in that.

Silicon thin plate manufacturing apparatus using an inert gas blowing according to the present invention for achieving the above object is a silicon raw material input unit is supplied with a silicon raw material; A silicon melter for melting the supplied silicon raw material to form a silicon melt; A silicon molten metal storage unit configured to receive and store the molten silicon, and then discharge the molten silicon into a melt having a predetermined thickness; A transfer unit for transferring the discharged silicon melt; And a cooling unit cooling the transferred silicon melt, wherein the cooling unit controls the surface shape of the silicon melt while cooling the silicon melt in an inert gas blowing manner.

The silicon substrate for a solar cell according to the present invention for achieving the above another object is manufactured using the above-described device, characterized in that having a thickness of 200 ~ 400㎛.

The method and apparatus for manufacturing a silicon thin plate using an inert gas blowing according to the present invention can improve the quality of a silicon thin plate manufactured by applying an inert gas blowing while using a continuous casting method in which productivity and property control are easy.

Therefore, the silicon substrate manufactured using the silicon thin film manufacturing apparatus using the inert gas blowing according to the present invention can have excellent surface quality, it can be applied to the substrate for solar cells.

Figure 1 schematically shows an apparatus for producing a thin silicon sheet using an inert gas blowing according to an embodiment of the present invention.
2 is a photograph showing the surface microstructure of the silicon thin plate manufactured from the silicon thin plate manufacturing apparatus using an inert gas blowing according to the present invention.
3 is a photograph showing a cross-sectional microstructure of the silicon thin plate illustrated in FIG. 2.
Figure 4 is a photograph showing the surface of the silicon thin plate produced when the inert gas is not applied.
Figure 5 is a photograph showing the surface of the thin silicon plate produced in an inert gas application.
FIG. 6 is a photograph showing the surface after polishing the surface of the silicon thin plate shown in FIG. 5.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the examples described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the examples disclosed below, but may be implemented in various forms, and only the examples are intended to complete the disclosure of the present invention and those skilled in the art to which the present invention pertains. It is provided to fully inform the scope of the invention, and the invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, a method and a device for manufacturing a silicon thin plate using an inert gas blowing according to the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 schematically shows an apparatus for producing a thin silicon sheet using an inert gas blowing according to an embodiment of the present invention.

Referring to FIG. 1, the illustrated silicon thin film manufacturing apparatus 100 may include a silicon raw material input unit 110, a silicon melter 120, a silicon melt storage unit 130, a transfer unit 140, and a cooling unit 150. Include.

The silicon raw material input unit 110 supplies the silicon raw material from the outside and inputs the silicon raw material in a predetermined amount into the silicon melting unit 120.

The silicon melter 120 melts the supplied silicon raw material to form a silicon melt.

In the case of silicon, unlike the metal, at a temperature of about 700 ° C. or less, the electrical conductivity is low, so that direct heating by electromagnetic induction is difficult. Therefore, the silicon raw material can be melted in an indirect melting method by crucible heat.

In the case of silicon melting by the indirect melting method, the crucible may be a graphite crucible. In the case of graphite, the crucible may be easily heated due to electromagnetic induction because the electrical conductivity and the thermal conductivity are very high. However, when silicon is indirectly melted by graphite crucible heat, there is a problem of contamination of silicon or the inner surface of the crucible.

Therefore, it is desirable to minimize the contamination problem of silicon by indirectly heating the silicon by crucible heat at a temperature of 700 ° C. or lower, and non-contact melting of the silicon raw material through induction melting at a temperature above that.

When the silicon raw material is melted by the induction melting method, the silicon melting part 120 includes a crucible 121, an induction coil 122, a tapping part 123, and a gate 124, as shown in FIG. 1. It may be an induction melting apparatus.

The crucible 121 stores a silicon raw material, and a tapping part 123 is formed at a lower portion thereof. Induction coil 122 surrounds the outer wall of the crucible 121. Induction coil 122 is connected to an AC power source. The gate 124 opens and closes the tapping part 123 formed under the crucible 121. The gate 124 may be bar type or valve type as shown in FIG. 1. The crucible 121 may be a graphite crucible or a water-freezing crucible, or may be a crucible of a complex type.

Next, the silicon molten metal storage unit 130 receives and stores the molten silicon, and then discharges the molten silicon into a melt having a predetermined thickness.

As shown in FIG. 1, the lower surface of the silicon melt storage unit 130 may be open. In this case, the transfer unit 140 disposed below the silicon melt storage unit 130 may include the silicon melt storage unit 130. It defines the bottom face of.

In addition, the molten silicon storage unit 130 has a discharge portion 132 is formed to discharge the molten silicon on the lower side. The discharge unit 132 may be a separate discharge groove, and as shown in FIG. 1, a lower surface of the discharge unit 132 may be defined by the transfer unit 140.

The thickness of the discharge part 132 may be one element that determines the thickness of the silicon thin plate, and may be about 0.2 to 2 mm.

In addition, a cooling device (not shown) may be disposed adjacent to the discharge part 132, and in this case, the silicon melt may be discharged from the silicon melt storage part 130 in a cooled state or a supercooled state.

The transfer unit 140 is disposed under the silicon melt storage unit 130, and continuously transfers the silicon melt discharged from the silicon melt storage unit 130. The transfer unit 140 may be in the form of a transfer substrate and may be in the form of a conveyor belt type transfer device.

When the transfer unit 140 is in the form of a transfer substrate, the transfer unit 140 may be formed of one substrate, and the transfer unit 140 may be separated into a lower substrate in contact with the transfer substrate responsible for transfer and the silicon molten metal and form a thin silicon plate. have.

The transfer unit 140 is preferably preheated by the preheating unit 142 in order to minimize the temperature difference with the molten silicon.

The transfer part 140 is preferably formed of a material having a different coefficient of thermal expansion from silicon, such as SiC, Si ₃ N ₄ , graphite, high density carbon, Al ₂ O ₃ , molybdenum, and the like. When the thermal expansion coefficient of the transfer unit 140 is different from the silicon, the silicon thin plate manufactured after the cooling of the silicon melt may be easily separated from the transfer unit 140, and the transfer unit 140 may be reused.

The cooling unit 150 cools the transferred silicon melt to form a silicon thin plate.

In the present invention, the cooling unit 150 may cool the silicon melt in an inert gas blowing method such as argon gas, helium gas, nitrogen gas, and the like.

In the case of inert gas blowing, it is possible to contribute to the rapid cooling of the silicon melt to remove the remaining melt, and it is also easy to control the surface shape of the silicon thin film produced through the surface planarization.

The amount of inert gas blown may be 0.1 ~ 2 Nm ³ / h, but is not limited thereto. The amount of inert gas blown may vary depending on the position and shape of the cooling unit 150.

When using the silicon thin film manufacturing apparatus shown in FIG. 1, the productivity and quality of the silicon thin sheet manufactured may be greatly influenced by the surface temperature of the silicon melt inside the molten metal reservoir, the temperature of the transfer unit, and the transfer speed of the transfer unit. These process variables each affect the productivity of the silicon sheet produced through a complex action rather than affecting each one alone.

Preferably, the surface temperature of the silicon melt in the silicon melt storage unit 130 is 1300 ~ 1400 ℃, the temperature of the transfer unit 140 is 800 ~ 1400 ℃, the moving speed of the transfer unit 140 is 300 ~ 1400 cm / min Can be presented.

If the surface temperature of the silicon melt in the silicon melt storage unit 130 is less than 1300 ° C., the silicon melt may harden before discharge. If the surface temperature of the silicon melt exceeds 1400 ° C., the silicon melt flows during the transfer process after discharge. There is a problem that can be lowered.

In addition, when the temperature of the transfer part 140 is less than 800 ° C., the molten silicon may harden at a portion where the transfer part 140 is in contact with the silicon melt. When the temperature of the transfer part 140 exceeds 1400 ° C., the silicon melt flows. There is a problem that can be lowered.

In addition, when the conveying speed of the conveying unit 140 is less than 300cm / min, the thickness of the silicon thin plate manufactured may be excessively thick, on the contrary, when the conveying speed of the conveying unit 140 exceeds 1400 cm / min There is a problem of becoming too thin.

2 is a photograph showing the surface microstructure of the silicon thin plate manufactured from the silicon thin plate manufacturing apparatus using the inert gas blowing according to the present invention, Figure 3 is a photograph showing the cross-sectional microstructure of the silicon thin plate shown in FIG.

In addition, Figure 4 is a photograph showing the surface of the silicon thin plate produced when the inert gas blowing is not applied.

Referring to FIG. 4, when the inert gas blowing is not applied, the surface of the silicon thin plate to be manufactured has a bumpy surface.

The liquid phase density of silicon is approximately 2.57 g / cm ³ and the solid phase density of silicon is approximately 2.33 g / cm ³ . As a result of the lower solid phase density of silicon, the volume expands when the silicon cools from the liquid phase to the solid phase, and the surface becomes uneven as shown in FIG. Therefore, the surface quality of the silicon thin film produced is not good.

However, as shown in FIG. 5, inert gas blowing, specifically argon gas blowing, can be seen to have much better surface quality than that of FIG. 4.

In addition, referring to Figures 2 and 3, in the case of the silicon thin film to be produced, it can be seen that it has a polycrystalline structure, has an average crystal size of 50 ~ 100 ㎛, and has a vertically grown columnar structure. Such columnar structure has the advantage of increasing the lifetime of the minority carriers excited by sunlight, when the production of a solar cell, the battery efficiency can be improved.

FIG. 6 is a photograph showing the surface after polishing the surface of the silicon thin plate shown in FIG. 5.

The silicon substrate for solar cells uses what has a thickness of 200-400 micrometers normally. Therefore, when the thickness of the silicon thin plate manufactured by the method shown in Figure 6 is also adjusted to 200 ~ 400㎛, it can be easily applied to the substrate for solar cells.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and those skilled in the art to which the art belongs can make various modifications and other equivalent embodiments therefrom. I will understand.

Therefore, the true technical protection scope of the present invention will be defined by the claims below.

110: silicon raw material inlet 120: silicon melter
121: crucible 122: induction coil
123: tapping section 124: gate
130: molten silicon storage unit 132: discharge part
140: transfer unit 142: preheating unit
150: cooling unit

Claims (11)

A silicon raw material input unit to which silicon raw materials are supplied;
A silicon melter for melting the supplied silicon raw material to form a silicon melt;
A silicon molten metal storage unit configured to receive and store the molten silicon, and then discharge the molten silicon into a melt having a predetermined thickness;
A transfer unit for transferring the discharged silicon melt; And
And a cooling unit cooling the transferred silicon melt.
The cooling unit is a silicon thin film manufacturing apparatus using an inert gas blowing, characterized in that for controlling the surface shape of the silicon melt while cooling the silicon melt in an inert gas blowing method.
The method of claim 1,
The amount of the inert gas is blown is a silicon thin plate manufacturing apparatus using an inert gas blowing, characterized in that 0.1 ~ 2 Nm ³ / h.
The method of claim 1,
The blown inert gas is silicon thin film manufacturing apparatus using an inert gas blowing, characterized in that selected from argon gas, helium gas and nitrogen gas.
The method of claim 1,
The silicon melt portion
An apparatus for producing a thin silicon sheet using an inert gas blowing, characterized by melting a silicon raw material by an induction melting method.
The method of claim 4, wherein
The silicon melt portion
A crucible for storing the silicon raw material and having a tapping part formed at a lower portion thereof;
An induction coil surrounding the crucible outer wall,
Silicon thin plate manufacturing apparatus using an inert gas blowing, characterized in that it comprises a gate for opening and closing the tapping unit.
The method of claim 1,
Apparatus for producing a thin silicon sheet using an inert gas blowing, characterized in that the transfer unit defines a lower surface of the molten silicon storage unit.
The method of claim 1,
The molten silicon storage unit
The discharge part for discharging the molten silicon is formed on one side of the lower side,
The lower surface of the discharge portion is a silicon thin film manufacturing apparatus using an inert gas blowing, characterized in that defined by the transfer unit.
It is manufactured using the apparatus of any one of Claims 1-7,
Silicon substrate for solar cells having a thickness of 200 ~ 400㎛. delete delete delete

Images