TW201400780A - Cooling plate - Google Patents

Abstract

Provided is a cooling plate for a crystalline ingot growth furnace. The cooling plate includes a main body, a plurality of heat dissipating elements, and at least one heat insulating element. The main body includes a first cuboid and a second cuboid protruding from the top surface of the first cuboid. The heat dissipating elements are disposed on the top surface of the first cuboid, and located at the corners of the top surface of the first cuboid. The at least one heat insulating element is disposed on the surface of the main body, wherein the at least one heat insulating element covers 5% to 30% of the surface area of the main body.

Description

Cooling plate

This invention relates to a crystal growth apparatus, and more particularly to a cooling disc suitable for use in a crystal growth furnace.

Solar energy has the characteristics of low pollution, high regeneration, easy access, etc., and its application is increasing in response to issues such as global warming and the oil crisis. The specific application of solar energy is currently dominated by twinned solar cells. The process of the twin-crystal solar cell generally includes a front-end wafer process, a battery process, and a back-end package process, wherein the front-end wafer process can be divided into a single-crystal germanium wafer process and a polysilicon wafer process.

The single crystal germanium wafer is produced by melting the purified barium sand in a crystal puller and then drawing it into an ingot. As for the polycrystalline germanium wafer, the purified germanium sand is melted in a crucible placed in a directional crystal growth furnace, and then cast into a crystal block by directional solidification.

1 is a schematic cross-sectional view of a conventional crystal growth furnace. Referring to FIG. 1, the crystal growth furnace 10 includes a heat insulating cage 11, a bottom plate 12, a heater 14, a support column 16, a cooling plate 18, and a conduit 19. The heat insulating cage 11 and the bottom plate 12 are relatively movable in the vertical direction. Specifically, the heat insulating cage 11 and the bottom plate 12 may not be in contact with each other, as shown in FIG. 1; or the heat insulating cage 11 and the bottom plate 12 may abut each other to define a closed space. The heater 14 is provided in the heat insulating cage 11. The support column 16 holds the cooling disk 18 in the heat insulating cage 11. The conduit 19 is used to pass gas into the insulating cage 11. Hereinafter, a conventional description will be briefly described with reference to FIG. 1. The long crystal method.

First, the crucible material 30 is placed in the crucible 20. Next, the internal temperature of the heat insulating cage 11 is raised by the heater 14, so that the tantalum raw material 30 starts to melt. Since the heater 14 is relatively close to the top of the heat insulating cage 11, and the heat insulating cage 11 and the bottom plate 12 are not in contact with each other, heat can escape from the bottom of the heat insulating cage 11, and thus, the inner space of the heat insulating cage 11 is formed. The temperature gradient, which is decremented from top to bottom, causes the crucible material 30 to melt from its top while its bottom remains solid. These solid-state parts are seed crystals, which are the starting point for grain growth during long crystal growth.

However, in the process of heating the crucible material 30, some of the seed crystals may be melted due to uneven distribution of heat in the heat insulating cage 11. For example, since heat is conducted to the crucible material 30 via the sidewall of the crucible 20, the more the crucible material 30 absorbs the heat closer to the sidewall of the crucible 20, the crucible material 30 near the corner of the crucible 20 is adjacent to the crucible. The side walls absorb more heat. In other words, the seed crystal above the corner of the cooling disk 18 has a higher temperature than the seed crystal above the center of the cooling disk 18, and thus may be first melted. Once the seed crystals melt, the grains cannot grow above them, increasing the defect density of the resulting ingot. In order to avoid seed crystal melting, a conventional solution is to increase the distance between the heat insulating cage 11 and the bottom plate 12, but as a result, the heat loss is increased and the energy loss is also increased.

In view of the foregoing problems, in order to reduce the defect density of the ingot, the design and arrangement of the crystal growth furnace itself and its various components still need to be improved.

The present invention provides a cooling disk capable of reducing the defect density of an ingot during growth.

The invention proposes a cooling disc suitable for use in a crystal growth furnace. The cooling disk includes a body, a plurality of heat dissipating members, and at least one heat insulating member. The body includes a first cuboid and a second moment protruding from a top surface of the first moment. The heat dissipating member is disposed on a top surface of the first rectangular body and located at a corner of the first rectangular body. The heat insulating member is disposed on a surface of the body, wherein the heat insulating member covers 5% to 30% of the total surface area of the body.

In an embodiment of the invention, the heat insulating member is disposed, for example, on a top surface of the first rectangular body and located between the heat dissipating members.

In an embodiment of the invention, the heat insulating member is connected to, for example, a heat dissipating member.

In an embodiment of the invention, the material of the heat dissipating member is, for example, graphite.

In an embodiment of the invention, the material of the body is, for example, graphite.

In an embodiment of the invention, the material of the heat insulating member is, for example, alumina.

In an embodiment of the invention, the material of the heat insulating member is, for example, carbon fiber.

In an embodiment of the invention, the heat dissipating member is, for example, L-shaped.

In an embodiment of the invention, the heat insulating member is, for example, a strip shape.

In an embodiment of the invention, the second moment body is located, for example, at the first The center of the top surface of the rectangular body.

Based on the above, the cooling disk of the present invention includes a heat radiating member and a heat insulating member. The heat dissipating member can help the cooling plate to dissipate heat, and the heat insulating member can block the radiant heat. Therefore, the cooling disk of the present invention has a good cooling effect.

The above described features and advantages of the present invention will be more apparent from the following description.

2A is a schematic view of a cooling disk according to an embodiment of the invention. Figure 2B is an exploded view of the cooling disk of Figure 2A.

Referring to FIG. 2A and FIG. 2B simultaneously, according to the embodiment, the cooling disk 100 includes a main body 110, a heat dissipating member 120, and a heat insulating member 130. The body 110 includes a first moment body 112 and a second moment body 114 protruding from the top surface 112a of the first moment body 112, wherein the second moment body 114 is disposed, for example, at the center of the top surface 112a. In this embodiment, the material of the body is, for example, graphite.

The heat dissipation member 120 is disposed on the top surface 112a and located at a corner of the top surface 112a. In this embodiment, the heat dissipating members 120 are L-shaped and have a total of four, respectively disposed at the corners of the top surface 112a, and are in contact with the top surface 112a and the side surface 114a of the second rectangular body 114, respectively, but the present invention does not The shape of the heat dissipation member 120 is particularly limited. For example, in other embodiments, the heat dissipating member 120 can also be a rectangular body or a cube. Further, the heat dissipation member 120 may include any material having good thermal conductivity such as graphite.

The heat insulating member 130 is disposed on the surface of the body 110 and covers a total surface area of the body 110 of about 5% to 30%. The so-called "total surface area of the subject", It refers to the area sum of all surfaces of the body 110. In other words, in the present embodiment, the area of each of the following is referred to (refer to FIG. 2B): the top surface of the second rectangular body 114, the four side surfaces 114a of the second rectangular body 114, and the top surface 112a are not subjected to the second moment. The portion covered by the body 114, the four sides of the first rectangular body 112, and the bottom surface of the first rectangular body 112.

In this embodiment, the total number of the heat insulating members 130 is four, which are disposed on the top surface 112a, respectively located between the heat dissipating members 120, and are respectively connected to the heat dissipating members 120. However, the present invention is not limited to such an arrangement. In other embodiments, one or more insulating members 130 may be disposed, and the heat insulating members 130 may not be in contact with the heat dissipating members 120.

The shape of the heat insulating member 130 is not particularly limited, and is depicted as an elongated shape in FIGS. 2A and 2B, but it may be in the form of a sheet, a block, or the like. In FIGS. 2A and 2B, the heat insulating member 130 is a rectangular body, and therefore the ratio of the surface of the main body 110 covered by the heat insulating member 130 can be adjusted by changing the length L of the heat insulating member 130 (refer to FIG. 2A). Of course, the ratio of the surface of the main body 110 covered by the heat insulating member 130 may be adjusted by other means as long as the ratio falls within 5% to 30%.

The heat insulating member 130 may include any material that can block radiant heat, such as alumina or carbon fiber. Specifically, the heat insulating member 130 may be an alumina blanket or a carbon fiber insulation strip.

The advantageous effects of the cooling disk 100 in the case of a crystal growth furnace will be described below.

As mentioned above, during the growth process, the interior of the insulation cage forms a temperature gradient that decreases from top to bottom. Maintaining the seed crystal in a solid state means that the temperature of the seed zone must be low enough. That is, the cooling plate 100 must effectively heat Transfer away from the seed area. However, the radiant heat from the heater (譬, heater 14 in Fig. 1) causes the temperature of the cooling disk 100 to rise, deteriorating its effect of cooling the seed region. The heat sink member 120 is provided at a corner of the cooling disk 100 of the present invention, and the heat dissipation effect of the cooling disk 100 can be enhanced. Further, the cooling plate 100 of the present invention is further provided with a heat insulating member 130 capable of blocking radiant heat from the heater so that the cooling plate 100 is maintained at a low temperature with respect to the seed crystal region. Thereby, the cooling disc 100 can provide a better cooling effect to the seed crystal, and reduce the melting of the seed crystal in the corner of the crucible due to excessive heating.

In order to confirm the effect of the cooling disk of the present invention, the ingot will be grown by using a conventional cooling disk and the cooling disk of the present invention. In the comparative example, in a known conventional crystal growth furnace (GT Solar selling company's GT-DSS450 ^TM) growing ingot. Further, in the experimental examples, the present invention is to replace the cooling coil GT-DSS450 ^TM cooling coils. In the experimental examples and comparative examples, the same crystal growth process parameters were used to grow the ingot. Then, the etch pit density (EPD) at the corners of the two ingots was compared, and the results are shown in FIG.

Can be seen from FIG. 3, GT-DSS450 ^TM contrast, using the present invention provided with a cooling plate of the crystal growth furnace to grow a low defect density is clearly ingot; In addition, by mounting the crystal growth furnace The top and bottom temperature measuring devices can measure the temperature drop at the bottom of the crucible by about 30 ° C, thereby confirming the effect of the cooling disc of the present invention.

In summary, the cooling disk of the present invention includes a heat dissipating member and a heat insulating member. The heat dissipating member can help the cooling plate to dissipate heat, and the heat insulating member can block the radiant heat from the heater. Therefore, the cooling disc of the present invention has a good cooling effect, and if used in a crystal growth furnace, the ingot defect can be effectively reduced. degree. In addition, if the cooling plate of the present invention is used, it is not necessary to increase the distance between the heat insulating cage and the bottom plate in order to avoid melting of the seed crystal during the crystal growth process, and therefore, the heat generated by the heater is not accelerated due to the increased pitch. . Thereby, energy consumption can be reduced and costs can be reduced.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

10‧‧‧Crystal furnace

11‧‧‧Insulation cage

12‧‧‧floor

14‧‧‧heater

16‧‧‧Support column

18,100‧‧‧Cooling plate

19‧‧‧ catheter

20‧‧‧坩埚

30‧‧‧Materials

110‧‧‧ Subject

112‧‧‧First moment

112a‧‧‧ top surface

114‧‧‧Second moment

114a‧‧‧ side

120‧‧‧heating components

130‧‧‧Insulation components

L‧‧‧ length

1 is a schematic cross-sectional view of a conventional crystal growth furnace.

2A is a schematic view of a cooling disk according to a first embodiment.

Figure 2B is an exploded view of the cooling disk of Figure 2A.

Figure 3 presents a comparison of defect densities of ingots grown using a conventional crystal growth furnace and a crystal growth furnace equipped with a cooling disk of the present invention.

100‧‧‧Cooling plate

110‧‧‧ Subject

112‧‧‧First moment

114‧‧‧Second moment

120‧‧‧heating components

130‧‧‧Insulation components

L‧‧‧ length

Claims (10)

A cooling plate suitable for a crystal growth furnace, the cooling plate comprising: a body comprising: a first rectangular body having a top surface; and a second rectangular body protruding from the top surface; the plurality of heat dissipating members And disposed on the top surface and located at a corner of the top surface; and at least one heat insulating member disposed on a surface of the main body, wherein the heat insulating member covers 5% to 30 of a total surface area of the main body %. The cooling disk of claim 1, wherein the heat insulating member is disposed on the top surface and located between the heat dissipating members. The cooling disk of claim 2, wherein the heat insulating member is coupled to the heat dissipating member. The cooling disk of claim 1, wherein the material of the heat dissipating member comprises graphite. The cooling disk of claim 1, wherein the material of the body comprises graphite. The cooling disk of claim 1, wherein the material of the heat insulating member comprises alumina. The cooling disk of claim 1, wherein the material of the heat insulating member comprises carbon fiber. The cooling disk of claim 1, wherein the heat dissipating member is L-shaped. The cooling plate of claim 1, wherein the The hot member is a long strip type. The cooling disk of claim 1, wherein the second rectangular body is located at a center of the top surface.