TWI449820B - Crystal growth system with close thermal cycling structure - Google Patents

Description

Crystal growth furnace with locked thermal cycle structure

A crystal growth furnace, especially a crystal growth furnace having a closed thermal cycle structure.

As the problem of energy shortages has become more serious, research on alternative energy sources has become increasingly hot. Sunlight is one of the important alternative energy sources because of its pollution-free and inexhaustible properties. A solar cell is a device that absorbs sunlight and converts it into electrical energy. A solar cell consists essentially of a multilayer film. The multilayer film material is derived from a semiconductor crystal. Crystal quality is an important factor affecting the photoelectric conversion efficiency of solar cells.

There are many ways to grow crystals. However, there are only a few long-crystal methods that can grow large-volume crystals and are cost-effective. In the solar industry, the Directional Solidification Method is often used to grow the initial material crystals of the crucible, such as antimony ingots. The basic principle of the directional solidification method is to place the niobium raw material in the furnace body in the polycrystalline ingot furnace, and to change the temperature field to make the niobium raw material crystallize from bottom to top to form polycrystalline crucible. During this process, the crucible material is placed at the bottom of the furnace and heated to form a melt. When heat is removed, the bottom layer of the melt begins to solidify, forming an initial solidified layer. As the temperature is gradually removed, the ruthenium solidified layer gradually builds up until all of the melt forms a complete solidified body. In the above curing process, the heat removal direction is opposite to the crystal growth direction. That is, heat is removed from the bottom of the furnace body, and the molten material grows toward the top of the furnace body. Therefore, the temperature gradient is an important parameter in the directional solidification method, and the control of the temperature gradient affects the quality of the crystal growth. huge.

The traditional DSS (DIRECTIONAL SOLIDFIATION SYSTEM) crystal growth system usually includes a furnace body, a bearing base and a heater. The furnace body has a bottom portion and at least one side wall, and the side wall forms an accommodating space around the bottom portion for placing the crystal growth material. A carrier base is provided under the bottom. The heater is usually disposed outside the side wall for the purpose of providing a temperature to the crystal growth material placed at the bottom of the furnace body to cause the raw material to melt. A heat insulating layer is disposed on the bearing base and the circumferential side of the furnace body. The vertical edges of the insulation layer can be moved up and down to expose the edges of the carrier base, allowing heat to be radiated to the water-cooled walls of the lower chamber of the furnace body. The water cools the load-bearing susceptor and returns to cool the bottom of the furnace body, thereby creating a vertical temperature gradient around the melt in the furnace. This vertical temperature gradient causes the crucible in the furnace to solidify from the bottom, starting from the bottom of the melt to the top.

In the above-mentioned crystal growth system, since the temperature change is extremely complicated, the required temperature gradient has not been effectively controlled, and therefore a crystal growth apparatus capable of controlling the temperature gradient is required.

The invention discloses a crystal growth furnace having a closed thermal cycle structure. By providing a heat guiding member between the sidewall of the furnace body and the insulating layer, the heat flow is locked in the space formed between the insulating layer and the furnace body, and the vertical temperature gradient required for the crystal growth is formed. Thereby, the controllability of the temperature gradient for the growth of the crystals is better. Moreover, the heat guide member side can have different structural combinations, so that the temperature gradient changes more precisely, and it can respond to the complicated temperature change in actual crystal growth.

An aspect of the present invention provides a crystal growth furnace having a closed thermal cycle structure, comprising a furnace body, a bearing base, at least one insulating layer, and at least one Thermal guide. The furnace body includes a bottom and at least one side wall surrounding the bottom. The carrier base is placed under the bottom. At least one insulating layer is disposed outside the sidewall and spaced apart from the sidewall. At least one heat guide is disposed between the insulating layer and the sidewall and relatively surrounds the bottom.

According to an embodiment of the invention, the material of the carrier base and the heat guiding member may be graphite. The heat guide may have a stepped structure or may include at least one plane, at least one slope, or at least one arc surface in the structure.

According to an embodiment of the invention, the distance between the side of the heat guide and the side wall is increased from the bottom of the side of the heat guide to the top of the side of the heat guide.

Another aspect of the present invention provides a crystal growth furnace having a locked thermal cycle structure including a furnace body, a carrier base, at least one heat exchange member, at least one insulation layer, and at least one heat guide. The furnace body includes a bottom and at least one side wall surrounding the bottom. The carrier base is disposed under the bottom portion and includes at least one recess formed on a circumferential side of the carrier base and located opposite the bottom periphery of the bottom. At least one heat exchange member is joined to the recess. The insulating layer is disposed outside the sidewall and spaced apart from the sidewall. At least one heat guide is disposed between the insulating layer and the sidewall and relatively surrounds the bottom. Wherein, the distance between the side of the heat guide and the side wall is increased from the bottom of the side of the heat guide to the top of the side of the heat guide.

According to an embodiment of the invention, the heat guiding member may have a stepped structure or may include at least one plane, at least one slope or at least one curved surface in the structure.

According to an embodiment of the invention, the heat exchange members are coupled to each other around the carrier base. In addition, a heat insulating member may be included, which is disposed between the bottom and the carrying base.

This paragraph first introduces the definition of "locking thermal cycle structure", thereby making this issue The technical characteristics of Ming can be more clear. The heat transfer application of the crystal growth furnace of the present invention is to supply the crystal growth temperature through the side heater of the furnace body, and argon gas is poured into the furnace body above the furnace body, and the radiant heat flow of the furnace body is evenly distributed through the flow of argon gas. Throughout the furnace, the argon gas is finally withdrawn through the pumping of the vacuum pump placed at the bottom of the furnace body, and the process is repeated as the so-called "thermal field cycle". The so-called lockout field is an additional heat guide that is closed to the side of the furnace by argon gas supplied from above, so that the heat flow is blocked in this interval to achieve the furnace. The effect of the body decreasing from top to bottom. The following embodiments are structural improvements implemented based on the above basic principles.

Referring to FIG. 1, FIG. 1 is a side view showing the structure of an embodiment of a crystal growth furnace having a closed thermal cycle structure according to the present invention. The crystal growth furnace having a locked thermal cycle structure includes a furnace body 100, a carrier base 200, an insulating layer 300, and a heat guide 400. The furnace body 100 includes a bottom portion 102 and at least one side wall 101 surrounding the bottom portion. The bottom portion 102 and the side wall 101 form an accommodating space for placing the crystal growth material. The insulating layer 300 is disposed on the periphery of the sidewall 101 and spaced apart from the sidewall 101 by a distance. The lower end of the insulating layer 300 has an extending portion 301 extending toward the furnace body 100. The heat guide 400 is disposed on the extension 301 and is located at the periphery of the bottom portion 102. Viewed from the side, the heat guide 400 faces the side of the furnace body 100 to form a side bottom 401, a side intermediate portion 402, and a side top portion 403 of unequal length. In other words, the distance between the heat guide 400 and the side wall 101 of the furnace body 100 is gradually increased from its side bottom 401 to the side top 403. In the first figure, the vertical distance between the bottom bottom portion 401 of the heat guiding member 400 and the side wall 101 is d1, the vertical distance between the side intermediate portion 402 of the heat guiding member 400 and the side wall 101 is d2, and the top side of the heat guiding member 400 is d1. 403 and side wall 101 The vertical distance is d3, which satisfies the relationship of d3>d2>d1. Thereby, in the process of crystal growth, the heat flow can change with d1, d2 and d3, and a successively changing temperature gradient is formed from the bottom of the furnace body 102 from bottom to top, which contributes to the vertical solidification of the crystal growth crystal, and further Make the crystal quality more stable. In Fig. 1, the arrow a is the direction of the thermal field circulation, and the circulating heat field is blocked on the circumferential side of the furnace body by the blocking action of the heat guiding member 400. In the following embodiments, the arrows b and c are the same, and will not be described again.

Referring to FIG. 2, FIG. 2 is a side view showing another embodiment of the crystal growth furnace having the closed thermal cycle structure according to FIG. 1. The peripheral side of the carrier base 200 has a recess 201. At least one additional heat exchange member 500 is joined to the recess 201 and engages around the carrier base 200. The heat exchange member 500 contacts the bottom periphery. Thereby, the temperature of the bottom peripheral region and the central region can be balanced to increase the temperature uniformity. Moreover, the arrangement of the heat guide 400 can be combined to make the crystal growth furnace 100 have better temperature controllability. In Fig. 2, the arrow b is the direction of the thermal field circulation.

Please refer to FIG. 3, which shows a side view of another embodiment of the crystal growth furnace having the closed thermal cycle structure according to FIG. A heat insulation member 600 is disposed between the bottom portion 102 and the carrier base 200. By the heat insulating member 600, the external thermal disturbance can be prevented from affecting the bottom portion 102, thereby ensuring the crystal growth quality. In Fig. 3, the arrow c is the direction of the thermal field circulation.

Please refer to FIG. 4, which shows a top view of the combination of the heat guides. The heat guide 400 is coupled around the periphery of the bottom portion 102 (please refer to FIG. 1 at the same time). Thereby the controllability of the temperature is better.

Referring to FIG. 5, FIG. 5 is a perspective view showing the structure of the heat guide according to FIG. 1. The heat guide 400 has a stepped structure on one side and a side bottom thereof The portion 401, the side intermediate portion 402 and the side top portion 403 are not unequal in length, thereby forming a structure that is not equidistant from the furnace body 100 (please refer to FIG. 1), and can form a temperature gradient change, which contributes to the improvement. Crystal quality.

Please refer to FIG. 6. FIG. 6 is a perspective view showing the structure of one embodiment of the heat guiding member. One side of the heat guiding member 400 does not necessarily have to be a step type change, and may be a structure having a continuous change. In Fig. 6, one side of the heat guide 400 has a continuously varying ramp 404. By the continuous variation of the slope 404, the temperature gradient is more precisely changed, thereby making the temperature control better.

Please refer to FIG. 7. FIG. 7 is a schematic view showing another embodiment of the inclined surface according to FIG. 6. The bevel 404 of the heat guide 400 can be formed at different tilt angles due to different control requirements for temperature gradients.

Please refer to FIG. 8. FIG. 8 is a perspective view showing the structure of one embodiment of the heat guiding member. One side of the heat guide 400 has a continuously varying curved surface 405. The curvature of the curved surface 405 can cause different temperature gradient changes, thereby being able to respond to different actual conditions.

Please refer to FIG. 9. FIG. 9 is a perspective view showing the structure of one embodiment of the heat guiding member. In Fig. 9, the side top 403 of the heat guide 400 has a vertical plane 406 structure, and the side intermediate portion 402 and the side bottom portion 401 respectively include slopes 404a and 404b having different inclination angles. By combining the different types of structures, a variety of varying temperature gradients can be produced, which is more controllable for temperature.

Referring to FIG. 10, FIG. 10 is a perspective view showing the structure of an embodiment of the heat guiding member. In Fig. 10, one side of the heat guide 400 includes three curved faces 405a, 405b and 405c having different curvatures. With this different combination of curvatures, A variety of varying temperature gradients can be produced with better temperature control.

Referring to FIG. 11, FIG. 11 is a perspective view showing the structure of one embodiment of the heat guiding member. In Fig. 11, the heat guide 400 side includes a combination of a slope 404c, a slope 404d, and a curved surface 405d. The slope 404c and the slope 404d have different inclination angles. By combining the different types of structures, a variety of varying temperature gradients can be produced, which is more controllable for temperature.

In summary, the crystal growth furnace of the present invention having a closed thermal cycle structure. By providing a heat guiding member between the sidewall and the insulating layer, the controllability of the temperature gradient for the growth of the crystal is better. The heat guide member side can have different structural combinations, so that the temperature gradient can have various changes, and the temperature gradient can be more precisely changed by the continuous change of the structure of the heat guide member side, thereby making the pair longer. The crystal is more controllable and the crystal quality is better.

100‧‧‧ furnace body

101‧‧‧ side wall

102‧‧‧ bottom

200‧‧‧bearing base

201‧‧‧ recess

300‧‧‧Insulation

301‧‧‧Extension

400‧‧‧Hot guides

401‧‧‧Bottom of the bottom

402‧‧‧ middle side of the side

403‧‧‧Side top

404‧‧‧Bevel

404a‧‧‧Bevel

404b‧‧‧Bevel

404c‧‧‧ Bevel

404d‧‧‧Bevel

405‧‧‧ curved surface

405a‧‧‧Arc face

405b‧‧‧ curved surface

405c‧‧‧ curved surface

405d‧‧‧ curved surface

406‧‧‧Vertical plane

500‧‧‧Hot exchange parts

600‧‧‧Insulation

D1‧‧‧The vertical distance between the bottom and the side wall of the hot guide

a, b, c‧‧ ‧ thermal field circulation direction

D2‧‧‧The vertical distance between the middle part of the side of the heat guide and the side wall

D3‧‧‧The vertical distance between the top and side walls of the hot guide

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side view showing the structure of an embodiment of a crystal growth furnace having a closed thermal cycle structure of the present invention.

Fig. 2 is a side view showing the structure of another embodiment of the crystal growth furnace having the closed thermal cycle structure according to Fig. 1.

Fig. 3 is a side view showing the structure of another embodiment of the crystal growth furnace having the closed thermal cycle structure according to Fig. 2.

Figure 4 is a top view of the combination of the heat guides.

Fig. 5 is a perspective view showing the structure of the heat guide according to Fig. 1.

Figure 6 is a perspective view showing the structure of one embodiment of the heat guiding member.

Fig. 7 is a schematic view showing another embodiment of the inclined surface according to Fig. 6.

Figure 8 is a perspective view showing the structure of one embodiment of the heat guide.

Figure 9 is a perspective view showing the structure of one embodiment of the heat guiding member.

Figure 10 is a perspective view showing the structure of one embodiment of the heat guiding member.

Figure 11 is a perspective view showing the structure of one embodiment of the heat guide.

100‧‧‧ furnace body

101‧‧‧ side wall

102‧‧‧ bottom

200‧‧‧bearing base

300‧‧‧Insulation

301‧‧‧Extension

400‧‧‧Hot guides

401‧‧‧Bottom of the bottom

402‧‧‧ middle side of the side

403‧‧‧Side top

A‧‧‧ Thermal field circulation direction

D1‧‧‧The vertical distance between the bottom and the side wall of the hot guide

D2‧‧‧The vertical distance between the middle part of the side of the heat guide and the side wall

D3‧‧‧The vertical distance between the top and side walls of the hot guide

Claims (14)

A crystal growth furnace having a locked thermal cycle structure, comprising: a furnace body comprising: a bottom; and at least one side wall surrounding the bottom; a bearing base disposed under the bottom; at least one insulating layer disposed on the Outside the sidewall and spaced apart from the sidewall; and at least one heat guiding member disposed between the insulating layer and the sidewall and surrounding the bottom portion and the sidewall side of the sidewall, wherein the heat guiding member side and the sidewall The distance between the sides of the side of the heat guide member increases toward the top of the side of the heat guide member, so that the furnace body gradually forms a successive temperature gradient from the bottom to the bottom. The crystal growth furnace of claim 1, wherein the carrier base is made of graphite. The crystal growth furnace of claim 1, wherein the heat guide is made of graphite. The crystal growth furnace of claim 1, wherein the heat guide has a stepped structure. The crystal growth furnace of claim 1, wherein the heat guide comprises at least one slope. The crystal growth furnace of claim 1, wherein the heat guide comprises at least one curved surface. The crystal growth furnace of claim 1, wherein the heat guide comprises at least one plane. A crystal growth furnace having a locked thermal cycle structure, comprising: a furnace body comprising: a bottom; and at least one side wall surrounding the bottom; a bearing base disposed under the bottom, the carrier base comprising: at least one a recess formed on a peripheral side of the carrier base and located opposite the bottom periphery; at least one heat exchange member is coupled to the recess; at least one insulating layer disposed outside the sidewall and spaced apart from the sidewall; and at least a heat guiding member is disposed between the insulating layer and the sidewall and relatively surrounding the bottom portion, wherein a distance between a side of the heat guiding member and the sidewall is from a bottom of the side of the heat guiding member to the heat guiding member The top of the side is incremented. The crystal growth furnace of claim 8, wherein the heat exchange members are coupled to each other around the carrier base. The crystal growth furnace of claim 8 further includes: A heat insulating member is disposed between the bottom and the bearing base. The crystal growth furnace of claim 8, wherein the heat guide has a stepped structure. The crystal growth furnace of claim 8, wherein the heat guide comprises at least one slope. The crystal growth furnace of claim 8, wherein the heat guide comprises at least one curved surface. The crystal growth furnace of claim 8, wherein the heat guide comprises at least one plane.