TWM526578U - Crucible insulation unit for crystal growth - Google Patents

Description

Insulation unit for long crystal

The present invention relates to an insulation unit, and more particularly to an insulation unit for a long crystal.

Referring to Figure 1, there is a conventional graphite baffle 11 for growing polycrystalline Si. Referring to FIG. 2, in the actual implementation of growing polycrystalline silicon, a heat insulating unit 1 composed of four graphite baffles 11 is vertically disposed in a certain heat extraction block 13 in a crystal growth furnace (not shown). The lining space 10 for arranging a raft 14 is defined by the graphite baffle 11 and the directional heat-receiving block 13 . In FIG. 2, the inside of the crucible 14 is filled with a molten soup 15, and the crucible soup 15 is supplied with heat through an upper heating unit 16 and a plurality of lateral heating units 17 of the crystal growth furnace to make a heat energy. The solid cerium raw material is in a molten state, and in the long crystal state, the directional heating block 13 under the crucible 14 is used to take away the heat energy of the crucible soup 15, thereby solidifying the crucible soup 15. In the process of growing polycrystalline germanium, the cooling direction of the crucible soup 15 is from top to bottom, so that a solid-liquid interface 151 is formed inside, and a polycrystalline ingot is obtained after finally solidifying completely.

However, those skilled in the art are aware that the most unpleasant problem in growing polycrystalline silicon is that the slope of the solid-liquid interface 151 adjacent to the crucible 14 is too steep, which tends to result in the original existence. The impurities in the crucible soup 15 move toward the center of the crucible 14 during the crystal growth process, and it is also easy to grow a lateral crystal during the crystal growth process, thereby causing the final twin crystals. Excessive impurities remain in the process and form defects that are not desired in the art, so as to affect the photoelectric conversion efficiency of the germanium germanium in the solar cell application of the back end (photon-to-current Conversion efficiency; PCE).

The accommodating space 10 surrounded by the graphite baffles 11 has a heat insulating effect. However, the graphite baffles 11 are not capable of providing a uniform lateral thermal field along the height direction (i.e., the longitudinal direction) of the crucible 15 in the crucible 14 to mitigate impurities to the twins. The phenomenon of the spread of the center. In addition, when the graphite baffles 1 are used for a long time in the crystal growth furnace, the problem of carbonization is inevitably caused, thereby contaminating the crucible soup 15 and affecting the crystal growth quality of the twin ingot.

In view of the above problem of lateral thermal field unevenness, referring to FIG. 3 and FIG. 4, the Republic of China No. M441678 new patent certificate number discloses that there is an insulation unit for crystal growth, which is suitable for use in one of the 坩埚14 A plurality of seeds 18 are placed at the bottom to grow a single type of monocrystalline ingot. The insulating unit for the crystal growth comprises four heat insulation panel combinations 2 that are circumferentially shaped and joined to each other. Each of the heat insulation panel assemblies 2 has a first plate body 21 composed of graphite having a thermal conductivity (hereinafter referred to as K value) of between 128 and 170 W/m·K, and a K value of 0.28. a second plate body 22 composed of carbon fibers of ~0.21 W/m·K, and a carbon/carbon composite material (CCM) having a K value of 4 to 27 W/m·K The third plate body 23 is. Each of the first plate bodies 21 is recessed with a groove 210 adjacent to each other on a plane 211 facing the crucible 14 , and the second plate body 22 of each of the heat insulation panel assemblies 2 and the third plate body 23 are correspondingly fixed. They are disposed in the grooves 210 of each of the first plate bodies 21 (as shown in FIG. 3).

The insulating unit for the crystal growth shown in FIG. 4 can provide a uniform transverse thermal field for the crucible soup 15 to slow the slope of the solid solution interface of the crucible soup 15 adjacent to the crucible 14 and Improve its long crystal quality. However, the same problem is that the heat insulating plate assembly 2 is inevitably inconsistent with carbonization in the crystal growth furnace for a long time, so that the enamel soup 15 is contaminated and the crystal growth quality is affected. Moreover, in the assembly process of the heat insulation panel combination 2, collision damage is inevitable, thus affecting the service life.

According to the above description, the overall structure of the improved thermal insulation unit provides an appropriate thermal field for the molten steel material in the crucible, and increases the use intensity of the thermal insulation unit to prevent the quality of the ingot from being adversely affected by the carbonization problem of the thermal insulation unit. It is a subject that can be further broken by relevant technical personnel in this technical field.

Accordingly, it is an object of the present invention to provide an insulating unit for use in the use of long crystals which avoids the problem of carbonization affecting the quality of the ingot.

Therefore, the thermal insulation unit of the present invention is used for facing a stack of at least one set of thermal insulation components. The thermal insulation assembly includes a first plate body, a second plate body, and a protective layer. The first plate body has opposite end faces disposed in a height direction, and a plane facing the weir. The first plate body is provided with a groove from the plane facing away from the recess, and the groove is adjacent to one end surface of the first plate body, and the first plate body further has a first heat transfer coefficient k ₁ . The second plate body is disposed in the groove and has a plane facing the cymbal and a second heat transfer coefficient k ₂ , and k ₁ > k ₂ . The protective layer covers a plane of the first board body and a plane of the second board body.

The utility model has the following advantages: let k ₁ >k ₂ , the second plate body is located at one end surface of the first plate body 31 to provide a uniform lateral thermal field, and the first and second covers are covered by the protective layer The surface of the plate body is prevented from colliding with the first and second plate bodies to extend the service life, and the surface of the first and second plate bodies is prevented from being directly exposed and facing the crucible in the high temperature crystal growth environment, thereby reducing the carbonization The problem of poor quality of the crystal growth.

The above and other technical contents, features and effects of the present invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings.

As shown in FIG. 5, FIG. 6 and FIG. 7, an embodiment of the thermal insulation unit of the present invention is for facing and surrounding the crucible 14, which comprises four groups of mouth-shaped surrounds. The heat assembly 3, and the heat insulating components 3 are respectively screwed and fixed to each other by a plurality of carbon fiber screw nut groups 4 (as shown in FIG. 5).

Each of the heat insulation components 3 of the present embodiment includes a first plate body 31, a second plate body 32, and a protective layer 33.

Each of the first plate bodies 31 has opposite end faces 311 along a height direction Z and a plane 312 facing the crucible 14. Each of the first plate bodies 31 is recessed from the plane 321 toward the rafter 14 and has a recess 310. The recess 310 is adjacent to one of the end faces 311 of the first plate body 31. The first plate body 31 further has a recess 311. The first heat transfer coefficient k ₁ . As shown in FIG. 6, in the embodiment of the present invention, the groove 310 is adjacent to the lower end surface of the first plate body 31. The second plate body 32 is disposed on the recess 310 and has a plane 321 facing the crucible 14 and a second heat transfer coefficient k ₂ , and k ₁ > k ₂ . The protective layer 33 covers the plane 312 of the first board body 31 and the plane 321 of the second board body 32.

The first plate body 31 and the second plate body 32 of each heat insulating component 3 further have a first thickness t ₁ and a second thickness t ₂ in a thickness direction X, respectively, and 1.0<t ₁ /t ₂ < 3.0. The first plate body 31 and the second plate body 32 of each heat insulating component 3 further have a first height h ₁ and a second height h ₂ in the height direction Z, respectively, and 1.0<h ₁ /h ₂ < 3.0. Preferably, k _{1 is} between 90 W/m·K and 110 W/m·K; and k _{2 is} between 5 W/m·K and 10 W/m·K. In this embodiment of the present invention, each of the first plate bodies 31 is made of graphite, and each of the second plate bodies 32 is made of carbon fiber of the FGM-201 model, and each of the protective layers 33 is made of tantalum carbide (SiC). Made, and t ₂ ≥ 10 mm, h ₂ ≥ 200 mm.

As shown in FIG. 5 and FIG. 6 , the plane 312 of each of the first board bodies 31 and the plane 321 of each of the second board bodies 32 of the present embodiment are aligned with each other so as to cover the planes 312 and 321 . The protective layer 33 defines an inner surface 331 facing the crucible 14 , and the second plate body 32 of each of the thermal insulation components 3 is screwed from the plane 321 by a plurality of carbon fiber screws 5 to be correspondingly fixed to the first plates. In the groove 310 of the body 31. In addition, the insulative shapes surrounding the insulative heat insulating components 3 are defined by the inner surface 331 of the protective layer 33 of the thermal insulation components 3 to define a space 30 for receiving the crucible 14.

Referring to FIG. 7 again, when the embodiment of the present invention is applied to a growing polycrystalline germanium ingot, the environment of the crystal growth furnace used is the same as that of FIG. 2, and the specific crystal growth process is to input the raw material and heat to melt the raw material into The simmering soup 15, from the directional heat take-up block 13 carries away the heat of the simmering soup 15 to solidify the bismuth melted soup into a bismuth ingot, annealing, cooling, and taking an ingot. The second embodiment of the present invention is such that the second heat transfer coefficient k _{2 of the} second plate body 32 is smaller than the first heat transfer coefficient k _{1 of the} first plate body 31, and the second plate body 32 is made. Is located at the lower end surface 311 of the first plate body 31 corresponding thereto, thereby maintaining a uniform lateral thermal field during the crystal growth of the crucible soup 15 to slow the crucible soup 15 adjacent to the crucible 14 The solid-liquid interface slope and improved its long crystal quality. On the other hand, by covering the first plate body 31 and the protective layers 33 of the second plate bodies 32 to increase the strength of the surfaces 312 and 321 respectively, the heat insulating components 3 are reduced during assembly. Colliding or damaging to extend the service life; in addition, avoiding the planes 312, 321 of the first plate body 31 and the second plate body 32 directly facing the cymbal 14 and being exposed to a high temperature environment to melt the soup 15 It is free from carbonization during the process of growing into polycrystalline niobium and maintains the long crystal quality it deserves.

To further confirm the crystal growth quality of this embodiment of the present invention, the Applicant provides a comparison of minority carrier life cycle distributions as shown in Figures 8 and 9. The applicant mainly uses a polycrystalline bismuth ingot obtained by using the present embodiment and the heat insulating unit 1 (hereinafter referred to as a comparative example) shown in FIG. 2, and squaring two sets of crystal bricks vertically and vertically (ie, 5 × 5 total 25), and from each of the groups of crystal bricks (see Figure 8) and a corner (see Figure 9), respectively, take a crystal brick for a minority carrier life cycle distribution comparison. The correlation analysis of the aforementioned minority carrier life cycle was obtained by an analyzer of the type Semi Lab WT-2000D; among them, the minority carrier life cycle was defined as a few carriers that were separated by illumination and then combined (recombination). The length of time required, and the distribution of the life cycle of a few carriers can also show the distribution of vertically growing columnar crystals and laterally growing lateral crystals.

It can be seen from Fig. 8 (refer to Appendix 1 with reference) and Fig. 9 (refer to Appendix 2) that the life cycle distribution of the minority carrier on the left side of Fig. 8 and Fig. 9 shows that there are obvious bricks at the periphery and corners of the comparative example. Distribution of lateral crystals. Moreover, from the color diagrams shown on the left side of Annex 1 and Annex 2, except that the top and bottom blocks of each brick show a red block distribution (representing a short carrier life cycle), the middle block is also It can be seen that there is a yellow block distribution, indicating that the minority carrier life cycle of the lateral crystal distribution of the comparative example is short; the reason is that the comparative example uses only the graphite baffles 11 to form the crystal growth. The thermal field failed to evenly distribute the transverse thermal field in the thermal field.

In contrast, the life cycle distribution of the minority carriers on the right side of FIG. 8 and FIG. 9 shows that the crystal bricks at the periphery and corners of the embodiment have only vertically growing columnar crystals and are displayed in the middle of the color pattern on the right side of Annex 1 and Annex 2. The yellow blocks in the block are less distributed, representing a minority carrier with a longer life cycle. It is confirmed that the embodiment of the present invention has k ₁ >k ₂ , and the corresponding positions of the second plate bodies 32 are adjacent to the lower end faces of the first plate bodies 31, which can provide a uniform lateral thermal field for the embodiment. . In addition, the protection of the protective layer 33 can prevent the first board body 31 and the second board body 32 of the heat insulating components 3 from being unnecessarily collided during the assembly process, thereby prolonging the service life. It is also possible to prevent the surfaces 312 and 321 of the first plate body 31 and the second plate body 32 from being directly exposed in the high temperature crystal growth environment and facing the crucible 14 to reduce the problem of poor crystal quality due to carbonization. .

In summary, the thermal insulation unit of the present invention uses k ₁ >k ₂ so that the corresponding positions of the second plate bodies 32 are adjacent to the lower end faces of the first plate bodies 31 to provide a uniform lateral thermal field. Moreover, through the protective layers 33, not only the first and second plate bodies 31, 32 of each heat insulating component 3 can be prevented from colliding during the assembly process, thereby prolonging the service life, and the first and second plates can be avoided. The surfaces 312, 321 of the bodies 31, 32 are directly exposed in the high temperature crystal growth environment and face the crucible 14, reducing the problem of poor crystal quality due to carbonization. Therefore, the purpose of the present invention can be achieved.

However, the above is only a preferred embodiment of the present invention, and when it is not possible to limit the scope of the present invention, any simple equivalent changes and modifications made in accordance with the scope of the present patent application and the contents of the patent specification are It is still within the scope of this new patent.

3‧‧‧Insulation components
330‧‧‧ inner surface
30‧‧‧ Space
4‧‧‧Carbon Nut Screw Set
31‧‧‧ first board body
5‧‧‧Carbon screws
310‧‧‧ Groove
X‧‧‧ thickness direction
311‧‧‧ end face
Z‧‧‧ Height direction
312‧‧‧ plane
t ₁ ‧‧‧first thickness
32‧‧‧Second board body
t ₂ ‧‧‧second thickness
321‧‧‧ plane
h ₁ ‧‧‧first height
33‧‧‧Protective layer
h ₂ ‧‧‧second height

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: FIG. 1 is a schematic cross-sectional view showing a graphite baffle for growing polycrystalline germanium; FIG. 2 is a front elevational view, The surrounding environment of the graphite baffle shown in FIG. 1 when the crystal growth is performed is shown; FIG. 3 is a side view showing a heat insulating unit for crystal growth disclosed in the Republic of China No. M441678 new patent certificate number; 4 is a front view showing the surrounding environment of the thermal insulation unit for the crystal growth in the implementation of the crystal growth; FIG. 5 is a top plan view showing an embodiment of the thermal insulation unit of the present invention; Figure 6 is a side elevational view showing the detailed structure of a heat insulating assembly of the present embodiment; Figure 7 is a front elevational view showing the surrounding environment of the embodiment of the present invention when the crystal is implemented; A comparison of lifespan mappings of a few carriers, illustrating the periphery of a polycrystalline germanium ingot obtained by using the present embodiment and the insulating unit shown in FIG. 2, respectively. a lateral crystal distribution of a brick; and FIG. 9 is a comparison diagram of a minority carrier life cycle distribution, illustrating a polycrystalline germanium ingot obtained by using the present embodiment and the insulating unit shown in FIG. 2, respectively. The lateral crystal distribution of one of the bricks at one corner.

3‧‧‧Insulation components

31‧‧‧ first board body

310‧‧‧ Groove

311‧‧‧ end face

312‧‧‧ plane

32‧‧‧Second board body

321‧‧‧ plane

33‧‧‧Protective layer

5‧‧‧Carbon screws

X‧‧‧ thickness direction

Z‧‧‧ Height direction

t ₁ ‧‧‧first thickness

t ₂ ‧‧‧second thickness

h ₁ ‧‧‧first height

h ₂ ‧‧‧second height

Claims (7)

An insulating unit for a long crystal is used for facing a stack, comprising at least one set of heat insulating components, the heat insulating component comprising: a first plate body having opposite end faces in a height direction and a plane facing the cymbal, the first plate body is provided with a groove from the plane facing away from the recess, and the groove is adjacent to one end surface of the first plate body, and the first plate body further has a first a heat transfer coefficient k ₁ ; a second plate body disposed in the groove and having a plane facing the weir and a second heat transfer coefficient k ₂ , and k ₁ >k ₂ ; and a protective layer covering The plane of the first plate body and the plane of the second plate body. The heat insulating unit for the long crystal according to claim 1, wherein the first plate body and the second plate body further have a first thickness t ₁ and a second thickness in a thickness direction, respectively. t _2, and _{1.0 <t 1 / t 2 <} 3.0; the first plate body further has a first height h ₁ and a second height h ₂ of the second plate and the body height direction, and 1.0 <h ₁ / h ₂ <3.0. The thermal insulation unit of the long crystal according to claim 2, wherein k _{1 is} between 90 W/m. K~110W/m. K; k _{2 is} between 5W/m. K to 10W/m. K room. Insulation unit for long crystals according to item 3 of the claim, wherein t ₂ 10mm; h ₂ 200mm. The thermal insulation unit of the long crystal according to claim 1, wherein the plane of the first plate body and the plane of the second plate body are aligned with each other to The protective layer overlying the plane defines an inner surface facing the crucible. The thermal insulation unit for a long crystal according to claim 5, wherein the protective layer is made of tantalum carbide. The thermal insulation unit for the long crystal according to claim 6 includes four sets of thermal insulation components that are connected around the mouth and are jointly defined by the inner surfaces of the protective layers of the thermal insulation components. Accommodate the space of the cockroach.