CN210711827U - Asymmetric side graphite heater of G7 polycrystal ingot furnace - Google Patents

Abstract

The asymmetric lateral graphite heater of the G7 polycrystalline ingot furnace comprises a first graphite heating plate, wherein the first graphite heating plate, a second graphite heating plate, a third graphite heating plate and a fourth graphite heating plate are connected end to end through connecting plates to form an annular heating plate, the annular heating plate is of a square frame structure, three graphite electrodes are arranged on the annular heating plate, U-shaped waves are arranged on the annular heating plate and are continuous, and the U-shaped wave number of four side surfaces of the annular heating plate is six; the corners of the annular heating plates are provided with U-shaped corner waves, and the U-shaped corner waves form 90-degree corners on two adjacent side surfaces of the annular heating plates; the three graphite electrodes on the annular heating plate are arranged in an equilateral triangle. The problem of current too big equipment stability poor and the unbalanced calorific capacity of symmetrical 9 ripples heater of conventional heater of G7 polycrystal ingot furnace is solved to the current.

Description

Asymmetric side graphite heater of G7 polycrystal ingot furnace

Technical Field

The utility model belongs to polycrystal ingot furnace firing equipment field, in particular to asymmetric lateral part graphite heater of G7 polycrystal ingot furnace.

Background

The production of the polycrystalline silicon ingot adopts a directional solidification method, and the silicon ingot grows from bottom to top in the production process. In both full-melting ingot casting (seed crystal is not paved at the bottom of a crucible) and semi-melting ingot casting (seed crystal is paved at the bottom of the crucible), the pursuit of good crystal quality, excellent impurity removal performance and stable equipment operation are theoretically required. These technical requirements are all inseparable from the side heater. In the existing polycrystalline silicon ingot casting industry, a side heating body in an ingot furnace thermal field is mainly made of isostatic pressing graphite, and a part of the side heating body is also made of carbon and has a rectangular structure, but the market utilization rate is not high. The function of the side heater is more and more important as the size of the inner cavity of the ingot furnace is larger.

The prior art scheme is as follows: the conventional ingot furnace side heater was developed from the earlier G4 ingot furnace development (cutting silicon block number 4x 4) to the G5, G6 and even the current G7 ingot furnaces, and in the development process, the shape of the side heater basically has not changed too much, all in the form of a 5-wave heater plus a measuring heater connecting plate, and only the size is enlarged and adjusted slightly, and the resistivity has changed correspondingly. However, with the G7 ingot furnace (7 x7 cut silicon ingots), most still conventional 5 wave side heaters have had significantly lower resistance due to the size of the enlarged heater, resulting in a correspondingly larger current.

In order to solve the problem, some G7 ingot furnace manufacturers adopt a scheme of increasing the number of side heater waveforms, and the most mature scheme at present is a 9-wave and 11-wave scheme: the resistance of the side heater is increased by increasing the waveform, so that the current is reduced, meanwhile, the radiation area of the multi-wave heater is correspondingly increased, and the production stability of the ingot furnace is enhanced. However, the multi-wave symmetrical heater has a new quality risk of affecting the silicon ingot due to uneven heat generation on four sides and excessive resistance.

In addition, some enterprises adopt plate heaters, one or more rectangles with different widths and same length are formed on one side of each plate heater, and the connecting plates of the side heaters are also changed and made of graphite or carbon. However, the heating temperature of the rectangular heating element is not uniform, the three-phase power supply is equally divided into four heating surfaces, the radiation temperature is difficult to be uniform by adopting the heating elements which are symmetrical up and down, and meanwhile, graphite electrodes and electrode connecting plates of the ingot furnace also need to be modified, so that the popularization on the G7 ingot furnace is limited at present.

At present, on ingot furnace equipment in the field of polycrystal ingot casting, a G7 ingot furnace is the latest mass production equipment (G8 ingot furnace is less common in the market at present), compared with a G6 ingot furnace which is the last generation of equipment, the feeding amount of a G7 ingot furnace is increased by nearly 30%, the size of an inner cavity of the equipment is enlarged, the size of a thermal field (a heat insulation material and a graphite heating and heat dissipation material) is correspondingly enlarged, the size of a crucible is changed, and the like, particularly, the change of a side graphite heater brings about the following problems:

1) the traditional 5-wave side graphite heater has overlarge current, poor equipment stability, easy breakdown and electric leakage of a thermal field and easy pulverization and falling of an insulating material to influence the telecommunication performance of a product;

2) the novel 9-wave side graphite heater has insufficient power, operates within a power limit range for a long time in the production process, has a narrow process window and poor fault-tolerant capability, and simultaneously;

3) the 5-wave and 9-wave heaters do not cover the four corners of the silicon ingot sufficiently, so that the corners of the silicon ingot are heated insufficiently, and the frozen silicon (non-growth and rapid solidification) of the corners is serious;

4) the thermal fields of the 5-wave heater and the 9-wave heater are not distributed uniformly, so that the thermal convection of the silicon ingot is unbalanced, the impurity removal capability is reduced, and the current diamond wire cutting is very sensitive to hard impurities in the silicon ingot, so that the yield and the yield of downstream silicon wafer cutting are seriously influenced;

5) the defects of the cast single crystal (small single crystal coverage area, more boundary defects and dislocations, poor verticality and the like) can be amplified in the process of casting the single crystal due to the problems of the conventional heater and the current novel heater.

Disclosure of Invention

In view of the technical problem that the background art exists, the utility model provides an asymmetric lateral part graphite heater of G7 polycrystal ingot furnace solves the too big equipment poor stability problem of electric current of the conventional heater symmetry 5 ripples heater of present G7 polycrystal ingot furnace and the unbalanced problem of calorific capacity of symmetry 9 ripples heater.

In order to solve the technical problem, the utility model discloses following technical scheme has been taken and has been realized:

the asymmetric lateral graphite heater of the G7 polycrystalline ingot furnace comprises a first graphite heating plate, wherein the first graphite heating plate, a second graphite heating plate, a third graphite heating plate and a fourth graphite heating plate are connected end to end through connecting plates to form an annular heating plate, the annular heating plate is of a square frame structure, three graphite electrodes are arranged on the annular heating plate, U-shaped waves are arranged on the annular heating plate and are continuous, and the U-shaped wave number of four side surfaces of the annular heating plate is six; the corners of the annular heating plates are provided with U-shaped corner waves, and the U-shaped corner waves form 90-degree corners on two adjacent side surfaces of the annular heating plates; the three graphite electrodes on the annular heating plate are arranged in an equilateral triangle.

In the preferred scheme, the first graphite heating plate, the second graphite heating plate, the third graphite heating plate and the fourth graphite heating plate are respectively provided with six 'U' -shaped waves, wherein three 'U' -shaped waves are arranged upwards, and the other three 'U' -shaped waves are arranged downwards;

connecting unit plates are arranged at two ends of the first graphite heating plate, the second graphite heating plate, the third graphite heating plate and the fourth graphite heating plate;

after the connecting unit plates between the first graphite heating plate and the second graphite heating plate are connected through the connecting plates, a U-shaped corner wave is formed;

after the connecting unit plates between the second graphite heating plate and the third graphite heating plate are connected through the connecting plate, a U-shaped corner wave is formed;

after the connecting unit plates between the third graphite heating plate and the fourth graphite heating plate are connected through the connecting plates, a U-shaped corner wave is formed;

after the connection unit plate between the fourth graphite heating plate and the first graphite heating plate is connected through the connecting plate, a U-shaped corner wave is formed.

In a preferred scheme, the resistance values of the first graphite heating plate, the second graphite heating plate, the third graphite heating plate and the fourth graphite heating plate are equal, the value of the resistance value is 20M omega, and the error is +/-1M omega.

In a preferred scheme, the resistance value of the connecting plate is 6M omega, and the error is +/-0.5M omega.

This patent can reach following beneficial effect:

the design aim at of this patent is solved the too big equipment poor stability problem of current of the conventional heater symmetry 5 ripples heater of G7 polycrystal ingot furnace at present and the unbalanced problem of calorific capacity of symmetry 9 ripples heater, improves the growth quality of silicon ingot, reduces impurity content in shade and the silicon ingot, because the thermal field homogeneity improves equally, temperature gradient is more reasonable, also can promote the single crystal area and the quality of casting single crystal.

This patent need not to reform transform ingot furnace equipment, and normal the change can bring the profit after the heater is ageing, and the heater of this patent adopts present mainstream heater's material and manufacture craft simultaneously, under the same conditions, can not additionally reduce the life of heater, because resistance sets for the relation, the electric leakage probability reduces, can practice thrift the energy consumption for 5 ripples lateral part heaters.

According to the drawing size of the lateral heater, the lateral heater is made of graphite, is manufactured through an isostatic pressing process and is directly installed on an ingot furnace, other interfaces of the ingot furnace are unchanged, and technological parameters can be kept unchanged during production and operation of equipment, namely, the technological parameters of the original equipment (heating, melting, crystal growth, annealing, cooling power setting, temperature setting and top coefficient setting) can be achieved.

Drawings

The invention will be further explained with reference to the following figures and examples:

FIG. 1 is a three-dimensional structure diagram of the present invention;

FIG. 2 is a three-dimensional structure diagram of a conventional 5-wave side heater according to the present invention;

fig. 3 is a three-dimensional structure diagram of the conventional 9-wave side heater of the present invention.

In the figure: a first graphite heating plate 1, a second graphite heating plate 2, a third graphite heating plate 3, a fourth graphite heating plate 4, a connecting plate 5, a graphite electrode 6, a 'U' -shaped wave 7 and a 'U' -shaped corner wave 8;

A. b, C show the connection points of each phase of the three-phase alternating current to the graphite electrodes.

Detailed Description

The preferable scheme is as shown in fig. 1, the asymmetric lateral graphite heater of the G7 polycrystalline ingot furnace comprises a first graphite heating plate 1, wherein the first graphite heating plate 1, a second graphite heating plate 2, a third graphite heating plate 3 and a fourth graphite heating plate 4 are connected end to end through connecting plates 5 to form an annular heating plate, the annular heating plate is of a square frame structure, three graphite electrodes 6 are arranged on the annular heating plate, U-shaped waves 7 are arranged on the annular heating plate, the U-shaped waves 7 on the annular heating plate are continuous, and the number of the U-shaped waves 7 on the four sides of the annular heating plate is six; a U-shaped corner wave 8 is arranged at the corner of the annular heating plate, and the U-shaped corner wave 8 forms a 90-degree corner on two adjacent side surfaces of the annular heating plate; three graphite electrodes 6 on the annular heating plate are arranged in an equilateral triangle.

Furthermore, the first graphite heating plate 1, the second graphite heating plate 2, the third graphite heating plate 3 and the fourth graphite heating plate 4 are respectively provided with six 'U' -shaped waves 7, wherein three 'U' -shaped waves 7 are arranged upwards, and the other three 'U' -shaped waves 7 are arranged downwards;

the two ends of the first graphite heating plate 1, the second graphite heating plate 2, the third graphite heating plate 3 and the fourth graphite heating plate 4 are respectively provided with a connecting unit plate 81;

after the connecting unit plates 81 between the first graphite heating plate 1 and the second graphite heating plate 2 are connected through the connecting plates 5, a U-shaped corner wave 8 is formed;

after the connecting unit plates 81 between the second graphite heating plate 2 and the third graphite heating plate 3 are connected through the connecting plates 5, a U-shaped corner wave 8 is formed;

after the connecting unit plates 81 between the third graphite heating plate 3 and the fourth graphite heating plate 4 are connected through the connecting plates 5, a U-shaped corner wave 8 is formed;

after the connection unit plate 81 between the fourth graphite heating plate 4 and the first graphite heating plate 1 is connected by the connection plate 5, a U-shaped corner wave 8 is formed.

Further, the resistance values of the first graphite heating plate 1, the second graphite heating plate 2, the third graphite heating plate 3 and the fourth graphite heating plate 4 are equal, the value of the resistance value is 20M Ω, and the error is ± 1M Ω.

Further, the resistance value of the connection plate 5 is 6M Ω, and the error is ± 0.5M Ω.

The working principle of the whole device is introduced in combination with the prior art as follows:

analysis of the disadvantages of the prior art:

as shown in fig. 2 and 3, for convenience of description and avoidance of ambiguity, the four-sided structure of the conventional 5-wave side heater and the novel 9-wave side heater is collectively referred to as a heating plate, and the device connected between the heating plates becomes a conventional connecting plate;

the resistance of a single heating plate of a traditional 5-wave side heater is about 12 +/-0.5M omega, the section thickness is 19.5mm, the section width is 130mm, the resistance of a traditional connecting plate is about 0.5M omega, and a transformer adopts 24V voltage; the resistance of the novel 9-wave side heater single heating plate is about 31 +/-2M omega, the section thickness is 19.5mm, the section width is 75mm, the resistance of a traditional connecting plate is about 0.5M omega, and the transformer adopts 36V voltage. Because the three-phase power supply is adopted for heating, the whole side heater in the prior art is front-back symmetrical or left-right symmetrical. The disadvantages are as follows:

1. as shown in fig. 2, in the conventional 5-wave side heater, as the size of the heating plate is increased (relative to a G6 ingot furnace), the resistance deformation is small, so that the current is too large, the electrode insulating material of the ingot furnace is easy to leak electricity due to impact, the production stability of ingot casting equipment is affected, the energy consumption loss is caused, and the cost is increased, and as a suitable substitute is not found yet in the boron nitride insulating gasket which is the most mature high-temperature insulating material at present, boron element is pulverized and falls off under the action of high-temperature and high-current, so that the resistivity of the head of the silicon ingot is greatly affected, even the whole ingot is scrapped, and the product quality and the utilization rate;

2. as shown in fig. 3, the novel 9-wave side heater has unbalanced three-phase resistance in the triangular circuit, so that the heating plate has too large heat productivity, hard impurities in the ingot furnace for producing the side silicon ingot cannot be effectively discharged to the bottom and the top of the silicon ingot, the yield of the silicon ingot is reduced due to too much hard impurities in the subsequent silicon wafer cutting process, and the cost is increased; meanwhile, the path of the novel 9-wave side heater is too long, the resistance is too large, the power loss is large, the integral heating power of the side part is insufficient, and microcrystals (infrared detection images are shown as shadows) are generated in silicon ingots due to unbalanced local supercooling degree when large silicon ingots of G7 or above are produced, so that the quality of the silicon ingots is influenced;

3. the novel 9 ripples lateral part heater also extends to use old version design always, does not have fine consideration silicon bulk four corners problem of being heated, and shape, broad width, resistance and the coverage area of the corner of novel 9 ripples lateral part heater all have very big difference with the wave form on the hot plate, lead to the long brilliant insufficient in limit, freeze the silicon phenomenon and take place occasionally. As can be seen from the attached figure 3, although the traditional connecting plate of the novel 9-wave side heater can also be regarded as a U shape, the U-shaped gap is obviously larger than the wave-shaped interval of the normal heating plate, the sectional area is also obviously large, the heat productivity of the traditional connecting plate is larger than that of the heating plate, and meanwhile, the radiation coverage area has a larger difference;

4. as can be seen from fig. 2, the conventional 5-wave side heater has seven "U" shaped waves in the part between the AB-phase electrode and the BC-phase electrode. The heater between the AC phase electrodes also has seven U-shaped waves, but the U-shaped waves formed by the heater connecting plates at two corner sides are included, so that the resistance is obviously different, which shows that the heating value is also obviously different, the thermal field is not uniform, the crystal direction is not vertical, and the impurity removing capability of hard impurities is insufficient;

5. as can be seen from fig. 3, although the radiation coverage area of the novel 9-wave side heater is more uniform, the heating uniformity of the novel 9-wave side heater is worse, and the heater between the AB-phase electrode and the BC-phase electrode has 13 "U" waves with symmetrical shapes, wherein each wave comprises a "U" wave formed by a side heater connecting plate. And the heater between the AC phase electrodes only has 11U-shaped waves and also contains the U-shaped waves formed by the two corner side heater connecting plates, so that the resistance of the whole AC phase heater is obviously smaller than that of the AB phase and BC phase heaters, the heat generation of the left part of the whole thermal field is high, and the hard impurities on the left side of the silicon ingot are seriously enriched.

Therefore, it is difficult for the heater of the related art to uniformly radiate heat energy to four heating surfaces in the power supply apparatus of the three-phase power supply.

The purpose of this patent: as can be seen from the attached drawing 1, after the whole side heater of this patent side view combines with the lateral part heater connecting plate, the area of coverage is more even saturation, A, B, C heaters are all eleven "U" shape ripples 7 between the three-phase, the "U" shape ripples 7 that the lateral part heater connecting plate formed keeps unanimous basically with the "U" type of lateral part heater, calorific capacity is relatively more close, whole resistance is in 18~21M omega (can finely tune according to material density and sectional area size), be fit for 24V voltage more, can not form the stability that increases the electric current influence equipment. Meanwhile, as can be seen from fig. 1 to 3, the heater is consistent with 5 waves and 9 waves in size, the graphite electrode and the electrode connecting plate can be shared, and only the side heater and the side heater connecting plate are replaced, so that extra cost is not caused. The produced normal silicon ingot and the cast monocrystalline silicon ingot have the advantages of less frozen silicon in appearance, good crystal orientation verticality, low hard impurities, large monocrystalline coverage area, high yield of cut silicon wafers, stable electrical property and improved quality; the equipment is more stable in the production process, and the electric leakage is reduced abnormally.

The structure design of this technical scheme is: compared with the graphite heater with odd-numbered wave shapes such as 5 waves and 9 waves, the graphite heater with 6 waves is asymmetric in central axis structure, so that the graphite heater is called an asymmetric 6-wave side heater.

All screw interface sizes of this patent all keep unanimous with the brilliant flourishing water-cooling G7 ingot furnace original position size, if need this patent configuration on other G7 ingot furnaces, only need to interface position size finely tune can.

The length of first graphite hot plate 1 of this patent, second graphite hot plate 2, third graphite hot plate 3, fourth graphite hot plate 4 is 1160mm, and is 10mm than 5 ripples and novel 9 ripples shortages of tradition, and this 10 mm's length difference has the lateral part heater connecting plate to supply, and whole installation dimension keeps unanimous, corresponds with G7 ingot furnace electrode interface, needn't increase other changes.

The resistances of the first graphite heating plate 1, the second graphite heating plate 2, the third graphite heating plate 3 and the fourth graphite heating plate 4 are all 6 +/-0.5 m omega.

Claims (4)

1. The utility model provides an asymmetric lateral part graphite heater of G7 polycrystal ingot furnace, includes first graphite hot plate (1), has formed annular hot plate through connecting plate (5) end to end between first graphite hot plate (1) and second graphite hot plate (2), third graphite hot plate (3) and fourth graphite hot plate (4), and annular hot plate is square frame structure, is equipped with three graphite electrode (6) on the annular hot plate, is equipped with "U" shape ripples (7) on the annular hot plate, its characterized in that: the U-shaped waves (7) on the annular heating plate are continuous, and the number of the U-shaped waves (7) on the four side surfaces of the annular heating plate is six; the corner of the annular heating plate is provided with a U-shaped corner wave (8), and the U-shaped corner wave (8) forms a 90-degree corner on two adjacent side surfaces of the annular heating plate; three graphite electrodes (6) on the annular heating plate are arranged in an equilateral triangle.

2. The asymmetric side graphite heater of the G7 polycrystalline ingot furnace of claim 1, wherein: the first graphite heating plate (1), the second graphite heating plate (2), the third graphite heating plate (3) and the fourth graphite heating plate (4) are respectively provided with six U-shaped waves (7), wherein three U-shaped waves (7) are arranged upwards, and the other three U-shaped waves (7) are arranged downwards;

connecting unit plates (81) are arranged at the two ends of the first graphite heating plate (1), the second graphite heating plate (2), the third graphite heating plate (3) and the fourth graphite heating plate (4);

after the connecting unit plate (81) between the first graphite heating plate (1) and the second graphite heating plate (2) is connected through the connecting plate (5), a U-shaped corner wave (8) is formed;

after the connecting unit plate (81) between the second graphite heating plate (2) and the third graphite heating plate (3) is connected through the connecting plate (5), a U-shaped corner wave (8) is formed;

after the connecting unit plate (81) between the third graphite heating plate (3) and the fourth graphite heating plate (4) is connected through the connecting plate (5), a U-shaped corner wave (8) is formed;

the connection unit plate (81) between the fourth graphite heating plate (4) and the first graphite heating plate (1) is connected through the connecting plate (5) to form a U-shaped corner wave (8).

3. The asymmetric side graphite heater of the G7 polycrystalline ingot furnace of claim 2, wherein: the resistance values of the first graphite heating plate (1), the second graphite heating plate (2), the third graphite heating plate (3) and the fourth graphite heating plate (4) are equal, the value of the resistance value is 20M omega, and the error is +/-1M omega.

4. The asymmetric side graphite heater of the G7 polycrystalline ingot furnace of claim 3, wherein: the resistance value of the connecting plate (5) is 6M omega, and the error is +/-0.5M omega.

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