CN214529320U

CN214529320U - Single crystal furnace

Info

Publication number: CN214529320U
Application number: CN202023152873.4U
Authority: CN
Inventors: 黄旭光; 苏立宁; 刘彬国
Original assignee: Ja Solar Co Ltd
Current assignee: Jingao Solar Co Ltd
Priority date: 2020-12-24
Filing date: 2020-12-24
Publication date: 2021-10-29
Anticipated expiration: 2030-12-24

Abstract

The utility model relates to a single crystal growing furnace makes the field, provides a single crystal growing furnace, including draft tube and the water-cooling heat shield of setting inside the draft tube, this single crystal growing furnace still includes the heat conduction ring, and wherein, the heat conduction ring includes the heat conduction ring body with the coaxial setting of water-cooling heat shield, and this heat conduction ring body is connected with the internal face of water-cooling heat shield, and its bottom edge downwardly extending extends to the same level with the draft tube bottom edge. The single crystal furnace indirectly prolongs the water-cooling heat shield by utilizing the heat conduction ring, increases the longitudinal temperature gradient of the crystal and further enables the single crystal silicon to grow rapidly.

Description

Single crystal furnace

Technical Field

The utility model relates to a single crystal growing furnace makes the field, especially relates to a single crystal growing furnace.

Background

The shadow and effect of "silicon" are seen everywhere in our lives, and crystalline silicon solar cells are the fastest forming industry in the last 15 years. Among them, single crystal silicon production is one of the major research directions. Single crystal silicon is a single crystal of silicon, is a crystal having a substantially complete lattice structure, has different properties in different directions, is electrically conductive but has lower conductivity than metal, and the conductivity thereof increases with increasing temperature, and is a good semiconductor material for manufacturing semiconductor devices, solar cells, and the like.

The single crystal silicon is classified into a czochralski method (CZ), an float zone method (FZ) and an epitaxial method according to the crystal growth method, and the czochralski method and the float zone method grow a single crystal silicon rod and the epitaxial method grows a single crystal silicon thin film. Although the float zone method is very similar to the Czochralski method, and even a single crystal silicon rod is produced, the float zone method has its own problems such as preheating, welding and the like of the silicon rod, and therefore, currently, single crystal silicon for solar use is mainly produced by the Czochralski method, in which the growth rate of single crystal silicon is greatly affected by the longitudinal temperature gradient of the crystal in the vicinity of the crystal interface, and the larger the gradient, the faster the single crystal silicon grows. Therefore, to increase the longitudinal temperature gradient of the crystal near the crystallization interface, the crystal must be rapidly cooled, especially near the crystallization interface. In the prior art, a water-cooling heat shield is added in a single crystal furnace to quickly dissipate heat of crystals, wherein the water-cooling heat shield is arranged inside a guide cylinder, the closer the water-cooling heat shield is to the liquid level of a quartz crucible, the more the crystals near a crystal interface can quickly dissipate heat, but when the water-cooling heat shield is too close to the liquid level of a molten liquid or contacts with silicon liquid, the water-cooling heat shield is easily melted through by the silicon liquid, so that the cooling water and the high-temperature silicon liquid are caused to contact and explode, and serious safety accidents are caused. Therefore, in the existing single crystal pulling production process, for safety, the distance between the lower edge of the water-cooling heat shield and the lower edge of the guide shell is generally 40-70 mm. In addition, because a gap is formed between the water-cooling heat shield and the guide cylinder, the turbulent flow is easily generated when argon passes through, and the adverse effect on the growth of crystals is also caused. Therefore, a new single crystal furnace is urgently needed to solve the above problems.

SUMMERY OF THE UTILITY MODEL

In order to overcome the problems in the prior art, the application provides the single crystal furnace, the inner wall surface of the water-cooling heat shield in the single crystal furnace is provided with the heat conducting ring, the heat conducting ring can indirectly prolong the water-cooling heat shield, the longitudinal temperature gradient of crystals is increased, and then the monocrystalline silicon grows rapidly.

In order to achieve the above object, the present invention provides the following technical solutions:

the utility model provides a single crystal growing furnace, be in including draft tube and setting the inside water-cooling heat shield of draft tube, single crystal growing furnace still includes the heat conduction ring, the heat conduction ring include with the heat conduction ring body of the coaxial setting of water-cooling heat shield, the heat conduction ring body with the internal face of water-cooling heat shield is connected, heat conduction ring body bottom edge downwardly extending to with the same level of draft tube bottom edge.

Furthermore, the width of the contact surface between the heat conduction ring body and the water-cooling heat shield is 5-180 mm.

Further, the outer diameter of the bottom edge of the heat conduction ring body is equal to the inner diameter of the bottom edge of the guide cylinder.

Furthermore, the outer wall of the heat conduction ring body is provided with a limiting structure, and the limiting structure is used for blocking a gap between the water-cooling heat shield and the guide cylinder.

Further, the heat conduction ring body is in contact with the inner wall surface of the lower part of the guide shell.

Furthermore, the lower end of the heat conduction ring body is provided with an observation hole.

Further, there are two observation holes, two the contained angle of observation hole central line is 60 ~ 120.

Further, the width of the observation hole is 20-80 mm.

Further, the length of the observation hole is 5-50 mm.

The technical scheme provided by the embodiment of the application has the following beneficial effects:

the utility model discloses the bottom edge of shown heat conduction ring main part extends to with the same level of draft tube bottom edge, and is more nearly apart from silicon liquid, simultaneously, because heat conduction ring body upper portion outer wall and water cooling heat shield face contact, overall temperature is lower, consequently, for prior art, the utility model discloses further increased near the vertical temperature gradient of silicon crystal crystallization interface crystal to monocrystalline silicon's growth has been accelerated.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.

Fig. 1 is a front cross-sectional view of a thermally conductive ring according to an embodiment of the present invention;

fig. 2 is an assembly view of a water-cooled heat shield and a draft tube without a heat conduction ring according to an embodiment of the present invention;

fig. 3 is an assembly view of a water-cooled heat shield and a draft tube with a heat conductive ring according to an embodiment of the present invention;

FIG. 4 is a schematic view of the argon gas flow during a crystal pulling process provided by one embodiment of the present invention;

fig. 5 is a top view of a heat transfer ring according to an embodiment of the present invention.

1. A heat conductive ring body; 11. a limiting structure; 12. an observation hole; 2. water cooling and heat shielding; 3. a draft tube; 4. a gap; 5. monocrystalline silicon; 6. a quartz crucible; 7. and (4) silicon liquid.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of methods and apparatus consistent with certain aspects of the present application, as detailed in the appended claims.

The utility model discloses the extension heat conduction of water-cooling heat shield in mainly used czochralski crystal growing furnace, the process of following the czochralski method of brief earlier: silicon raw materials are put into a quartz crucible, a seed crystal rod which can be lifted and rotated is arranged above the quartz crucible, the lower end of the seed crystal rod is provided with a chuck, and a seed crystal is fixed on the chuck. Then the raw materials are heated and melted, and then the seed crystal is inserted into the melt body and pulled while rotating, so that the required monocrystalline silicon can be obtained. Wherein, the growth speed of the monocrystalline silicon is greatly influenced by the longitudinal temperature gradient of the crystal near the crystallization interface, and the larger the gradient is, the faster the monocrystalline silicon grows. In order to increase the longitudinal temperature gradient of the crystal, the purpose is mainly realized by adding a water-cooling heat shield in a single crystal furnace at present, but for production safety, the distance between the lower edge of the water-cooling heat shield and the lower edge of the guide cylinder is generally 40-70 mm so as to ensure that the water-cooling heat shield has enough safety distance with the high-temperature silicon liquid. However, as the silicon liquid is lowered, the distance is gradually increased, thereby causing certain difficulty in the rapid production of the single crystal silicon. To solve the above problems, the present invention provides the following embodiments.

Examples

As shown in fig. 1-3, the embodiment of the utility model provides a single crystal growing furnace, this single crystal growing furnace includes draft tube 3, the water-cooling heat shield 2 of setting in draft tube 3 inside, and the heat conduction ring, this heat conduction ring includes the heat conduction ring body 1 with the coaxial setting of water-cooling heat shield 2, the apical margin external diameter of this heat conduction ring body 1 is greater than the internal diameter at water-cooling heat shield 2 root edge, and borrow this card on water-cooling heat shield 2, the upper portion lateral wall of heat conduction ring body 1 still is connected with the internal face of water-cooling heat shield 2 lower part simultaneously, the face contact more is favorable to thermal conduction, be convenient for the cooling of heat conduction ring body 1, in order to strive for and provide the bigger longitudinal temperature gradient of monocrystalline silicon, wherein, the contact surface width of heat conduction ring body 1 and water-cooling heat shield 2 is preferred 5 ~ 180mm, the width is too little to be unfavorable for the conduction of temperature, and the width is too big better heat conduction effect that also can not gain. In addition, the bottom edge of the heat conduction ring body 1 further extends downwards until the bottom edge of the heat conduction ring body is at the same level with the bottom edge of the guide cylinder 3, so that the longitudinal temperature gradient is increased as close to the liquid level of the silicon liquid as possible.

The embodiment of the utility model provides a among the shown single crystal growing furnace, the bottom edge of heat conduction ring body 1 extends to with 3 same level in bottom edges of draft tube, and is more nearly apart from silicon liquid, simultaneously, because 1 upper portion outer wall of heat conduction ring body and 2 face contactings of water-cooling heat shield, whole temperature is lower, consequently, for prior art, the utility model discloses further increased near the vertical temperature gradient of silicon crystal crystallization interface crystal to monocrystalline silicon's growth has been accelerated.

Further, as shown in FIG. 4, in the conventional Czochralski method for producing silicon single crystal 5, it is necessary to pull the silicon single crystal under reduced pressure in an argon atmosphere, in which the arrow direction is the flow direction of argon gas, that is, argon gas is introduced into the silicon single crystal, and the argon gas flow under reduced pressure is formed by evacuation by a vacuum pump. Oxides volatilized from the high-temperature molten silicon are carried away by the flow of argon gas to prevent oxide particles from falling into the silicon liquid 7 in the quartz crucible 6 and moving to a solid-liquid interface, which destroys the consistency of the arrangement of single crystal atoms. However, as shown in fig. 2, since the water-cooled heat shield 2 and the guide cylinder 3 have the gap 4, the argon gas is easily disturbed to generate a turbulent flow when passing through, which is not favorable for removing oxide particles and further seriously affects the growth of the single crystal silicon 5. Therefore, as shown in fig. 3, in some embodiments, the outer diameter of the bottom edge of the heat conduction ring body 1 is equal to the inner diameter of the bottom edge of the guide cylinder 3, so that the gap 4 between the water-cooling heat shield 2 and the guide cylinder 3 is blocked by the lower edge of the heat conduction ring body 1 to maintain the argon gas flow stable. In addition, as shown in fig. 1 and 3, in some embodiments, the outer wall of the heat conducting ring body 1 is provided with a circle of convex limiting structures 11, and the limiting structures 11 are matched with the gaps 4 between the water-cooling heat shields 2 and the guide shell 3 and just block the gaps 4 so as to avoid the argon from flowing in a turbulent manner.

As shown in fig. 3, since the heat conduction ring is located between the water-cooling heat shield 2 and the silicon liquid, the temperature span is large, and the stress applied to the inside of the structure is large, in order to prevent the deformation of the heat conduction ring body 1, in some embodiments, the outer side wall of the lower part of the heat conduction ring body 1 is preferably arranged to contact the inner wall surface of the lower part of the draft tube 3, so that the heat conduction ring body is supported by an external force, and the influence of the deformation on the growth of the monocrystalline silicon is avoided. Therefore, the heat conductive ring body 1 has a truncated cone shape.

Further, as shown in fig. 5, the lower end of the heat conductive ring body 1 in some embodiments is provided with an observation hole 12. The two observation holes 12 are arranged, one observation window of the furnace cover parallel to the single crystal furnace is arranged and used for communicating with an eye observation channel of the observation window of the single crystal furnace, the other observation window is used for communicating with a sight channel of a CCD (charge coupled device) of a camera of the furnace cover, and the included angle of the central lines of the two observation holes 12 is 60-120 degrees. Meanwhile, in order to facilitate the arrangement of the sight channel of the camera, the included angle between the central lines of the two observation holes 12 is preferably set to be 90 degrees, namely, the observation hole 12 for communicating the sight channel of the furnace cover camera CCD is formed perpendicular to the furnace cover observation window of the single crystal furnace. In addition, in order to better observe the growth of the monocrystalline silicon, the width of the observation hole 12 is preferably 20-80 mm, and the length is preferably 5-50 mm.

In the embodiment of the present invention, the material of the heat conducting ring is not particularly limited, and may be, for example, graphite, metal, or ceramic.

In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application, and that variations, modifications, substitutions and alterations may be made to the above embodiments by those of ordinary skill in the art within the scope of the present application.

Claims

1. The utility model provides a single crystal growing furnace, is in including draft tube and setting the inside water-cooling heat shield of draft tube, its characterized in that, single crystal growing furnace still includes the heat conduction ring, the heat conduction ring include with the heat conduction ring body of the coaxial setting of water-cooling heat shield, the heat conduction ring body with the internal face of water-cooling heat shield is connected, heat conduction ring body bottom edge downwardly extending to with the same level of draft tube bottom edge.

2. The single crystal furnace of claim 1, wherein the width of the contact surface between the heat conducting ring body and the water cooling heat shield is 5-180 mm.

3. The single crystal furnace of claim 1, wherein the outer diameter of the bottom edge of the heat conducting ring body is equal to the inner diameter of the bottom edge of the guide shell.

4. The single crystal furnace of claim 1, wherein the outer wall of the heat conducting ring body is provided with a limiting structure, and the limiting structure is used for blocking a gap between the water cooling heat shield and the guide cylinder.

5. The single crystal furnace of claim 1, wherein the heat conducting ring body is in contact with an inner wall surface of a lower portion of the guide cylinder.

6. The single crystal furnace of claim 1, wherein the lower end of the heat conducting ring body is provided with an observation hole.

7. The single crystal furnace of claim 6, wherein the number of the observation holes is two, and the included angle between the center lines of the two observation holes is 60-120 °.

8. The single crystal furnace of claim 6, wherein the width of the observation hole is 20-80 mm.

9. The single crystal furnace of claim 6, wherein the length of the sight hole is 5-50 mm.