Patent ID: 12252805

DETAILED DESCRIPTION

In order to make the objects, the technical solutions and the advantages of the embodiments of the present disclosure more apparent, the embodiments of the present disclosure will be described hereinafter in a clear and complete manner in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the following embodiments merely relate to a part of, rather than all of, the embodiments of the present disclosure. All other embodiments obtained by a person of ordinary skill in the art based on the described embodiments of the present disclosure, shall fall within the scope of the present disclosure.

In a growing process of a single crystal silicon material, especially in a growing process of the single crystal silicon material in a single crystal pulling apparatus by using a czochralski method, a graphite Hot-Zone is usually used to provide controls of growth temperature, temperature gradient, etc. Specifically, a polycrystalline raw material is melted in a low vacuum and inert gas environment, and then is in contact with a seed, and a single crystal material is growing along with the rotating and lifting of the seed, where, the heat needed in this process mainly comes from a graphite heater. However, since splashing of a silicon liquid occurs during a recharging and silicon monoxide (SiO) escaping from a surface of the silicon liquid at a high temperature and flowing with the airflow in the single crystal pulling apparatus reacts with the graphite heater after it comes into contact with the graphite heater, on the one hand, silicon carbide (SiC) deposition will be formed on a surface of the heater, on the other hand, due to the chemical reaction, a thickness of the heater may gradually decrease with the increase of the number of uses, which directly leads to a change in material properties of the heater surface and a change in the thickness of the heater, thereby to lead to a problem such as a decrease of the heating performance of the heater, eventually reduce the service life of the heater and adversely affect the quality of the product.

In order to avoid the above problems, in the related art, an exhaust hole is provided in an upper position of a side heat insulation cylinder, so that a gas does not flow through a side heater and a bottom Hot-Zone component, thereby to protect the heater and a lower Hot-Zone. However, a specific implementation of this method is extremely complex. On the one hand, the design of the side exhaust hole may greatly increase the number of types of Hot-Zone components and the design difficulty, which directly leads to an increase in cost. In addition, in the case where this structure is used, the airflow carried the silicon monoxide may crystallize on Hot-Zone components above the liquid surface, and once a crystallization falls into the melt, it may directly cause a crystal to lose its single crystal characteristics, resulting in a product waste.

Therefore, the embodiments of the present disclosure provide a single crystal pulling apparatus Hot-Zone structure. As shown inFIG.1, the single crystal pulling apparatus Hot-Zone structure is applied to a single crystal pulling apparatus including a puller body13and a crucible provided in the center of the puller body13, the single crystal pulling apparatus Hot-Zone structure may include: a side heater3and a diversion assembly. The side heater3is provided in a periphery of the crucible, that is, between an inner wall of the puller body13and the crucible, and is used to heat the crucible from the outside of the crucible. The diversion assembly is enclosed between the side heater3and a side wall of the crucible and below the crucible, and configured to form a gas flow passage with an outer wall of the crucible, the gas flow passage is connected to the outside of the puller body to discharge a gas to the outside of the puller body13. In other words, the diversion assembly and the outer wall of the crucible form the gas flow passage. When the gas is introduced into the single crystal pulling apparatus, the gas may be discharged to the outside of the puller body13through the gas flow passage, so that the diversion assembly isolates the side heater3to prevent the side heater3from being damaged by harmful substances such as silicon monoxide carried in the gas.

In the embodiments of the present disclosure, the diversion assembly may include a side heat conduction cylinder1, a bottom heat conduction plate2and an exhaust cylinder6. The side heat conduction cylinder1is provided between the side heater3and the crucible, that is, the side heat conduction cylinder1is provided in the periphery of the crucible, the bottom heat conduction plate2is provided below the crucible, a bottom end of the side heat conduction cylinder1is connected to the bottom heat conduction plate2in a sealed manner, at least one exhaust hole is provided in the bottom heat conduction plate2, and the exhaust cylinder6is provided through the exhaust hole, one end of the exhaust cylinder6is connected to the gas flow passage, and the other end of the exhaust cylinder extends to the outside of the puller body13. In other words, the gas flow passage is formed among the side heat conduction cylinder1, the bottom heat conduction plate2and the outer wall of the crucible. Since the side heater3is located in the periphery of the side heat conduction cylinder1, the gas flow passage and the side heater3are located on both sides of the side heat conduction cylinder1respectively, and are isolated by the side heat conduction cylinder1, and the bottom heat conduction plate2is provided with the exhaust hole. When the exhaust cylinder6is provided through the exhaust hole, the gas flow passage is connected to the outside of the puller body13, so as to discharge the gas to the outside of the puller body13from the gas flow passage smoothly.

In the embodiments of the present disclosure, the single crystal pulling apparatus Hot-Zone structure further includes a bottom heater4, which is used to heat the crucible from the bottom of the crucible, and the bottom heater4is provided under the bottom heat conduction plate2. Therefore, the gas flow passage and the bottom heater4are located on both sides of the bottom heat conduction plate2respectively and are isolated by the bottom heat conduction plate2, so as to prevent the bottom heater4from being damaged by the harmful substances such as silicon monoxide carried in the gas.

In the embodiments of the present disclosure, the number of exhaust holes provided in the bottom heat conduction plate2may be four, four exhaust holes are spaced apart from each other at a same circumference, and one of exhaust cylinders6is provided in each exhaust hole. Thus, the gas in the gas flow passage may be discharged to the outside of the puller body13quickly and efficiently through the four exhaust cylinders6. Of course, according to different requirements, the number of exhaust holes may be increased or decreased.

As shown inFIGS.2and3, the exhaust cylinder6needs to pass through a plane where the bottom heater4is located. A specific arrangement depends on an actual shape and structure of the bottom heater4. For example, when a heating area of the bottom heater4is relatively small, the exhaust cylinder6may be provided in the periphery of the bottom heater4, and when the heating area of the bottom heater4is relatively large, an exhaust hole needs to be provided in the bottom heater4, so that the exhaust cylinder6may pass through the exhaust hole.

In some embodiments of the present disclosure, the side heat conduction cylinder1and the bottom heat conduction plate2are each made of a graphite-based material. The graphite-based material should have a high thermal conductivity, usually the thermal conductivity may reach 1500 W/MK, so as to ensure that the heat generated when the side heater3and the bottom heater4operate may quickly pass through the side heat conduction cylinder1and the bottom heat conduction plate2and reach the crucible, prevent a heating efficiency and heating capacity of the side heater3and the bottom heater4from being affected, and prevent a distribution of the heat field generated by the side heater3and the bottom heater4from being affected. The graphite-based material is resistant to high temperature and resistant to corrosion, has stable chemical properties, may adapt to a high temperature scenario in the single crystal pulling apparatus and has a long service life. In the embodiments of the present disclosure, the graphite-based material may include graphene, and graphene has very good heat conduction performance.

In some embodiments of the present disclosure, the single crystal pulling apparatus Hot-Zone structure further includes a vacuum pump (not shown in the figure), and the vacuum pump is connected to the end of the exhaust cylinder6extending to the outside of the puller body. The vacuum pump is configured to extract the gas in the gas flow passage by providing a negative pressure at one end of the exhaust cylinder6, so as to ensure that the gas in the puller body13is quickly guided out of the puller body13.

In some other embodiments of the present disclosure, the single crystal pulling apparatus Hot-Zone structure further includes a filtering device (not shown in the figure), and the filtering device is provided between the exhaust cylinder6and the vacuum pump, and configured to filter impurity particles in the flowing gas, so as to avoid pollution.

In some embodiments of the present disclosure, the single crystal pulling apparatus Hot-Zone structure further includes: a side heat insulation material layer71and a bottom heat insulation material layer72, the side heat insulation material layer71is provided between the side heater3and an inner side wall of the puller body13, and the bottom heat insulation material layer72is provided between the bottom heater4and a bottom wall of the puller body13. A good thermal insulation effect may be achieved by providing the side thermal insulation material layer71and the bottom thermal insulation material layer72, so as to prevent the heat in the puller body13from leaking to the outside. InFIG.1, the uppermost side heat insulation material layer71also plays a role in blocking the gas in the single crystal pulling apparatus. In fact, a length of the side heat conduction cylinder1may be appropriately increased, so as to isolate and protect the side heat insulation material layer71as well.

As shown inFIG.1, in some embodiments of the present disclosure, the single crystal pulling apparatus Hot-Zone structure further includes a heat shield14provided above the crucible, and the crucible includes a graphite crucible11and a quartz crucible10provided in the graphite crucible11, a bottom of the graphite crucible11is connected to a crucible shaft12, and the crucible shaft12is used to drive the crucible to rotate, so that the inside of the crucible is heated evenly. In a single crystal ingot manufacturing process, after a silicon material is heated in the quartz crucible10to obtain a polycrystalline silicon melt9, a single crystal is growing along with the lifting of the seed, so as to obtain a crystal ingot8. In the process of lifting the seed, it is necessary to supply an inert gas into a gap between the crystal ingot8and the heat shield14. As shown by an air flow trajectory5in the figure, the inert gas flows to a solid-liquid interface under the diversion action of the heat shield14, so as to control a temperature of the solid-liquid interface. Then it flows into the gas flow passage, and finally flows out of the single crystal pulling apparatus from the bottom of the puller body13through the exhaust cylinder6. As a result, even if the inert gas is mixed with harmful substances such as silicon monoxide, due to the existence of the diversion assembly, the side heater3and the bottom heater4are well insulated and protected, thereby avoiding the damage of the side heater3and the bottom heater4by silicon monoxide, improving the service life of the side heater3and the bottom heater4. In addition, it is able to avoid a process instability due to changes in surface properties and thicknesses of the side heater3and the bottom heater4and prevent the problem of affecting product quality. It may further prevent the melt from splashing to the surfaces of the side heater3and the bottom heater4during the recharging process. In addition, due to the formed gas flow passage, a regular pattern of the gas flow in the single crystal pulling apparatus is controllable, so as to facilitate effective management on the temperature of the solid-liquid interface through inert gas.

In another aspect, the embodiments of the present disclosure further provide a single crystal pulling apparatus including a puller body, a crucible provided in the center of the puller body and the single crystal pulling apparatus Hot-Zone structure as described above. According to the single crystal pulling apparatus Hot-Zone structure of the present disclosure, the gas flowing into the single crystal pulling apparatus may be guided by the formed gas flow passage to be discharged to the outside of the single crystal pulling apparatus, so as to isolate and protect the heater in the single crystal pulling apparatus, prevent the heater from being damaged by silicon monoxide carried in the gas, thereby to prolong the service life of the heater in the single crystal pulling apparatus and ensure the normal operation of the heater. Therefore, the single crystal pulling apparatus in the embodiments of the present disclosure also has the above-mentioned beneficial effects, and in order to avoid repetition, it is not particularly defined herein.

The present disclosure further provides a crystal ingot that is manufactured by using the single crystal pulling apparatus as described above. The crystal ingot manufactured by using the above single crystal pulling apparatus has higher quality and fewer defects.

The foregoing descriptions are optional implementations of the present disclosure. It should be appreciated that persons of ordinary skill in the art may make various improvements or modifications without departing from the principle of the present disclosure and the improvements and modifications shall fall within the protection scope of the present disclosure.