Rapid annealing equipment and method

Abstract

The invention provides rapid annealing equipment and a rapid annealing method. The rapid annealing equipment comprises a furnace body, a loading disc structure and a purging device, the carrying disc structure comprises a plurality of supporting parts and a carrying disc, one ends of the supporting parts are connected with the top surface of the furnace body, and the other ends of the supporting parts are connected with the bottom surface of the carrying disc; the purging device is located on one side of the furnace body and used for purging gas to the carrying disc structure and the furnace body.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor equipment, and in particular to a rapid annealing apparatus and method. Background Technology

[0002] Rapid annealing equipment is an important tool in the semiconductor manufacturing industry, especially suitable for devices with extremely high requirements for heat treatment, such as high-brightness light-emitting diodes (LEDs) and semiconductor lasers.

[0003] The related technology provides a rapid annealing device, which includes a furnace body and a carrier plate structure. The carrier plate structure is located on the furnace body and is in direct contact with the furnace body.

[0004] In the rapid annealing equipment provided by related technologies, the carrier disk structure is in direct contact with the furnace body. The poor heat dissipation performance of the carrier disk structure results in a slow temperature drop during the heat dissipation process of the wafer on the carrier disk structure, which in turn leads to increased stress on the substrate in the wafer and makes it prone to cracking. Summary of the Invention

[0005] This disclosure provides a rapid annealing apparatus and method, which can reduce wafer substrate breakage during rapid annealing. The technical solution is as follows: On the one hand, a rapid annealing apparatus is provided, the rapid annealing apparatus comprising: a furnace body, a carrier plate structure, and a purging device; The carrier structure includes multiple support parts and a carrier plate. One end of each support part is connected to the top surface of the furnace body, and the other end of each support part is connected to the bottom surface of the carrier plate. The purging device is located on one side of the furnace body and is used to purge gas onto the carrier structure and the furnace body.

[0006] Optionally, the material of the support portion is crystalline quartz, zirconium oxide ceramic, or phenolic resin.

[0007] Optionally, the carrier disk is made of crystal quartz, zirconium oxide ceramic, or phenolic resin.

[0008] Optionally, the purging device includes a support and a plurality of air outlets, the support extending in a direction perpendicular to the top surface of the furnace body, and the plurality of air outlets being arranged at intervals on the support along the extending direction of the support.

[0009] On the other hand, a rapid annealing method is provided, the method employing the aforementioned annealing equipment, the method comprising: At the end of the annealing isothermal stage, the wafers inside the furnace are transferred to the carrier tray; When the furnace body temperature drops to 400~600℃, nitrogen gas is purged by the purging device. When the furnace temperature drops below 400°C, oxygen and nitrogen are purged by the purging device.

[0010] Optionally, purging nitrogen gas using the purging device includes: The purging device is used to purge 5-20L of nitrogen gas.

[0011] Optionally, purging 5-20 L of nitrogen gas using the purging device includes: Within 30 to 120 seconds, 5 to 20 L of nitrogen gas is purged using the purging device.

[0012] Optionally, purging oxygen and nitrogen using the purging device includes: The purging device is used to purge 60-120L of nitrogen gas. While purging the nitrogen, oxygen is purged at a flow rate of 0.7~2 sccm using the purging device.

[0013] Optionally, purging 60-120L of nitrogen gas using the purging device includes: Within 200 to 400 seconds, 60 to 120 L of nitrogen gas is purged using the purging device.

[0014] Optionally, purging oxygen and nitrogen using the purging device further includes: When the temperature inside the furnace drops below 350°C, the oxygen supply is stopped.

[0015] The beneficial effects of the technical solutions provided in this disclosure are: In this embodiment of the disclosure, the carrier disk structure includes multiple support parts and a carrier disk. One end of the multiple support parts is connected to the top surface of the furnace body, and the other end of the multiple support parts is connected to the bottom surface of the carrier disk. The multiple support parts can make the carrier disk bear the force evenly, avoid the stress caused by uneven force, and prevent the wafers carried by it from being affected by stress. It can also improve the service life of the carrier disk structure and reduce maintenance costs.

[0016] In addition, multiple support sections prevent the carrier tray from directly contacting the furnace body, which is beneficial for heat dissipation. The purging device is located on one side of the furnace body and is used to purge gas onto the carrier tray structure and the furnace body. It can continuously and stably blow gas (atmosphere or nitrogen) to lower the temperature inside the furnace. At the same time, the continuous and stable blowing of gas by the purging device can prevent local airflow from impacting the wafer and causing shaking or collision.

[0017] In summary, the rapid annealing apparatus provided in this embodiment of the present disclosure features multiple support sections and a carrier tray that ensure uniform stress on the substrate while simultaneously improving the heat dissipation rate of the carrier tray. Combined with a continuous and stable blowing gas supply from the purging device, the furnace temperature drops rapidly, reducing the risk of substrate breakage during rapid annealing. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a rapid annealing apparatus provided in an embodiment of this disclosure; Figure 2 This is a schematic diagram of a carrier disk structure provided in an embodiment of this disclosure; Figure 3 This is a flowchart of a rapid annealing process provided in an embodiment of this disclosure; Figure 4 This is a flowchart of a rapid annealing process provided in an embodiment of this disclosure; Figure 5 This is a summary diagram of the number of broken wafer substrates after annealing using annealing apparatus provided by related technologies and rapid annealing equipment provided in the embodiments of this disclosure.

[0020] The attached figures are labeled as follows: 10: Furnace body; 11: Furnace door; 20: Carrier disk structure; 30: Purging device; 201: Support section; 202: Carrier disk; 301: Stent; 302: Air vent; 2021: Groove. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0022] Light-emitting diodes (LEDs), as a highly influential new product in the optoelectronics industry, are characterized by their small size, long lifespan, rich and varied colors, and low power consumption. They are widely used in lighting, displays, signal lights, backlights, toys, and other fields. With the increasing maturity of LED technology, the performance requirements for LEDs are becoming more stringent, making it crucial to achieve efficient production of high-quality LEDs.

[0023] In related technologies, during the rapid thermal annealing process in the fabrication of light-emitting diodes, substrate breakage often occurs, which directly affects production efficiency and cost control.

[0024] The purpose of this disclosure is to overcome the deficiencies of the rapid annealing equipment and methods provided by related technologies, and to provide a rapid annealing equipment and method that effectively reduces the substrate breakage rate.

[0025] Figure 1 This is a schematic diagram of a rapid annealing apparatus provided in an embodiment of this disclosure. See also... Figure 1 The rapid annealing equipment includes: furnace body 10, carrier plate structure 20, and purging device 30.

[0026] The tray structure 20 includes multiple support parts 201 and a tray 202. One end of the multiple support parts 201 is connected to the top surface of the furnace body 10, and the other end of the multiple support parts 201 is connected to the bottom surface of the tray 202.

[0027] The purging device 30 is located on one side of the furnace body 10 and is used to purge gas onto the carrier structure 20 and the furnace body 10.

[0028] In this embodiment of the disclosure, the carrier disk structure includes multiple support parts and a carrier disk. One end of the multiple support parts is connected to the top surface of the furnace body, and the other end of the multiple support parts is connected to the bottom surface of the carrier disk. The multiple support parts can make the carrier disk bear the force evenly, avoid the stress caused by uneven force, and prevent the wafers carried by it from being affected by stress. It can also improve the service life of the carrier disk structure and reduce maintenance costs.

[0029] In addition, multiple support sections prevent the carrier tray from directly contacting the furnace body, which is beneficial for heat dissipation. The purging device is located on one side of the furnace body and is used to purge gas onto the carrier tray structure and the furnace body. It can continuously and stably blow gas (atmosphere or nitrogen) to lower the temperature inside the furnace. At the same time, the continuous and stable blowing of gas by the purging device can prevent local airflow from impacting the wafer and causing shaking or collision.

[0030] In summary, the rapid annealing apparatus provided in this embodiment of the present disclosure features multiple support sections and a carrier tray that ensure uniform stress on the substrate while simultaneously improving the heat dissipation rate of the carrier tray. Combined with a continuous and stable blowing gas supply from the purging device, the furnace temperature drops rapidly, reducing the risk of substrate breakage during rapid annealing.

[0031] In this embodiment of the disclosure, a plurality of support portions 201 are perpendicular to the top surface of the furnace body 10.

[0032] In this embodiment, the furnace body 10 may include a shell, a substrate tray, a reaction chamber, a heating module, a temperature control unit, and a temperature measuring component. This embodiment does not limit the structure of the furnace body 10.

[0033] like Figure 1 As shown, the furnace body 10 has a box-like shape, such as a cuboid, and the aforementioned tray structure 20 is disposed on the top surface of the box.

[0034] Figure 1The image shows the outer shell of the furnace body 10, which can be made of a high-strength alloy.

[0035] In this embodiment of the disclosure, the furnace body 10 may further include a furnace door 11.

[0036] The furnace door 11 is located on the outer shell of the furnace body 10. During rapid annealing, the furnace door 11 can be opened so that the purging device 30 blows air into the furnace door 11, causing the temperature inside the furnace to drop rapidly. The carrier tray 202 continuously blows in a stable and uniform airflow, which allows the substrate to cool rapidly while avoiding local airflow impact on the substrate, causing shaking or collision.

[0037] In this embodiment of the disclosure, the furnace door 11 can be rectangular.

[0038] In other embodiments, the furnace door 11 may also be other shapes, such as circular.

[0039] In this embodiment, the support portion 201 is made of crystal quartz, zirconium oxide ceramic, or phenolic resin.

[0040] In this implementation, the support is made of crystal quartz, zirconia ceramic, or phenolic resin. Crystal quartz, zirconia ceramic, or phenolic resin have the advantages of high thermal conductivity and good heat dissipation. The support made of the above materials has good thermal conductivity, which can accelerate the cooling rate of the wafer.

[0041] For example, the material of the support portion 201 is crystalline quartz.

[0042] In this embodiment, the carrier disk 202 is made of crystal quartz, zirconium oxide ceramic, or phenolic resin.

[0043] In this implementation, the carrier disk is made of crystal quartz, zirconium oxide ceramic, or phenolic resin, which has the advantages of smooth surface and moderate hardness. The carrier disk made of the above materials can reduce the damage caused by friction between the carrier disk and the substrate during rapid annealing. At the same time, the above materials also have the advantages of high thermal conductivity and good heat dissipation, which can accelerate the cooling rate of the substrate.

[0044] For example, the material of the carrier disk 202 is crystalline quartz.

[0045] In one embodiment, the support 201 and the carrier 202 are made of the same material, and the support 201 and the carrier 202 can be integrally molded.

[0046] In another embodiment, the support 201 and the carrier 202 are made of different materials. The support 201 and the carrier 202 can be fabricated first, and then the support 201 and the carrier 202 can be assembled into the carrier structure 20.

[0047] In this embodiment, one end of the support 201 and the top of the furnace body 10 can be connected by a detachable connector or by using glue or other fixatives. This embodiment does not limit the scope of the invention.

[0048] Figure 2 This is a schematic diagram of a carrier plate structure provided in an embodiment of this disclosure, specifically a cross-sectional view perpendicular to the top of the furnace body. See also... Figure 1 and Figure 2 The carrier structure 20 may include 3 to 9 support parts 201, which are evenly spaced.

[0049] In other embodiments, the number of support portions 201 in the carrier structure 20 can be adjusted according to the size of the wafer.

[0050] For example, when the wafer size is 4 inches, the carrier structure 20 may include 6 support portions 201.

[0051] In this implementation, when the wafer size is 4 inches, the carrier disk structure includes 6 support parts. Too many support parts would increase costs; too few support parts would cause excessive stress on the carrier disk, resulting in damage.

[0052] In this embodiment of the disclosure, the support portion 201 can be a cylinder.

[0053] In other embodiments, the support portion 201 may also be other shapes, such as a prism.

[0054] In this embodiment of the disclosure, the outer contour of the carrier disk 202 can be circular.

[0055] In other embodiments, the outer contour of the carrier disk 202 may also be other shapes, such as rectangles.

[0056] In this embodiment of the disclosure, the carrier disk 202 has a groove 2021 in the middle for placing the wafer. In this embodiment of the disclosure, the groove 2021 is circular.

[0057] In this embodiment of the disclosure, Figure 1 and Figure 2 The image shows a carrier disk 202 including a recess 2021.

[0058] In other embodiments, a carrier disk 202 may also include a plurality of spaced-apart grooves 2021.

[0059] In this embodiment, the rapid annealing equipment may include 2 to 5 carrier plate structures 20, which are evenly distributed at intervals on the top of the furnace body 10. On the one hand, this significantly improves the uniformity of heating of the carrier plate structure and enhances the annealing effect; on the other hand, it improves the stability of the equipment, reduces the stress on the carrier plate structure, and extends its service life.

[0060] For example, the rapid annealing apparatus includes two tray structures 20.

[0061] In this embodiment of the present disclosure, the purging device 30 includes a bracket 301 and a plurality of air outlets 302. The bracket 301 extends in a direction perpendicular to the top surface of the furnace body 10, and the plurality of air outlets 302 are arranged at intervals on the bracket 301 along the extending direction of the bracket 301.

[0062] In this implementation, the support extends in a direction perpendicular to the top surface of the furnace body, and multiple air outlets are arranged at intervals on the support along the extension direction of the support, so that the blown gas can cover the surface of the support and cause the temperature inside the furnace to drop rapidly.

[0063] In this embodiment, the air outlet 302 is connected to a gas supply pipeline to blow gas into the furnace body 10.

[0064] In this embodiment of the present disclosure, the rapid annealing equipment also includes a gas storage tank, which is connected to the air outlet of the purging device 30 via a gas supply pipeline.

[0065] In this embodiment of the disclosure, the rapid annealing apparatus further includes a compressor, and the gas storage tank is connected to the compressor input terminal via a pipeline.

[0066] In this embodiment of the disclosure, the compressor may be a piston, screw, or centrifugal compressor.

[0067] For example, the compressor can be a reciprocating compressor.

[0068] In this embodiment of the disclosure, the support 301 may be columnar.

[0069] In this embodiment of the disclosure, the air outlets 302 can be distributed equidistantly along the columnar support.

[0070] In other embodiments, the air outlets 302 may also be distributed in groups at equal intervals along the columnar support.

[0071] For example, the air outlets 302 are divided into two groups. The group of air outlets 302 corresponding to the furnace body 10 is more densely distributed, while the group of air outlets 302 corresponding to the carrier plate structure 20 is more sparsely distributed.

[0072] In this implementation, the air outlets of the furnace body are more densely distributed, while the air outlets of the carrier disk structure are more sparsely distributed. Under the same flow rate, the cooling effect on the furnace body is higher than that on the carrier disk. This can ensure rapid cooling of the furnace body while avoiding sudden temperature changes in the carrier disk that could lead to substrate breakage.

[0073] In other embodiments, the support 301 may also be in other shapes, such as a platform.

[0074] In this embodiment of the disclosure, the bracket 301 can be an alloy bracket.

[0075] In this embodiment of the present disclosure, the purging device 30 may include 2 to 10 air outlets 302, which are evenly spaced.

[0076] For example, the purging device 30 includes six air outlets 302.

[0077] In this embodiment of the disclosure, the outer contour of the air outlet 302 can be circular.

[0078] In other embodiments, the outer contour of the air outlet 302 may also be other shapes, such as a rectangle.

[0079] Figure 3 This is a flowchart of a rapid annealing process provided in an embodiment of this disclosure. See also... Figure 3 This method employs, for example Figure 1 The rapid annealing equipment is implemented, and the method includes the following steps: S11. At the end of the annealing isothermal stage, the wafer in the furnace is transferred to the carrier tray.

[0080] S12. When the furnace body temperature drops to 400~600℃, nitrogen gas is purged by the purging device.

[0081] S13. When the furnace body temperature drops below 400°C, oxygen and nitrogen are purged by the purging device.

[0082] In this embodiment, when the furnace temperature drops to 400-600°C, nitrogen is purged using the purging device to ensure that the gas atmosphere inside the furnace does not change abruptly during the cooling phase, preventing the wafer substrate from breaking due to sudden changes in the gas atmosphere inside the furnace. When the furnace temperature drops below 400°C, oxygen and nitrogen are purged using the purging device to rapidly reduce the temperature inside the furnace, thereby reducing the high-temperature dwell time and lowering the risk of thermal fatigue. When the temperature drops below 400°C, oxygen is introduced, which can cause a slight oxidation reaction on the surface of the wafer substrate, reducing material brittleness, lowering the probability of crack initiation, and effectively improving substrate breakage.

[0083] Figure 4This is a flowchart of a rapid annealing process provided in an embodiment of this disclosure. See also... Figure 4 This method employs, for example Figure 1 The rapid annealing equipment is implemented, and the method includes the following steps: S21. At the end of the annealing isothermal stage, transfer the wafers in the furnace to the carrier tray.

[0084] In this embodiment of the present disclosure, when performing rapid annealing on the wafer, the heating module can heat the wafer on the wafer carrier disk.

[0085] The constant temperature stage is a period of time during which the rapid annealing equipment maintains a relatively stable temperature after the furnace temperature reaches the set value by adjusting the power of the heating module and utilizing the heat insulation performance of the furnace body, ensuring that the wafer completes the heat treatment reaction.

[0086] In this embodiment of the disclosure, the constant temperature stage begins when the temperature inside the furnace is uniformly close to the target value and ends when the preset time is reached or the material reaction is completed.

[0087] Therefore, at the end of the annealing isothermal stage, the wafers need to be removed from the furnace and transferred to a carrier tray at the top of the furnace for cooling.

[0088] S22. When the furnace temperature drops to 400~600℃, nitrogen is purged using a purging device.

[0089] In this step, when purging nitrogen, the annealing furnace door is opened, and the gas is blown into the furnace to rapidly reduce the temperature inside the furnace. A stable and uniform airflow is continuously blown into the carrier tray, which allows the substrate to cool rapidly while avoiding local airflow impacts on the substrate, causing shaking or collisions.

[0090] In this embodiment of the disclosure, the temperature inside the furnace can be detected in real time using a temperature sensing component.

[0091] In this embodiment of the disclosure, 5 to 20 L of nitrogen gas is purged using a purging device.

[0092] In this implementation, 5-20L of nitrogen is purged using a purging device to prevent insufficient purging volume, which would make it difficult to fully replace oxygen in the furnace and may lead to oxidation of the wafer surface; at the same time, excessive purging volume should be avoided, as it may cause turbulent airflow in the furnace, affecting temperature uniformity, wasting nitrogen, and increasing costs.

[0093] For example, 10L of nitrogen gas is purged using a purging device.

[0094] In this embodiment of the present disclosure, 5 to 20 L of nitrogen gas is purged by a purging device within 30 to 120 seconds.

[0095] In this implementation, 5-20L of nitrogen gas is purged within 30-120 seconds. The nitrogen gas introduction time should not be too short, as this would result in an excessive nitrogen flow rate, causing a sudden change in the atmosphere inside the furnace, which could lead to wafer breakage. Conversely, the nitrogen gas introduction time should not be too long, as this would result in an insufficient nitrogen flow rate, which would lead to incomplete annealing.

[0096] For example, 10L of nitrogen gas is purged by a purging device within 60 seconds.

[0097] In this embodiment of the present disclosure, the purging device includes multiple air outlets, and the purging device controls the air volume of the multiple air outlets through a control circuit.

[0098] In this embodiment of the disclosure, the air volume of multiple air outlets can be the same.

[0099] In other embodiments, the air volume of the multiple air outlets may also be different. For example, the air volume of the air outlet of the corresponding furnace may be greater than the air volume of the air outlet of the corresponding carrier plate.

[0100] In this implementation, the air volume of the corresponding furnace outlet is greater than that of the corresponding carrier tray outlet, which can avoid sudden temperature changes in the carrier tray that could lead to substrate breakage.

[0101] S23. When the furnace temperature drops below 400°C, oxygen and nitrogen are purged using a purging device.

[0102] In one example, step S23 includes: The first step is to purge 60-120L of nitrogen gas using a purging device.

[0103] In this implementation, the nitrogen flow rate is 60~120L to prevent insufficient purging volume, which would lead to uneven heating and cooling of the wafer and unsatisfactory annealing effect; at the same time, it avoids excessive purging volume, which would increase the operating pressure of the equipment and reduce its service life.

[0104] For example, 100L of nitrogen gas is purged using a purging device.

[0105] In this embodiment of the present disclosure, 60-120L of nitrogen gas is purged by a purging device within 200-400 seconds.

[0106] In this implementation, 60-120L of nitrogen gas is purged by a purging device within 200-400 seconds. If the purging time is too short, the nitrogen flow rate will be too high, which will increase the cost. If the purging time is too long, the nitrogen flow rate will be too low, which will prevent the annealing temperature from dropping quickly. This will cause the wafer to remain in the furnace at high temperature for too long, which may lead to the risk of thermal fatigue.

[0107] For example, 100L of nitrogen gas is purged by a purging device within 300 seconds.

[0108] The second step involves purging oxygen at a flow rate of 0.7 to 2 sccm simultaneously with the nitrogen purging.

[0109] In this implementation, the oxygen flow rate is 0.7~2 sccm. The oxygen flow rate will not be too high, as this would lead to excessive oxidation of the wafer substrate, increasing the risk of wafer chip substrate breakage. The oxygen flow rate will also not be too low, as this would lead to insufficient oxidation of the wafer substrate, increasing the risk of wafer chip substrate breakage.

[0110] For example, oxygen is purged at a flow rate of 1 sccm using a purging device.

[0111] In this embodiment of the present disclosure, the purging device can purge nitrogen from some of the air outlets and purge oxygen from some of the air outlets.

[0112] In other embodiments, the purging device may also purge a mixture of nitrogen and oxygen at each outlet.

[0113] S24. When the temperature inside the furnace drops below 350°C, stop the oxygen supply.

[0114] In this implementation, when the temperature inside the furnace drops below 350°C, the oxygen supply is stopped, which can reduce the probability of substrate crack growth on the wafer and effectively improve substrate breakage.

[0115] Figure 5 This is a summary diagram of the number of broken wafer substrates after annealing using annealing apparatus provided by related technologies and rapid annealing equipment provided in the embodiments of this disclosure. (Reference) Figure 5 The horizontal axis represents the date, and the vertical axis represents the number of substrate fragments. Figure 5 It can be seen that before May 9th, wafer substrates annealed using the annealing apparatus provided by the relevant technology were prone to breakage. However, after May 9th, the number of broken wafer substrates annealed using the annealing apparatus provided by the embodiments of this disclosure was 0 (the annealing apparatus provided by the embodiments of this disclosure is not shown in this figure after May 22nd).

[0116] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A rapid annealing apparatus, characterized in that, The rapid annealing equipment includes: furnace body (10), carrier plate structure (20), and purging device (30); The carrier structure (20) includes multiple support parts (201) and a carrier (202). One end of the multiple support parts (201) is connected to the top surface of the furnace body (10), and the other end of the multiple support parts (201) is connected to the bottom surface of the carrier (202). The purging device (30) is located on one side of the furnace body (10) and is used to purge gas onto the carrier structure (20) and the furnace body (10).

2. The rapid annealing equipment according to claim 1, characterized in that, The material of the support (201) is crystal quartz, zirconium oxide ceramic or phenolic resin.

3. The rapid annealing equipment according to claim 1, characterized in that, The carrier disk (202) is made of crystal quartz, zirconium oxide ceramic or phenolic resin.

4. The rapid annealing apparatus according to any one of claims 1 to 3, characterized in that, The purging device (30) includes a bracket (301) and a plurality of air outlets (302). The bracket (301) extends in a direction perpendicular to the top surface of the furnace body (10), and the plurality of air outlets (302) are arranged at intervals on the bracket (301) along the extension direction of the bracket (301).

5. A rapid annealing method, characterized in that, The method employs the annealing equipment as described in any one of claims 1 to 3, and the method comprises: At the end of the annealing isothermal stage, the wafers inside the furnace are transferred to the carrier tray; When the furnace body temperature drops to 400~600℃, nitrogen gas is purged by the purging device. When the furnace temperature drops below 400°C, oxygen and nitrogen are purged by the purging device.

6. The method according to claim 5, characterized in that, Purging nitrogen gas using the purging device includes: The purging device is used to purge 5-20L of nitrogen gas.

7. The method according to claim 6, characterized in that, Purging 5-20L of nitrogen gas using the purging device includes: Within 30 to 120 seconds, 5 to 20 L of nitrogen gas is purged using the purging device.

8. The method according to any one of claims 5 to 7, characterized in that, Purging oxygen and nitrogen using the purging device includes: The purging device is used to purge 60-120L of nitrogen gas. While purging the nitrogen, oxygen is purged at a flow rate of 0.7~2 sccm using the purging device.

9. The method according to claim 8, characterized in that, Purging 60-120L of nitrogen gas using the purging device includes: Within 200 to 400 seconds, 60 to 120 L of nitrogen gas is purged using the purging device.

10. The method according to claim 8, characterized in that, The purging of oxygen and nitrogen via the purging device also includes: When the temperature inside the furnace drops below 350°C, the oxygen supply is stopped.

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