Furnace tube with cleaning function and cleaning process of furnace tube

Abstract

The application provides a furnace tube with a cleaning function and a furnace tube cleaning process. The furnace tube comprises a furnace body, and a temperature control area is arranged on the side wall of the furnace body. The process comprises the following steps: lifting a wafer boat and a heat preservation barrel into the furnace body, closing the furnace body and vacuumizing; and introducing a cleaning gas into the furnace body to clean a layer to be cleaned in the furnace body. In the cleaning process, the heating temperature of a first temperature control area in the temperature control area is gradually reduced, so that the final target temperature of the first temperature control area at the end of the cleaning is 5-10 DEG C lower than the initial target temperature at the beginning of the cleaning, wherein the first temperature control area corresponds to the upper part area of the heat preservation barrel. In the application, the heating temperature of the first temperature control area corresponding to the upper part area of the heat preservation barrel is gradually reduced, so that the target temperature of the first temperature control area at the end of the cleaning is 5-10 DEG C lower than the initial target temperature of the temperature control area, the heat preservation barrel is protected, the generation of particle pollution sources caused by over-etching during the cleaning is prevented, and the wafer processing quality is ensured.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing equipment technology, and specifically relates to a furnace tube with a cleaning function and a cleaning process for the furnace tube. Background Technology

[0002] Semiconductor manufacturing processes involve various steps to create complex semiconductor devices. Some processes, such as diffusion, often require high-temperature and long-duration heat treatment. Furnace tube systems are commonly used for thin-film deposition processes during heat treatment.

[0003] like Figure 1 , Figure 2 As shown, Figure 1 A schematic diagram of the furnace tube structure is shown; Figure 2 A cross-sectional structural diagram of the furnace tube is shown. The furnace tube includes a furnace body 100, and a temperature control zone 200 is provided on the side wall of the furnace body 100 to control the internal thermal field temperature. A fixing member 300 is provided at the bottom of the furnace body 100. An inner tube 400 and an outer tube 500 are provided inside the furnace body 100. The inner tube 400 is vertically installed inside the furnace body 100, and its bottom is fixed to the fixing member 300. The outer tube 500 is sleeved on the inner tube 400, and its bottom is also fixed to the fixing member 300. A through hole is provided in the middle of the fixing member 300 to allow the crystal boat 600 and the insulation tank 700 to enter and exit the inner tube 400. The crystal boat 600 is fixedly installed directly above the insulation tank 700. Figure 3 As shown, the insulated container 700 is composed of several fins, which are generally made of quartz material. The insulated container 700 is an integral structure, and the fins are not detachable.

[0004] During non-process periods, the wafer boat 600 is generally located below the furnace body 100. When processing is required, the wafer is first placed on the wafer boat 600, and then the wafer boat 600 is raised from below the furnace body 100 into the inner tube 400 of the furnace body 100. Simultaneously, the insulation container 700 also rises into the inner tube 400. The bottom of the insulation container 700 is equipped with a sealing cap 800. When both the wafer boat 600 and the insulation container 700 reach the inner tube 400, the sealing cap 800 and the bottom of the fixing component 300 form a seal. At this time, a sealed space is formed inside the furnace body. The temperature control zone 200 can adjust the thermal field of this sealed space, making the thermal field inside the furnace tube corresponding to the temperature control zone 200 uniform and stable. Figure 1 and Figure 2As can be seen, the temperature control zone 200 is divided into multiple temperature control areas to achieve more precise control over the overall temperature of the furnace body 100. The temperature control zone 200 is generally divided into five heating units: the first heating unit 201, the second heating unit 202, the third heating unit 203, the fourth heating unit 204, and the fifth heating unit 205. During the process, by controlling multiple heating units to simultaneously heat the furnace body 100 to the same target temperature, the temperature inside the furnace tube 100 is better controlled to achieve uniformity. When the crystal boat 600 and the insulation tank 700 rise into the inner tube 400, the upper part 701 of the insulation tank 700 corresponds to the fifth heating unit 205 of the temperature control zone 200, while the lower part 702 of the insulation tank 700 is located outside the temperature control zone 200. This design ensures that all wafers on the crystal boat 600 are in a uniform and stable thermal field during the process, which is beneficial to the uniformity of thin film deposition.

[0005] After each thin film deposition process, the crystal boat 600 and the insulation tank 700 need to be placed into the inner tube 400 to re-seale the furnace body 100. Then, the entire furnace body 100 is etched and cleaned to remove the thin film deposition reactants generated from the previous thin film deposition process, ensuring a clean environment for the next thin film deposition process. However, in actual process, it was found that after a certain number of thin film deposition processes and cleanings, some areas of the insulation tank 700 corresponding to the temperature control zone 200 are damaged. The fin surface of the temperature control zone 200 is prone to over-etching due to repeated exposure to high temperatures and cleaning, thus becoming rougher and more prone to particle generation, becoming a potential source of particulate contamination. During the thin film deposition process, the reactive gas enters the inner tube 400 through the inlet 301 on the fixture 300, is then transported upwards within the inner tube 400, and is discharged through the exhaust port 302 on the fixture 300 via the gap between the inner tube 400 and the outer tube 500. When the reactive gas is transported upwards from the bottom of the inner tube 400, it easily carries particulate contaminants upwards, which then fall onto the wafer surface, leading to a decrease in wafer yield during the thin film deposition process. Currently, the chosen solution to this problem is to replace the insulation tank 700 after it has been cleaned and etched a certain number of times. However, this method incurs significant maintenance, labor, and material costs. Summary of the Invention

[0006] To prevent the furnace tube from becoming a potential source of particulate contamination due to over-etching in the upper part of the insulation tank after a certain number of cleaning cycles, and to avoid the situation where particulate contamination falls on the wafer surface and affects the wafer processing quality during subsequent thin film deposition processes, this invention proposes a furnace tube with cleaning function and a furnace tube cleaning process.

[0007] In a first aspect, the present invention proposes a cleaning process for furnace tubes, wherein the furnace tubes include a furnace body, and a temperature control zone is provided on the side wall of the furnace body, comprising:

[0008] The crystal boat and insulation barrel were raised into the furnace body, the furnace body was sealed and a vacuum was drawn.

[0009] Cleaning gas is introduced into the furnace to clean the layer to be cleaned inside the furnace. During the cleaning process, the heating temperature of the first temperature control zone in the temperature control area is gradually reduced, so that the final target temperature of the first temperature control zone at the end of the cleaning is 5-10°C lower than the initial target temperature at the beginning of the cleaning. The first temperature control zone corresponds to the upper part of the heat preservation tank.

[0010] According to a specific implementation of an embodiment of this application, before introducing cleaning gas into the furnace body, the method further includes: controlling the temperature of the temperature control area to an initial target temperature; wherein the initial target temperature of the first temperature control area is 5 to 10°C higher than the initial target temperature of the second temperature control area, and the second temperature control area corresponds to other areas in the temperature control area other than the first temperature control area.

[0011] According to a specific implementation of the present application, while controlling the temperature of the temperature control zone to the initial target temperature, the method further includes: introducing inert gas or nitrogen into the furnace body until the pressure inside the furnace body is 100 mtorr to 1000 mtorr.

[0012] According to a specific implementation of an embodiment of this application, it further includes:

[0013] During the cleaning process, the pressure inside the furnace is maintained at 100 mtorr to 1000 mtorr.

[0014] According to one specific implementation of the embodiments of this application, the cooling rate of the first temperature control zone is 0.1 to 1°C / min.

[0015] According to a specific implementation of an embodiment of this application, it further includes:

[0016] After the layer to be cleaned inside the furnace is cleaned, cleaning gas is continuously introduced into the furnace for a period of time to ensure that the layer to be cleaned is completely cleaned.

[0017] According to a specific implementation of an embodiment of this application, it further includes:

[0018] After the layer to be cleaned inside the furnace is cleaned, inert gas or nitrogen is continuously introduced into the furnace for a period of time to remove by-products inside the furnace.

[0019] Secondly, the present invention proposes a furnace tube with a cleaning function, the furnace tube comprising a furnace body, wherein a temperature control area is provided on the side wall of the furnace body, including:

[0020] A temperature control module for heating a sealed furnace tube and furnace body, the temperature control module includes a first temperature control module, the temperature control area corresponding to the first temperature control module is a first temperature control area, the first temperature control area corresponds to the upper part of the heat preservation barrel;

[0021] The control module is configured to: control the introduction of cleaning gas into the furnace body to clean the layer to be cleaned in the furnace body; during the cleaning process, control the heating temperature of the first temperature control zone to gradually decrease, so that the final target temperature of the first temperature control zone at the end of the cleaning is 5-10°C lower than the initial target temperature at the beginning of the cleaning.

[0022] According to a specific implementation of an embodiment of this application, the temperature control module further includes a second temperature control module, the temperature control area corresponding to the second temperature control module is a second temperature control area, and the second temperature control area corresponds to other areas in the temperature control area other than the first temperature control area;

[0023] Before the cleaning gas is introduced into the furnace, the control module is also configured to: control the temperature control module to control the temperature of the temperature control area to the initial target temperature; wherein, the initial target temperature of the first temperature control area corresponding to the first temperature control area is 5 to 10°C higher than the initial target temperature of the second temperature control area corresponding to the second temperature control module.

[0024] According to a specific implementation of an embodiment of this application, it further includes:

[0025] A pressure control module used to regulate the pressure conditions inside the furnace body;

[0026] The control module is also configured to: control the temperature control module to control the temperature of the temperature control zone to the initial target temperature, while controlling the pressure control module to adjust the internal pressure of the furnace body to 100 mtorr to 1000 mtorr; and during the cleaning process, control the pressure control module to adjust the internal pressure of the furnace body to 100 mtorr to 1000 mtorr.

[0027] The furnace tube with cleaning function and the furnace tube cleaning process of the present invention gradually reduce the heating temperature of the first temperature control area corresponding to the upper part of the insulation barrel by controlling the upper part of the insulation barrel. When the cleaning process ends, the target temperature of the temperature control area corresponding to the upper part of the insulation barrel is 5-10°C lower than the initial target temperature of the temperature control area. This achieves the purpose of protecting the insulation barrel, preventing the generation of particulate contaminants due to over-etching during cleaning, ensuring wafer processing quality, and reducing production costs. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A schematic diagram of the furnace tube structure is shown;

[0030] Figure 2 A schematic diagram of the cross-sectional structure of the furnace tube is shown; and

[0031] Figure 3 A three-dimensional structural diagram of the insulated container is shown;

[0032] Figure 4 A schematic diagram of the furnace tube cleaning process according to an embodiment of the present invention is shown;

[0033] Figure 5 A schematic diagram of the structure of a furnace tube with a cleaning function according to an embodiment of the present invention is shown. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Figure 1 , Figure 2The furnace tube shown in the diagram, due to its large actual structural dimensions, is prone to uneven heating during the heating of the furnace body 100 by the temperature control area 200, resulting in some areas being too hot and others too cold. However, wafer thin-film deposition processes require high temperature accuracy and uniformity. During manufacturing, to ensure uniform temperature across all areas of the furnace body 100 and more precisely control the overall temperature consistency, the temperature control area 200 is typically divided into multiple heating units, with temperature control applied to each area. For example, in this embodiment, the temperature control area 200 is divided into five heating units: a first heating unit 201, a second heating unit 202, a third heating unit 203, a fourth heating unit 204, and a fifth heating unit 205. During the process, by controlling multiple heating units to simultaneously heat the furnace body 100 to the same target temperature, the temperature inside the furnace tube 100 is better controlled to achieve uniformity. Specifically, each heating unit includes a heater (not shown), a temperature sensor (not shown), and a controller (not shown). During the heating process, the controller controls the heater to heat the sealed space inside the furnace body 100. At the same time, the temperature sensor monitors the temperature inside the furnace body 100 and transmits the monitored temperature data to the controller in real time. Once the temperature inside the furnace body 100 reaches the preset target temperature, the controller immediately controls the heater to stop heating.

[0036] After the thin film deposition process on the wafer is completed, the entire interior of the furnace body 100 needs to be etched and cleaned to remove the thin film deposition reactants generated in the previous thin film deposition process, ensuring a clean environment for the next thin film deposition process. Considering the need to accommodate the existing furnace tube structure, the general approach is to control each heating unit in the temperature control zone 200 to uniformly heat the furnace body 100 at the same temperature. Then, cleaning gas is introduced into the inner tube 400 through the air inlet 301 on the fixture 300, transported upwards within the inner tube 400, and then discharged through the exhaust port 302 on the fixture 300 via the gap between the inner tube 400 and the outer tube 500. However, the inventors of this application have discovered that after a certain number of furnace body cleaning cycles, the wafer processing yield decreases. Analysis by the inventors of this application revealed that after the furnace body 100 is cleaned a certain number of times, the surface of the fins in the upper region 701 of the insulation tank 700, corresponding to the fifth heating unit 205, becomes rough. Furthermore, the roughness varies across different areas of the same fin, with the edges of the fins experiencing higher temperatures and thus undergoing more severe etching than the center. This over-etching creates a rough surface, and the more severe the roughness, the more likely it is to become a potential source of particulate matter. During subsequent thin-film deposition processes on the wafer, the rough surface of the insulation tank fins becomes a source of particulate contamination. When the reactive gas in the diffusion process is transported upwards from the bottom of the inner tube 400, it easily carries these particulate contaminants upwards, eventually settling on the wafer surface, leading to a decrease in the yield rate of wafer processing during thin-film deposition. To address this problem, the inventors of this application have researched and proposed a furnace tube with a cleaning function and a furnace tube cleaning method to solve the problem of roughened fin surfaces in areas of the insulation tank frequently subjected to high-temperature reactions, thereby extending the service life of the furnace tube and ensuring the quality of wafer processing. It is worth noting that, in this article, the upper region 701 of the insulation container specifically refers to the area inside the furnace body 100 and corresponding to the temperature control area when the insulation container lifts the crystal boat into the furnace body 100. Please refer to the following for details. Figure 2 and Figure 3 The upper part of the insulated container 701 is characterized by fins with relatively small diameters and several fins below the relatively small diameter fins.

[0037] Please refer to Figure 4 , Figure 4 A process flow diagram for cleaning furnace tubes according to an embodiment of the present invention is shown. Figure 4 As shown, the furnace tube cleaning process of the present invention includes the following steps:

[0038] Step S100: Raise the crystal boat and the insulation barrel into the furnace body, seal the furnace body with the layer to be cleaned inside and evacuate the vacuum.

[0039] Specifically, when closed, such as Figure 2As shown, the crystal boat 600 and the insulation barrel 700 rise into the inner tube 400, and the sealing cover 800 forms a seal with the bottom of the fixing part 300, making the inside of the furnace a closed environment and evacuating the internal space of the furnace to ensure the vacuum degree inside the furnace.

[0040] Step S300: Introduce cleaning gas into the furnace to clean the layer to be cleaned inside the furnace. During the cleaning process, the heating temperature of the first temperature control zone in the temperature control area is gradually reduced, so that the final target temperature of the first temperature control zone at the end of the cleaning is 5-10°C lower than the initial target temperature at the beginning of the cleaning. The first temperature control zone corresponds to the upper part of the heat preservation barrel.

[0041] Specifically, when cleaning gas enters the furnace for cleaning, the heating unit is constantly heated, resulting in a consistently higher temperature in the upper region 701 of the insulation container compared to the lower region 702. When the cleaning time is extended to ensure complete cleaning of the insulation container 700, the upper region 701 is prone to over-etching. Furthermore, because the heating unit surrounds the furnace, the edge temperature of the fins in the upper region 701 is higher than the center temperature. This causes the cleaning and etching reaction to be slower at the center and faster at the edges, resulting in inconsistent cleaning rates across different areas of the same fin. While the edges of the fin are already cleaned, the center is not. After the cleaning process, the roughness of the edge region of the insulation container fins is significantly higher than that of the center region. This rougher area becomes a potential source of particles, affecting the wafer processing quality. To prevent the generation of particulate matter, over-etching must be avoided. Therefore, during cleaning, the upper part of the insulation tank, especially the edge area, must not experience localized overheating. To this end, this invention groups the temperature control area 200 during the cleaning process. For example, in this embodiment, the temperature control area 200 is divided into two temperature control areas: the first temperature control area is the fifth heating unit 205 located at the bottom of the furnace tube, corresponding to the upper part of the insulation tank 701; the second temperature control area includes all other temperature control areas besides the first temperature control area. In this embodiment, the second temperature control area includes the first heating unit 201, the second heating unit 202, the third heating unit 203, and the fourth heating unit 204. During the cleaning process, the heating temperature of the first temperature control area, i.e., the fifth heating unit 205 in this embodiment, gradually decreases. By the end of the cleaning, the final target temperature of the first temperature control area corresponding to the upper part of the insulation tank 701 is 5-10°C lower than the initial target temperature of the first temperature control area. Furthermore, the cooling rate of the fifth heating unit 205 within the first temperature control zone corresponding to the insulation tank is controlled at 0.1–1°C / min. By gradually reducing the temperature of the first temperature control zone from the initial target temperature by 5–10°C during the cleaning process, the cleaning efficiency of the entire furnace body becomes more consistent. This achieves the goal of ensuring that the cleaning process begins as soon as the cleaning gas enters the furnace body, thus improving cleaning efficiency; it also avoids over-etching caused by the upper part of the insulation tank continuously being subjected to strong cleaning etching; at the same time, the gradual reduction of the temperature in the first temperature control zone corresponding to the upper part of the insulation tank avoids uneven heating between the center and the edge of the fins in the upper part of the insulation tank; and it avoids the phenomenon of the insulation tank fin surface becoming rough and becoming a potential source of particulate contamination, thus protecting the various components of the furnace tube, extending the service life of the furnace tube, ensuring wafer processing quality, and reducing production costs.

[0042] Preferably, before step S300, the cleaning process further includes: step S200: controlling the temperature of the temperature control area to the initial target temperature; wherein the initial target temperature of the first temperature control area is 5-10°C higher than the initial target temperature of the second temperature control area, wherein the second temperature control area corresponds to the other areas in the temperature control area besides the first temperature control area.

[0043] Specifically, when the cleaning gas enters the bottom of the inner tube 400, its temperature is too low to reach the reaction temperature. Therefore, the cleaning gas does not immediately begin cleaning upon entering the inner tube 400. As the cleaning gas flows upwards, it is continuously heated, resulting in partial thermal decomposition. Since this reaction is exothermic, the gas temperature at the top of the inner tube 400 is significantly higher than that at the bottom. During the cleaning process, the cleaning gas first completely decomposes at the top of the inner tube 400 and the upper part of the outer tube 500, producing sufficient substances to react with the layer to be cleaned within the furnace tube and gradually extending towards the bottom of the furnace. This easily leads to the top of the furnace being cleaned first, while the bottom is cleaned only after the top has been cleaned for some time. Consequently, the top of the furnace is cleaned before the bottom. Therefore, to ensure that the inner bottom of the outer tube 500 and the lower part of the insulation tank 702 are thoroughly cleaned, the entire cleaning process must be extended. This inevitably leads to damage to the top of the furnace body due to excessive cleaning.

[0044] In the actual cleaning process, different cleaning gases are selected based on the different layers to be cleaned produced by different thin film deposition processes. Then, based on the actual reaction temperature of the cleaning gas, the multiple heating units in the temperature control zone 200 are grouped and controlled in the above manner, thereby selecting and setting the heating temperature of each area of ​​the furnace body 100. Before introducing the cleaning gas into the furnace body, the initial target temperature of the first temperature control zone is set to be 5-10°C higher than the initial target temperature of the second temperature control zone to accelerate the cleaning process at the bottom of the furnace body and improve the cleaning efficiency of the furnace body.

[0045] Furthermore, while controlling the temperature of the temperature control zone to the initial target temperature, inert gas or nitrogen is introduced into the furnace body until the internal pressure reaches 100 mtorr to 1000 mtorr. Then, the introduction of inert gas or nitrogen is stopped, and cleaning gas is introduced into the furnace body 100 to clean the layer to be cleaned. Similarly, during the cleaning process, the internal pressure of the furnace body is maintained at...

[0046] 100mtorr~1000mtorr.

[0047] Preferably, the cleaning process further includes step S400: after the layer to be cleaned in the furnace is cleaned, cleaning gas is continuously introduced into the furnace for a period of time to ensure that the layer to be cleaned is completely cleaned. For example, in this embodiment of the invention, the continuous introduction of cleaning gas lasts for 3-5 minutes, and the flow rate can remain constant. It is worth noting that the time required to clean the layer in the furnace can be judged empirically, and the cleaning time is directly determined as complete cleaning. Alternatively, the temperature can be monitored in real time by a temperature sensor within the heating unit to determine the cleanliness. When the temperature monitored by the temperature sensor is consistent with the temperature controlled by the temperature control zone during continuous introduction of cleaning gas, i.e., when the detected temperature is equal to the temperature heated by the heating unit in that temperature control zone, it can be determined that the layer is clean. The reason for this judgment is that when the cleaning gas cleans the layer to be cleaned, the reaction that occurs is an exothermic reaction. As long as the layer to be cleaned is not cleaned, the cleaning gas will continue to react with the layer to be cleaned. The temperature inside the furnace detected by the temperature sensor will continue to be higher than the temperature heated by the heating unit in the temperature control area until the temperature inside the furnace detected by the temperature sensor is equal to the temperature heated by the heating unit in the temperature control area. This indicates that the cleaning reaction no longer occurs and the layer to be cleaned is completely cleaned.

[0048] Preferably, the cleaning process further includes step S500: after the layer to be cleaned in the furnace is cleaned, inert gas or nitrogen is continuously introduced into the furnace for a period of time to remove by-products in the furnace, thus completing the cleaning process. For example, in this embodiment of the invention, nitrogen is selected. Furthermore, in this embodiment of the invention, the flow rate of nitrogen introduced into the furnace is 1.5SL to 2SL, and the continuous introduction time is 3 to 5 minutes.

[0049] This invention also proposes a furnace tube with a cleaning function. Please refer to... Figure 5 , Figure 5 A schematic diagram of a furnace tube structure with a cleaning function according to an embodiment of the present invention is shown. Figure 5 As shown, the furnace tube 501 with cleaning function includes:

[0050] Temperature control module 5012 is used to heat the sealed furnace tube and furnace body 5011.

[0051] The control module 5014 is configured to: control the introduction of cleaning gas into the furnace body 5011 to clean the layer to be cleaned within the furnace body 5011; during the cleaning process, the heating temperature of the first temperature control module in the temperature control area is gradually reduced, so that the final target temperature of the first temperature control module at the end of cleaning is 5-10°C lower than the initial target temperature at the beginning of cleaning; wherein the temperature control area of ​​the first temperature control module corresponds to the upper part 701 of the insulation tank. Furthermore, when introducing cleaning gas into the furnace body 5011, the cleaning gas is controlled to enter the furnace body 5011 from the bottom to clean the layer to be cleaned within the furnace body 5011.

[0052] Furthermore, the number of temperature control modules 5012 is at least two, and each temperature control module 5012 includes at least one heating unit 50121; before the cleaning gas is introduced into the furnace body, the control module 5014 is also configured to control the temperature control modules 5012 to control the temperature of the temperature control area to the initial target temperature; wherein the initial target temperature of the first temperature control module is 5 to 10°C higher than the initial target temperature of the second temperature control module, and the second temperature control module corresponds to other areas in the temperature control module other than the temperature control area corresponding to the first temperature control module.

[0053] Preferably, the furnace tube 501 further includes a pressure control module 5013 for adjusting the pressure inside the furnace body.

[0054] Furthermore, the control module 5014 is also configured to: control the temperature rise of the temperature control zone while controlling the pressure control module 5013 to adjust the internal pressure of the furnace body to 100 mtorr to 1000 mtorr, and during the cleaning process, control the pressure control module 5013 to adjust the internal pressure of the furnace body to 100 mtorr to 1000 mtorr.

[0055] It should be understood that the furnace tube with cleaning function and the furnace tube cleaning process are applicable not only to the cleaning of furnace tubes after thin film deposition, but also to the cleaning of furnace tubes after thermal diffusion. Next, this invention will continue to illustrate the furnace tube cleaning process of this embodiment of the invention by using silicon nitride thin film as the product of the thin film deposition process as the layer to be cleaned, and non-metallic fluorinated gas, exemplarily using chlorine trifluoride gas as the cleaning gas, to clean the furnace tube and furnace body.

[0056] Please refer to Figure 1This invention provides a furnace body with an internal silicon nitride thin film, which is sealed and evacuated to ensure a high vacuum level inside the furnace. In this embodiment, the temperature control zone 200 is divided into five heating units: a first heating unit 201, a second heating unit 202, a third heating unit 203, a fourth heating unit 204, and a fifth heating unit 205. These five heating units are further divided into two temperature control zones. The first temperature control zone is the fifth heating unit 205 located in area 701 of the insulation tank 700 at the bottom of the furnace tube. The second temperature control zone includes all other temperature control zones except the first one. In this embodiment, the second temperature control zone includes the first heating unit 201, the second heating unit 202, the third heating unit 203, and the fourth heating unit 204. After dividing these five heating units, precise heating and temperature control can be achieved within each temperature control zone, thereby enabling different temperature control for different areas within the furnace.

[0057] Based on the temperature requirements for the reaction between the silicon nitride thin film and the cleaning gas, the heating temperature of each temperature control zone is selected and set. Before the cleaning gas is introduced into the furnace, the target temperature of the first temperature control zone is set to 305-310℃, that is, the heating temperature of the fifth heating unit 205 is 305-310℃. The target temperature of the second temperature control zone is set to 300℃, that is, the heating temperature of the first heating unit 201, the second heating unit 202, the third heating unit 203, and the fourth heating unit 204 is the same, all at 300℃.

[0058] While controlling the internal temperature of the furnace body 100 to rise, inert gas or nitrogen is introduced into the furnace body until the internal pressure of the furnace body 100 reaches 100 mtorr to 1000 mtorr. Then, cleaning gas is introduced into the furnace body 100 to clean the layer to be cleaned. During the cleaning process, the heating temperature of the fifth heating unit 205 corresponding to region 701 of the insulation tank 700 is gradually reduced. Furthermore, the cooling rate of the heating temperature of the first temperature control region corresponding to region 701 of the insulation tank 700 is controlled at 0.1 to 1°C / min until the cleaning is completed. The final target temperature of the first temperature control region is 5 to 10°C lower than the initial target temperature of the first temperature control region. In this embodiment, after the cleaning is completed, the final target temperature of the first temperature control region reaches 290 to 295°C, while the temperature of the second temperature control region remains at 300°C. Similarly, during the cleaning process, the internal pressure of the furnace body is maintained at 100 mtorr to 1000 mtorr.

[0059] To ensure a complete reaction, the silicon nitride layer inside the furnace tube is thoroughly cleaned. After confirming that it is clean, chlorine trifluoride gas is continuously introduced at a flow rate of 1.5 SL to 2 SL for 3 to 5 minutes to further ensure complete cleaning of the silicon nitride film layer and ensure the cleaning effect. Then, nitrogen gas is introduced at a flow rate of 1.5 SL to 2 SL for 3 to 5 minutes to facilitate the removal of byproducts.

[0060] This invention implements zoned temperature control of the furnace tube to achieve precise control of different temperatures in different areas. This ensures that the cleaning efficiency of the entire furnace body is consistent. Furthermore, it dynamically adjusts the temperature of local temperature control areas to protect the various components of the furnace tube and avoid the generation of potential particulate sources. This improves the cleaning efficiency of the furnace tube and furnace body, protects the various components of the furnace tube, extends the service life of the furnace tube, ensures the quality of wafer processing, and reduces production costs.

[0061] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for cleaning a furnace tube, said furnace tube comprising a furnace body, the side wall of said furnace body being provided with a temperature control zone, characterized in that, include: The crystal boat and insulation barrel were raised into the furnace body, the furnace body was sealed and a vacuum was drawn. Cleaning gas is introduced into the furnace to clean the layer to be cleaned inside the furnace. During the cleaning process, the heating temperature of the first temperature control zone in the temperature control area is gradually reduced, so that the final target temperature of the first temperature control zone at the end of the cleaning is 5~10℃ lower than the initial target temperature at the beginning of the cleaning. The first temperature control zone corresponds to the upper part of the heat preservation barrel. Before introducing cleaning gas into the furnace, the process also includes: controlling the temperature of the temperature control zone to the initial target temperature; wherein the initial target temperature of the first temperature control zone is 5~10℃ higher than the initial target temperature of the second temperature control zone, and the second temperature control zone corresponds to the other temperature control zones besides the first temperature control zone.

2. The cleaning process according to claim 1, characterized in that, While controlling the temperature of the temperature control zone to the initial target temperature, it also includes: introducing inert gas or nitrogen into the furnace body until the pressure inside the furnace body is 100 mtorr~1000 mtorr.

3. The cleaning process of claim 1, wherein, Also includes: During the cleaning process, the pressure inside the furnace is maintained at 100 mtorr to 1000 mtorr.

4. The cleaning process of claim 1, wherein, The cooling rate of the first temperature control zone is 0.1~1℃ / min.

5. The cleaning process of claim 1, wherein, Also includes: After the layer to be cleaned inside the furnace is cleaned, cleaning gas is continuously introduced into the furnace for a period of time to ensure that the layer to be cleaned is completely cleaned.

6. The cleaning process of claim 1, wherein, Also includes: After the layer to be cleaned inside the furnace is cleaned, inert gas or nitrogen is continuously introduced into the furnace for a period of time to remove by-products inside the furnace.

7. A furnace tube with a cleaning function, the furnace tube comprising a furnace body, wherein a temperature control zone is provided on the side wall of the furnace body, characterized in that, include: A temperature control module for heating a sealed furnace tube and furnace body, the temperature control module includes a first temperature control module, the temperature control area corresponding to the first temperature control module is a first temperature control area, the first temperature control area corresponds to the upper part of the heat preservation barrel; The control module is configured to: control the flow of cleaning gas into the furnace body to clean the layer to be cleaned in the furnace body; and during the cleaning process, control the heating temperature of the first temperature control module to gradually decrease so that the final target temperature of the first temperature control module at the end of the cleaning is 5-10°C lower than the initial target temperature at the beginning of the cleaning. The temperature control module further includes a second temperature control module, and the temperature control area corresponding to the second temperature control module is the second temperature control area, which corresponds to other areas in the temperature control area other than the first temperature control area. Before the cleaning gas is introduced into the furnace, the control module is also configured to: control the temperature control module to control the temperature of the temperature control area to the initial target temperature; wherein, the initial target temperature of the first temperature control area corresponding to the first temperature control module is 5~10℃ higher than the initial target temperature of the second temperature control area corresponding to the second temperature control module.

8. The furnace tube according to claim 7, characterized in that, Also includes: A pressure control module used to regulate the pressure conditions inside the furnace body; The control module is also configured to: control the temperature control module to control the temperature of the temperature control zone to the initial target temperature, while controlling the pressure control module to adjust the internal pressure of the furnace body to 100 mtorr~1000 mtorr; and during the cleaning process, control the pressure control module to adjust the internal pressure of the furnace body to 100 mtorr~1000 mtorr.

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