Furnace tube structure for thin film deposition

Abstract

The invention discloses a furnace tube structure for thin film deposition, and relates to the technical field of atomic layer deposition, the furnace tube structure comprises a support flange, a quartz furnace tube, a fixed flange, a crystal boat and a plurality of silicon wafers, the left and right ends of the front side of the fixed flange are provided with a plurality of first air inlets; a second air inlet and a third air inlet are formed in the middle of the front side of the fixing flange, the quartz furnace tube comprises an ionization cavity, a furnace tube outer wall, a furnace tube inner wall and an exhaust pipe, and a first temperature sensor and a second temperature sensor are arranged in the quartz furnace tube. The gas pipe, the electrode bar, the electrode plate and the third chamber are communicated in the ionization chamber to realize full coverage of gas on all silicon wafers, the exhaust pipe is arranged opposite to the rectangular hole to form stable gas flow, and the stacked wafer boat drives the silicon wafers to rotate at a low speed, so that plasma and raw material gas efficiently and uniformly react; and prolonging of process time consumption caused by insufficient ionization and non-uniform airflow is avoided, and the film deposition efficiency is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of atomic layer deposition technology, and in particular to a furnace tube structure for thin film deposition. Background Technology

[0002] Atomic layer deposition (ALD) technology, a key process in semiconductor manufacturing, is widely used in the manufacturing processes of various semiconductor devices, including logic chips, memory devices, and power semiconductors, due to its core advantages of achieving atomic-level precision thin film deposition, high film thickness uniformity, and excellent conformal properties. It is used to prepare key functional thin films such as gate dielectric layers, passivation layers, and electrode layers. Among these, plasma-enhanced atomic layer deposition (PEAD) technology significantly improves the reaction rate and film quality by ionizing reactive gases to form highly active plasma, making it one of the mainstream technologies for high-precision semiconductor thin film preparation.

[0003] Existing plasma-enhanced atomic layer deposition (PALDS) equipment still suffers from problems such as long process times, complex furnace structures, and short lifespans of related components in practical applications. Existing equipment often suffers from incomplete ionization of reactant gases and uneven gas flow distribution, with some reactant gases entering the deposition area before being fully converted into plasma, resulting in low reaction efficiency between the raw material gases and the plasma. To achieve functions such as gas ionization, temperature control, and exhaust gas emission, existing equipment often employs a multi-module splicing design, with cumbersome connections between modules. This not only increases the difficulty of equipment assembly and maintenance but also easily leads to gas leakage due to excessive sealing interfaces, affecting the stability of the deposition environment. Furthermore, the core ionization components lack effective heat dissipation mechanisms in high-temperature, high-ionization-intensity operating environments, leading to heat accumulation and accelerated electrode wear. A furnace tube structure for thin film deposition needs to be designed to address the problems mentioned above. Summary of the Invention

[0004] To achieve the above objectives, the present invention is implemented through the following technical solution: a furnace tube structure for thin film deposition, comprising a supporting flange, a quartz furnace tube, a fixing flange, a crystal boat and multiple silicon wafers, wherein the quartz furnace tube is placed on the upper part of the supporting flange, and the fixing flange is used to fix the quartz furnace tube on the upper part of the supporting flange. The fixed flange is provided with several first air inlets on the left and right sides of the front side, and a second air inlet and a third air inlet are provided in the middle of the front side of the fixed flange. The first air inlet, the second air inlet and the third air inlet are used to introduce the reaction gas, raw material gas and inert gas required for thin film deposition, while reserving air inlets required for the subsequent development of new processes. The quartz furnace tube includes an ionization chamber, an outer wall of the furnace tube, an inner wall of the furnace tube, and an exhaust pipe. The interior of the quartz furnace tube is equipped with a first temperature sensor and a second temperature sensor, which are used to measure the temperature near the silicon wafer and the temperature near the outer wall of the furnace tube, respectively. The first temperature sensor is located near the outer edge of the silicon wafer.

[0005] Preferably, the quartz furnace tube is provided with multiple air inlet pipes on the front left and right sides. The air inlet pipe in the middle of the left side is the first raw material air inlet pipe, the air inlet pipe in the right side is the second raw material air inlet pipe, and the air inlet pipes in the right side of the left side and the left side of the right side are clean gas injection pipes. Each air inlet pipe is designed with an air outlet, and the air outlet points to the center of the silicon wafer. The first raw material inlet pipe, the second raw material inlet pipe, and the clean gas injection pipe are all located at both ends of the ionization chamber, and the gas is transmitted to the inner cavity of the quartz furnace tube through the designed gas outlet. The air intake pipes are all connected to the corresponding first air intake ports on the support flanges.

[0006] Preferably, the first temperature sensor and the second temperature sensor are used to ensure the temperature required for thin film deposition in the chamber, and both the first temperature sensor and the second temperature sensor pass through the support flange, with the second temperature sensor (206) fixed in the corresponding position. The inner wall of the furnace tube is provided with a rectangular hole. The space formed by the outer wall of the furnace tube and the inner wall of the furnace tube is a first chamber and a second chamber. The first chamber is connected to the exhaust pipe, which is used to discharge excess gas and by-products during the thin film deposition process.

[0007] Preferably, the reactive gas in the ionization chamber is ionized into plasma and enters the second chamber enclosed by the inner wall and outer wall of the furnace tube, the second chamber being the space for the silicon wafer thin film deposition process; The ionization chamber includes a connecting gas pipe, an electrode rod, a third chamber, and two electrode plates. The connecting gas pipe is connected to the third gas inlet and is used to introduce the reaction gas required for thin film deposition. A certain number of gas outlets are arranged on the connecting gas pipe. The two electrode plates are arranged in parallel, the electrode rod is supplied with the power required for ionization gas, the two electrode plates are grounded, and the electrode rod and electrode plates form an ionization space; The third chamber is connected to the second chamber. When the reactant gas comes out from the outlet of the connecting gas pipe, the gas can only enter the second chamber from the open side of the third chamber. Before entering the second chamber, the reactant gas must pass through the ionization space. After being ionized, the reactant gas enters the third chamber.

[0008] Preferably, a retainer is provided on the upper part of the support flange. The upper part of the retainer is provided with a slit. The cylindrical surface of the retainer has a groove. The slit is connected to the third chamber. After inert gas is introduced from the second air inlet, the retainer introduces the gas into the slit. The retainer is designed to facilitate the installation of the electrode rod and provide heat dissipation for the electrode rod through the guide groove and the hollow middle part. At the same time, the gas injected can improve the concentration of the reaction gas in the vertical space of the ionization chamber.

[0009] Preferably, the slot can guide the incoming gas, and the gas introduced from here can remove some of the heat around the electrode rod and increase the life of the electrode rod. Multiple silicon wafers are placed on the upper part of the crystal boat, which rotates at a low speed under the action of a motor.

[0010] Preferably, the centerline of the exhaust pipe forms a 60-70° angle with the centerline of the ionization chamber, and the open surface of the third chamber is directly opposite the rectangular hole. In the pump chamber connected to the exhaust pipe, when the reaction gas and raw material gas are alternately introduced, they will flow from the intake pipe side to the rectangular hole under the action of the airflow generated by the pump. During this process, as the crystal boat rotates, the gas will be adsorbed on the surface of the silicon wafer, thus depositing a uniform thin film on the surface of the silicon wafer.

[0011] Preferably, the first raw material inlet pipe is designed with a row of vent holes in the middle section, and the second raw material inlet pipe is designed with a row of vent holes in the upper section. The diameters of the two vent holes are the same, which is used to reduce the impact of the different air pressures at the top and bottom of the pipe to a certain extent, and improve the airflow uniformity at the vent holes. At the same time, the combined ventilation of the first raw material inlet pipe and the second raw material inlet pipe can cover all the silicon wafers in the furnace tube.

[0012] In summary, the present invention provides a furnace tube structure for thin film deposition, which has the following beneficial effects: 1. The ionization chamber is connected to a gas pipe, electrode rod, electrode plate, and a third chamber. The gas pipe uniformly delivers the reaction gas, and the electrode rod and the parallel grounded electrode plate form a uniform ionization space. The third chamber forces the reaction gas to pass through the ionization space before entering the second chamber, ensuring that the reaction gas is fully ionized into highly active plasma. At the same time, the first and second raw material inlet pipes are combined to provide gas, and the inlet holes are pointed towards the center of the silicon wafers to achieve full gas coverage of all silicon wafers. With the exhaust pipe and the rectangular hole facing each other, a stable airflow is formed. The superimposed crystal boat drives the silicon wafers to rotate at a low speed, so that the plasma and raw material gas react efficiently and uniformly, avoiding the prolongation of process time caused by insufficient ionization and uneven airflow, and significantly improving the thin film deposition efficiency.

[0013] 2. By using a supporting flange, a fixed flange, and a quartz furnace tube, the fixed flange integrates the first, second, and third air inlets, enabling centralized introduction and future expansion of different functional gases. The supporting flange simultaneously supports the quartz furnace tube, the cage, and the first and second temperature sensors passing through it, reducing the need for multi-module splicing. The first and second chambers formed by the outer and inner walls of the quartz furnace tube, combined with the integrated design of the ionization chamber, integrate ionization, deposition, and exhaust gas emission functions into a single furnace tube. At the same time, the cage, through guide grooves, gaps, and slots, simultaneously achieves electrode rod installation and fixation, heat dissipation, and pollution prevention functions, reducing sealing interfaces and connection links, simplifying the furnace structure, and reducing assembly and maintenance difficulties and the risk of gas leakage.

[0014] 3. Through the retainer, the second air inlet, and the electrode rod, the inert gas introduced through the second air inlet enters the gap through the guide groove of the retainer, and then flows through the groove of the cylindrical surface, forming an air curtain to block non-reactive gas from entering the gas channel, thus avoiding contamination of the electrode rod surface. At the same time, the airflow carries away the heat around the electrode rod, solving the heat dissipation problem of the core ionization component. The single-row air hole design of the first and second raw material air inlets reduces the impact of the airflow on the pressure difference between the upper and lower parts of the pipe, reduces the gas scouring loss of the air inlet pipe, and the stable connection between the fixed flange and the supporting flange avoids the loosening and wear of components caused by furnace vibration, significantly extending the service life of components, reducing the frequency of equipment downtime for replacement, and reducing operation and maintenance costs. Attached Figure Description

[0015] Figure 1 This is a front view of a furnace tube structure for thin film deposition according to the present invention; Figure 2 This is a front cross-sectional view of a furnace tube structure for thin film deposition according to the present invention; Figure 3 This is a top cross-sectional view of a furnace tube structure for thin film deposition according to the present invention; Figure 4 This is a top view of a furnace tube structure for thin film deposition according to the present invention; Figure 5 This is a cross-sectional view of the ionization chamber of a furnace tube structure for thin film deposition according to the present invention; Figure 6 This is a schematic diagram of the first and second raw material inlet pipes of a furnace tube structure for thin film deposition according to the present invention. Figure 7 This is a schematic diagram of the first raw material inlet pipe, the second raw material inlet pipe, and the silicon wafer structure of a furnace tube structure for thin film deposition according to the present invention. Figure 8 This is a schematic diagram of a cage structure for a furnace tube structure used for thin film deposition according to the present invention.

[0016] Explanation of reference numerals in the attached figures: Support flange; 101, first air inlet; 102, second air inlet; 103, third air inlet; 104, cage; 105, gap; 106, slot; Quartz furnace tube; 201, ionization chamber; 202, inlet pipe; 203, outer wall of furnace tube; 204, inner wall of furnace tube; 205, first temperature sensor; 206, second temperature sensor; 207, exhaust pipe; 208, rectangular hole; 209, first chamber; 210, second chamber; Connecting trachea; 2012, electrode rod; 2013, third chamber; 2014, electrode plate; 2021, First raw material inlet pipe; 2022, Second raw material inlet pipe; 2023, Clean gas injection pipe; 3. Fixed flange; 4. Crystal boat; 5. Silicon wafer. Detailed Implementation

[0017] The following is in conjunction with the appendix Figure 1 - Appendix Figure 8 This application will be described in further detail below. Example

[0018] Please see Figures 1-8 As shown, the present invention provides a technical solution: a furnace tube structure for thin film deposition, including a supporting flange 1, a quartz furnace tube 2, a fixing flange 3, a crystal boat 4, and multiple silicon wafers 5. The quartz furnace tube 2 is placed on the upper part of the supporting flange 1, and a sealing strip is placed between the quartz furnace tube 2 and the supporting flange 1. The fixing flange 3 is used to fix the quartz furnace tube 2 on the upper part of the supporting flange 1, and a gasket is provided between the fixing flange 3 and the quartz furnace tube 2. The fixing flange 3 achieves a stable connection between the quartz furnace tube 2 and the supporting flange 1, ensuring the stability of the quartz furnace tube 2 during the thin film deposition process. At the same time, it avoids minor collisions between the quartz furnace tube and the fixing flange 3 caused by thermal expansion and contraction, increases the life of the quartz furnace tube, and also enhances the sealing between the quartz furnace tube 2 and the supporting flange 1 to prevent gas leakage in the chamber. Several first air inlets 101 are provided on the left and right sides of the front side of the support flange 1. A second air inlet 102 and a third air inlet 103 are provided in the middle of the front side of the support flange 1. Part of the first air inlet 101, the second air inlet 102 and the third air inlet 103 are used to introduce the raw material gas, inert gas and reaction gas required for thin film deposition, respectively. At the same time, air inlets required for the subsequent development of new processes are reserved. Through the classified setting of the first air inlet 101, the second air inlet 102 and the third air inlet 103, the raw material gas, inert gas and reaction gas can be accurately introduced, avoiding the mixing and interference of different functional gases, meeting the differentiated requirements of thin film deposition for gas types, and the reserved air inlets do not require modification of the support flange 1 and the main structure of the furnace tube. The quartz furnace tube 2 includes an ionization chamber 201, an outer wall 203, an inner wall 204, and an exhaust pipe 207. The interior of the quartz furnace tube 2 is equipped with a first temperature sensor 205 and a second temperature sensor 206, which are used to measure the temperature near the silicon wafer 5 and the temperature near the outer wall 203 of the furnace tube, respectively. The first temperature sensor 205 is close to the outer edge of the silicon wafer 5. The first temperature sensor 205 and the second temperature sensor 206 form a dual temperature monitoring system to capture the temperature near the silicon wafer 5 and the ambient temperature inside the outer wall 203 of the furnace tube, respectively, so as to achieve comprehensive control of the temperature of the deposition core area. The design of the first temperature sensor 205 close to the edge of the silicon wafer 5 can accurately capture the temperature differences that are prone to occur at the edge of the silicon wafer 5, and avoid the fluctuation of thin film deposition quality caused by local temperature unevenness.

[0019] Multiple air inlet pipes 202 are provided on the front left and right sides of the quartz furnace tube 2. The middle air inlet pipe 202 on the left is the first raw material air inlet pipe 2021, the right air inlet pipe 202 on the right is the second raw material air inlet pipe 2022, and the right air inlet pipes 202 on the left and right are both clean gas injection pipes 2023. Each air inlet pipe 202 is designed with an air outlet, and the air outlets all point to the center of the silicon wafer 5. By subdividing the air inlet pipe 202 into the first raw material air inlet pipe 2021, the second raw material air inlet pipe 2022 and the clean gas injection pipe 2023, the raw material gas and the clean gas are delivered independently, avoiding the clean gas from contaminating the raw material gas. The design of the air outlet pointing to the center of the silicon wafer 5 allows the gas to act directly on the deposition core area of ​​the silicon wafer 5, reducing the ineffective diffusion of gas in the quartz furnace tube 2 and improving the utilization rate of raw material gas. At the same time, the clean gas can accurately clean the surface of the silicon wafer 5 and the key areas of the chamber. The first raw material inlet pipe 2021, the second raw material inlet pipe 2022, and the clean gas injection pipe 2023 are all distributed at both ends of the ionization chamber 201. The gas is transmitted to the inner cavity of the quartz furnace tube 2 through the designed gas outlet. The distribution of the first raw material inlet pipe 2021 and the second raw material inlet pipe 2022 at both ends of the ionization chamber 201 allows the gas to diffuse from both sides of the inner cavity of the quartz furnace tube 2 towards the middle, forming a more uniform gas distribution field. At the same time, combined with the gas outlet pointing to the center of the silicon wafer 5, it further ensures that the gas covers all silicon wafers 5 and avoids insufficient local gas concentration from affecting the deposition effect. The inlet pipes 202 are all connected to the corresponding first inlet ports 101 on the support flange 1, which reduces the risk of leakage in the gas transmission path and ensures that the gas introduced from the first inlet port 101 can be delivered to the inner cavity of the quartz furnace tube 2 in a sufficient and stable manner, thus ensuring the stability and reliability of the gas supply.

[0020] The first temperature sensor 205 and the second temperature sensor 206 are used to ensure the temperature required for thin film deposition in the chamber. Both the first temperature sensor 205 and the second temperature sensor 206 pass through the support flange 1. The second temperature sensor 206 is fixed in the corresponding position. The first temperature sensor 205 and the second temperature sensor 206 ensure that the temperature in the second chamber 210 always meets the deposition process requirements. A rectangular hole 208 is provided on the inner wall 204 of the furnace tube. The space formed by the outer wall 203 of the furnace tube and the inner wall 204 of the furnace tube is the first chamber 209 and the second chamber 210. The first chamber 209 is connected to the exhaust pipe 207. The exhaust pipe 207 is used to discharge excess gas and by-products during the thin film deposition process. Through the design of the first chamber 209 being connected to the exhaust pipe 207, excess gas and by-products can be quickly discharged, preventing them from reacting in the quartz furnace tube 2 to generate particulate matter that contaminates the surface of the silicon wafer 5. At the same time, the gas pressure in the chamber is kept stable, providing a clean and stable environment for the deposition reaction.

[0021] The reactive gas in the ionization chamber 201 is ionized into plasma and enters the second chamber 210, which is enclosed by the inner wall 204 and the outer wall 203 of the furnace tube. The second chamber 210 is the space for the thin film deposition process of silicon wafer 5. After the reactive gas is ionized into plasma in the ionization chamber 201, its activity is significantly enhanced, and it can react more efficiently on the surface of silicon wafer 5, thereby increasing the thin film deposition rate. By clearly defining the second chamber 210 as the deposition space, the deposition reaction is concentrated in a specific area, which facilitates precise control of reaction conditions such as temperature and gas concentration, thereby improving the controllability of thin film deposition. The ionization chamber 201 includes a connecting gas pipe 2011, an electrode rod 2012, a third chamber 2013, and two electrode plates 2014. The connecting gas pipe 2011 is connected to the third air inlet 103 and is used to introduce the reaction gas required for thin film deposition. A certain number of air outlets are arranged on the connecting gas pipe 2011. Through the air outlets on the connecting gas pipe 2011, the reaction gas can be evenly dispersed into the ionization chamber 201, avoiding local gas accumulation that leads to insufficient ionization. At the same time, the connecting gas pipe 2011 is directly connected to the third air inlet 103, which shortens the gas transmission path, reduces gas loss, and ensures that the reaction gas enters the ionization area in sufficient quantity. Two electrode plates 2014 are arranged in parallel, and the electrode rod 2012 is supplied with the power required for ionization gas. The two electrode plates 2014 are grounded. The electrode rod 2012 and the electrode plate 2014 form an ionization space. The parallel electrode plates 2014 and the charged electrode rod 2012 form a uniform electric field, ensuring that the electric field strength in the ionization space is consistent, so that the reaction gas is uniformly ionized in the entire space, generating plasma with stable concentration, which provides a guarantee for the uniform deposition on the surface of the subsequent silicon wafer 5. The grounding design of the electrode plate 2014 improves the safety of equipment use. The third chamber 2013 is connected to the second chamber 210. When the reactive gas comes out from the outlet of the connecting gas pipe 2011, the gas can only enter the second chamber 210 from the open side of the third chamber 2013. Before entering the second chamber 210, the reactive gas must pass through the ionization space. After being ionized, the reactive gas enters the third chamber 2013. The structural design of the third chamber 2013 forces the reactive gas to pass through the ionization space formed by the electrode rod 2012 and the electrode plate 2014, ensuring that the reactive gas is fully ionized. At the same time, the third chamber 210 can briefly buffer the ionized plasma, so that the plasma concentration is further homogenized before entering the second chamber 210, thereby improving the deposition uniformity.

[0022] A retainer 104 is also provided on the upper part of the support flange 1. A slot 105 is provided on the upper part of the retainer 104. A groove 106 is provided on the cylindrical surface of the retainer 104. The slot 105 is connected to the third chamber 2013. In order to prevent other non-reactive gases from entering the gas channel, after inert gas is introduced from the second air inlet 102, the retainer 104 introduces the gas into the slot 105. The retainer 104 is designed with a guide groove and a hollow center, which facilitates the installation of the electrode rod 2012 and provides heat dissipation for the electrode rod 2012. The injected gas can improve the concentration of the reactant gas in the vertical space of the ionization chamber. The inert gas introduced through the second air inlet 102 via the retainer 104 forms an air curtain, which effectively blocks non-reactant gas from entering the gas channel and ensures the purity of the ionization environment. The guide groove and hollow design in the middle of the retainer 104 simplify the installation process of the electrode rod 2012. At the same time, the inert gas can carry away the heat of the electrode rod 2012 when it flows through, extending the service life of the electrode rod 2012. The inert gas can also regulate the concentration of reactant gas in the third chamber 2013 and improve the uniformity of the reactant gas concentration.

[0023] The slot 106 can guide the gas flow, and the gas introduced from here can remove some of the heat around the electrode rod 2012 and increase the life of the electrode rod 2012. The guiding effect of the slot 106 on the holder 104 makes the gas flow more orderly and improves the heat dissipation efficiency of the electrode rod 2012. Multiple silicon wafers 5 are placed on the upper part of the crystal boat 4. The crystal boat 4 rotates at low speed under the action of a motor. The crystal boat 4 drives the silicon wafers 5 to rotate at low speed, so that each part of the silicon wafer 5 can be evenly contacted with the gas and plasma in the second chamber 210. This avoids local deposition thickness differences caused by fixing the silicon wafers 5 and ensures that the film thickness is uniform.

[0024] The centerline of the exhaust pipe 207 forms a 60-70° angle with the centerline of the ionization chamber 201. The open surface of the third chamber 2013 is directly opposite the rectangular hole 208, which is used to connect the exhaust pipe 207 to the pump chamber. When the reaction gas and raw material gas are alternately introduced, under the action of the airflow generated by the pump, they will flow from the side of the inlet pipe 202 to the rectangular hole 208. During this process, as the crystal boat 4 rotates, the gas will be adsorbed on the surface of the silicon wafer 5, thus depositing a uniform layer on the surface of the silicon wafer 5. The uniform thin film, the design of the exhaust pipe 207 forming a 60-70° angle with the ionization chamber 201, combined with the structure of the open surface of the third chamber 2013 facing the rectangular hole 208, forms a stable airflow path from the intake pipe 202 to the exhaust pipe 207, allowing the gas to fully cover the surface of the silicon wafer 5 before being discharged, thus improving gas utilization; combined with the crystal boat 4 driving the silicon wafer 5 to rotate, it further enhances the uniform contact between the gas and the silicon wafer 5, ultimately achieving uniform deposition of the thin film on the surface of the silicon wafer 5 and reducing the film thickness deviation.

[0025] The first raw material inlet pipe 2021 is designed with a row of vent holes in the middle section, and the second raw material inlet pipe 2022 is designed with a row of vent holes in the upper section. The diameter of the two vent holes is the same, which is used to reduce the impact of the pressure difference between the upper and lower parts of the pipe to a certain extent, and improve the airflow uniformity at the vent holes. At the same time, the combined ventilation of the first raw material inlet pipe 2021 and the second raw material inlet pipe 2022 can cover all silicon wafers 5 in the furnace tube. The single-row vent design of the first raw material inlet pipe 2021 and the second raw material inlet pipe 2022 reduces the impact of the pressure difference between the upper and lower parts of the pipe on the airflow, ensures the stable gas flow of each vent hole, improves the airflow uniformity, and achieves full coverage of silicon wafers 5 at different positions in the quartz furnace tube 2. This avoids poor deposition quality of some silicon wafers 5 due to uneven gas supply and ensures the consistency of deposition effect of all silicon wafers 5.

[0026] The working principle is as follows: First, the quartz furnace tube 2 is placed on the upper part of the support flange 1 and secured with the fixing flange 3 to achieve a sealed fit. At the same time, a retainer 104 is installed on the upper part of the support flange 1 to ensure that the gap 105 of the retainer 104 is connected to the third chamber 2013 inside the quartz furnace tube 2. Then, multiple silicon wafers 5 are evenly placed in the carrying area of ​​the crystal boat 4, and the crystal boat 4 is then raised to the second chamber 210 inside the quartz furnace tube 2. The drive motor on the crystal boat 4 rotates at low speed. Then, check the sealing of each gas passage to confirm that the first air inlet 101 and the air inlet pipe 202, the first raw material air inlet pipe 2021, the second raw material air inlet pipe 2022 and the clean gas injection pipe 2023, the second air inlet 102 and the air passage of the retainer 104, and the air passage 2011 connecting the third air inlet 103 and the ionization chamber 201 are all sealed without leakage. Then, clean gas such as high-purity nitrogen is introduced into the clean gas injection pipe 2023 through the first air inlet 101. The gas enters the second chamber 210 through the air outlet pointing to the center of the silicon wafer 5 through the clean gas injection pipe 2023. The vacuum pump connected to the exhaust pipe 207 runs continuously during the process to exhaust the residual air in the chamber through the passage between the first chamber 209 and the exhaust pipe 207. After a period of time, the introduction of clean gas is stopped. Next, the first temperature sensor 205 and the second temperature sensor 206 are passed through the support flange 1, the sensor power is turned on to collect temperature data in real time, and the temperature is raised by the external heating device of the furnace tube. According to the thin film deposition process requirements, the temperature near the silicon wafer 5 monitored by the first temperature sensor 205 and the ambient temperature of the inner wall 204 of the furnace tube monitored by the second temperature sensor 206 are adjusted to the target value. After the temperature stabilizes, the next step is carried out.

[0027] Furthermore, raw material gas matching the reaction gas is introduced into the first raw material inlet pipe 2021 and the second raw material inlet pipe 2022 through the first air inlet 101. The first raw material inlet pipe 2021 has an outlet in the middle section, and the second raw material inlet pipe 2022 has an outlet in the upper section. Combined with the design of the air inlet pipe 202 pointing to the center of the silicon wafer 5, the raw material gas is fully covered in the second chamber 210, avoiding uneven airflow caused by the pressure difference between the upper and lower parts of the pipe. Under the action of the drive motor of the crystal boat 4, the silicon wafer 5 is driven to rotate at a low speed. During the process of raw material gas introduction, the raw material gas will be adsorbed on the surface of the silicon wafer 5. After the raw material gas is introduced for a period of time, the introduction of raw material gas is stopped, and then different amounts of inert gas are introduced into each air inlet for purging. Under the action of the pump, the excess raw material gas is pumped away.

[0028] Furthermore, the reaction gas required for thin film deposition is introduced into the connecting gas pipe 2011 through the third air inlet 103. The gas enters the ionization chamber 201 evenly through the air outlet on the connecting gas pipe 2011. At the same time, the power supply required for the electrode rod 2012 is turned on, so that the electrode rod 2012 and the two grounded parallel electrode plates 2014 form an ionization space. The reaction gas is ionized into plasma in the ionization space. Due to the structural limitation that the third chamber 2013 is only open and connected to the second chamber 210, the plasma can only enter the second chamber 210 through the open surface of the third chamber 2013. After the reaction gas is introduced for a period of time, the introduction of the reaction gas is stopped and the power supply of the electrode rod 2012 is turned off. The raw material gas adsorbed on the silicon wafer surface and the plasma undergo chemical reaction and thin film deposition on the surface of the silicon wafer 5 under the action of airflow. The design of the rectangular hole 208 facing the open surface of the third chamber 2013 allows the airflow to pass through the surface of the silicon wafer 5, ensuring uniform film thickness. Simultaneously, while the reaction gas is introduced, inert gas is introduced through the second air inlet 102. The gas enters the gap 105 through the guide groove of the retainer 104 and then flows into the third chamber 2013. The inert gas mixes with the plasma in the third chamber 2013 to improve the concentration distribution of the reaction gas and avoid local concentration anomalies. On the other hand, when it flows through the slot 106 of the retainer 104, it carries away the heat generated by the operation of the electrode rod 2012 and extends the service life of the electrode rod 2012. Meanwhile, during the deposition process, the second temperature sensor 206 continuously collects temperature data. If it deviates from the target value, it is adjusted in real time by the heating device. At the same time, the rotation state of the crystal boat 4 and the gas flow rate of each air inlet are observed to ensure that the parameters are stable. Excess gas and gaseous byproducts generated during film deposition enter the first chamber 209 through the rectangular hole 208 in the inner wall 204 of the furnace tube, and are finally discharged from the furnace tube through the exhaust pipe 207 to avoid possible accumulation of solid byproducts that may affect the film quality. The above process is a film deposition process.

[0029] After performing the above thin film deposition process multiple times to achieve the required thin film thickness, once the temperature in the temperature chamber drops to a certain value and the chamber pressure returns to normal, the crystal boat 4 is lowered and the deposited silicon wafer 5 is removed.

[0030] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A furnace tube structure for thin film deposition, comprising a supporting flange (1), a quartz furnace tube (2), a fixing flange (3), a crystal boat (4), and a plurality of silicon wafers (5), characterized in that: The quartz furnace tube (2) is placed on the upper part of the support flange (1), and the fixing flange (3) is used to fix the quartz furnace tube (2) on the upper part of the support flange (1); The front left and right ends of the support flange (1) are provided with a number of first air inlets (101), and the front middle of the support flange (1) is provided with a second air inlet (102) and a third air inlet (103). The first air inlet (101), the second air inlet (102) and the third air inlet (103) are used to introduce the reaction gas, raw material gas and inert gas required for thin film deposition, and at the same time, air inlets required for subsequent development of new processes are reserved. The quartz furnace tube (2) includes an ionization chamber (201), an outer wall (203), an inner wall (204), and an exhaust pipe (207). The interior of the quartz furnace tube (2) is provided with a first temperature sensor (205) and a second temperature sensor (206), which are used to measure the temperature near the silicon wafer (5) and the temperature near the outer wall (203) of the furnace tube, respectively. The first temperature sensor (205) is located near the outer edge of the silicon wafer (5).

2. The furnace tube structure for thin film deposition according to claim 1, characterized in that: The quartz furnace tube (2) is provided with multiple air inlet pipes (202) on the left and right sides. The air inlet pipe (202) in the middle of the left side is the first raw material air inlet pipe (2021), and the air inlet pipe (202) in the right side is the second raw material air inlet pipe (2022). The air inlet pipes (202) in the right side of the left side and the left side of the right side are both clean gas injection pipes (2023). Each air inlet pipe (202) is designed with an air outlet, and the air outlet points to the center of the silicon wafer (5). The first raw material inlet pipe (2021), the second raw material inlet pipe (2022), and the clean gas injection pipe (2023) are all distributed at both ends of the ionization chamber (201), and the gas is transmitted to the inner cavity of the quartz furnace tube (2) through the designed gas outlet. The air inlet pipes (202) are all connected to the corresponding first air inlet (101) on the support flange (1).

3. A furnace tube structure for thin film deposition according to claim 2, characterized in that: The first temperature sensor (205) and the second temperature sensor (206) are used to ensure the temperature required for thin film deposition in the chamber, and both the first temperature sensor (205) and the second temperature sensor (206) pass through the support flange (1), with the second temperature sensor (206) fixed in the corresponding position. The inner wall (204) of the furnace tube is provided with a rectangular hole (208). The space formed by the outer wall (203) of the furnace tube and the inner wall (204) of the furnace tube is a first chamber (209) and a second chamber (210). The first chamber (209) is connected to the exhaust pipe (207), which is used to discharge excess gas and by-products during the thin film deposition process.

4. A furnace tube structure for thin film deposition according to claim 1, characterized in that: The reactive gas in the ionization chamber (201) is ionized into plasma and enters the second chamber (210) enclosed by the inner wall (204) and outer wall (203) of the furnace tube. The second chamber (210) is the space for the silicon wafer (5) thin film deposition process. The ionization chamber (201) includes a connecting gas pipe (2011), an electrode rod (2012), a third chamber (2013), and two electrode plates (2014). The connecting gas pipe (2011) is connected to the third gas inlet (103) and is used to introduce the reaction gas required for thin film deposition. A certain number of gas outlet holes are arranged on the connecting gas pipe (2011). The two electrode plates (2014) are arranged in parallel, the electrode rod (2012) is supplied with the power required for ionization gas, the two electrode plates (2014) are grounded, and the electrode rod (2012) and the electrode plate (2014) form an ionization space; The third chamber (2013) is connected to the second chamber (210). When the reaction gas comes out from the outlet of the connecting gas pipe (2011), the gas can only enter the second chamber (210) from the open side of the third chamber (2013). Before entering the second chamber (210), the reaction gas must pass through the ionization space. After being ionized, the reaction gas enters the third chamber (2013).

5. A furnace tube structure for thin film deposition according to claim 1, characterized in that: The upper part of the support flange (1) is also provided with a retainer (104), the upper part of the retainer (104) is provided with a slit (105), the cylindrical surface of the retainer (104) has a slot (106), the slit (105) is connected to the third chamber (2013), after inert gas can be introduced from the second air inlet (102), the retainer (104) introduces the gas into the slit (105), the retainer (104) is used to facilitate the installation of the electrode rod (2012) through the form of the guide groove and the middle hollow, and can also dissipate heat from the electrode rod (2012). At the same time, the gas injected from here can improve the concentration of the reaction gas in the vertical space of the ionization chamber.

6. A furnace tube structure for thin film deposition according to claim 5, characterized in that: The slot (106) can guide the gas introduced, and the gas introduced from here can carry away some of the heat around the electrode rod (2012) and increase the life of the electrode rod (2012). Multiple silicon wafers (5) are placed on the upper part of the crystal boat (4), which rotates at low speed under the action of a motor.

7. A furnace tube structure for thin film deposition according to claim 3 or 5, characterized in that: The centerline of the exhaust pipe (207) forms an angle of 60-70° with the centerline of the ionization chamber (201). The open surface of the third chamber (2013) is directly opposite the rectangular hole (208). The pump chamber connected to the exhaust pipe (207) is used for pumping. When the reaction gas and raw material gas are alternately introduced, under the action of the airflow generated by the pump, they will flow from the side of the air inlet pipe (202) to the rectangular hole (208). During this process, as the crystal boat (4) rotates, the gas will be adsorbed on the surface of the silicon wafer (5), thus depositing a uniform thin film on the surface of the silicon wafer (5).

8. A furnace tube structure for thin film deposition according to claim 2, characterized in that: The first raw material inlet pipe (2021) is designed with a row of vent holes in the middle section, and the second raw material inlet pipe (2022) is designed with a row of vent holes in the upper section. The diameters of the two vent holes are the same, which is used to reduce the impact of the different air pressures at the top and bottom of the pipe to a certain extent, and improve the airflow uniformity at the vent holes. At the same time, the combined ventilation of the first raw material inlet pipe (2021) and the second raw material inlet pipe (2022) can cover all the silicon wafers (5) in the furnace tube.

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