Diffusion furnace, diffusion system and diffusion method

Abstract

The invention relates to a diffusion furnace, a diffusion system and a diffusion method, and relates to the field of semiconductor manufacturing. The furnace mouth and the air inlet are communicated with the interior of the quartz outer tube, and the furnace mouth is formed in one end of the quartz outer tube in the axial direction; the quartz inner tube is provided with a material placing port and an air outlet which are communicated with the interior of the quartz inner tube, the quartz inner tube is further provided with a furnace door, the material placing port is arranged at one end of the quartz inner tube in the axial direction, the furnace door is arranged close to the other end of the quartz inner tube in the axial direction or arranged at the other end of the quartz inner tube in the axial direction, and a material placing area is arranged in the quartz inner tube and used for placing wafers; according to the invention, through the cooperation of the quartz inner tube and the quartz outer tube, a closed and clean oxidation space can be created, preparation of the gate oxide film layer can be realized, introduction of metal and a movable ion contamination source is reduced through the quartz inner tube, and the quality of the gate oxide film layer can be improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing, and particularly to a diffusion furnace, a diffusion system, and a diffusion method. Background Art

[0002] As the most important oxide layer in a metal-oxide-semiconductor (MOS) device, the quality of the gate oxide layer (gate oxidation dielectric film, gate oxide film layer) directly affects the performance and lifespan of a MOS field-effect transistor (MOS transistor). During the high-temperature furnace tube process, when a silicon wafer (wafer) is oxidized, if metals and mobile ion contamination sources are present in the furnace tube, they will be distributed within the oxide layer. Additionally, heavy metal contaminants (such as copper and iron) diffuse extremely quickly in silicon and can thus enter the silicon substrate from the oxide layer, leading to a sharp increase in the leakage current at the PN junction. Mobile ion contaminants (such as sodium and potassium) diffuse quickly in the oxide layer and can cause instability in the MOS transistor's turn-on voltage. All of the above will seriously damage the electrical performance and long-term reliability of MOS devices. Summary of the Invention

[0003] This application provides a diffusion furnace, comprising: a quartz outer tube provided with a furnace opening and an air inlet communicating with the interior of the quartz outer tube, the furnace opening being disposed at one end of the quartz outer tube in the axial direction; a quartz inner tube provided with a material placement opening and an air outlet communicating with the interior of the quartz inner tube, and further provided with a furnace door, the material placement opening being disposed at one end of the quartz inner tube in the axial direction, the furnace door being disposed near the other end of the quartz inner tube in the axial direction or at the other end of the quartz inner tube in the axial direction, a material placement area being provided inside the quartz inner tube for placing wafers; wherein, when the quartz inner tube is placed inside the quartz outer tube, the furnace door is used to block the furnace opening, the material placement opening and the material placement area are placed inside the quartz outer tube, and the air outlet communicates the interior of the quartz inner tube with the exterior of the quartz outer tube.

[0004] This application provides a diffusion system, comprising the diffusion furnace described above; the diffusion system further comprises: a workbench; a wafer picking and placing device slidably connected to the workbench, when a part of the wafer picking and placing device is placed inside the quartz inner tube, the wafer picking and placing device is configured to slide relative to the workbench to slide out of the quartz outer tube in the axial direction of the quartz inner tube; and is configured to expand and contract in the direction of gravity to slide out of the quartz inner tube; a fixing device slidably connected to the workbench and connected to the quartz inner tube, when a part of the quartz inner tube is placed inside the quartz outer tube, the fixing device is configured to slide relative to the workbench to slide out of the quartz outer tube in the axial direction of the quartz outer tube.

[0005] The present application provides a diffusion method, including: placing a wafer in an oxygen environment and performing dry oxidation at a first temperature; placing the wafer in a wet oxygen environment and performing wet oxidation at a second temperature, where the second temperature is less than the first temperature; placing the wafer in the oxygen environment and performing dry oxidation at the first temperature; placing the wafer in a protective gas environment and performing annealing at a third temperature, where the third temperature is greater than the first temperature.

[0006] The beneficial effects brought by the present application are as follows: Through the cooperation mode of the quartz inner tube and the quartz outer tube, a closed and clean oxidation space can be created, thereby enabling the preparation of a gate oxide film layer. At the same time, the introduction of metal and mobile ion contamination sources is reduced through the quartz inner tube, thereby improving the quality of the gate oxide film layer. Description of the Drawings

[0007] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0008] Figure 1 It is a schematic structural diagram of the cooperation between a diffusion furnace and a wafer in some embodiments of the present application;

[0009] Figure 2 is Figure 1 a schematic structural diagram of the shown quartz inner tube in some embodiments;

[0010] Figure 3 is Figure 1 a schematic cross-sectional diagram at the online III-III when the shown diffusion furnace and wafer are cooperating;

[0011] Figure 4 It is a schematic structural diagram of a diffusion system in some embodiments of the present application;

[0012] Figure 5 It is a schematic flow diagram of a diffusion method in some embodiments of the present application.

[0013] 10. Quartz outer tube; 20. Quartz inner tube; 21. Tube body; 22. Furnace door; 23. Fixed part; 30. Boat; 31. Carrying main body; 32. Support leg; 40. Heat insulation part; 41. Carrier; 42. Heat insulation body; 50. Workbench; 51. First slide rail; 52. Second slide rail; 60. Fixing device; 70. Wafer picking and placing device; 100. Diffusion furnace; 101. Air inlet; 102. Furnace opening; 200. Wafer; 201. Loading port; 202. Air outlet; 203. Notch; 300. Diffusion system; 311. First surface; 312. Second surface; 2001. Loading area Detailed implementation manners

[0014] The following further describes the present application in detail with reference to the accompanying drawings and embodiments. It should be specifically noted that the following embodiments are only used to illustrate the present application, but do not limit the scope of the present application. Similarly, the following embodiments are only partial embodiments of the present application rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0015] When the present application mentions "embodiments", it means that the specific features, structures or characteristics described in combination with the embodiments may be included in at least one embodiment of the present application. Those skilled in the art explicitly and implicitly understand that the embodiments described in the present application can be combined with other embodiments.

[0016] In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0017] The present application describes a diffusion furnace, which can be used for thermal oxidation of wafers, and a relatively clean oxide layer (gate oxide layer) can be obtained on the basis of minimizing surface defects, so as to improve electrical performance. Thermal oxidation is to prepare a SiO2 thin film (gate oxide layer) by using the oxidation reaction between silicon and oxidation gases such as high-purity oxygen (dry oxygen) and wet oxygen (high-purity oxygen plus water vapor) at high temperature.

[0018] Please refer to Figure 1 , Figure 1 , which is a schematic structural diagram of the cooperation between the diffusion furnace and the wafer in some embodiments of the present application. The diffusion furnace 100 can be a horizontal diffusion furnace. The diffusion furnace 100 can include a quartz outer tube 10 and a quartz inner tube 20. The quartz inner tube 20 can be partially placed inside the quartz outer tube 10 to cooperate with the quartz outer tube 10 to form a closed and clean oxidation space. The wafer 200 can be placed inside the quartz inner tube 20. The cooperation between the quartz outer tube 10 and the quartz inner tube 20 can isolate the metal and mobile ion contamination sources outside the oxidation space as much as possible, reducing the interference of the metal and mobile ion contamination sources to the wafer 200. And the quartz inner tube 20 contains very few metal ions, or even none, and thus the precipitation of metal ions in the oxidation space can be reduced. In addition, the quartz inner tube 20 can also reduce the possibility of other metal and mobile ion contamination sources being brought into the oxidation space by the quartz inner tube 20. Therefore, the setting of the quartz inner tube 20 can improve the quality of the gate oxide film layer.

[0019] The quartz outer tube 10 may be provided with an air inlet 101. The air inlet 101 may communicate with the inside of the quartz outer tube 10 and facilitate the entry of oxidation gas into the quartz outer tube 10. In some embodiments, the air inlet 101 may be provided at one end of the quartz outer tube 10 in the axial direction (e.g., the direction of the axis O1). Of course, the position of the air inlet 101 can be adjusted and is not limited to the positions listed here. Specifically, it can be adjusted according to the well-known technical solutions in the art. In some embodiments, the air inlet 101 may be provided below and / or above the quartz inner tube 20 in the direction of gravity. In some embodiments, the air inlet 101 may be provided on one side or opposite sides of the quartz inner tube 20 in the horizontal direction. In some embodiments, the axis O1 of the quartz outer tube 10 passes through the air inlet 101. In some embodiments, the axis O1 of the quartz outer tube 10 coincides with the axis of the air inlet 101.

[0020] The quartz outer tube 10 may be provided with a furnace opening 102. The furnace opening 102 may communicate with the inside of the quartz outer tube 10 to allow the quartz inner tube 20 to pass through, such that a part of the quartz inner tube 20 is placed inside the quartz outer tube 10. The provision of the furnace opening 102 may facilitate the insertion of the quartz inner tube 20 into the quartz outer tube 10 or the removal of the quartz inner tube 20 from the quartz outer tube 10.

[0021] In some embodiments, the furnace opening 102 is provided at one end of the quartz outer tube 10 in the axial direction. Of course, the position of the furnace opening 102 can be adjusted and is not limited to the positions listed here. Specifically, it can be adjusted according to the well-known technical solutions in the art. In some embodiments, the axis O1 of the quartz outer tube 10 passes through the furnace opening 102. In some embodiments, the axis O1 of the quartz outer tube 10 coincides with the axis of the furnace opening 102.

[0022] Please refer to Figure 1 and Figure 2 , Figure 2 for Figure 1 the schematic structural diagram of the quartz inner tube 20 in some embodiments as shown. A material placement area 2001 may be provided inside the quartz inner tube 20 for placing the wafers 200. When the quartz inner tube 20 is placed inside the quartz outer tube 10, the material placement area 2001 may be placed inside the quartz outer tube 10, thereby facilitating the thermal oxidation of the wafers 200 in the material placement area 2001.

[0023] The quartz inner tube 20 may be provided with a material placement opening 201. The material placement opening 201 may communicate with the inside of the quartz inner tube 20 to allow the wafers 200 to pass through, such that the wafers 200 can be placed inside the quartz inner tube 20, for example, in the material placement area 2001. The provision of the material placement opening 201 may facilitate the insertion of the wafers 200 into the quartz inner tube 20 or the removal of the wafers 200 from the quartz inner tube 20. Additionally, it may also facilitate the entry of oxidation gas into the quartz inner tube 20.

[0024] In some embodiments, the material feeding port 201 may be provided at one end of the quartz inner tube 20 in the axial direction (e.g., the direction of the axis O2). Of course, the position of the material feeding port 201 can be adjusted and is not limited to the positions listed here. Specifically, it can be adjusted according to the well-known technical solutions in the art. In some embodiments, the axis O2 of the quartz inner tube 20 passes through the material feeding port 201. In some embodiments, the axis O2 of the quartz inner tube 20 coincides with the axis of the material feeding port 201.

[0025] The quartz inner tube 20 may be provided with an air outlet 202. The air outlet 202 can communicate the inside and outside of the quartz inner tube 20 to discharge the waste gas (which may include oxidation gas and / or waste gas) in the oxidation space. When the quartz inner tube 20 is placed inside the quartz outer tube 10, the air outlet 202 communicates the inside of the quartz inner tube 20 with the outside of the quartz outer tube 10. In some embodiments, the air outlet 202 may be provided at the other end of the quartz inner tube 20 in the axial direction. Of course, the position of the air outlet 202 can be adjusted and is not limited to the positions listed here. Specifically, it can be adjusted according to the well-known technical solutions in the art. In some embodiments, the axis O2 of the quartz inner tube 20 passes through the air outlet 202. In some embodiments, the axis O2 of the quartz inner tube 20 coincides with the axis of the air outlet 202.

[0026] It can be understood that during thermal oxidation, the oxidation gas can enter the oxidation space from the air inlet 101 of the quartz outer tube 10, then enter the quartz inner tube 20 from the material feeding port 201 of the quartz inner tube 20, and can reach the material placement area 2001, and then chemically react with the wafer 200 to generate waste gas, and the waste gas further discharges from the air outlet 202 of the quartz inner tube 20 to the outside of the quartz outer tube 10.

[0027] The quartz inner tube 20 may include a furnace door 22. The furnace door 22 can block the furnace opening 102 of the quartz outer tube 10 so that the quartz outer tube 10 and the quartz inner tube 20 cooperate to form a closed and clean oxidation space. In some embodiments, the furnace door 22 is preferably provided near the other end of the quartz inner tube 20 in the axial direction. Of course, the position of the furnace door 22 can be adjusted and is not limited to the positions listed here. Specifically, it can be adjusted according to the well-known technical solutions in the art. In some embodiments, the furnace door 22 may be provided at the other end of the quartz inner tube 20 in the axial direction.

[0028] In some embodiments, the air outlet 202 in the above embodiments may be provided on the furnace door 22.

[0029] The quartz inner tube 20 may include a tube body 21. The tube body 21 can be used to place the wafer 200. When the quartz inner tube 20 is placed inside the quartz outer tube 10, the tube body 21 can be at least partially located in the oxidation space, so that the wafer 200 can be thermally oxidized in the oxidation space. In some embodiments, when the quartz inner tube 20 is placed inside the quartz outer tube 10, the tube body 21 can be isolated from the outside of the quartz outer tube 10 and the outside of the quartz inner tube 20. In some embodiments, the tube body 21 can be provided with the material placement area 2001 in the above embodiments. The material placement area 2001 can be located inside the tube body 21. In some embodiments, the tube body 21 can be provided with the material placement opening 201 in the above embodiments. The material placement opening 201 communicates with the inside of the tube body 21. In some embodiments, the material placement opening 201 can be provided at one end in the axial direction of the tube body 21. In some embodiments, the axial direction of the tube body 21 can be the axial direction of the quartz inner tube 20 (for example, the direction of the axis O2). In some embodiments, when the quartz inner tube 20 is placed inside the quartz outer tube 10, the tube body 21 can be arranged at intervals with the quartz outer tube 10. In some embodiments, when the quartz inner tube 20 is placed inside the quartz outer tube 10, the quartz inner tube 20 can be moved to adjust the position of the tube body 21 inside the quartz outer tube 10, so that the axis of the tube body 21, such as the axis O2, is as close as possible to the axis O1 of the quartz outer tube 10. Of course, the axis of the tube body 21, such as the axis O2, can also coincide with the axis O1 of the quartz outer tube 10. Furthermore, the wafer 200 can be heated evenly during thermal oxidation, ensuring the uniformity of film layer growth. In some embodiments, when the quartz inner tube 20 is placed inside the quartz outer tube 10, the quartz inner tube 20 can be moved in a direction perpendicular to the axis O1 and / or the axis O2 to adjust the position of the tube body 21 inside the quartz outer tube 10. In some embodiments, the tube body 21 can be partially located in the oxidation space. Furthermore, the gas outlet 202 in the above embodiments can be provided.

[0030] In some embodiments, the tube body 21 can be fixedly connected to the furnace door 22. In some embodiments, the tube body 21 and the furnace door 22 can be integrally formed as an integral structure. In some embodiments, the cross-sectional area of the tube body 21 perpendicular to the axis O2 can be smaller than the area of the furnace door 22 for blocking the furnace opening 102, which can facilitate the movement of the quartz inner tube 20 inside the quartz outer tube 10 to adjust the position of the tube body 21 inside the quartz outer tube 10. In some embodiments, the surface area of the furnace door 22 for blocking the furnace opening 102 can be larger than the area of the furnace opening 102, which can facilitate the movement of the quartz inner tube 20 inside the quartz outer tube 10 to adjust the position of the tube body 21 inside the quartz outer tube 10.

[0031] The quartz inner tube 20 can be clamped and fixed or connected and fixed by a fixing device. The setting of the fixing device can facilitate the movement of the quartz inner tube 20, for example, the quartz inner tube 20 is moved into the quartz outer tube 10 or moved out of the quartz outer tube 10. In addition, it can also prevent the operator from directly contacting the quartz inner tube 20. In some embodiments, the quartz inner tube 20 can be detachably connected to the fixing device, which is convenient for replacing the quartz inner tube 20.

[0032] The quartz inner tube 20 can include a fixing portion 23 to cooperate with the fixing device, such as being clamped and fixed or connected and fixed. The specific structure of the fixing portion 23 can be set based on the structure of the fixing device or can also be set based on the well-known technical solutions in the art, as long as the cooperation between the fixing portion 23 and the fixing device can be achieved, which will not be elaborated here.

[0033] In some embodiments, the fixing portion 23 can be fixedly connected to the furnace door 22. In some embodiments, the fixing portion 23 can be integrally formed with the furnace door 22 as an integral structure. In some embodiments, the fixing portion 23 and the tube body 21 can be located on opposite sides of the furnace door 22.

[0034] In some embodiments, the fixing device can drive the quartz inner tube 20, such as the fixing portion 23, to move, so as to realize the movement of the quartz inner tube 20 in the quartz outer tube 10, and can also adjust the position of the tube body 21 in the quartz outer tube 10. In some embodiments, the fixing device can drive the quartz inner tube 20, such as the fixing portion 23, to move on the axis O2. In some embodiments, the fixing device can drive the quartz inner tube 20, such as the fixing portion 23, to move in a direction perpendicular to the axis O2.

[0035] In some embodiments, the air outlet 202 in the above embodiments can be provided on the fixing portion 23.

[0036] In some embodiments, when the quartz inner tube 20, such as the tube body 21, is placed in the quartz outer tube 10, the quartz inner tube 20, such as the tube body 21, can move, and then can drive the wafer 200 to move, so as to adjust the relative position between the axis O of the wafer 200 and the axis O1 of the quartz outer tube 10, making the axis O of the wafer 200 as close as possible to the axis O1 of the quartz outer tube 10 to ensure the uniformity of the growth of the gate oxide film layer. Of course, the axis O of the wafer 200 can also coincide with the axis O1 of the quartz outer tube 10.

[0037] In some embodiments, the fixing device can drive the quartz inner tube 20, such as the fixing part 23, to move, so as to realize the movement of the quartz inner tube 20 and the wafer 200 within the quartz outer tube 10. It can also adjust the positions of the tube body 21 and the wafer 200 within the quartz outer tube 10, making the axis O of the wafer 200 as close as possible to the axis O1 of the quartz outer tube 10. Of course, the axis O of the wafer 200 can also be made to coincide with the axis O1 of the quartz outer tube 10. Furthermore, the wafer 200 can be evenly heated during thermal oxidation, ensuring the uniformity of the film layer growth.

[0038] In some embodiments, when the quartz inner tube 20, such as the tube body 21, is placed within the quartz outer tube 10, the quartz inner tube 20, such as the furnace door 22, can move in a direction perpendicular to the axial direction of the quartz outer tube 10, thereby driving the wafer 200 to move and adjusting the relative position between the axis O of the wafer 200 and the axis O1 of the quartz outer tube 10.

[0039] In some embodiments, the fixing device can drive the quartz inner tube 20, such as the fixing part 23, to move, so as to realize the movement of the quartz inner tube 20 and the wafer 200 within the quartz outer tube 10 and in a direction perpendicular to the axial direction of the quartz outer tube 10. It can also adjust the positions of the tube body 21 and the wafer 200 within the quartz outer tube 10.

[0040] Please refer to Figure 1 、 Figure 2 and Figure 3 , Figure 3 for Figure 1 the schematic cross-sectional view at the online III-III when the diffusion furnace 100 and the wafer 200 cooperate as shown. The quartz inner tube 20, such as the tube body 21, is provided with a notch 203 at the bottom in the gravity direction. The notch 203 can communicate the inside and outside of the quartz inner tube 20, facilitating the entry of oxidation gas into the oxidation space and ensuring the uniformity and consistency of the thickness of the gate oxide film layer.

[0041] In some embodiments, the notch 203 can only penetrate the side wall of the quartz inner tube 20, such as the tube body 21. Thus, the notch 203 can also be referred to as a "communication hole". The size and number of the communication holes can be set according to the well-known technical solutions in the art. Moreover, in other embodiments, the position of the communication holes may not be limited to the bottom of the quartz inner tube 20, such as the tube body 21, in the gravity direction, and can also be set at other positions, which will not be elaborated here.

[0042] In some embodiments, the communication holes communicate the inside and outside of the quartz inner tube 20, such as the tube body 21.

[0043] It can be understood that the size and number of the notch 203 can also be set according to the well-known technical solutions in the art, such as one, such as two, such as more than two.

[0044] In some embodiments, the notch 203 may be provided corresponding to the material placing area 2001 in the above embodiments. That is, the notch 203 may be provided at the bottom of the material placing area 2001 in the direction of gravity. Since the wafer 200 is placed at the bottom of the material placing area 2001 based on gravity, it can be relatively close to the bottom of the material placing area 2001, and even directly or indirectly in contact. Further, the gap between the bottom of the material placing area 2001 and the wafer 200 is not sufficient for the oxidation gas to flow through, which will further cause poor growth of the gate oxide film layer, resulting in uneven film layer thickness. The setting of the notch 203 can ensure the fluidity of the oxidation gas, so that the oxidation gas can be filled between the bottom of the material placing area 2001 and the wafer 200, facilitating the growth of the film layer to ensure the uniformity and consistency of the gate oxide film layer thickness.

[0045] In some embodiments, the communication hole may be provided corresponding to the material placing area 2001 in the above embodiments. That is, the communication hole may be provided at the bottom of the material placing area 2001 in the direction of gravity.

[0046] In some embodiments, the notch 203 may be extended and provided in the axial direction of the quartz inner tube 20, such as the tube body 21, to form a long strip-shaped notch. In some embodiments, the notch 203 may not only be located at the bottom of the material placing area 2001, but also extend outside the material placing area 2001. In some embodiments, the notch 203 may be extended and provided toward the side close to the furnace door 22. In some embodiments, the notch 203 may also be extended and provided toward the side close to the material placing port 201. Further, in a further embodiment, the notch 203 may be extended and provided toward the side close to the material placing port 201 to communicate with the material placing port 201.

[0047] Please refer to Figure 1 The diffusion furnace 100 may further include a wafer boat 30. The wafer boat 30 can be used to carry the wafer 200, and then can carry the wafer 200 and be placed together in the quartz inner tube 20, such as the tube body 21. That is, the wafer boat 30 can be placed in the quartz inner tube 20, such as the tube body 21.

[0048] When the wafer boat 30 carries the wafer 200, the wafer boat 30 can be transported into the quartz inner tube 20, such as the tube body 21, under the transportation of the wafer picking and placing device and / or under the operation of the operator, which can reduce the direct contact between the wafer 200 and other structures or the operator, etc., and further reduce the contact between the wafer 200 and the metal and movable ion contamination sources, improving the quality of the gate oxide film layer.

[0049] In some embodiments, the wafer boat 30 can be placed in the material placing area 2001 in the above embodiments.

[0050] In some embodiments, there may be multiple susceptors 30, which may be arranged in the axial direction of the quartz inner tube 20, such as the tube body 21. In some embodiments, adjacent susceptors 30 are spaced apart so that the oxidation gas can flow between adjacent susceptors 30. Even the oxidation gas can flow from the bottom of the susceptor 30 to the gap between adjacent susceptors 30 and further flow between adjacent wafers 200 to ensure the thickness uniformity and consistency of the gate oxide film layer. In some embodiments, the spacing distance between adjacent susceptors 30 may be 1-2 mm. Of course, the spacing distance can also be adjusted according to the needs of those skilled in the art and is not limited to the embodiments listed here.

[0051] In some embodiments, when the susceptor 30 is placed in the loading area 2001, it may be located above the notch 203. Of course, the susceptor 30 may also be partially placed in the notch 203.

[0052] Please refer to Figure 3 , the susceptor 30 may have a first surface 311 and a second surface 312 arranged opposite to each other. In some embodiments, the first surface 311 and / or the second surface 312 are non-planar structures such as curved surfaces or irregular surfaces, which can be specifically set according to the needs of those skilled in the art and will not be elaborated here. In other embodiments, the first surface 311 and / or the second surface 312 may also be planar. In some embodiments, the first surface 311 and / or the second surface 312 are curved surfaces, which can improve the firmness of the susceptor 30, can avoid deformation problems in the thermal oxidation environment as much as possible, and can also avoid particle contamination caused by mechanical vibration or friction as much as possible. In some embodiments, the first surface 311 is a curved surface to fit the inner surface of the quartz inner tube 20, such as the tube body 21, increasing the contact area between the susceptor 30 and the inner surface of the quartz inner tube 20, such as the tube body 21, and thus enhancing the support of the quartz inner tube 20, such as the tube body 21, for the susceptor 30.

[0053] In some embodiments, the first surface 311 may be in contact with the inner surface of the quartz inner tube 20, such as the tube body 21, to enhance the support of the quartz inner tube 20, such as the tube body 21, for the susceptor 30. In some embodiments, the second surface 312 is used to carry the wafer 200 to stabilize the wafer 200.

[0054] In some embodiments, please refer to Figure 3, on a reference section perpendicular to the axial direction of the quartz inner tube 20, such as the tube body 21, the curvature of the first surface 311 can be set according to the needs of those skilled in the art. Furthermore, the curvature of the first surface 311 can be less than the curvature of the inner surface of the quartz inner tube 20, such as the tube body 21, can be equal to the curvature of the inner surface of the quartz inner tube 20, such as the tube body 21, or can be greater than the curvature of the inner surface of the quartz inner tube 20, such as the tube body 21. In some embodiments, when the curvature of the first surface 311 is less than the curvature of the inner surface of the quartz inner tube 20, such as the tube body 21, it is convenient for the first surface 311 to contact the inner surface of the quartz inner tube 20, such as the tube body 21, on both sides of the middle, enhancing the support of the quartz inner tube 20, such as the tube body 21, for the susceptor 30. In some embodiments, when the curvature of the first surface 311 is equal to the curvature of the inner surface of the quartz inner tube 20, such as the tube body 21, it is convenient for the entire first surface 311 to contact the inner surface of the quartz inner tube 20, such as the tube body 21, enhancing the support of the quartz inner tube 20, such as the tube body 21, for the susceptor 30.

[0055] In some embodiments, the curvature of the second surface 312 is less than or equal to the curvature of the wafer 200, so as to enhance the support of the susceptor 30 for the wafer 200.

[0056] In some embodiments, the setting of the notch 203 facilitates the wafer pick-and-place device for picking and placing the susceptor 30 to slide into the quartz inner tube 20, such as the tube body 21, from the notch 203 in the gravity direction, or to slide out of the quartz inner tube 20, such as the tube body 21, from the notch 203, and also facilitates the wafer pick-and-place device for picking and placing the susceptor 30 to slide into the quartz inner tube 20, such as the tube body 21, from the notch 203 in the axial direction of the quartz inner tube 20, such as the tube body 21, or to slide out of the quartz inner tube 20, such as the tube body 21, from the notch 203.

[0057] In some scenarios, when placing the susceptor 30 into the quartz inner tube 20, such as the tube body 21, the wafer pick-and-place device for picking and placing the susceptor 30 can slide into the notch 203 and the quartz inner tube 20, such as the tube body 21, along the axial direction of the quartz inner tube 20, such as the tube body 21, from the notch 203 and the loading port 201, and make the susceptor 30 slide into the quartz inner tube 20, such as the tube body 21, from the loading port 201. Furthermore, the wafer pick-and-place device can slide within the notch 203 until it reaches the loading area 2001. Then, the wafer pick-and-place device slides out of the quartz inner tube 20, such as the tube body 21, from the notch 203 in the gravity direction, and places the susceptor 30 in the loading area 2001 within the quartz inner tube 20, such as the tube body 21.

[0058] In some scenarios, when removing the susceptor 30 from the quartz inner tube 20, such as the tube body 21, the wafer handling device for picking and placing the susceptor 30 can be placed below the susceptor 30. The wafer handling device slides into the quartz inner tube 20, such as the tube body 21, from the notch 203 in the direction of gravity, lifts the susceptor 30, and places the susceptor 30 on the wafer handling device. Furthermore, the wafer handling device can slide within the notch 203. Meanwhile, the susceptor 30 moves within the quartz inner tube 20, such as the tube body 21. Then, the wafer handling device can move along the axial direction of the quartz inner tube 20, such as the tube body 21, and can slide out of the quartz inner tube 20, such as the tube body 21, from the notch 203 and the loading port 201, and cause the susceptor 30 to slide out of the quartz inner tube 20, such as the tube body 21, from the loading port 201. Then, the wafer handling device transports the susceptor 30 to the unloading area.

[0059] Please refer to Figure 3 , the susceptor 30 can include a carrying body 31 and support legs 32. The carrying body 31 and the support legs 32 are connected. The carrying body 31 can be used to carry wafers 200 on the side facing away from the support legs 32. The support legs 32 can be used to support the susceptor 30 on the wafer handling device and / or within the quartz inner tube 20, such as the tube body 21.

[0060] In some embodiments, the carrying body 31 can be provided with the first surface 311 and / or the second surface 312 in the above embodiments.

[0061] In some embodiments, the support legs 32 can be located within the notch 203 to facilitate the quartz inner tube 20, such as the tube body 21, to limit the susceptor 30 and enhance the support of the quartz inner tube 20, such as the tube body 21, for the susceptor 30. Of course, the support legs 32 located within the notch 203 also facilitate cooperation with the wafer handling device to support the susceptor 30 on the wafer handling device.

[0062] In some embodiments, the support legs 32 can be one or more. In some embodiments, one or more support legs 32 can all be located within one notch 203. In some embodiments, there can also be multiple notches 203, and the multiple support legs 32 cooperate with the multiple notches 203 so that one support leg 32 is located within one notch 203.

[0063] In some embodiments, the susceptor 30 can be a quartz susceptor.

[0064] Please refer to Figure 3, on a reference cross-section perpendicular to the axial direction of the quartz outer tube 10 or a reference cross-section perpendicular to the axial direction of the quartz inner tube 20, such as the tube body 21, the ratio between the distance between the axis O of the wafer 200 and the axis O1 of the quartz outer tube 10 and the radius of the wafer 200 is between 0 and 50%. Further, the wafer 200 can be uniformly heated during thermal oxidation, ensuring the uniformity of the film layer growth. Between 0 and 50% means greater than or equal to 0 and less than or equal to 50%. In some embodiments, this ratio is between 0 and 30%. In some embodiments, this ratio is between 0 and 10%. In some embodiments, this ratio is between 0 and 3%. In some embodiments, this ratio is between 15 and 35%.

[0065] Please refer to Figure 1 and Figure 2 , the diffusion furnace 100 may further include a heat insulation member 40. The heat insulation member 40 is disposed inside the quartz inner tube 20, such as the tube body 21, and may be located between the furnace door 22 and the loading area 2001. The setting of the heat insulation member 40 can prevent the heat inside the quartz inner tube 20, such as the tube body 21, from dissipating in the form of thermal radiation, playing a heat preservation role.

[0066] In some embodiments, the heat insulation member 40 may be a quartz product. In some embodiments, the heat insulation member 40 may include a carrier 41 and a heat insulation body 42 disposed on the carrier 41. The setting of the carrier 41 can dispose the heat insulation body 42 inside the quartz inner tube 20, such as the tube body 21. In some embodiments, the carrier 41 may be the crystal boat 30 in the above embodiments. Further, in some embodiments, the wafer picking and placing device can be used for picking and placing. Further, in some embodiments, the notch 203 can be disposed below the heat insulation member 40. Further, in some embodiments, the operation method for picking and placing the heat insulation member 40 can refer to the operation method in the above embodiments, which will not be elaborated.

[0067] In some embodiments, the heat insulation member 40 may include quartz wool.

[0068] In some embodiments, the heat insulation member 40 may be located between the air outlet 202 and the loading area 2001.

[0069] In some embodiments, the air outlet 202 is located on the side of the heat insulation member 40 away from the material placement area 2001, so that the waste gas at the material placement area 2001 passes through the gap between the heat insulation member 40 and the quartz outer tube 10 and is further discharged through the air outlet 202. The ratio between the effective flow-through area between the heat insulation member 40 and the quartz outer tube 10 (i.e., the size of the gap between the heat insulation member 40 and the quartz outer tube 10) and the effective flow-through area of the quartz outer tube 10 at the heat insulation member 40 is between 10 - 50%. By restricting this ratio, the heat insulation effect of the heat insulation member 40 can be ensured, and the thickness uniformity and consistency of the gate oxide film layer can also be ensured. In some embodiments, this ratio is between 10 - 30%. In some embodiments, this ratio is between 15 - 30%. In some embodiments, this ratio is between 20 - 35%. In some embodiments, this ratio is between 10 - 25%. In some embodiments, this ratio is between 25 - 30%.

[0070] Next, a diffusion system will be described. The diffusion system can be used for thermal oxidation of wafers, and a relatively clean oxide layer (gate oxide layer) can be obtained on the basis of minimizing surface defects, so as to improve electrical performance. Thermal oxidation is an oxidation reaction between silicon and oxidation gases such as high-purity oxygen (dry oxygen) and wet oxygen (high-purity oxygen plus water vapor) at high temperature to prepare a SiO2 thin film (gate oxide layer).

[0071] Please refer to Figure 4 , Figure 4 which is a schematic structural diagram of the diffusion system in some embodiments of the present application. The diffusion system 300 may include the diffusion furnace 100 in the above embodiments. The diffusion system 300 may further include a workbench 50, a fixing device 60, and a wafer picking and placing device 70.

[0072] The workbench 50 is used to support and install the diffusion furnace 100 in the above embodiments, and can also support and install the fixing device 60 and the wafer picking and placing device 70. The first slide rail 51 and the second slide rail 52 may be provided on the workbench 50. The first slide rail 51 and the second slide rail 52 may be slide rails and / or tracks in well-known technical solutions in the art, and will not be elaborated.

[0073] The fixing device 60 can be connected to the quartz inner tube 20 by well-known fixing methods in the art such as plugging, welding, screwing, or clamping. Of course, the fixing device 60 can also clamp and fix the quartz inner tube 20, or the quartz inner tube 20 can be clamped and fixed on the fixing device 60. Even the fixing device 60 and the quartz inner tube 20 can be an integral structure.

[0074] In some embodiments, the fixing device 60 can be connected and cooperated with the quartz inner tube 20, such as the fixing part 23.

[0075] In some embodiments, the fixing device 60 can be installed on the workbench 50 and can be slidably connected to the workbench 50. In some embodiments, the fixing device 60 can be arranged on the first slide rail 51 and can slide along the extending direction of the first slide rail 51. In some embodiments, the extending direction of the first slide rail 51 can be the axial direction of the quartz inner tube 20 or the axial direction of the quartz outer tube 10.

[0076] In some scenarios, when the fixing device 60 slides on the first slide rail 51, it can drive the quartz inner tube 20 to move, so that the quartz inner tube 20 slides out of the quartz outer tube 10 or slides into the quartz outer tube 10.

[0077] In some embodiments, the fixing device 60 can adjust the relative position between the quartz inner tube 20 and the quartz outer tube 10. In some embodiments, the fixing device 60 can adjust the relative position between the quartz inner tube 20 and the quartz outer tube 10 in a plane perpendicular to the axial direction of the quartz outer tube 10 or the axial direction of the quartz inner tube 20. Of course, when the fixing device 60 stops sliding on the first slide rail 51, the fixing device 60 can also adjust the relative position between the quartz inner tube 20 and the quartz outer tube 10 in the axial direction of the quartz inner tube 20 or the axial direction of the quartz outer tube 10 or the extending direction of the first slide rail 51.

[0078] It can be understood that the fixing device 60 can adjust the relative position between the quartz inner tube 20 and the quartz outer tube 10 in a suitable manner in the required direction based on the need, so that the quartz inner tube 20 cooperates with the quartz outer tube 10. In addition, the fixing device 60 can also be a structure well-known in the art that can adjust the relative position between the quartz inner tube 20 and the quartz outer tube 10 by means of its own expansion, bending or state change, etc. It is not limited to the embodiments listed here and can also be other, which will not be elaborated.

[0079] In some embodiments, the fixing device 60 can be a telescopic structure to adjust the relative position of the quartz inner tube 20 relative to the quartz outer tube 10 through telescoping, so that the axis O of the wafer 200 is as close as possible to the axis O1 of the quartz outer tube 10, so as to ensure uniform heating of the wafer 200 during thermal oxidation and further ensure the uniformity of film layer growth. In some embodiments, the telescopic structure can be a telescopic rod, a telescopic frame, a structure similar to the structures listed here or other, which will not be elaborated.

[0080] In some embodiments, the quartz inner tube 20 can be slidably connected to the fixing device 60 so that the quartz inner tube 20 can move to adjust the relative position of the quartz inner tube 20 relative to the quartz outer tube 10.

[0081] The wafer pick - and - place device 70 can be connected to the susceptor 30 by a detachable connection method well - known in the art, such as plugging or clamping, etc. Of course, the wafer pick - and - place device 70 can also clamp the susceptor 30. Even the fixing device 60 can be only used to place the susceptor 30, and it is only necessary to realize the function of lifting and lowering the susceptor 30.

[0082] In some embodiments, the wafer pick - and - place device 70 can contact the susceptor 30, such as the support leg 32, so that the susceptor 30 is supported on the wafer pick - and - place device 70 through the support leg 32. In some embodiments, the wafer pick - and - place device 70 can also be provided with a positioning portion to cooperate with the support leg 32 to achieve stable support for the susceptor 30. In some embodiments, the positioning portion is provided with a groove to fit with the support leg 32 and accommodate the support leg 32.

[0083] In some embodiments, the wafer pick - and - place device 70 can extend into the quartz inner tube 20 from the notch 203.

[0084] In some embodiments, the wafer pick - and - place device 70 can be installed on the workbench 50 and can be slidably connected to the workbench 50. In some embodiments, the wafer pick - and - place device 70 can be arranged on the second slide rail 52 and can slide along the extension direction of the second slide rail 52. In some embodiments, the extension direction of the second slide rail 52 can be the axial direction of the quartz inner tube 20 or the axial direction of the quartz outer tube 10.

[0085] In some scenarios, when the wafer pick - and - place device 70 slides on the second slide rail 52, it can drive the susceptor 30 to move, so that the susceptor 30 slides out of the quartz inner tube 20 or slides into the quartz inner tube 20.

[0086] In some embodiments, the wafer pick - and - place device 70 can adjust the relative position between the susceptor 30 and the quartz inner tube 20. In some embodiments, the wafer pick - and - place device 70 can adjust the relative position between the susceptor 30 and the quartz inner tube 20 in a plane perpendicular to the axial direction of the quartz outer tube 10 or the axial direction of the quartz inner tube 20. Of course, when the wafer pick - and - place device 70 stops sliding on the second slide rail 52, the wafer pick - and - place device 70 can also adjust the relative position between the susceptor 30 and the quartz inner tube 20 in the axial direction of the quartz inner tube 20 or the axial direction of the quartz outer tube 10 or the extension direction of the second slide rail 52.

[0087] In some embodiments, the wafer pick - and - place device 70 can be detachably connected to the workbench 50.

[0088] It can be understood that the wafer pick - and - place device 70 can adjust the relative position of the susceptor 30 and the quartz inner tube 20 in the required direction and in a suitable manner based on the need, so that the susceptor 30 cooperates with the quartz inner tube 20. In addition, the wafer pick - and - place device 70 can also be a structure well - known in the art that can adjust the relative position of the susceptor 30 and the quartz inner tube 20 by means of its own expansion, bending, or state change, etc. It is not limited to the embodiments listed here and can also be other, which will not be elaborated.

[0089] In some embodiments, the wafer pick - and - place device 70 can be a telescopic structure to adjust the relative position of the susceptor 30 and the quartz inner tube 20 by telescoping.

[0090] In some embodiments, the wafer pick - and - place device 70 can be a telescopic structure to adjust the relative position of the susceptor 30 and the quartz inner tube 20 in the direction of gravity by telescoping.

[0091] In some embodiments, the extending direction of the first slide rail 51 is the same as the extending direction of the second slide rail 52.

[0092] Next, a diffusion method will be described. The diffusion method can be used in the diffusion furnace 100 in the above - mentioned embodiments and can also be used in the diffusion system 300 in the above - mentioned embodiments. Please refer to Figure 5 , Figure 5 which is a schematic flow chart of the diffusion method in some embodiments of the present application. The diffusion method may include:

[0093] Step S501: Place the wafer in an oxygen environment and perform dry - oxygen oxidation at a first temperature.

[0094] The oxygen environment can be an environment formed by the oxidation gas such as high - purity oxygen (dry oxygen) in the above - mentioned embodiments. For example, an environment formed by filling the oxidation space in the above - mentioned embodiments with the oxidation gas. The oxide layer prepared in step S501 has a dense structure, fewer defects, high breakdown resistance, and good integrity of the oxide layer.

[0095] In some embodiments, a chlorine - doped compound can be introduced into the oxidation gas to decompose Cl−, further neutralize metal ions and mobile charges, and reduce metal ion contamination.

[0096] In some embodiments, step S501 may include dry - oxygen oxidation in an oxygen environment at 700 - 900 °C for preparing a dense dry - oxygen layer on the top - layer interface. Of course, the first temperature can also be adjusted and controlled according to actual needs and is not limited to the embodiments listed here.

[0097] Step S502: Place the wafer in a wet - oxygen environment and perform wet - oxygen oxidation at a second temperature.

[0098] The wet oxygen environment may be an environment formed by the oxidizing gas in the above embodiment, such as wet oxygen (high purity oxygen plus water vapor), for example, an environment formed by filling the oxidizing space in the above embodiment with the oxidizing gas.

[0099] Since the gate oxide layer (gate oxide layer) prepared in step S501 has low ionizing radiation resistance, it can be strengthened in step S502 to enhance the ionizing radiation resistance. - Base, and OH - The base is an electron trap. The negative charge accumulation it produces can compensate for the accumulation of positive charge in the oxide layer, making it difficult for the threshold voltage of the MOS device to drift negatively after being exposed to ionizing radiation, thereby improving reliability and stability.

[0100] In some embodiments, the second temperature is less than the first temperature.

[0101] In some embodiments, step S502 may include lowering the first temperature to a second temperature for wet oxygen oxidation. Low temperature oxidation can effectively control the wet oxygen oxidation rate while reducing interface charge and lattice defect density. In some embodiments, the second temperature is 700-900° C. Of course, the second temperature can also be adjusted and controlled according to actual needs and is not limited to the embodiments listed here.

[0102] Step S503: placing the wafer in an oxygen environment and performing dry oxygen oxidation at a first temperature.

[0103] Please refer to the above step S501 and no further details will be given.

[0104] Since the oxidation rate of wet oxygen oxidation in step S502 is fast and difficult to control, which leads to problems such as loose gate oxide layer quality, low anti-breakdown ability, high interface charge density, etc., step S503 can be used for strengthening to reduce the problems caused by step S502 as much as possible and retain the better effect of step S502.

[0105] In some embodiments, step S503 may include heating the temperature to the first temperature again to perform dry oxygen oxidation to prepare a dense dry oxygen layer at the bottom interface.

[0106] Step S504: placing the wafer in a protective gas environment and annealing at a third temperature.

[0107] The protective gas environment may be formed by an inert gas or other gas that is not easy to react with the diffusion furnace 100, the wafer 200, the diffusion system 300, etc. For example, an environment formed by filling the oxidation space in the above embodiment with an inert gas or other gas that is not easy to react with the diffusion furnace 100, the wafer 200, the diffusion system 300, etc.

[0108] In some embodiments, step S504 may include annealing at a third temperature by heating up from a first temperature in a protective gas environment to further reduce the interface charge density.

[0109] In some embodiments, the third temperature is greater than the first temperature.

[0110] In some embodiments, the third temperature is greater than or equal to 700 °C and less than or equal to 900 °C. Of course, the third temperature can also be adjusted and controlled according to actual needs, and is not limited to the embodiments listed here.

[0111] In some embodiments, the film layer thickness is 25 - 35 nm. In some embodiments, the film layer thickness is 30 nm. Of course, the film layer thickness can also be adjusted and controlled according to actual needs, and is not limited to the embodiments listed here.

[0112] In some embodiments, step S501 may include dry oxidation in an oxygen environment at 850 °C for 5 min.

[0113] In some embodiments, step S502 may include reducing the temperature to 800 °C for wet oxidation for 15 - 20 min.

[0114] In some embodiments, step S503 may include heating up to 850 °C again for dry oxidation for 5 min.

[0115] In some embodiments, step S504 may include continuing to heat up to 875 °C for annealing in an N2 atmosphere for 30 min.

[0116] The diffusion method in this application can enable the top and bottom dense dry oxygen layers (gate oxide layers generated in an oxygen environment) of the wafer 200 to provide good breakdown resistance and passivation effects. The wet oxygen layer in the middle (gate oxide layer generated in a wet oxygen environment) provides OH - -based electron traps, reducing the threshold voltage drift problem caused by gate oxide charging, and enhancing the anti-ionizing radiation ability of the device. At the same time, annealing in a protective gas environment can reduce the interface charge density and reduce the device leakage current.

[0117] In several implementation manners provided in this application, it should be understood that the disclosed method and device can be implemented in other ways. For example, the device implementation manner described above is only illustrative. For example, the division of modules or units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0118] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or may be distributed across multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0119] In addition, each functional unit in various embodiments of the present application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0120] The above are only the embodiments of the present application, and do not limit the patent scope of the present application accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A diffusion furnace, characterized in that: include: The quartz outer tube is provided with a furnace port and an air inlet which are connected with the inside of the quartz outer tube, and the furnace port is provided at one end of the quartz outer tube in the axial direction; The quartz inner tube is provided with a material placement port and an air outlet communicated with the inner tube, and is also provided with a furnace door, the material placement port is provided at one end of the quartz inner tube in the axial direction, the furnace door is provided close to or at the other end of the quartz inner tube in the axial direction, and a material placement area is provided in the quartz inner tube for placing wafers; Wherein, when the quartz inner tube is placed in the quartz outer tube, the furnace door is used to block the furnace port, the material placement port and the material placement area are placed in the quartz outer tube, and the gas outlet connects the inside of the quartz inner tube with the outside of the quartz outer tube.

2. The diffusion furnace according to claim 1, characterized in that: The material placement area is provided with a connecting hole at the bottom in the gravity direction, and the connecting hole connects the inside and outside of the quartz inner tube.

3. The diffusion furnace according to claim 1, characterized in that: The diffusion furnace further comprises a wafer boat, which is placed in the quartz inner tube and is used for carrying wafers.

4. The diffusion furnace according to claim 3, characterized in that: The wafer boat has a first surface and a second surface arranged opposite to each other, the first surface is in contact with the inner surface of the quartz inner tube, and the second surface is used to carry the wafer. On a reference section perpendicular to the axial direction of the quartz inner tube, the curvature of the first surface is greater than or equal to the curvature of the inner surface of the quartz inner tube, and the curvature of the second surface is less than or equal to the curvature of the wafer.

5. The diffusion furnace according to claim 3 or 4, characterized in that: The quartz inner tube is provided with a notch at the bottom in the direction of gravity. The notch extends in the axial direction of the quartz inner tube and connects the inside and outside of the quartz inner tube and the loading port. The notch is configured to allow a wafer placing device for placing and picking up the wafer boat to slide into or out of the quartz inner tube in the direction of gravity or the axial direction of the quartz inner tube.

6. The diffusion furnace according to claim 5, characterized in that: The wafer boat is provided with supporting legs located in the notch, and the supporting legs are used for supporting on the wafer taking and placing device.

7. The diffusion furnace according to claim 1, characterized in that: The quartz inner tube is arranged on a reference section perpendicular to the axial direction of the quartz outer tube so that the ratio of the distance between the axis of the wafer and the axis of the quartz outer tube to the radius of the wafer is between 0-50%.

8. The diffusion furnace according to claim 1 or 7, characterized in that: The quartz inner tube also includes: A tube body, wherein the tube body is fixedly connected to the furnace door, the material placement port is arranged on the tube body, and when the quartz inner tube is placed in the quartz outer tube, the tube body and the quartz outer tube are arranged at a distance; A fixing part, fixedly connected to the furnace door, and located on opposite sides of the furnace door with the tube body; Wherein, the furnace door is configured to move in a direction perpendicular to the axial direction of the quartz outer tube to adjust the relative position between the axis of the wafer and the axis of the quartz outer tube.

9. The diffusion furnace according to claim 1, characterized in that: The diffusion furnace further comprises a heat insulating member, which is arranged in the quartz inner tube and located between the furnace door and the material placing area.

10. The diffusion furnace according to claim 9, characterized in that: The air outlet is located on a side of the heat insulating member away from the material placement area, and the ratio of the effective flow area between the heat insulating member and the quartz outer tube to the effective flow area of ​​the quartz outer tube at the heat insulating member is between 10-50%.

11. A diffusion system, characterized in that: The diffusion furnace comprises the diffusion furnace according to any one of claims 1 to 10; the diffusion system further comprises: Workbench; A wafer pick-and-place device is slidably connected to the workbench. When the wafer pick-and-place device is partially placed in the quartz inner tube, the wafer pick-and-place device is configured to slide relative to the workbench to slide out of the quartz outer tube in the axial direction of the quartz inner tube; and is configured to extend and retract in the direction of gravity to slide out of the quartz inner tube; A fixing device is slidably connected to the workbench and connected to the quartz inner tube. When the quartz inner tube is partially placed in the quartz outer tube, the fixing device is configured to slide relative to the workbench to slide out of the quartz outer tube in the axial direction of the quartz outer tube.

12. A diffusion method, characterized in that: include: placing the wafer in an oxygen environment and performing dry oxygen oxidation at a first temperature; placing the wafer in a wet oxygen environment and performing wet oxygen oxidation at a second temperature, wherein the second temperature is lower than the first temperature; placing the wafer in the oxygen environment and performing dry oxygen oxidation at the first temperature; The wafer is placed in a protective gas environment and annealed at a third temperature, where the third temperature is greater than the first temperature.

13. The diffusion method according to claim 12, characterized in that: The diffusion method is used in the diffusion furnace according to any one of claims 1 to 10, or the diffusion system according to claim 11.

14. The diffusion method according to claim 13, characterized in that: The first temperature, the second temperature and the third temperature are greater than or equal to 700° C. and less than or equal to 900° C.

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