Diffusion furnace and diffusion furnace system

Abstract

The utility model discloses a diffusion furnace and a diffusion furnace system, and relates to the technical field of solar cell processing. The diffusion furnace comprises a furnace tube body, a quartz boat and at least one gas inlet pipe group; the quartz boat is arranged in the furnace tube body, and the quartz boat is provided with a placing position extending along a first direction; at least one gas inlet pipe set comprises a gas inlet section located in the furnace tube body, and the gas inlet section is obliquely arranged relative to the first direction. According to the diffusion furnace provided by the invention, the moving path of the process gas can be increased, the contact time of the process gas and the silicon wafer is prolonged, the process gas can fully react with the silicon wafer, and the usage amount of the process gas and the doped medium solution is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of solar cell processing, and in particular to a diffusion furnace and a diffusion furnace system. Background Art

[0002] In the production process of solar cells, doping diffusion is the core process for preparing the PN junction of solar cells. The quality of the PN junction also has a decisive influence on the performance of solar cells. It is usually necessary to introduce process gas carrying doping media (phosphorus, boron) into the diffusion furnace to diffuse the elemental phosphorus and boron into the silicon wafer to form the PN junction in the solar cell.

[0003] However, when the process gas is introduced into the existing diffusion furnace, the process gas cannot fully contact with the silicon wafer, resulting in excessive consumption of the process gas and doping medium, resulting in cost waste. Utility Model Content

[0004] The present application provides a diffusion furnace and a diffusion furnace system to enable process gas to fully contact and react with silicon wafers.

[0005] In a first aspect, the present application provides a diffusion furnace, comprising:

[0006] Furnace tube body;

[0007] A quartz boat is disposed in the furnace tube body, and the quartz boat is provided with a placement position extending along a first direction;

[0008] At least one air inlet pipe group includes an air inlet section located in the furnace tube body, and the air inlet section is inclined relative to the first direction.

[0009] Based on the above technical scheme, in the diffusion furnace provided by the present application, the air inlet section is tilted relative to the silicon wafer, so that the process gas can be tilted relative to the silicon wafer for input, and then the process gas can be reflected multiple times between two adjacent silicon wafers, thereby increasing the movement path of the process gas, and then increasing the contact time between the process gas and the silicon wafer, so that the process gas can fully react with the silicon wafer, reducing the usage of process gas and doping medium solution, and reducing production costs.

[0010] In some possible implementations, an angle α is configured between the air inlet section and the first direction, wherein 0°<α≤45°.

[0011] In some possible implementations, an angle α is configured between the air inlet section and the first direction, wherein 20°≤α≤30°.

[0012] In some possible implementations, the diffusion furnace includes two air inlet pipe groups;

[0013] Along the first direction, the two air inlet pipe components are arranged on both sides of the quartz boat.

[0014] In some possible implementations, the diffusion furnace further includes two exhaust pipes connected to the furnace tube body, and along the first direction, the two exhaust pipes are respectively arranged on both sides of the quartz boat.

[0015] In some possible implementations, the quartz boat is configured with a plurality of placement positions, and the plurality of placement positions are sequentially spaced along the second direction;

[0016] The air inlet pipe group includes at least one group of air inlet pipe sections located in the furnace tube body, each group of air inlet pipe sections includes a plurality of air inlet pipe sections, and each air inlet pipe section is configured with an air inlet section;

[0017] The air inlet sections connected to the plurality of air inlet pipe sections in the same group are sequentially spaced apart along the second direction.

[0018] In some possible implementations, the air intake pipe group includes two groups of air intake pipe segments;

[0019] In a direction perpendicular to both the first direction and the second direction, two groups of the air inlet pipe sections are arranged on both sides of the quartz boat.

[0020] In some possible implementations, the air inlet pipe group further includes a first transition section connected to the air inlet section, and the first transition section is located outside the furnace tube body;

[0021] The diffusion furnace further comprises at least one heating tube, and the first transfer section of the at least one air inlet pipe group is disposed in a one-to-one correspondence through the at least one heating tube.

[0022] In a second aspect, the present application further provides a diffusion furnace system, comprising the diffusion furnace provided in the above embodiments.

[0023] In some possible implementations, the diffusion furnace system further includes a first medium delivery pipeline, a second medium delivery pipeline, and a third medium delivery pipeline, and the first medium delivery pipeline, the second medium delivery pipeline, and the third medium delivery pipeline are all connected to the at least one air inlet pipe group;

[0024] The first medium delivery pipe comprises a first branch pipe and a second branch pipe in parallel, and the second branch pipe is connected to a first container for containing a doping medium solution;

[0025] The second medium delivery pipeline includes a third branch pipeline and a fourth branch pipeline which are arranged in parallel, and the fourth branch pipeline is connected to a second container for containing a wetting liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 Shows a schematic diagram of the structure of a diffusion furnace system in some embodiments;

[0028] Figure 2 Shows a schematic diagram of the structure of a diffusion furnace in some embodiments;

[0029] Figure 3 The schematic diagrams of the structures of the furnace tube body and the air inlet tube group in some embodiments are shown;

[0030] Figure 4 A partial structural schematic diagram of a diffusion furnace system in some embodiments is shown;

[0031] Figure 5 A schematic flow chart of a diffusion method in some embodiments is shown;

[0032] Figure 6 A schematic diagram of the process of first through-source deposition in some embodiments is shown;

[0033] Figure 7 A schematic diagram of the process of the second homologous deposition in some embodiments is shown.

[0034] Description of main component symbols:

[0035] 1000-Diffusion furnace;

[0036] 1100-furnace tube body;

[0037] 1200-quartz boat; 1210-placement;

[0038] 1300-intake pipe group; 1301-first intake pipe group; 1302-second intake pipe group; 1310-intake port section; 1320-intake pipe section; 1330-first transition section; 1340-second transition section;

[0039] 1400-exhaust pipe; 1410-first exhaust pipe; 1411-tenth control valve; 1420-second exhaust pipe; 1421-eleventh control valve;

[0040] 1500-heating tube;

[0041] 2100-first medium delivery pipeline; 2110-first branch pipeline; 2111-third control valve; 2120-second branch pipeline; 2121-first container; 2122-fourth control valve; 2123-fifth control valve; 2130-first flow meter;

[0042] 2200-second medium delivery pipeline; 2210-third branch pipeline; 2211-sixth control valve; 2220-fourth branch pipeline; 2221-second container; 2222-seventh control valve; 2223-eighth control valve; 2230-second flow meter;

[0043] 2300-third medium delivery pipeline; 2310-ninth control valve; 2320-third flow meter;

[0044] 2410-main pipe; 2420-branch pipe; 2431-first control valve; 2432-second control valve. DETAILED DESCRIPTION

[0045] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0046] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0047] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0048] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0049] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0050] Embodiment 1

[0051] like Figure 2 and Figure 3 As shown, a Cartesian coordinate system is established, and it is defined that the length direction of the diffusion furnace 1000 is parallel to the direction shown by the x-axis, the width direction of the diffusion furnace 1000 may be parallel to the direction shown by the y-axis, and the height direction of the diffusion furnace 1000 may be parallel to the direction shown by the z-axis. It can be understood that the above definitions are only for the purpose of facilitating the understanding of the relative positional relationship of the various structures in the diffusion furnace 1000, and should not be construed as limiting the present application.

[0052] like Figure 2 As shown, the diffusion furnace 1000 includes a furnace tube body 1100 , a quartz boat 1200 and at least one air inlet pipe set 1300 .

[0053] The quartz boat 1200 can be used to carry silicon wafers to be processed. The quartz boat 1200 can be configured with a placement position 1210 extending along a first direction, and the silicon wafer can be inserted into the placement position 1210 of the quartz boat 1200 along the first direction. In addition, the quartz boat 1200 can be movably arranged in the furnace tube body 1100. Thus, the quartz boat 1200 can be moved in and out relative to the open end of the furnace tube body 1100, so as to take and place the silicon wafer. In some embodiments, the first direction can be parallel to the height direction of the diffusion furnace 1000.

[0054] The air inlet pipe assembly 1300 may include an air inlet section 1310, and the air inlet section 1310 may be located in the furnace tube body 1100. The air inlet section 1310 may be tilted relative to the first direction, that is, the air inlet section 1310 may be tilted relative to the silicon wafer.

[0055] During operation, the silicon wafer to be processed can be placed on the quartz boat 1200 and placed in the furnace tube body 1100. In addition, the process gas can be transported into the furnace tube body 1100 through the air inlet pipe group 1300, wherein the process gas can include a medium gas such as nitrogen or an inert gas, a medium gas carrying a doping medium, and oxygen, etc. Among them, the air inlet section 1310 is tilted relative to the silicon wafer, so that the process gas can be reflected multiple times between two adjacent silicon wafers, increasing the moving path of the process gas, thereby increasing the contact time between the process gas and the silicon wafer, so that the process gas can fully react with the silicon wafer, reducing the usage of the process gas and the doping medium solution, and reducing the production cost.

[0056] like Figure 2 and Figure 3 As shown, further, the quartz boat 1200 may include a plurality of placement positions 1210, and the plurality of placement positions 1210 may be sequentially spaced along the second direction. That is, a plurality of silicon wafers to be processed may be arranged and placed on a quartz boat 1200. In some embodiments, the second direction may be parallel to the length direction of the diffusion furnace 1000.

[0057] In some embodiments, the diffusion furnace 1000 may include two groups of air inlet pipe groups 1300, namely a first air inlet pipe group 1301 and a second air inlet pipe group 1302. Along the height direction of the diffusion furnace 1000, the two air inlet pipe groups 1300 may be disposed on both sides of the quartz boat 1200. In some embodiments, the first air inlet pipe group 1301 may be located above the quartz boat 1200, and the second air inlet pipe group 1302 may be located below the quartz boat 1200.

[0058] In addition, the diffusion furnace 1000 further includes two exhaust pipes 1400, namely a first exhaust pipe 1410 and a second exhaust pipe 1420. The two exhaust pipes 1400 can be used to exhaust the gas in the diffusion furnace 1000. Along the first direction, the two exhaust pipes 1400 can also be arranged on both sides of the quartz boat 1200. Specifically, the first exhaust pipe 1410 can be arranged near the lower side of the quartz boat 1200, and the second exhaust pipe 1420 can be arranged near the upper side of the quartz boat 1200.

[0059] During operation, when the process gas enters the furnace tube body 1100 from the first air inlet pipe group 1301, the process gas can be discharged from the furnace tube body 1100 through the first exhaust pipe 1410 after passing through the quartz boat 1200. When the process gas enters the furnace tube body 1100 from the second air inlet pipe group 1302, the process gas can be discharged from the furnace tube body 1100 through the second exhaust pipe 1420 after passing through the quartz boat 1200. In this way, the process gas can fully immerse various parts of the silicon wafer in the height direction of the diffusion furnace 1000, so that the doping medium can fully contact and react with the silicon wafer, and more evenly adhere to the silicon wafer, thereby improving the uniformity of doping at various parts of the same silicon wafer in the height direction of the diffusion furnace 1000.

[0060] In other embodiments, the diffusion furnace 1000 may also include an air inlet pipe group 1300 and an exhaust pipe 1400. Along the height direction of the diffusion furnace 1000, the air inlet pipe group 1300 and the exhaust pipe 1400 may be disposed on both sides of the quartz boat 1200.

[0061] In some embodiments, the first exhaust pipe 1410 may be provided with a tenth control valve 1411 for controlling its on-off. The second exhaust pipe 1420 may be provided with an eleventh control valve 1421 for controlling its on-off. Both the tenth control valve 1411 and the eleventh control valve 1421 may be solenoid valves.

[0062] In other embodiments, the tenth control valve 1411 and the eleventh control valve 1421 may also be manual valves.

[0063] like Figure 2 and Figure 3 As shown, further, the air inlet pipe group 1300 may include at least one group of air inlet pipe sections 1320 arranged in the furnace tube body 1100, and each group of air inlet pipe sections 1320 includes a plurality of air inlet pipe sections 1320. In addition, each air inlet pipe section 1320 is connected to an air inlet section 1310.

[0064] In the embodiment, the multiple air inlet pipe sections 1320 of the same group may have different lengths in the second direction. Accordingly, the air inlet section 1310 connected to the multiple air inlet pipe sections 1320 of the same group may be opposite to different positions of the quartz boat 1200 in the second direction. Thus, in the length direction of the diffusion furnace 1000, the air inlet pipe sections 1320 of the same group may transport the process gas to different positions of the quartz boat 1200, and transport the process gas to the quartz boat 1200 through the air inlet section 1310 connected to the same group, so that the process gas can be dispersed more evenly in the length direction of the diffusion furnace 1000, the stability of the air flow field in the diffusion furnace 1000, the uniformity of the square resistance at both ends of the diffusion furnace 1000, so that the silicon wafers at each position can fully react with the doping medium, and the uniformity of doping between the silicon wafers is improved.

[0065] In some embodiments, the air inlet pipe group 1300 may include two groups of air inlet pipe sections 1320. Along the width direction of the diffusion furnace 1000, the two groups of air inlet pipe sections 1320 may be arranged one by one close to both sides of the quartz boat 1200. Thus, in the width direction of the diffusion furnace 1000, the process gas can be more evenly dispersed in the furnace tube body 1100, so that the doping of the same silicon wafer at each position in the width direction of the diffusion furnace 1000 is more uniform, that is, the uniformity of the doping of the silicon wafer is further improved.

[0066] In other embodiments, the air inlet pipe group 1300 may also include one, three, or five groups of air inlet pipe segments 1320. When the air inlet pipe group 1300 includes multiple groups of air inlet pipe segments 1320, the multiple groups of air inlet pipe segments 1320 may be evenly spaced along the width direction of the diffusion furnace 1000.

[0067] In the embodiment, an angle α may be configured between the air inlet section 1310 and the first direction, that is, an angle α may be configured between the air inlet section 1310 and the silicon wafer, wherein 0°<α≤45°. Exemplarily, the angle α between the air inlet section 1310 and the silicon wafer may be set to 5°, 12°, 15°, 20°, 24°, 28°, 30°, 35°, 42°, 45°, or any other angle between 0° and 45° (excluding 0°). Thus, the process gas flow output from the air inlet section 1310 may be inclined relative to the silicon wafer, may be reflected multiple times between two adjacent silicon wafers, extend the flow path of the process gas, increase the contact time between the process gas and the silicon wafer, and allow the process gas and the doping medium carried by it to fully react with the silicon wafer. Especially for large-sized silicon wafers, the airflow pattern of the process gas will not be disturbed due to the close arrangement of the silicon wafers, and the airflow pattern is ensured to be stably moved from the air inlet section 1310 to the exhaust pipe 1400. In addition, the flow rate of the process gas can be changed by adjusting the flow rate of the process gas during the diffusion process, so that the process gas can fully reach the center of the silicon wafer. This can also effectively reduce the usage of process gas and doping medium and reduce material costs.

[0068] In some embodiments, preferably, the angle α between the air inlet section 1310 and the silicon wafer can be set to 20°≤α≤30°.

[0069] In some embodiments, the air inlet pipe group 1300 further includes a first transition section 1330 and a second transition section 1340. The second transition section 1340 may be connected between the first transition section 1330 and the air inlet pipe section 1320. The first transition section 1330 may be located outside the furnace tube body 1100, and the second transition section 1340 may be disposed inside the furnace tube body 1100, and may be connected to all the air inlet pipe sections 1320 in the air inlet pipe group 1300. During operation, the first transition section 1330 may be used to connect the process gas pipeline, and may transport the process gas to the second transition section 1340, and the second transition section 1340 may divert the process gas to different air inlet pipe sections 1320.

[0070] In some embodiments, the diffusion furnace 1000 further includes two heating tubes 1500, which can be disposed outside the furnace tube body 1100. The first transition sections 1330 in the two air inlet pipe groups 1300 can be disposed in the two heating tubes 1500 in a one-to-one correspondence. Thus, the heating tubes 1500 can preheat the process gas passing through the first transition section 1330, thereby avoiding a large temperature difference between the temperature of the process gas entering the furnace tube body 1100 and the furnace tube body 1100, thereby preventing the temperature fluctuation in the furnace tube body 1100.

[0071] In other embodiments, the number of heating tubes 1500 may also be adjusted according to the number of intake pipe groups 1300 , for example, set to one.

[0072] In addition, a heating element (not shown) is disposed outside the furnace tube body 1100 to heat the furnace tube body 1100 .

[0073] In summary, the diffusion furnace 1000 provided by the present application can improve the uniformity of the diffusion of the process gas in the furnace tube body 1100, so that the process gas fully reacts with each part of the silicon wafer, and can also improve the uniformity of the doping of the silicon wafer, so that the square resistance uniformity of the silicon wafer is better. In addition, it is also possible to realize double inlet and double outlet of the process gas, or to make the two groups of inlet pipe groups 1300 and exhaust pipes 1400 alternately realize the input and output of the process gas, thereby reducing the problem of blockage of the inlet pipe group 1300 and the exhaust pipe 1400, and also reducing other faults of the diffusion furnace 1000 caused by long process time.

[0074] Embodiment 2

[0075] A diffusion furnace system is provided in the embodiment, which may include the diffusion furnace 1000 provided in the embodiment.

[0076] like Figure 1 , Figure 2 and Figure 4As shown, the diffusion furnace system further includes a first medium delivery pipeline 2100, a second medium delivery pipeline 2200 and a third medium delivery pipeline 2300. The first medium delivery pipeline 2100, the second medium delivery pipeline 2200 and the third medium delivery pipeline 2300 can all be connected to the first transition section 1330 of the two intake pipe groups 1300.

[0077] In the embodiment, the first medium delivery pipeline 2100, the second medium delivery pipeline 2200 and the third medium delivery pipeline 2300 can be connected to a main pipe 2410 at one end close to the diffusion furnace 1000, and the main pipe 2410 is connected to the first transfer sections 1330 of the two groups of air intake pipe groups 1300 through two branch pipes 2420. In addition, a first control valve 2431 for controlling the opening and closing of the main pipe 2410 and the first air intake pipe group 1301 can be provided. A second control valve 2432 for controlling the opening and closing of the main pipe 2410 and the second air intake pipe group 1302 can be provided. In some embodiments, both the first control valve 2431 and the second control valve 2432 can be electromagnetic valves.

[0078] In other embodiments, the first control valve 2431 and the second control valve 2432 may also be manual valves or other structures.

[0079] In some embodiments, the first medium delivery pipeline 2100 can be used to deliver medium gas such as nitrogen to the diffusion furnace 1000. The second medium delivery pipeline 2200 can be used to deliver oxygen to the diffusion furnace 1000. The third medium delivery pipeline 2300 can be used to deliver medium gas such as nitrogen to the diffusion furnace 1000.

[0080] like Figure 1 , Figure 2 and Figure 4 As shown, one end of the first medium delivery pipeline 2100 can be used to connect to a medium gas source such as a nitrogen source. The other end of the first medium delivery pipeline 2100 can include a first branch pipeline 2110 and a second branch pipeline 2120 arranged in parallel. The first branch pipeline 2110 can be provided with a third control valve 2111.

[0081] The second branch pipeline 2120 may be connected to a first container 2121 for containing a doping medium solution. During operation, the first container 2121 may contain a doping medium solution. In addition, a fourth control valve 2122 and a fifth control valve 2123 are also provided on the second branch pipeline 2120. The fourth control valve 2122 may be provided upstream of the first container 2121, and the fifth control valve 2123 may be provided downstream of the first container 2121.

[0082] In some embodiments, the third control valve 2111 , the fourth control valve 2122 , and the fifth control valve 2123 may all be solenoid valves.

[0083] In other embodiments, the third control valve 2111 , the fourth control valve 2122 , and the fifth control valve 2123 may all be manual valves.

[0084] In addition, a first flow meter 2130 is also provided on the first medium delivery pipeline 2100. The first flow meter 2130 can be provided at one end of the first medium delivery pipeline 2100 close to the medium gas source, that is, upstream of the first branch pipeline 2110 and the second branch pipeline 2120, and can be used to detect the flow of the medium gas.

[0085] like Figure 1 , Figure 2 and Figure 4 As shown, one end of the second medium delivery pipeline 2200 can be used to connect to the oxygen source. The other end of the second medium delivery pipeline 2200 can include a third branch pipeline 2210 and a fourth branch pipeline 2220 arranged in parallel. Among them, the third branch pipeline 2210 can be provided with a sixth control valve 2211, which can be used to control its on and off.

[0086] The fourth branch pipeline 2220 may be connected to a second container 2221 for containing a wetting liquid. During operation, the second container 2221 may contain a wetting liquid such as ultrapure water to wet the oxygen passing therethrough. In addition, the fourth branch pipeline 2220 further includes a seventh control valve 2222 and an eighth control valve 2223. The seventh control valve 2222 may be located upstream of the second container 2221, and the eighth control valve 2223 may be located downstream of the second container 2221.

[0087] In some embodiments, the sixth control valve 2211 , the seventh control valve 2222 , and the eighth control valve 2223 may all be solenoid valves.

[0088] In other embodiments, the sixth control valve 2211 , the seventh control valve 2222 , and the eighth control valve 2223 may all be manual valves.

[0089] In addition, the second medium delivery pipeline 2200 further includes a second flow meter 2230, which can be disposed at one end of the second medium delivery pipeline 2200 close to the oxygen source, that is, the second flow meter 2230 can be located upstream of the third branch pipeline 2210 and the fourth branch pipeline 2220. During operation, the second flow meter 2230 can detect the flow rate of oxygen flowing through.

[0090] The end of the third medium delivery pipeline 2300 away from the main pipe 2410 can be used to connect to a medium gas source such as a nitrogen source. In addition, the third medium delivery pipeline 2300 may include a ninth control valve 2310 and a third flow meter 2320. The ninth control valve 2310 can be used to control the on-off of the third medium delivery pipeline 2300, and the third flow meter 2320 can be used to detect the flow rate of the medium gas flowing through. In some embodiments, the ninth control valve 2310 can be a solenoid valve.

[0091] In some other embodiments, the ninth control valve 2310 may also be a manual valve.

[0092] Embodiment 3

[0093] like Figure 5 As shown, a diffusion method is provided in the embodiment, which can be performed by a diffusion furnace system provided in the embodiment. In some embodiments, the diffusion method may include:

[0094] S10, silicon wafer pretreatment.

[0095] Specifically, the silicon wafer is first placed in a mixed solution of NaOH and H2O2 to remove dirt and damage layers on the surface of the silicon wafer. Then, the silicon wafer is placed in a 1-5% mass concentration NaOH and texturing additive solution for double-sided texturing to form a pyramid velvet surface on the surface of the silicon wafer.

[0096] S11, placing the textured silicon wafer on the quartz boat 1200.

[0097] Specifically, the quartz boat 1200 can be pulled out of the furnace tube body 1100 , and then a plurality of silicon wafers are sequentially placed on the quartz boat 1200 at intervals along the length direction of the diffusion furnace 1000 , and then the quartz boat 1200 is returned to the furnace tube body 1100 .

[0098] S12, vacuumizing and leak checking the furnace tube body 1100.

[0099] Specifically, the interior of the furnace tube body 1100 may be evacuated, and the furnace tube body 1100 may be tested by a leak detection instrument to ensure that the sealing of the furnace tube body 1100 meets the requirements.

[0100] S13, introducing medium gas to heat the furnace tube body 1100.

[0101] Specifically, nitrogen can be delivered into the furnace tube body 1100 through the third medium delivery pipeline 2300 until the pressure in the furnace tube body 1100 is 150 mbar-250 mbar. In addition, the furnace tube body 1100 is heated to 800°C-850°C by a heating element.

[0102] S14, introducing dry oxygen and medium gas to perform pre-oxidation treatment on the silicon wafer.

[0103] Specifically, the temperature in the furnace tube body 1100 is maintained at 800°C-850°C. The third medium delivery pipeline 2300 delivers nitrogen to the diffusion furnace 1000. The seventh control valve 2222 and the eighth control valve 2223 on the fourth branch pipeline 2220 are closed, and the sixth control valve 2211 on the third branch pipeline 2210 is opened. Dry oxygen (i.e., dry oxygen) is delivered to the diffusion furnace 1000 by the second medium delivery pipeline 2200 to perform pre-oxidation treatment on the silicon wafers in the furnace tube body 1100. Among them, the flow rate of nitrogen can be controlled at 400sccm-1500sccm, and the flow rate of dry oxygen can be controlled at 400sccm-1500sccm. In addition, the total time of the pre-oxidation treatment can be controlled at 300s-1800s.

[0104] In some embodiments, step S14 may specifically include:

[0105] First, open the first control valve 2431 and close the second control valve 2432, that is, connect the main pipe 2410 and the inside of the furnace tube body 1100 through the first air inlet pipe group 1301. Dry oxygen is transported through the third branch pipe 2210 of the second medium delivery pipeline 2200, and nitrogen is transported through the third medium delivery pipeline 2300. Among them, the nitrogen flow rate can be controlled at 400sccm-1500sccm, and the nitrogen flow rate can be gradually changed according to time, that is, it decreases from large to small or increases from small to small, for example, it increases by 1sccm-3sccm per second or decreases by 1sccm-3sccm per second. The dry oxygen flow rate can be controlled at 400sccm-1500sccm. This step can be maintained for 150s-900s. The gas in the furnace tube body 1100 can be discharged through the first exhaust pipe 1410.

[0106] Then, open the second control valve 2432 and close the first control valve 2431, that is, connect the main pipe 2410 and the inside of the furnace tube body 1100 through the second air inlet pipe group 1302. Dry oxygen is transported through the third branch pipe 2210 of the second medium delivery pipeline 2200, and nitrogen is transported through the third medium delivery pipeline 2300. Among them, the nitrogen flow rate can be controlled at 400sccm-1500sccm, and the nitrogen flow rate can be gradually changed according to time, that is, it decreases from large to small or increases from small to large, for example, it increases by 1sccm-3sccm per second or decreases by 1sccm-3sccm per second. The dry oxygen flow rate can be controlled at 400sccm-1500sccm. This step can be maintained for 150s-900s. The gas inside the furnace tube body 1100 can be discharged through the second exhaust pipe 1420.

[0107] In other embodiments, the main pipe 2410 and the furnace tube body 1100 may be connected through the second air intake pipe group 1302 first, and then through the first air intake pipe group 1301.

[0108] S15, performing the first through-source deposition on the silicon wafer.

[0109] The temperature in the furnace tube body 1100 can be maintained at 800°C-850°C.

[0110] like Figure 6 As shown, in some embodiments, step S15 may specifically include:

[0111] S151, dry oxygen and a medium gas carrying a doping medium are introduced into the furnace tube body 1100 through an air inlet pipe group 1300.

[0112] Specifically, the first control valve 2431 can be opened, and the second control valve 2432 can be closed, that is, the main pipe 2410 and the furnace pipe body 1100 are connected through the first air inlet pipe group 1301. In addition, the fourth control valve 2122 and the fifth control valve 2123 are opened, and the third control valve 2111 is closed, so that the second branch pipeline 2120 is connected to the main pipe 2410 and the nitrogen source to transport nitrogen carrying the doping medium to the diffusion furnace 1000. The sixth control valve 2211 is opened, and the seventh control valve 2222 and the eighth control valve 2223 are closed to transport dry oxygen to the diffusion furnace 1000. In addition, the ninth control valve 2310 is closed.

[0113] The dry oxygen flow rate is 400sccm-1500sccm. The doping medium may be BCl3, and its flow rate may be controlled at 100sccm-500sccm. The nitrogen flow rate may be controlled at 300sccm-20000sccm. In addition, the nitrogen flow rate may be gradually changed according to time, i.e., decreasing from large to small or increasing from small to large, for example, increasing by 1sccm-3sccm per second or decreasing by 1sccm-3sccm per second. This step may be maintained for 100s-800s. The gas in the furnace tube body 1100 may be discharged through the first exhaust pipe 1410.

[0114] S152, introducing medium gas to purge the furnace tube body 1100.

[0115] Specifically, the third medium delivery pipeline 2300 and the first air inlet pipe group 1301 can be connected, and the first medium delivery pipeline 2100, the second medium delivery pipeline 2200 and the second air inlet pipe group 1302 can be disconnected. Nitrogen is delivered to the interior of the furnace tube body 1100 through the third medium delivery pipeline 2300 through the first air inlet pipe group 1301. The nitrogen flow rate can be controlled at 600 sccm-2000 sccm, and the time can be sustained for 20s-100s.

[0116] S153, dry oxygen and a medium gas carrying a doping medium are introduced into the furnace tube body 1100 through another air inlet pipe group 1300.

[0117] Specifically, the second control valve 2432 may be opened, and the first control valve 2431 may be closed, that is, the main pipe 2410 and the furnace pipe body 1100 may be connected through the second air inlet pipe group 1302. In addition, the fourth control valve 2122 and the fifth control valve 2123 may be opened, and the third control valve 2111 may be closed, so that the second branch pipe 2120 may be connected to the main pipe 2410 and the nitrogen source to deliver nitrogen carrying the doping medium to the diffusion furnace 1000. The sixth control valve 2211 may be opened, and the seventh control valve 2222 and the eighth control valve 2223 may be closed to deliver dry oxygen to the diffusion furnace 1000. In addition, the ninth control valve 2310 may be closed.

[0118] The dry oxygen flow rate is 400sccm-1500sccm. The doping medium can be BCl3, and its flow rate can be controlled at 100sccm-500sccm. The nitrogen flow rate can be controlled at 300sccm-20000sccm. In addition, the nitrogen flow rate can be gradually changed according to time, that is, it decreases from large to small or increases from small to large, for example, it increases by 1sccm-3sccm per second or decreases by 1sccm-3sccm per second. This step can be maintained for 100s-800s. The gas in the furnace tube body 1100 can be discharged through the second exhaust pipe 1420.

[0119] In other embodiments, the flow rate of dry oxygen may also be varied gradually, increasing from a small amount or decreasing from a large amount.

[0120] S154, introducing medium gas to purge the furnace tube body 1100.

[0121] Specifically, the third medium delivery pipeline 2300 and the second air inlet pipe group 1302 can be connected, and the first medium delivery pipeline 2100, the second medium delivery pipeline 2200 and the first air inlet pipe group 1301 can be disconnected. Nitrogen is delivered to the interior of the furnace tube body 1100 through the third medium delivery pipeline 2300 and the second air inlet pipe group 1302. The nitrogen flow rate can be controlled at 600 sccm-2000 sccm, and the time can be sustained for 20s-100s.

[0122] In the embodiment, when the silicon wafer is subjected to the first source deposition, two source passes and two purges are performed alternately, which can reduce the corrosion of the silicon wafer and the quartz boat 1200 caused by the chlorine gas produced by the reaction in the furnace tube body 1100, ensure the quality of the silicon wafer, and extend the service life of the diffusion furnace 1000.

[0123] S16, introducing medium gas and heating the furnace tube body 1100 to increase the temperature.

[0124] Specifically, the furnace tube body 1100 may be heated to 850° C.-900° C. by the heating element. In addition, nitrogen may be delivered to the diffusion furnace 1000 through the third medium delivery pipeline 2300 , and the nitrogen flow rate may be controlled at 400 sccm-1500 sccm.

[0125] S17, performing a second through-source deposition on the silicon wafer.

[0126] The temperature in the furnace tube body 1100 can be maintained at 850°C-900°C.

[0127] like Figure 7 As shown, in some embodiments, step S17 may specifically include:

[0128] S171, dry oxygen and a medium gas carrying a doping medium are introduced into the furnace tube body 1100 through an air inlet pipe group 1300.

[0129] Specifically, the first control valve 2431 can be opened, and the second control valve 2432 can be closed, that is, the main pipe 2410 and the furnace pipe body 1100 are connected through the first air inlet pipe group 1301. In addition, the fourth control valve 2122 and the fifth control valve 2123 are opened, and the third control valve 2111 is closed, so that the second branch pipeline 2120 is connected to the main pipe 2410 and the nitrogen source to transport nitrogen carrying the doping medium to the diffusion furnace 1000. The sixth control valve 2211 is opened, and the seventh control valve 2222 and the eighth control valve 2223 are closed to transport dry oxygen to the diffusion furnace 1000. In addition, the ninth control valve 2310 is closed.

[0130] The dry oxygen flow rate is 400sccm-1500sccm. The doping medium may be BCl3, and its flow rate may be controlled at 100sccm-500sccm. The nitrogen flow rate may be controlled at 300sccm-20000sccm. In addition, the nitrogen flow rate may be gradually changed according to time, i.e., decreasing from large to small or increasing from small to large, for example, increasing by 1sccm-3sccm per second or decreasing by 1sccm-3sccm per second. This step may be maintained for 100s-800s. The gas in the furnace tube body 1100 may be discharged through the first exhaust pipe 1410.

[0131] S172, introducing medium gas to purge the furnace tube body 1100.

[0132] Specifically, the third medium delivery pipeline 2300 and the first air inlet pipe group 1301 can be connected, and the first medium delivery pipeline 2100, the second medium delivery pipeline 2200 and the second air inlet pipe group 1302 can be disconnected. Nitrogen is delivered to the interior of the furnace tube body 1100 through the third medium delivery pipeline 2300 through the first air inlet pipe group 1301. The nitrogen flow rate can be controlled at 600 sccm-2000 sccm, and the time can be sustained for 20s-100s.

[0133] S173, dry oxygen and a medium gas carrying a doping medium are introduced into the furnace tube body 1100 through another air inlet pipe group 1300.

[0134] Specifically, the second control valve 2432 may be opened, and the first control valve 2431 may be closed, that is, the main pipe 2410 and the furnace pipe body 1100 may be connected through the second air inlet pipe group 1302. In addition, the fourth control valve 2122 and the fifth control valve 2123 may be opened, and the third control valve 2111 may be closed, so that the second branch pipe 2120 may be connected to the main pipe 2410 and the nitrogen source to deliver nitrogen carrying the doping medium to the diffusion furnace 1000. The sixth control valve 2211 may be opened, and the seventh control valve 2222 and the eighth control valve 2223 may be closed to deliver dry oxygen to the diffusion furnace 1000. In addition, the ninth control valve 2310 may be closed.

[0135] The dry oxygen flow rate is 400sccm-1500sccm. The doping medium can be BCl3, and its flow rate can be controlled at 100sccm-500sccm. The nitrogen flow rate can be controlled at 300sccm-20000sccm. In addition, the nitrogen flow rate can be gradually changed according to time, that is, it decreases from large to small or increases from small to large, for example, it increases by 1sccm-3sccm per second or decreases by 1sccm-3sccm per second. This step can be maintained for 100s-800s. The gas in the furnace tube body 1100 can be discharged through the second exhaust pipe 1420.

[0136] S174, introducing medium gas to purge the furnace tube body 1100.

[0137] Specifically, the third medium delivery pipeline 2300 and the second air inlet pipe group 1302 can be connected, and the first medium delivery pipeline 2100, the second medium delivery pipeline 2200 and the first air inlet pipe group 1301 can be disconnected. Nitrogen is delivered to the interior of the furnace tube body 1100 through the third medium delivery pipeline 2300 and the second air inlet pipe group 1302. The nitrogen flow rate can be controlled at 600 sccm-2000 sccm, and the time can be sustained for 20s-100s.

[0138] In the embodiment, when the silicon wafer is subjected to the second source deposition, two source passes and two purges are performed alternately, which can reduce the corrosion of the silicon wafer and the quartz boat 1200 caused by the chlorine gas produced by the reaction in the furnace tube body 1100, ensure the quality of the silicon wafer, and extend the service life of the diffusion furnace 1000.

[0139] S18, introducing medium gas and heating the furnace tube body 1100 to increase the temperature.

[0140] Specifically, the third medium delivery pipeline 2300 can be connected, the first medium delivery pipeline 2100 and the second medium delivery pipeline 2200 can be disconnected, and nitrogen can be delivered to the diffusion furnace 1000 through the third medium delivery pipeline 2300. The first air inlet pipe group 1301 and / or the second air inlet pipe group 1302 can be connected to the diffusion furnace 1000. The nitrogen flow rate can be controlled at 400sccm-1500sccm. In addition, the furnace tube body 1100 can be heated by the heating element to raise the temperature of the furnace tube body 1100 to 900℃-1050℃, which can be continued for 20s-1000s.

[0141] S19, wet oxygen and medium gas are introduced, and the temperature of the furnace tube body 1100 is lowered to perform a temperature-lowering oxidation treatment on the silicon wafer.

[0142] Specifically, the temperature in the furnace tube body 1100 is maintained at 850°C-950°C. The third medium delivery pipeline 2300 delivers nitrogen to the diffusion furnace 1000. The seventh control valve 2222 and the eighth control valve 2223 on the fourth branch pipeline 2220 are opened, and the sixth control valve 2211 on the third branch pipeline 2210 is closed. Wet oxygen (i.e., oxygen carrying water vapor) is delivered to the diffusion furnace 1000 by the second medium delivery pipeline 2200 to perform a temperature reduction oxidation treatment on the silicon wafers in the furnace tube body 1100. Among them, the flow rate of nitrogen can be controlled at 400sccm-1500sccm, and the flow rate of wet oxygen can be controlled at 400sccm-1500sccm. In addition, the total time of the temperature reduction oxidation treatment can be controlled at 600s-3600s.

[0143] In some embodiments, step S19 may specifically include:

[0144] First, open the first control valve 2431 and close the second control valve 2432, that is, connect the main pipe 2410 and the inside of the furnace tube body 1100 through the first air inlet pipe group 1301. Wet oxygen is transported through the fourth branch pipe 2220 of the second medium delivery pipeline 2200, and nitrogen is transported through the third medium delivery pipeline 2300. Among them, the nitrogen flow rate can be controlled at 400sccm-1500sccm, and the nitrogen flow rate can be gradually changed according to time, that is, it decreases from large to small or increases from small to small, for example, it increases by 1sccm-3sccm per second or decreases by 1sccm-3sccm per second. The wet oxygen flow rate can be controlled at 400sccm-1500sccm. This step can be maintained for 300s-1800s. The gas in the furnace tube body 1100 can be discharged through the first exhaust pipe 1410.

[0145] Then, the second control valve 2432 is opened, and the first control valve 2431 is closed, that is, the main pipe 2410 and the inside of the furnace tube body 1100 are connected through the second air inlet pipe group 1302. Wet oxygen is transported through the fourth branch pipe 2220 of the second medium delivery pipeline 2200, and nitrogen is transported through the third medium delivery pipeline 2300. Among them, the nitrogen flow rate can be controlled at 400sccm-1500sccm, and the nitrogen flow rate can be gradually changed according to time, that is, it decreases from large to small or increases from small to large, for example, it increases by 1sccm-3sccm per second or decreases by 1sccm-3sccm per second. The wet oxygen flow rate can be controlled at 400sccm-1500sccm. This step can be maintained for 300s-1800s. The gas inside the furnace tube body 1100 can be discharged through the second exhaust pipe 1420.

[0146] In other embodiments, the main pipe 2410 and the furnace tube body 1100 may be connected through the second air intake pipe group 1302 first, and then through the first air intake pipe group 1301.

[0147] In other embodiments, the flow rate of wet oxygen may also be varied gradually, increasing from a small amount or decreasing from a large amount.

[0148] S20, introducing medium gas into the furnace tube body 1100 to normal pressure, and cooling the furnace tube body 1100.

[0149] Nitrogen can be delivered to the diffusion furnace 1000 through the third medium delivery pipeline 2300 until the pressure in the furnace tube body 1100 returns to normal pressure and the furnace tube body 1100 is cooled to normal temperature. Then the quartz boat 1200 is moved out of the furnace tube body 1100 to remove the doped silicon wafer.

[0150] The diffusion method provided in the present application is implemented by the diffusion furnace 1000 provided in the embodiment, which can have at least the following advantages:

[0151] (1) The lower part of the furnace tube body 1100 is evenly distributed for air intake, and the upper part of the furnace tube body 1100 is out of air; or, the upper part of the furnace tube body 1100 is evenly distributed for air intake, and the lower part of the furnace tube body 1100 is out of air, so as to avoid the occurrence of problems such as unstable air flow field in the furnace tube body 1100, unstable control of the square resistance at both ends of the length direction of the furnace tube body 1100, and inconsistent uniformity.

[0152] (ii) The process gas can diffuse along the height direction of the diffusion furnace 1000 to fully immerse the silicon wafer, so that the doping medium carried in the medium gas can fully contact the silicon wafer and evenly adhere to the surface of the silicon wafer to react.

[0153] (III) The process gas flow direction is tilted with the silicon wafer, so that the process gas can be reflected multiple times between adjacent silicon wafers, increasing the contact time between the process gas and the silicon wafer, so that the process gas and the silicon wafer can fully react. Especially for large-sized silicon wafers, the air flow pattern will not be disturbed by the close arrangement of the silicon wafers, ensuring the process gas pattern is stable from the inlet pipe group 1300 to the exhaust pipe 1400, and the flow rate of the process gas can be changed by adjusting the flow rate of the process gas during the diffusion process, so that the process gas can fully reach the center of the silicon wafer. At the same time, it can also effectively reduce the use of process gas and doping medium, reducing costs.

[0154] (iv) It is possible to realize dual inlet and dual outlet of process gas, or to make two groups of air inlet pipes 1300 and exhaust pipes 1400 alternately realize the input and output of process gas, thereby reducing the problem of blockage of the air inlet pipes 1300 and the exhaust pipes 1400, and also reducing other faults of the diffusion furnace 1000 caused by long process time.

[0155] (V) During the deposition process, two source passes and two purges are performed alternately, which can reduce the corrosion of the silicon wafer and the quartz boat 1200 by the chlorine gas generated by the reaction in the furnace tube body 1100, ensure the quality of the silicon wafer, and extend the service life of the diffusion furnace 1000. In addition, the process gas can be injected from both ends of the silicon wafer. It is easy to understand that this method can ensure that the process gas only needs enough flow rate and flow velocity, that is, enough kinetic energy to move to the center of the silicon wafer. Similarly, the entire silicon wafer can be completely covered by the process gas to react fully and evenly.

[0156] (VI) By adjusting the flow rate / flow velocity of the nitrogen gas during the through-source deposition process, the kinetic energy and movement path of the process gas can be adjusted to ensure that each position of the silicon wafer can obtain sufficient doping medium.

[0157] (VII) Compared with conventional constant flow / velocity diffusion, the nitrogen in the present application adopts a gradual flow / velocity diffusion method, which can make the doping medium more evenly distributed in the furnace tube body 1100, and each silicon wafer can fully contact and react with the process gas.

[0158] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0159] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A diffusion furnace, characterized in that: include: Furnace tube body; A quartz boat is disposed in the furnace tube body, and the quartz boat is provided with a placement position extending along a first direction; At least one air inlet pipe group includes an air inlet section located in the furnace tube body, and the air inlet section is inclined relative to the first direction.

2. The diffusion furnace according to claim 1, characterized in that: An angle α is arranged between the air inlet section and the first direction, wherein 0°<α≤45°.

3. The diffusion furnace according to claim 2, characterized in that: An angle α is arranged between the air inlet section and the first direction, wherein 20°≤α≤30°.

4. The diffusion furnace according to any one of claims 1 to 3, characterized in that: The diffusion furnace comprises two air inlet pipe groups; Along the first direction, the two air inlet pipe components are arranged on both sides of the quartz boat.

5. The diffusion furnace according to claim 4, characterized in that: The diffusion furnace further comprises two exhaust pipes communicated with the furnace tube body. Along the first direction, the two exhaust pipes are respectively arranged on two sides of the quartz boat.

6. The diffusion furnace according to claim 1, characterized in that: The quartz boat is provided with a plurality of placement positions, and the plurality of placement positions are sequentially spaced along the second direction; The air inlet pipe group includes at least one group of air inlet pipe sections located in the furnace tube body, each group of air inlet pipe sections includes a plurality of air inlet pipe sections, and each air inlet pipe section is configured with an air inlet section; The air inlet sections connected to the plurality of air inlet pipe sections in the same group are sequentially spaced apart along the second direction.

7. The diffusion furnace according to claim 6, characterized in that: The air intake pipe group includes two groups of air intake pipe sections; In a direction perpendicular to both the first direction and the second direction, two groups of the air inlet pipe sections are arranged on both sides of the quartz boat.

8. The diffusion furnace according to claim 1, characterized in that: The air inlet pipe group further includes a first transition section connected to the air inlet section, and the first transition section is located outside the furnace tube body; The diffusion furnace further comprises at least one heating tube, and the first transfer section of the at least one air inlet pipe group is disposed in a one-to-one correspondence through the at least one heating tube.

9. A diffusion furnace system, characterized in that: Comprising the diffusion furnace according to any one of claims 1 to 8.

10. The diffusion furnace system according to claim 9, characterized in that: The diffusion furnace system further comprises a first medium delivery pipeline, a second medium delivery pipeline and a third medium delivery pipeline, wherein the first medium delivery pipeline, the second medium delivery pipeline and the third medium delivery pipeline are all connected to the at least one air inlet pipe group; The first medium delivery pipe comprises a first branch pipe and a second branch pipe in parallel, and the second branch pipe is connected to a first container for containing a doping medium solution; The second medium delivery pipeline includes a third branch pipeline and a fourth branch pipeline which are arranged in parallel, and the fourth branch pipeline is connected to a second container for containing a wetting liquid.

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