Gas phase doping apparatus and doping method for low resistivity heavily doped phosphorus silicon single crystal

Abstract

The application provides a kind of for low resistivity heavily doped phosphorus silicon single crystal gas phase doping device and doping method, belongs to heavily doped silicon single crystal production technical field. Including containing component, weighing box, transmission component, volatilization heating cavity, gas conveying component;Containing component is set in weighing box to contain the red phosphorus of predetermined weight, transmission component is connected with volatilization heating cavity to be loaded with red phosphorus containing component from weighing box to be transported to volatilization heating cavity by transmission component;Volatilization heating cavity is used to heat the red phosphorus in containing component, to convert solid red phosphorus into gaseous state;Gas inlet of gas conveying component is connected with volatilization heating cavity, and the gas outlet of gas conveying component is used to extend into single crystal furnace, and the gaseous state red phosphorus in volatilization heating cavity is transported into the silicon melt of single crystal furnace. The application uses the way of gas phase doping to directly input gas phase phosphorus into single crystal furnace body for doping, avoids the serious volatilization when traditional doping, and ensures to reach the resistivity requirement of single crystal silicon.

Description

Technical Field

[0001] This invention relates to the field of heavy-doped single-crystal silicon production technology, specifically to a vapor-phase doping device and doping method for low-resistivity heavy-doped phosphorus silicon single crystals. Background Technology

[0002] As power devices demand increasingly lower power consumption, lower resistivity requirements are being placed on single-crystal silicon substrates. Next-generation silicon microwave power devices, Schottky devices, field-controlled high-frequency power electronic devices, and power integrated circuits require silicon single-crystal substrates with ultra-low resistivity (i.e., below 0.0011 Ω·cm). Currently, the main dopants for N-type silicon single crystals are arsenic and antimony, but the resistivity of the resulting single-crystal silicon after doping with arsenic and antimony is generally between 0.002 and 0.005 Ω·cm. Since phosphorus has a higher solid solubility in the silicon lattice, phosphorus doping can yield single-crystal silicon with even lower resistivity, hence the development of heavily phosphorus-doped silicon single crystals.

[0003] Currently, in the pulling of heavily phosphorus-doped silicon single crystals, red phosphorus is typically placed inside a quartz bell jar, which is then suspended above the molten silicon inside the furnace. The phosphorus then vaporizes at high temperature and enters the molten metal. However, throughout this dopant addition process, the dopant is constantly in a volatilized state. Some of the vaporized dopant is expelled from the furnace with the argon gas, reducing the actual amount of dopant entering the molten metal. This results in insufficient red phosphorus doping concentration, leading to a high resistivity in the single crystal, failing to meet the resistivity requirements for single-crystal silicon. Summary of the Invention

[0004] In view of this, the present invention provides a vapor phase doping device and doping method for low resistivity heavily phosphorus-doped silicon single crystals, in order to solve the technical problem that the red phosphorus doping concentration is insufficient when using a traditional quartz bell jar for doping, resulting in the inability to meet the resistivity requirements of single-crystal silicon.

[0005] The technical solution adopted by this invention to solve its technical problem is: A vapor-phase doping device for low-resistivity heavily phosphorus-doped silicon single crystals includes a material holding assembly, a weighing bin, a transfer assembly, a volatilization heating chamber, and a gas conveying assembly. The material holding assembly is disposed in the weighing bin to hold a predetermined weight of red phosphorus. The transfer assembly connects the weighing bin to the volatilization heating chamber to transport the material holding assembly containing red phosphorus from the weighing bin to the volatilization heating chamber. The volatilization heating chamber heats the red phosphorus in the material holding assembly to convert the solid red phosphorus into a gaseous state. The gas conveying assembly's inlet is connected to the volatilization heating chamber, and its outlet extends into the single crystal furnace to transfer the gaseous red phosphorus in the volatilization heating chamber to the silicon melt in the single crystal furnace.

[0006] Preferably, a weighing platform is provided inside the weighing box, and a first robotic arm is provided next to the weighing platform; the material holding assembly is placed on the weighing platform to weigh the red phosphorus contained in the material holding assembly; the first robotic arm is used to transfer the material holding assembly containing red phosphorus from the weighing platform to the transmission assembly.

[0007] Preferably, the weighing box is provided with a protective gas inlet and a protective gas outlet for filling the weighing box with protective gas.

[0008] Preferably, the transmission assembly includes a connecting pipe, a conveyor belt, and a guide rail; the connecting pipe is connected to the weighing box via a first flange, the connecting pipe is connected to the volatile heating chamber via a second flange, the conveyor belt is disposed in the connecting pipe, the guide rail is disposed below the conveyor belt, and the guide rail is fixedly connected to the conveyor belt so as to drive the conveyor belt to move via the guide rail.

[0009] Preferably, the volatile heating chamber is provided with a heating device and a second robotic arm. The second robotic arm is positioned between the transmission component and the heating device to grab the material-holding component on the transmission component and place it inside the heating device. The heating device is provided with a sealing cover to seal the heating device when it is heating.

[0010] Preferably, the gas supply assembly includes a first gas supply pipe, a second gas supply pipe, a third gas supply pipe, a quartz tube, and a telescopic component; one end of the first gas supply pipe is connected to the heating device, the other end of the first gas supply pipe is connected to one end of the second gas supply pipe, and the other end of the second gas supply pipe is connected to the inlet of the third gas supply pipe; the quartz tube is disposed inside the third gas supply pipe, and one end of the quartz tube is connected to the third gas supply pipe through the telescopic component, so that the quartz tube is driven to extend out of the third gas supply pipe and approach the silicon melt in the single crystal furnace under the control of the telescopic component.

[0011] The present invention also provides a vapor-phase doping method for low-resistivity heavily phosphorus-doped silicon single crystals, employing the vapor-phase doping apparatus for low-resistivity heavily phosphorus-doped silicon single crystals as described above, comprising the following steps: S1. Add a predetermined weight of red phosphorus into the material holding assembly; S2. The material container containing red phosphorus is transported from the weighing box to the volatilization heating chamber through the transmission component; S3. The red phosphorus in the material holding assembly is heated in the volatilization heating chamber to convert the solid red phosphorus into a gaseous state. S4. Set the predetermined doping parameters and move the gas outlet of the gas delivery component to the surface of the silicon melt. Inject gaseous red phosphorus into the silicon melt through the gas delivery component for doping.

[0012] Preferably, a first robotic arm is provided inside the weighing box, and a second robotic arm is provided inside the evaporation heating chamber; step S2 specifically includes: S21. Control the first robotic arm to grasp the material holding component and place the material holding component on the transmission component; S22. Drive the transmission component to move the material holding component from the weighing box into the volatilization heating chamber; S23. Control the second robotic arm to grab the material holding assembly, remove the material holding assembly from the transport assembly, and place it in the evaporation heating chamber.

[0013] Preferably, in step S3, while heating the red phosphorus, pressurization is applied to the volatilization heating chamber so that the gas pressure in the volatilization heating chamber is greater than the furnace pressure of the single crystal furnace.

[0014] Preferably, in step S4, setting the predetermined doping parameters includes: setting the magnetic field in the single crystal furnace to 1000-2000GS, the furnace rotation speed to 2-4rpm, the argon flow rate to 90-SLM, and the furnace pressure to 12-14KPa.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: When using the vapor-phase doping apparatus for low-resistivity heavily phosphorus-doped silicon single crystals of the present invention, a predetermined weight of red phosphorus is first placed in a loading assembly, wherein the predetermined weight refers to the weight of red phosphorus corresponding to the target resistivity of the pulled heavily phosphorus-doped silicon single crystal; next, the loading assembly containing red phosphorus is placed on a transport assembly, and the loading assembly is transported to a volatilization heating chamber through the transport assembly, and then the red phosphorus in the loading assembly is heated in the volatilization heating chamber to vaporize the red phosphorus, and the vaporized phosphorus is input into the silicon melt of the single crystal furnace through a gas conveying assembly for doping. Thus, the vaporized phosphorus is directly input into the single crystal furnace for doping using the vapor-phase doping method, avoiding the severe volatilization during traditional doping, ensuring that the red phosphorus and silicon melt are fully doped, and guaranteeing that the resistivity requirements of single crystal silicon are met. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the vapor phase doping device for low resistivity heavily phosphorus-doped silicon single crystals according to the present invention.

[0017] Figure 2 This is a schematic diagram illustrating the assembly and use of the vapor phase doping device and single crystal furnace for low resistivity heavily phosphorus-doped silicon single crystals according to the present invention.

[0018] Figure 3 This is a flowchart of the vapor phase doping method for low resistivity heavily phosphorus-doped silicon single crystals according to the present invention.

[0019] Figure 4This is a resistivity measurement diagram of a crystal rod in an embodiment of the present invention.

[0020] Figure 5 This is a resistivity measurement diagram of a crystal rod, which is a comparative example in this invention.

[0021] In the diagram: weighing bin 100, material holding assembly 110, first robotic arm 120, protective gas inlet 130, protective gas outlet 140, transmission assembly 200, connecting pipe 210, conveyor belt 220, first flange 230, second flange 240, volatile heating chamber 300, heating device 310, second robotic arm 320, sealing cover 330, gas supply assembly 400, first gas supply pipe 410, second gas supply pipe 420, third gas supply pipe 430, quartz tube 440, third flange 450, pressure holding valve 460, red phosphorus 500, single crystal furnace 600. Detailed Implementation

[0022] The technical solutions and effects of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0023] Please refer to Figure 1 A vapor-phase doping device for low-resistivity heavily phosphorus-doped silicon single crystals includes a material holding assembly 110, a weighing tank 100, a transfer assembly 200, a volatilization heating chamber 300, and a gas supply assembly 400. The material holding assembly 110 is disposed in the weighing tank 100 to hold a predetermined weight of red phosphorus 500. The transfer assembly 200 connects the weighing tank 100 to the volatilization heating chamber 300, so as to transport the material holding assembly containing red phosphorus 500 through the transfer assembly 200. 110 is conveyed from the weighing box 100 to the volatilization heating chamber 300; the volatilization heating chamber 300 is used to heat the red phosphorus 500 in the material holding assembly 110 to convert the solid red phosphorus into gaseous state; the air inlet of the gas conveying assembly 400 is connected to the volatilization heating chamber 300, and the air outlet of the gas conveying assembly 400 is used to extend into the single crystal furnace 600 to transfer the gaseous red phosphorus 500 in the volatilization heating chamber 300 to the silicon melt in the single crystal furnace 600.

[0024] When using the vapor phase doping apparatus for low resistivity heavily phosphorus-doped silicon single crystals of the present invention, a predetermined weight of red phosphorus 500 is first placed in the material holding assembly 110, wherein the predetermined weight refers to the weight of red phosphorus corresponding to the target resistivity of the pulled heavily phosphorus-doped silicon single crystal; next, the material holding assembly 110 containing red phosphorus 500 is placed on the transmission assembly 200, and the material holding assembly 110 is transported to the volatilization heating chamber 300 through the transmission assembly 200. Then, the red phosphorus in the material holding assembly 110 is heated in the volatilization heating chamber 300 to vaporize the red phosphorus 500. The vapor phase phosphorus is then input into the silicon melt of the single crystal furnace 600 for doping through the gas conveying assembly 400. Thus, the vapor phase phosphorus is directly input into the single crystal furnace for doping using the vapor phase doping method, avoiding the severe volatilization during traditional doping, ensuring that the red phosphorus and silicon melt are fully doped, and guaranteeing that the resistivity requirements of single crystal silicon are met.

[0025] Further, please see Figure 1 A weighing platform is installed inside the weighing bin 100, and a first robotic arm 120 is installed next to the weighing platform. A holding assembly 110 is placed on the weighing platform to weigh the red phosphorus 500 contained in the holding assembly 110. The first robotic arm 120 is used to transfer the holding assembly 110 containing the red phosphorus 500 from the weighing platform to the transfer assembly 200. The holding assembly 110 is a container made of quartz, such as a crucible. In one embodiment, the operator can first weigh a predetermined weight of red phosphorus externally, then place the predetermined weight of red phosphorus into the holding assembly 110, and then control the first robotic arm 120 to move the holding assembly 110 to the transfer assembly 200. In this embodiment, the weighing platform can serve as a secondary verification mechanism, that is, after the weighed red phosphorus is placed into the holding assembly 110, it is weighed again through the weighing platform to ensure that the red phosphorus in the holding assembly 110 meets the predetermined weight. As another implementation method, the staff first places the holding component 110 on the weighing platform for weighing and records the weight of the holding component 110. Then, red phosphorus is continuously added into the holding component 110, and the value on the weighing platform is observed. When the value on the weighing platform is equal to the sum of the weight of the holding component 110 and the predetermined weight of the red phosphorus, it indicates that the red phosphorus 500 contained in the holding component 110 has met the predetermined weight. At this time, the first robotic arm 120 can be controlled to move the holding component 110 to the transmission component 200.

[0026] Furthermore, the weighing box 100 is provided with a protective gas inlet 130 and a protective gas outlet 140 for filling the weighing box 100 with protective gas. Since red phosphorus is flammable, filling the weighing box 100 with protective gas ensures that the entire process of weighing and storing the red phosphorus takes place within the weighing box 100, thus preventing combustion. The protective gas can be nitrogen, argon, etc. Specifically, before placing the red phosphorus into the holding assembly 110, the protective gas inlet 130 and protective gas outlet 140 are opened to fill the weighing box 100 with protective gas. Once the weighing box 100 is full of protective gas, the red phosphorus is placed into the holding assembly 110, ensuring that the entire process of weighing and storing the red phosphorus takes place within the weighing box 100 containing protective gas.

[0027] Further, the transmission assembly 200 includes a connecting pipe 210, a conveyor belt 220, and a guide rail. The connecting pipe 210 is connected to the weighing bin 100 via a first flange 230 and to the evaporation heating chamber 300 via a second flange 240. The conveyor belt 220 is disposed within the connecting pipe 210, and the guide rail is disposed below the conveyor belt 220 and fixedly connected to it, so as to drive the conveyor belt 220 to move. Specifically, in the initial state, the first flange 230 and the second flange 240 are normally open, forming a through area between the weighing bin 100, the connecting pipe 210, and the evaporation heating chamber 300. The guide rail can move within the through area, thereby driving the conveyor belt to move within the through area. Also, in the initial state, one end of the conveyor belt 220 and the guide rail is located within one end of the weighing bin 100, while the other end of the conveyor belt 220 and the guide rail is located within the connecting pipe 210. Once the loading assembly 110 has contained a predetermined weight of red phosphorus, the first robotic arm 120 is controlled to pick up the loading assembly 110 and place it on the conveyor belt 220. Simultaneously, the conveyor belt 220 and the guide rail are started. With the conveyor belt 220 started, the loading assembly 110 is transported from one end to the other. With the guide rail started, the other end of the guide rail moves into the volatilization heating chamber 300, thereby driving the conveyor belt 220 into the volatilization heating chamber 300. By controlling the speed of the conveyor belt 220 and the speed of the guide rail, it is ensured that while the guide rail and the other end of the conveyor belt 220 enter the volatilization heating chamber, the loading assembly 110 is also simultaneously transported from one end of the conveyor belt 220 to the other. At this point, the conveyor belt 220 and the guide rail are stopped, and the loading assembly 110 is now positioned inside the volatilization heating chamber 300. After the material holding assembly 110 is removed, the control rail moves to the right, driving the conveyor belt 220 to move to the right, so that the conveyor belt 220 and the guide rail move out of the evaporation heating chamber 300. In some embodiments, a wheel is provided at the bottom of the guide rail, and the wheel is connected to a motor so that the motor drives the wheel to rotate clockwise or counterclockwise, thereby driving the guide rail to move to the left or right.

[0028] In some embodiments, one end of the guide rail is located inside the weighing bin 100, and the other end is located inside the evaporation heating chamber 300. The length of the conveyor belt 220 is shorter than the length of the guide rail, and the conveyor belt 220 can move left and right along the guide rail. In the initial state, one end of the conveyor belt 220 is flush with the end of the guide rail located in the weighing bin 100, so that one end of the conveyor belt 220 also enters the weighing bin 100. When the first robotic arm 120 places the material-holding assembly 110 on the conveyor belt 220, the conveyor belt 220 and the guide rail are started simultaneously, so that the conveyor belt 220 starts to run, and the conveyor belt 220 moves along the guide rail into the evaporation heating chamber 300. When the material-holding assembly 110 is inside the evaporation heating chamber 300, the conveyor belt 220 and the guide rail are stopped. After removing the material holding assembly 110, control the conveyor belt 220 to move to the left along the guide rail and move out of the volatilization heating chamber 300. At the same time, control the guide rail to retract at one end of the volatilization heating chamber 300 so that the other end of the guide rail also moves out of the volatilization heating chamber 300, so as to avoid affecting the sealing of the second flange 240.

[0029] Furthermore, please also refer to Figure 1 and Figure 2 A heating device 310 and a second robotic arm 320 are installed inside the evaporation heating chamber 300. The second robotic arm 320 is positioned between the conveyor assembly 200 and the heating device 310 to pick up the material-holding assembly 110 from the conveyor assembly 200 and place it inside the heating device 310. A sealing cover 330 is installed on the heating device 310 to seal it during heating. When the material-holding assembly 110 enters the evaporation heating chamber 300 along with the conveyor belt 220 and guide rail, after the conveyor belt 220 and guide rail are stopped, the second robotic arm 320 is controlled to pick up the material-holding assembly 110 and place it into the heating device 310. At this time, the conveyor belt 220 and guide rail are controlled to move out of the evaporation heating chamber 300, and the second flange 240 is closed, with the sealing cover 330 placed on the heating device 310. Then, the heating device 310 is controlled to start heating and pressurize the volatilization heating chamber 300 to ensure that the phosphorus can be fully heated and vaporized. At the same time, a pressure difference is created to allow the gaseous phosphorus to enter the gas conveying component 400 from the heating device 310. Finally, the gaseous phosphorus is fed into the single crystal furnace through the gas conveying component 400.

[0030] In some embodiments, a resistance heating plate is provided at the bottom of the heating device 310. Through resistance heating, the internal temperature of the heating device 310 is rapidly increased, thereby ensuring that phosphorus can be fully heated and volatilized.

[0031] In some embodiments, the volatilization heating chamber 300 is also provided with a protective gas inlet 130 and a protective gas outlet 140 to fill the volatilization heating chamber 300 with protective gas. When the material container 110 containing red phosphorus 500 enters the volatilization heating chamber 300 through the transfer component 200, protective gas is circulated into the volatilization heating chamber 300 through the protective gas inlet 130 and the protective gas outlet 140 to prevent the red phosphorus from reacting with oxygen. Further, the material container 110 is placed in the heating device 310 for heating. At this time, the flow rates of the protective gas inlet 130 and the protective gas outlet 140 are adjusted to modulate the gas pressure in the volatilization heating chamber 300, so that the gas pressure in the volatilization heating chamber 300 is greater than the furnace pressure of the single crystal furnace 600, thereby creating a pressure difference between the volatilization heating chamber and the single crystal furnace, allowing the phosphorus volatiles to quickly enter the single crystal furnace for effective doping. The protective gas inlet 130 is connected to a booster pump. When pressurization is required, the booster pump is turned on to increase the gas pressure in the evaporation heating chamber 300.

[0032] Further, please see Figure 1The gas supply assembly 400 includes a first gas supply pipe 410, a second gas supply pipe 420, a third gas supply pipe 430, a quartz tube 440, and a telescopic component. One end of the first gas supply pipe 410 is connected to the heating device 310, and the other end of the first gas supply pipe 410 is connected to one end of the second gas supply pipe 420. The other end of the second gas supply pipe 420 is connected to the inlet of the third gas supply pipe 430. The quartz tube 440 is disposed inside the third gas supply pipe 430, and one end of the quartz tube 440 is connected to the third gas supply pipe 430 through the telescopic component, so that the quartz tube 440 is driven to extend out of the third gas supply pipe 430 and approach the silicon melt inside the single crystal furnace 600 under the control of the telescopic component. The outlet of the third gas supply pipe 430 is fixedly connected to the single crystal furnace 600, and the quartz tube 440 extends out of the third gas supply pipe 430 and enters the single crystal furnace 600 under the control of the telescopic component, reaching the surface of the melt. A third flange 450 is installed between one end of the first gas supply pipe 410 and the heating device 310. The third flange 450 is a flange with a valve. After the red phosphorus is heated by the heating device 310, the phosphorus is converted into a gaseous state. At this time, the quartz tube 440 is controlled by the telescopic component to extend out of the third gas supply pipe 430, into the single crystal furnace 600, and approach the silicon melt, stopping at a preset distance from the surface of the silicon melt. When the valve of the third flange 450 is opened, the gaseous phosphorus enters the first gas supply pipe 410, the second gas supply pipe 420, and the third gas supply pipe 430 in sequence under the action of pressure difference, and finally enters the quartz tube 440, and enters the silicon melt from the quartz tube 440 for doping. The telescopic component controls the extension and retraction of the quartz tube 440, which can precisely control the extension distance of the quartz tube, thereby precisely controlling the distance between the quartz tube 440 and the liquid surface. This achieves the goal of reducing the volatilization of gaseous phosphorus while meeting the normal single crystal pulling requirements, thus ensuring that the doping requirements are met. Meanwhile, the cooperation between the telescopic component and the quartz tube 440 allows gaseous phosphorus to directly reach the vicinity of the silicon melt surface, enabling more phosphorus atoms to enter the silicon melt and increasing the phosphorus concentration within the silicon melt.

[0033] In some implementations, please refer to Figure 1A pressure-holding valve 460 is installed between the first gas supply pipe 410 and the second gas supply pipe 420. The pressure-holding valve 460 is normally closed. After the heating device 310 heats the red phosphorus for a period of time, the valve of the third flange 450 is opened. At this time, the gaseous phosphorus enters the first gas supply pipe 410 under the action of the pressure difference. When the gaseous phosphorus accumulates in the first gas supply pipe 410 and reaches a certain pressure value, the pressure-holding valve 460 is opened. At this time, the pressure difference between the first gas supply pipe 410 and the single crystal furnace 600 increases, allowing the gaseous phosphorus to quickly enter the single crystal furnace under the action of the pressure difference, thereby improving the phosphorus doping efficiency. In some embodiments, an argon purging is performed before doping to ensure that the furnace pressure of the single crystal furnace body is consistent with the furnace pressure in the volatilization heating chamber, and then the pressure-holding valve 460 is closed. When the heating device 310 heats, the volatilization heating chamber begins to pressurize, and then the pressure-holding valve 460 is opened to begin doping. After doping is completed, the pressure-holding valve 460 and the third flange 450 are closed.

[0034] In some embodiments, the telescopic component includes a motor and an electric telescopic rod. The motor is mounted on the outer wall of the third gas supply pipe 430, and the output shaft of the motor is connected to the electric telescopic rod. The other end of the electric telescopic rod is connected to the wall of the quartz tube 440, so that by starting the motor, the motor drives the electric telescopic rod to extend, and the electric telescopic rod pushes the quartz tube 440 out of the third gas supply pipe 430.

[0035] In some embodiments, the second gas supply pipe 420 is a flexible hose, and the first gas supply pipe 410 may be provided with multiple gas outlets. Each gas outlet is connected to the second gas supply pipe 420 through a pressure holding valve. The multiple second gas supply pipes are respectively connected to a single crystal furnace through a third gas supply pipe 430 and a quartz tube 440, so that multiple furnaces can be doped by using one gas phase doping device of the present invention.

[0036] Please refer to Figure 3 The present invention also provides a vapor-phase doping method for low-resistivity heavily phosphorus-doped silicon single crystals, employing the vapor-phase doping apparatus for low-resistivity heavily phosphorus-doped silicon single crystals as described above, comprising the following steps: S1. Add a predetermined weight of red phosphorus into the material holding assembly; S2. The material container containing red phosphorus is transported from the weighing box to the volatilization heating chamber through the transmission component; S3. The red phosphorus in the material holding assembly is heated in the volatilization heating chamber to convert the solid red phosphorus into a gaseous state. S4. Set the predetermined doping parameters and move the gas outlet of the gas delivery component to the surface of the silicon melt. Inject gaseous red phosphorus into the silicon melt through the gas delivery component for doping.

[0037] When using the apparatus of this invention for doping, a predetermined weight of red phosphorus is first placed into the holding assembly. Then, the holding assembly containing the predetermined weight of red phosphorus is transported from the weighing box to the volatilization heating chamber via the transfer assembly. The red phosphorus in the holding assembly is heated in the volatilization heating chamber, causing the solid red phosphorus to convert into a gaseous state. The parameters in the single crystal furnace are set to predetermined doping parameters, and the gas outlet of the gas delivery assembly is moved to the surface of the silicon melt, allowing the gaseous phosphorus to directly reach the vicinity of the silicon melt surface. This avoids the severe volatilization that occurs in traditional doping, allowing more phosphorus atoms to enter the silicon melt, increasing the phosphorus concentration within the silicon melt, and thus ensuring that the resistivity requirements of single-crystal silicon are met.

[0038] Further, please see Figure 2 The weighing bin 100 is equipped with a first robotic arm 120, and the evaporation heating chamber 300 is equipped with a second robotic arm 320; step S2 specifically includes: S21. Control the first robotic arm 120 to grab the material holding assembly 110 and place the material holding assembly 110 on the transmission assembly 200; S22, drive the transmission component 200 to drive the material holding component 110 from the weighing box 100 into the volatile heating chamber 300; S23. Control the second robotic arm 320 to grab the material holding assembly 110, remove the material holding assembly 110 from the transport assembly 200, and place it in the evaporation heating chamber 300.

[0039] Specifically, after the material holding assembly 110 contains a predetermined weight of red phosphorus, the first robotic arm 120 grasps the material holding assembly 110 and places it on the transmission assembly 200, specifically on the conveyor belt 220 of the transmission assembly 200. The transmission assembly 200 is activated, and as the belt on the conveyor belt 220 moves, it moves along the guide rail towards the volatilization heating chamber 300. When the conveyor belt 220 reaches the volatilization heating chamber 300, the material holding assembly 110 also moves synchronously from one end of the conveyor belt 220 to the other end, allowing it to enter the volatilization heating chamber 300. At this time, the second robotic arm 320 is controlled to grasp the material holding assembly 110, remove it from the transmission assembly 200, and place it in the heating device 310 within the volatilization heating chamber 300 to heat the red phosphorus inside the material holding assembly 110. The entire process of the material receiving assembly 110 from the weighing bin 100 to the volatilization heating chamber 300 is mechanically controlled, which can improve production efficiency. At the same time, the entire process is carried out in a closed environment filled with protective gas, which can prevent the red phosphorus from burning.

[0040] Further, in step S3, while heating the red phosphorus, pressure is applied to the volatilization heating chamber to make the gas pressure inside the volatilization heating chamber greater than the furnace pressure of the single crystal furnace. This creates a pressure difference between the volatilization heating chamber and the single crystal furnace, allowing the gaseous phosphorus to quickly enter the single crystal furnace for effective doping. In some embodiments, the gas pressure inside the volatilization heating chamber 300 is twice the furnace pressure of the single crystal furnace 600. Specifically, during the doping process, the furnace pressure of the single crystal furnace is set to 12-14 kPa, and the gas pressure inside the volatilization heating chamber is set to 24-28 kPa.

[0041] Further, in step S4, setting the predetermined doping parameters includes: setting the magnetic field in the single crystal furnace to 1000-2000 GS, the furnace rotation speed to 2-4 rpm, the argon flow rate to 90-120 SLM, and the furnace pressure to 12-14 kPa. When using a traditional quartz bell jar for doping, the corresponding doping parameters generally include a magnetic field of 3000-4000 GS, a furnace rotation speed of 1-2 rpm, a furnace pressure of 12-16 kPa, and an argon flow rate of 120-150 SLM. Since increasing the magnetic field strength inhibits convection in the silicon melt, leading to uneven phosphorus distribution, and the magnetic field is not turned off because it takes a long time to increase the magnetic field strength from 0 GS to the strength required for crystal pulling, resulting in wasted time, this invention sets the magnetic field strength to 1000-2000 GS during doping. This reduces wasted time while increasing convection in the silicon melt, allowing phosphorus to be evenly distributed in the silicon melt, thereby improving the uniformity of the resistivity of the silicon single crystal. Meanwhile, the improved pot-turn phase of this invention, compared to conventional doping, enhances the convection intensity of the silicon melt, allowing for a more uniform distribution of phosphorus within the melt. Furthermore, the reduced argon flow rate during doping compared to conventional methods reduces the amount of phosphorus volatiles carried away by argon, enabling more phosphorus to enter the melt and ensuring that the resistivity requirements of silicon single crystals are met.

[0042] To facilitate understanding, the present invention is further illustrated by the following embodiments and comparative examples. The embodiments and comparative examples all involve pulling 12-inch heavily phosphorus-doped silicon single crystals with a target resistivity of less than 0.0013 Ω·cm. Example

[0043] Weigh 1 kg of silicon material and 10 g of red phosphorus. Place the silicon material in a crucible for melting, using the following method: Figure 1 and Figure 2The vapor phase doping apparatus of the present invention is shown for doping. Specifically, the protective gas inlet 130 and protective gas outlet 140 of the weighing tank 100 are opened to fill the weighing tank 100 with protective gas. Red phosphorus is placed into the holding assembly 110, and then the first robotic arm 120 is controlled to place the holding assembly 110 containing red phosphorus onto the conveyor belt 220. Through the cooperation of the conveyor belt 220 and the guide rail, the holding assembly 110 is transported into the volatilization heating chamber 300. The second robotic arm 320 is controlled to grab the holding assembly 110 and place it into the heating device 310, while the conveyor belt 220 and the guide rail are moved out of the volatilization heating chamber 300, and the second flange 240 is closed. Immediately afterwards, the sealing cover 330 is placed on the heating device 310, and the heating device 310 starts heating, causing the red phosphorus to begin volatilization to form vapor phase phosphorus. At the same time, the volatilization heating chamber 300 is pressurized to increase the pressure difference between the volatilization heating chamber 300 and the single crystal furnace 600. When red phosphorus begins to volatilize, the quartz tube 440 is extended from the third gas supply pipe 430 via a telescopic component, entering the interior of the single crystal furnace 600 and reaching a position at a preset distance from the surface of the silicon melt. At this time, the third flange 450 and the pressure holding valve 460 are opened. Under the action of pressure difference, the gaseous phosphorus enters the quartz tube 440 through the first gas supply pipe 410, the second gas supply pipe 420, and the third gas supply pipe 430, and then enters the silicon melt to begin doping.

[0044] The parameters of the single crystal furnace during the doping process included a magnetic field of 1000 GS, a furnace rotation speed of 2 rpm, an argon flow rate of 90 SLM, a furnace pressure of 12 kPa, and a gas pressure of 24 kPa in the volatilization heating chamber. After doping, crystal pulling was performed to complete the pulling of heavily phosphorus-doped silicon single crystals. The above steps were repeated to pull three crystal rods, and the resistivity of each crystal rod was measured to obtain the following results: Figure 4 The resistivity measurement diagram of the crystal rod is shown.

[0045] Comparative Example Weigh 1 kg of silicon material and 10 g of red phosphorus. Place the silicon material in a crucible for melting and doping using a traditional quartz bell jar. Specifically, place the red phosphorus inside the quartz bell jar, and begin argon purging in the single crystal furnace, with the upper furnace tube used for isolation. Then, open the upper furnace tube and lower the seed crystal rope, hanging the quartz bell jar containing the red phosphorus on the seed crystal rope. Raise the seed crystal rope to a certain position and close the upper furnace tube. Immediately afterward, perform argon purging again and open the upper furnace tube isolation valve, lowering the quartz bell jar to the liquid surface. At this point, the red phosphorus begins to volatilize at the high temperature of the single crystal furnace and enters the molten silicon. After the red phosphorus has completely volatilized, move the quartz bell jar back up, perform argon purging again, and isolate it with the upper furnace tube. Finally, open the upper furnace tube, remove the quartz bell jar, close the upper furnace tube, perform argon purging again, and then open the upper furnace tube again to begin crystal pulling, thus completing the pulling of heavily phosphorus-doped silicon single crystals.

[0046] The parameters of the single-crystal furnace during the doping process included a magnetic field of 3000 GS, a furnace rotation speed of 1 rpm, an argon flow rate of 120 SLM, and a furnace pressure of 12 kPa. After doping, crystal pulling was performed to complete the pulling of heavily phosphorus-doped silicon single crystals. The above steps were repeated to pull three crystal rods, and the resistivity of each crystal rod was measured to obtain the following results: Figure 5 The resistivity measurement diagram of the crystal rod is shown.

[0047] contrast Figure 4 and Figure 5 It can be seen that the head resistivity of Examples 1, 2, and 3 reached below 0.0012 Ω·cm, and the tail resistivity reached below 0.0007 Ω·cm. In contrast, the head resistivity of Comparative Examples 1, 2, and 3 was around 0.0014 Ω·cm, and the tail resistivity was above 0.0008 Ω·cm. Therefore, the resistivity of the single-crystal silicon pulled after doping using the vapor-phase doping device of this invention is much lower than that using traditional doping methods. Furthermore, the resistivity of the examples all reached the target resistivity of below 0.0013 Ω·cm, while the resistivity of the comparative examples did not reach the target resistivity. Therefore, the vapor-phase doping device and doping method of this invention can effectively reduce phosphorus volatilization and ensure that the resistivity requirements of single-crystal silicon are met. Moreover, the doping steps are cumbersome when using a traditional quartz bell jar for doping; therefore, the vapor-phase doping device of this invention can also effectively reduce doping time and improve production efficiency.

[0048] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A vapor-phase doping device for low-resistivity heavily phosphorus-doped silicon single crystals, characterized in that, The system includes a material holding assembly, a weighing bin, a conveying assembly, a volatilization heating chamber, and a gas conveying assembly. The material holding assembly is disposed in the weighing bin to hold a predetermined weight of red phosphorus. The conveying assembly connects the weighing bin to the volatilization heating chamber, allowing the material holding assembly containing red phosphorus to be conveyed from the weighing bin to the volatilization heating chamber. The volatilization heating chamber heats the red phosphorus within the material holding assembly, converting the solid red phosphorus into a gaseous state. The gas conveying assembly's inlet is connected to the volatilization heating chamber, and its outlet extends into the single-crystal furnace, conveying the gaseous red phosphorus in the volatilization heating chamber to the silicon melt in the single-crystal furnace. The conveying assembly includes a connecting pipe, a conveyor belt, and a guide rail. The connecting pipe is connected to the weighing bin via a first flange and to the volatilization heating chamber via a second flange. The conveyor belt is disposed within the connecting pipe, and the guide rail is disposed below and fixedly connected to the conveyor belt. The conveyor belt is moved by the guide rail; a heating device and a second robotic arm are provided in the volatile heating chamber. The second robotic arm is located between the transmission assembly and the heating device to grab the material-holding assembly on the transmission assembly and place it in the heating device; a sealing cover is provided on the heating device to seal it when it is heating; the gas supply assembly includes a first gas supply pipe, a second gas supply pipe, a third gas supply pipe, a quartz tube, and a telescopic component; one end of the first gas supply pipe is connected to the heating device, the other end of the first gas supply pipe is connected to one end of the second gas supply pipe, and the other end of the second gas supply pipe is connected to the inlet of the third gas supply pipe; the quartz tube is located inside the third gas supply pipe, and one end of the quartz tube is connected to the third gas supply pipe through the telescopic component, so that the quartz tube is driven to extend out of the third gas supply pipe and approach the silicon melt in the single crystal furnace under the control of the telescopic component.

2. The vapor-phase doping device for low-resistivity heavily phosphorus-doped silicon single crystals according to claim 1, characterized in that, The weighing box is equipped with a weighing platform, and a first robotic arm is provided next to the weighing platform; the material holding assembly is placed on the weighing platform to weigh the red phosphorus contained in the material holding assembly; the first robotic arm is used to transfer the material holding assembly containing red phosphorus from the weighing platform to the transmission assembly.

3. The vapor-phase doping device for low-resistivity heavily phosphorus-doped silicon single crystals according to claim 2, characterized in that, The weighing box is provided with a protective gas inlet and a protective gas outlet for filling the weighing box with protective gas.

4. A vapor-phase doping method for low-resistivity heavily phosphorus-doped silicon single crystals, employing the vapor-phase doping apparatus for low-resistivity heavily phosphorus-doped silicon single crystals as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Add a predetermined weight of red phosphorus into the material holding assembly; S2. The material container containing red phosphorus is transported from the weighing box to the volatilization heating chamber through the transmission component; S3. The red phosphorus in the material holding assembly is heated in the volatilization heating chamber to convert the solid red phosphorus into a gaseous state. S4. Set the predetermined doping parameters and move the gas outlet of the gas conveying component to the surface of the silicon melt. Inject gaseous red phosphorus into the silicon melt through the gas conveying component for doping. The weighing bin is equipped with a first robotic arm, and the evaporation heating chamber is equipped with a second robotic arm; step S2 specifically includes: S21. Control the first robotic arm to grasp the material holding component and place the material holding component on the transmission component; S22. Drive the transmission component to move the material holding component from the weighing box into the volatilization heating chamber; S23. Control the second robotic arm to grab the material holding assembly, remove the material holding assembly from the transport assembly, and place it in the evaporation heating chamber.

5. The vapor-phase doping method for low-resistivity heavily phosphorus-doped silicon single crystals according to claim 4, characterized in that, In step S3, while heating the red phosphorus, pressurization is applied to the volatilization heating chamber so that the gas pressure inside the volatilization heating chamber is greater than the furnace pressure of the single crystal furnace.

6. The vapor-phase doping method for low-resistivity heavily phosphorus-doped silicon single crystals according to claim 5, characterized in that, In step S4, setting the predetermined doping parameters includes: setting the magnetic field inside the single crystal furnace to 1000-2000GS, the furnace rotation speed to 2-4rpm, the argon flow rate to 90-120SLM, and the furnace pressure to 12-14KPa.

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