Dopant addition method, silicon single crystal manufacturing method, dopant addition control unit, and silicon single crystal manufacturing system

Abstract

To provide a dopant addition method capable of properly determining the end of addition of a dopant.SOLUTION: A dopant addition method comprises: an addition start process of fitting a dopant addition device in which a volatile solid dopant is charged to one end side of a wire, and lowering the dopant addition device to an addition position above the silicon melt surface in a crucible arranged in a chamber to blow a dopant gas, produced by sublimation of the solid dopant, to the silicon melt; and an addition end process of determining that the weight of the dopant addition device, fitted to the one end side of the wire, detected by a weight detection part enters a reference state, and elevating the dopant addition device, wherein the reference state is a state in which the weight detected by the weight detection part does not change any more or a state in which the weight detected by the weight detection part is equal to the weight of the dopant addition device alone.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a dopant addition method, a silicon single crystal manufacturing method, a dopant addition control device, and a silicon single crystal manufacturing system. [Background technology]

[0002] Conventionally, when producing silicon single crystals, a method for adding a volatile dopant to a silicon melt is known in which the dopant is sublimated to generate a dopant gas, and the dopant gas is sprayed onto the silicon melt (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a doping device comprising a container body having a container body main body and a discharge pipe, and an outer cylinder that houses the container body and has an open lower end. When the doping device is lowered to near the surface of the silicon melt, solid arsenic (solid dopant) contained in the container body sublimes due to radiant heat from the silicon melt, generating arsenic gas (dopant gas). When the dopant gas is released from the lower end of the discharge pipe and sprayed onto the silicon melt, the dopant contained in the dopant gas dissolves in the silicon melt, and the dopant is added to the silicon melt. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-342094 Summary of the Invention [Problem to be solved by the invention]

[0005] However, Patent Document 1 does not disclose a method for determining whether or not the addition of the dopant has been completed.

[0006] In the configuration described in Patent Document 1, it is difficult to directly visually check the inside of the container body. Therefore, a conceivable method for determining the completion of dopant addition is to determine that the dopant addition has completed when a set time has elapsed since the doping device was lowered to the addition position near the silicon melt, regardless of the amount of solid dopant loaded into the doping device. However, the sublimation rate of the solid dopant may change due to changes in the pressure or temperature in the chamber, or changes in the thermal environment due to deterioration or replacement of components in the hot zone, etc. Therefore, even when the same amount of dopant is added, the sublimation of all the solid dopants may finish earlier or later than the set time.

[0007] If the sublimation of the solid dopant is completed earlier than the set time, the silicon single crystal growth process cannot be performed until the set time has elapsed, even though the sublimation of the solid dopant has already been completed, and therefore manufacturing efficiency cannot be improved. Furthermore, the dopant added to the silicon melt may evaporate before the set time has elapsed, which may prevent the production of a silicon single crystal with the desired resistivity. On the other hand, if the sublimation of the solid dopant finishes later than the set time, the silicon single crystal will be produced without all of the dopant being added, and there is a risk that a silicon single crystal with the desired resistivity will not be obtained.

[0008] An object of the present invention is to provide a dopant addition method, a silicon single crystal manufacturing method, a dopant addition control device, and a silicon single crystal manufacturing system that are capable of appropriately determining the end of dopant addition. [Means for solving the problem]

[0009] The dopant addition method of the present invention includes an addition start step of attaching a dopant addition device loaded with a volatile solid dopant to one end of a wire, lowering the dopant addition device to an addition position above the surface of the silicon melt in a crucible placed in a chamber, and spraying dopant gas generated by sublimation of the solid dopant onto the silicon melt, and an addition end step of determining that the addition of dopant to the silicon melt has been completed and raising the dopant addition device when the weight of the dopant addition device attached to one end of the wire detected by a weight detection unit reaches a reference state, wherein the reference state is a state where there is no change in the weight detected by the weight detection unit, or a state where the weight detected by the weight detection unit matches the weight of the dopant addition device alone.

[0010] In the dopant addition method of the present invention, it is preferable that the addition completion step determines that the addition of the dopant has been completed when a preset waiting period has elapsed since the reference state was reached, and the waiting period is the period from the time the reference state was reached until it is estimated that all of the dopant gas in the dopant addition device has been sprayed onto the silicon melt.

[0011] In the dopant addition method of the present invention, a drum is fixed to the other end of the wire, which rotates by driving a motor to wind up or unwind the wire, and the weight detection unit is a load cell that detects the weight of the dopant addition device attached to the one end of the wire by detecting the load acting on the motor, and it is preferable that the addition start process and the addition end process control the motor to move the dopant addition device.

[0012] The silicon single crystal manufacturing method of the present invention includes a dopant addition step of adding the dopant to the silicon melt by the above-described dopant addition method, and a growth step of growing a silicon single crystal by the CZ method using the silicon melt to which the dopant has been added.

[0013] The dopant addition control device of the present invention comprises an addition start control unit that lowers a dopant addition device, which is loaded with a volatile solid dopant and is attached to one end of a wire, to an addition position above the silicon melt surface in a crucible and sprays dopant gas generated by sublimation of the solid dopant onto the silicon melt, and an addition end control unit that determines that the addition of dopant to the silicon melt has ended when the weight of the dopant addition device attached to one end of the wire detected by a weight detection unit reaches a reference state and raises the dopant addition device, wherein the reference state is a state in which there is no change in the weight detected by the weight detection unit or a state in which the weight detected by the weight detection unit matches the weight of the dopant addition device alone.

[0014] In the dopant addition control device of the present invention, it is preferable that the addition termination control unit determines that the addition of the dopant has ended when a preset waiting period has elapsed since the reference state was reached, and that the waiting period is the period from the time the reference state was reached until it is estimated that all of the dopant gas in the dopant addition device has been sprayed onto the silicon melt.

[0015] In the dopant addition control device of the present invention, it is preferable that a drum is fixed to the other end of the wire, which rotates by driving a motor to wind up or wind down the wire, the weight detection unit is a load cell that detects the weight of the dopant addition device attached to the one end of the wire by detecting the load acting on the motor, and the addition start control unit and the addition end control unit control the motor to move the dopant addition device.

[0016] The silicon single crystal manufacturing system of the present invention includes the above-mentioned dopant addition control device, the dopant addition device, the wire to one end of which the dopant addition device or a seed crystal is attached, the weight detection unit, and a growth control unit that grows a silicon single crystal by immersing the seed crystal attached to the one end of the wire in the silicon melt to which the dopant has been added and then pulling it up.

[0017] The silicon single crystal manufacturing system of the present invention includes the above-mentioned dopant addition control device, the dopant addition device, the wire to one end of which the dopant addition device or seed crystal is attached, the drum, and a lifting unit having the motor, the load cell, and a growth control unit that grows a silicon single crystal by immersing the seed crystal attached to the one end of the wire in the silicon melt to which the dopant has been added and then lifting it up. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram of a silicon single crystal production system according to an embodiment, showing a state during silicon single crystal growth. [Figure 2] 1 is a schematic diagram of a silicon single crystal production system according to an embodiment, showing a state during dopant addition. [Figure 3] 1 is a vertical cross-sectional view of a dopant addition device according to an embodiment. [Figure 4] 10 is a graph showing the relationship between time and detected weight in a load cell in a dopant addition method according to an embodiment. [Figure 5] 1 is a flowchart of a silicon single crystal manufacturing method according to an embodiment. [Figure 6] 10 is a flowchart of a dopant addition step according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] [Embodiment] <Configuration of silicon single crystal production system> First, the configuration of a silicon single crystal production system according to one embodiment of the present invention will be described. The silicon single crystal production system 1 shown in FIGS. 1 and 2 includes a silicon single crystal production apparatus 2. The silicon single crystal manufacturing apparatus 2 uses the Czochralski (CZ) method to manufacture a silicon single crystal (ingot) SM doped with a volatile dopant. Examples of the volatile dopant include arsenic, red phosphorus, and antimony. The silicon single crystal manufacturing apparatus 2 includes a chamber 21, a crucible 22, a heater 23, a heat-retaining tube 24, a shield 25, and a pulling unit 26.

[0020] The chamber 21 includes a main chamber 211 in which the silicon single crystal SM is pulled, and a pull chamber 212 connected to the top of the main chamber 211 and accommodating the pulled silicon single crystal SM. The main chamber 211 accommodates a crucible 22 , a heater 23 , a heat-retaining tube 24 and a shield 25 . A gate valve 213 is provided at the bottom of the pull chamber 212 to isolate the upper end of the main chamber 211 from the lower end of the pull chamber 212 . A first gas supply unit 214 is provided at the top of the pull chamber 212 to supply an inert gas Gf, such as argon (Ar) gas, into the pull chamber 212. A first gas exhaust unit 215 is provided at the bottom of the pull chamber 212 to exhaust the inert gas Gf from the pull chamber 212. A second gas supply unit 216 is provided at the top of the main chamber 211 to introduce the inert gas Gf into the chamber 21. A second gas exhaust unit 217 is provided at the bottom of the main chamber 211 to exhaust an internal gas Gn, such as Ar gas, containing evaporated products such as SiO generated in the main chamber 211, to the outside of the silicon single crystal production apparatus 2.

[0021] Crucible 22 is composed of an outer graphite crucible and an inner quartz crucible. Crucible 22 is placed in main chamber 211 and stores silicon melt M to which a volatile dopant has been added. Crucible 22 is fixed to the upper end of support shaft 221, which is rotatable and can be raised and lowered. The heater 23 is formed in a cylindrical shape and is disposed so as to surround the crucible 22. The heater 23 generates heat to melt the silicon raw material in the crucible 22. The heat-retaining cylinder 24 is formed in a cylindrical shape and is disposed so as to surround the heater 23 . The shield 25 is made of a carbon material and has a substantially cylindrical shape. The shield 25 is disposed so as to surround the silicon single crystal SM being pulled up from the silicon melt M, and blocks radiant heat from the heater 23 to the silicon single crystal SM.

[0022] The pulling unit 26 is provided above the pull chamber 212 and includes a wire 261, a drum 262, a motor 263, and a load cell 264 as a weight measuring unit. One end of the wire 261 is attached to the seed crystal SC shown in FIG. 1 or the dopant adding device 3 shown in FIG. The other end of the wire 261 is fixed to the drum 262. The drum 262 is rotated by the drive of a motor 263, and winds up and down the wire 261 while maintaining the wire 261 positioned coaxially with the support shaft 221 above the crucible 22. The load cell 264 detects the load acting on the motor 263 , thereby detecting the weight of the silicon single crystal SM or the dopant addition device 3 attached to one end of the wire 261 .

[0023] The silicon single crystal production system 1 further includes a dopant addition device 3. The dopant adding device 3 adds a volatile dopant to the silicon melt M stored in the crucible 22. As shown in FIG.

[0024] The dopant accommodation section 31 is made of quartz and is formed in the shape of a cylinder with an open top end and a closed bottom end. As indicated by the two-dot chain line, a solid dopant (hereinafter, sometimes referred to as a "solid dopant") D is loaded inside the dopant accommodation section 31. This solid dopant D is sublimated by radiant heat from the silicon melt M, generating dopant gas Gd. The generated dopant gas Gd is released from the opening at the top end of the dopant accommodation section 31. The opening for releasing the dopant gas Gd may be provided on the side surface of the dopant accommodation section 31.

[0025] The outer cylinder 32 is made of quartz and is formed in a cylindrical shape with an open lower end and a closed upper end. The outer cylinder 32 has a dopant accommodating section 31 provided therein, and the dopant gas Gd released from the dopant accommodating section 31 is made to flow out from the lower end and sprayed onto the silicon melt M.

[0026] The support section 33 includes a plurality of supported members 331 made of a carbon material and a plurality of receiving members 332 that support the lower surfaces of the supported members 331. The supported members 331 are provided on the outer peripheral surface of the dopant accommodating section 31 at equal intervals along the circumferential direction thereof, and the receiving members 332 are provided on the inner peripheral surface of the outer cylinder 32 at equal intervals along the circumferential direction thereof. The dopant accommodating section 31 is supported within the outer cylinder 32 by fitting each supported member 331 onto the upper surface of each receiving member 332. The dopant gas Gd released from the dopant accommodating section 31 passes through a space between the dopant accommodating section 31 and the outer cylinder 32 where the supported member 331 and the receiving member 332 are not positioned, and flows out from the lower end of the outer cylinder 32.

[0027] The silicon single crystal production system 1 further includes a control device 4 shown in FIGS. The control device 4 is connected to the load cell 264. The weight measurement value detected by the load cell 264 is transferred to the control device 4 and recorded. The control device 4 is configured to be able to control a first gas supply control unit 271 that supplies an inert gas Gf from a first gas supply unit 214 into the pulling chamber 212, a first gas exhaust control unit 272 that exhausts the inert gas Gf from the pulling chamber 212 through a first gas exhaust unit 215, a second gas supply control unit 273 that supplies an inert gas Gf from a second gas supply unit 216 into the chamber 21, a second gas exhaust control unit 274 that exhausts the internal gas Gn from the chamber 21 through a second gas exhaust unit 217, a gate valve driving unit 275 that drives the gate valve 213, a crucible driving unit 276 that rotates the crucible 22, the heater 23, and the motor 263. The control device 4 includes an input unit 41, a display unit 42, a memory unit 43, and a control unit 44.

[0028] The input unit 41 is configured by, for example, a touch panel or physical buttons, and outputs a signal corresponding to an input operation to the control unit 44. The display unit 42 displays various information based on the control of the control unit 44. The storage unit 43 stores various pieces of information relating to the addition of dopants and the growth of silicon single crystal SM so that the control unit 44 can read them.

[0029] The control unit 44 includes a CPU, and realizes various functions by the CPU executing programs stored in the storage unit 43. The control unit 44 includes an addition start control unit 45, an addition end control unit 46, and a growth control unit 47. The addition start control unit 45 and the addition end control unit 46 constitute a dopant addition control device 5, and control the addition of the dopant to the silicon melt M.

[0030] The addition start control unit 45 moves the dopant addition device 3 containing the solid dopant D to an addition position near the silicon melt M, and sprays the dopant gas Gd generated by sublimation of the solid dopant D onto the silicon melt M. The addition position is the position in the dopant addition device 3 where the solid dopant D sublimes.

[0031] 4, the addition completion control unit 46 may determine that the addition of the dopant to the silicon melt M has ended at time T3 when the weight detected by the load cell 264 reaches a reference state. Alternatively, the addition completion control unit 46 may determine that the addition of the dopant to the silicon melt M has ended at time T4 when a waiting period P has elapsed since time T3 when the reference state was reached. When the addition completion control unit 46 determines that the addition of the dopant has ended, it raises the dopant addition device 3.

[0032] The dopant is added to the silicon melt M using a dopant adding device 3. If the weight of the dopant adding device 3 is W1 and the total weight of the solid dopant D loaded into the dopant adding device 3 is W2, as shown in Fig. 4, the weight detected by the load cell 264 at the time when the dopant gas Gd is not being generated is weight W3 obtained by adding weight W1 and weight W2. After this, the dopant addition device 3 is moved into the main chamber 211, and at time T1, dopant gas Gd begins to be generated as the solid dopant D sublimates. As time passes, the weight detected by the load cell 264 gradually decreases from weight W3. Then, at time T2, when all of the solid dopant D in the dopant addition device 3 has sublimated, the weight detected by the load cell 264 becomes weight W1. When weight W3 at the time when dopant gas Gd is not being generated is used as a reference, the weight deviation at time T1 becomes 0 (= W3 - W3). The weight deviation at time T2 becomes -W2 (= W1 - W3 = W1 - (W1 + W2)). After time T2, there is no change in the weight detected by the load cell 264. For example, at time T3 when the results of multiple consecutive weight detections become the same or almost the same, it can be determined that the reference state has been reached, where there is no change in weight (change in weight deviation). This makes it possible to determine that the entire amount of solid dopant D has sublimated, and it can be automatically determined that the addition of the dopant to the silicon melt M has been completed.

[0033] After time T3, the dopant gas Gd that has completed sublimation in the dopant addition device 3 is not immediately discharged from the dopant addition device 3. Therefore, it takes time for all of the remaining dopant gas Gd to be sprayed onto the silicon melt M and disappear. If the dopant addition device 3 is raised at time T3, an error, however slight, will occur in the amount of dopant added to the silicon melt M. While this error is negligible in growing an extremely low-resistivity silicon single crystal SM with a large amount of dopant added, it may cause variations in resistivity in growing a high-resistivity silicon single crystal SM. For this reason, it is more preferable to provide a waiting period P after time T3 until all of the dopant gas Gd remaining in the dopant addition device 3 is sprayed onto the silicon melt M and disappears. The waiting period P is the period from time T3 until it is estimated that all of the dopant gas Gd in the dopant adding device 3 has been sprayed onto the silicon melt M. The waiting period P is set to be equal to or greater than 1 minute and equal to or less than 30 minutes, and is stored in the memory unit 43. The waiting period P can be determined by simulation or experiment. The waiting period P is preferably set according to at least one of the type of dopant and the total weight of the solid dopant D loaded into the dopant adding device 3.

[0034] The growth control unit 47 grows a silicon single crystal SM by immersing the seed crystal SC in a silicon melt M to which a dopant has been added and then pulling it up. The growth control unit 47 acquires the weight detection result of the silicon single crystal SM being grown from the load cell 264, and adjusts the manufacturing conditions so that a silicon single crystal SM having a desired shape can be manufactured.

[0035] <Silicon single crystal manufacturing method> Next, a silicon single crystal manufacturing method will be described, in which it is determined that the addition of dopant to silicon melt M has been completed at time T4, which is the time T3 at which the reference state was reached and a waiting period P has elapsed. 5, the growth control unit 47 of the control device 4 generates a silicon melt M by a well-known method (step S1: silicon melt generating step). In the silicon melt generating step of step S1, the gate valve 213 is opened, and the chamber 21 is maintained in a reduced pressure state by supplying an inert gas Gf only from the first gas supply unit 214 and exhausting an internal gas Gn only from the second gas exhaust unit 217. The dopant addition control device 5 of the control device 4 performs a dopant addition step of adding a dopant to the silicon melt M (step S2). The growth control unit 47 performs a growth step of growing a silicon single crystal SM by immersing the seed crystal SC in the silicon melt M to which the dopant has been added and then pulling it up (step S3).

[0036] 6, in the dopant addition process of step S2, the addition start control unit 45 of the dopant addition control device 5 controls the gate valve driving unit 275 to close the gate valve 213 (step S11). By the process of step S11, the pulling chamber 212 is isolated from the main chamber 211, which has an inert gas atmosphere. The addition start control unit 45 closes the gate valve 213 and simultaneously controls the second gas supply control unit 273 to supply the inert gas Gf into the main chamber 211. The addition start control unit 45 controls the first gas supply control unit 271 to stop the supply of the inert gas Gf into the pulling chamber 212. After the pressure inside the pull chamber 212 is set to atmospheric pressure, an operator or an attachment / detachment device (not shown) attaches the dopant addition device 3 loaded with the solid dopant D to the lower end of the wire 261 at the attachment / detachment position (step S12).

[0037] After the installation of the dopant addition device 3 is completed, the addition start control unit 45 controls the first gas supply control unit 271 to supply the inert gas Gf into the pull chamber 212, and controls the first gas exhaust control unit 272 to exhaust the inert gas Gf from the pull chamber 212, thereby reducing the pressure inside the pull chamber 212. The addition start control unit 45 drives the motor 263 to lower the dopant addition device 3 to the standby position above the gate valve 213, and then controls the gate valve driving unit 275 to open the gate valve 213 (step S13). The addition start control unit 45 opens the gate valve 213 and simultaneously controls the second gas supply control unit 273 to stop the supply of the inert gas Gf from the second gas supply unit 216 into the main chamber 211. Furthermore, the addition start control unit 45 controls the first gas exhaust control unit 272 to stop the exhaust of the inert gas Gf from the first gas exhaust unit 215, and controls the second gas exhaust control unit 274 to adjust the gas exhaust amount so that the pressure inside the main chamber 211 becomes a pressure suitable for adding the dopant.

[0038] The addition start control unit 45 acquires the weight detection result of the load cell 264 as the initial weight (step S14). Note that the addition start control unit 45 may acquire the initial weight before lowering the dopant addition device 3 to the standby position, or may acquire the initial weight after lowering the dopant addition device 3 to the standby position above the gate valve 213 and before opening the gate valve 213. The addition start control unit 45 drives the motor 263 to wind down the wire 261, and lowers the dopant adding device 3 to an adding position near the silicon melt M, thereby starting the addition of the dopant (step S15). The processes of steps S11 to S15 constitute an addition start step.

[0039] When a preset detection standby period has elapsed since the processing of step S15 was performed at time T1 shown in Fig. 4, the addition end control unit 46 acquires the weight detection result of the load cell 264 (step S16). The detection standby period is not particularly limited, but is, for example, 30 seconds. Based on the weight acquired in step S16, the addition end control unit 46 determines whether or not there is no change in the weight deviation based on the initial weight (step S17).

[0040] When the addition end control unit 46 of the dopant addition control device 5 determines that the change in weight deviation has not disappeared (step S17: NO), it acquires the weight detection result after the detection waiting period has elapsed (step S16). On the other hand, if the addition end control unit 46 determines that the weight deviation has stopped changing (step S17: YES), it determines that the addition of the dopant has ended when the waiting period P has elapsed since the weight deviation stopped changing (step S18).

[0041] The addition end control unit 46 winds up the wire 261 by driving the motor 263, and raises the dopant addition device 3 to the attachment / detachment position, thereby ending the addition of the dopant (step S19). The processes of steps S16 to S19 constitute an addition completion step. The addition end control unit 46 controls the gate valve driving unit 275 to close the gate valve 213 (step S20). At the same time as closing the gate valve 213, the addition end control unit 46 controls the second gas supply control unit 273 to supply the inert gas Gf into the main chamber 211. The addition end control unit 46 controls the first gas supply control unit 271 to stop the supply of the inert gas Gf into the pulling chamber 212. After the pressure inside the pull chamber 212 is set to atmospheric pressure, the operator or the attachment / detachment device detaches the dopant addition device 3 from the wire 261 (step S21). Thereafter, the seed crystal SC is attached to the wire 261 by an operator or an attachment / detachment device, and the growing step of step S3 is carried out.

[0042] <Effects of the embodiment> The dopant addition control device 5 starts adding the dopant by lowering the dopant addition device 3 loaded with the solid dopant D to the addition position, and then, based on the detection result of the load cell 264, when there is no change in the weight deviation based on the initial weight, i.e., when there is no change in weight, it determines that the addition of the dopant to the silicon melt M has been completed and raises the dopant addition device 3. Therefore, even if the sublimation rate of the solid dopant D changes due to a change in the thermal environment in the chamber 21, it can be properly determined that all of the solid dopant D has sublimated and the addition of the dopant has been completed. Therefore, after the addition of all the dopants has actually been completed, the process can be shifted to the growth step quickly, improving manufacturing efficiency. Furthermore, evaporation of the dopants added to the silicon melt M before the shift to the growth step and the shift to the growth step in a state where all the dopants have not been added can be suppressed, thereby making it possible to obtain a silicon single crystal SM with a desired resistivity.

[0043] The dopant addition control device 5 determines that the addition of dopant has ended at time T4, which is the time when a waiting period P has elapsed from time T3 when there is no longer any change in weight detected by the load cell 264 until it is estimated that all of the dopant gas Gd in the dopant addition device 3 has been sprayed onto the silicon melt M. This reduces the possibility of proceeding to the growth step in a state where all dopants have not been added, and makes it possible to obtain a silicon single crystal SM with the desired resistivity.

[0044] The dopant addition control device 5 uses a load cell 264 that detects the weight of the silicon single crystal SM being grown to determine whether or not the addition of the dopant has been completed. Therefore, there is no need to provide the silicon single crystal production system 1 with a weight detection unit that is used only to determine the completion of dopant addition, and the configuration of the silicon single crystal production system 1 can be simplified.

[0045] [Variations] Although the reference state is exemplified as a state in which there is no change in weight deviation, the reference state may also be a state in which there is no change in the weight acquired in step S16 without performing the process of acquiring the initial weight in step S14. Alternatively, the reference state may be a state in which the weight of the dopant addition device 3 alone is measured before attaching the dopant addition device 3 to the wire 261, and the weight detected by the load cell 264 matches the weight of the dopant addition device 3 alone. Although it is determined that the addition of dopant is completed at time T4 when the waiting period P has elapsed since time T3 when the reference state was reached, it may also be determined that the addition of dopant is completed at time T3 when the reference state was reached. Even with these configurations, even if the sublimation rate of the solid dopant D changes due to a change in the thermal environment in the chamber 21, it is possible to appropriately determine that all of the solid dopant D has sublimated and the addition of the dopant has been completed.

[0046] Although the load cell 264 for detecting the weight of the silicon single crystal SM being grown is used to determine the end of dopant addition, a weight detection unit other than the load cell 264 may also be used. An example of such a weight detection unit is a weighing scale on which the drum 262 is placed. [Industrial Applicability]

[0047] Low / medium voltage power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) used as power devices in mobile devices have a certain electrical resistance (called "on-resistance") between the drain and source when they are operating (on). If the on-resistance of low / medium voltage power MOSFETs can be reduced, the power consumption of mobile devices can be reduced. Against this background, device manufacturers are requesting the provision of silicon wafers doped with high concentrations of n-type dopants, typically arsenic (As), phosphorus (P), and antimony (Sb), in order to reduce the on-resistance of low / medium voltage power MOSFETs. One aspect of the present invention is useful in the field of silicon wafer manufacturing. The automation of n-type dopant addition reduces lead time, reducing the workload on workers and ultimately improving the production yield of n-type wafers. This improves product productivity and quality, enabling greater demand to be met. This will improve productivity across the semiconductor industry and contribute to promoting economic growth (Development Goal: SDG 8). [Explanation of symbols]

[0048] 1...silicon single crystal manufacturing system, 3...dopant addition device, 5...dopant addition control device, 26...pulling section, 45...addition start control section, 46...addition end control section, 47...growth control section, 261...wire, 262...drum, 263...motor, 264...load cell (weight detection section), D...solid dopant, Gd...dopant gas, M...silicon melt, SC...seed crystal, SM...silicon single crystal.

Claims

1. an addition start step of attaching a dopant addition device loaded with a volatile solid dopant to one end of a wire, lowering the dopant addition device to an addition position above the surface of the silicon melt in a crucible disposed in a chamber, and spraying a dopant gas generated by sublimation of the solid dopant onto the silicon melt; an addition completion step of determining that addition of the dopant to the silicon melt has been completed when the weight of the dopant addition device attached to one end of the wire detected by a weight detection unit reaches a reference state, and lifting the dopant addition device; The dopant addition method, wherein the reference state is a state in which there is no change in the weight detected by the weight detection unit, or a state in which the weight detected by the weight detection unit matches the weight of the dopant addition device alone.

2. The dopant addition method according to claim 1, the addition completion step determines that the addition of the dopant has been completed when a preset waiting period has elapsed since the reference state was reached, The dopant adding method, wherein the waiting period is a period from when the reference state is reached until it is estimated that all of the dopant gas in the dopant adding device has been sprayed onto the silicon melt.

3. 3. The dopant addition method according to claim 1 or 2, A drum is fixed to the other end of the wire, and the drum rotates by driving a motor to wind up or down the wire. the weight detection unit is a load cell that detects a load acting on the motor to thereby detect a weight of the dopant addition device attached to the one end of the wire; The dopant adding method includes controlling the motor to move the dopant adding device in the addition start step and the addition end step.

4. a dopant addition step of adding the dopant to the silicon melt by the dopant addition method according to claim 1 or 2; a growing step of growing a silicon single crystal by a CZ method using the silicon melt to which the dopant has been added.

5. an addition start control unit that lowers a dopant addition device, which is loaded with a volatile solid dopant and has one end of a wire attached thereto, to an addition position above the surface of the silicon melt in the crucible, and sprays a dopant gas generated by sublimation of the solid dopant onto the silicon melt; an addition completion control unit that determines that addition of the dopant to the silicon melt has been completed when the weight of the dopant addition device attached to one end of the wire detected by a weight detection unit reaches a reference state, and raises the dopant addition device; Equipped with The reference state is a state in which there is no change in the weight detected by the weight detection unit, or a state in which the weight detected by the weight detection unit matches the weight of the dopant addition device alone.

6. 6. The dopant addition control device according to claim 5, the addition completion control unit determines that the addition of the dopant has been completed when a preset waiting period has elapsed since the reference state was reached, and The dopant addition control device, wherein the waiting period is a period from when the reference state is reached until it is estimated that all of the dopant gas in the dopant addition device has been sprayed onto the silicon melt.

7. 7. The dopant addition control device according to claim 5 or 6, A drum is fixed to the other end of the wire, and the drum rotates by driving a motor to wind up or down the wire. the weight detection unit is a load cell that detects a load acting on the motor to thereby detect a weight of the dopant addition device attached to the one end of the wire; The dopant addition control device, wherein the addition start control unit and the addition end control unit control the motor to move the dopant addition device.

8. The dopant addition control device according to claim 5 or 6; the dopant adding device; the wire to one end of which the dopant addition device or the seed crystal is attached; The weight detection unit; a growth control unit that grows a silicon single crystal by immersing the seed crystal attached to the one end of the wire in the silicon melt to which the dopant has been added and then pulling it up.

9. The dopant addition control device according to claim 7; the dopant adding device; a pulling unit having the wire, the drum, and the motor, to one end of which the dopant adding device or the seed crystal is attached; The load cell; a growth control unit that grows a silicon single crystal by immersing the seed crystal attached to the one end of the wire in the silicon melt to which the dopant has been added and then pulling it up.

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