Method for monitoring metal pollution in ion implantation process by using PFG and PFG metal pollution monitoring system of ion implanter

Abstract

The invention discloses a method for monitoring metal pollution in an ion implantation process by using PFG and a PFG metal pollution monitoring system of an ion implanter. The method comprises the following steps: providing a P-type semiconductor wafer, and carrying out ion implantation and annealing treatment on the P-type semiconductor wafer; adopting a plasma gun as an electron source to neutralize positive charges on the surface of the P-type semiconductor wafer in ion implantation treatment; and measuring the diffusion length of a carrier of the P-type semiconductor wafer, calculating the service life of the carrier according to the diffusion length, and outputting a PFG metal pollution degree result. The SPV method is adopted, and the service life of the carriers is calculated by measuring the diffusion length of the carriers in the silicon crystal, so that the PFG metal pollution degree is monitored, the PFG metal pollution condition of the ion implanter can be monitored efficiently and accurately, process parameters are adjusted in time, and the manufacturing quality of semiconductor devices is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor manufacturing, and in particular to a method for monitoring metal contamination in ion implantation process using a plasma flood gun (PFG) and a PFG metal contamination monitoring system for ion implanters. BACKGROUND

[0002] In semiconductor manufacturing process, ion implanters are important equipment for implanting dopant ions into semiconductor materials to change their electrical properties. The core of ion implantation is to make dopant ions (e.g. B⁺, P⁺, As⁺, etc. positively charged ions) accelerated to bombard the wafer surface, so that the ions are embedded into the semiconductor lattice to change the electrical properties. However, in this process, the implanted ions are mostly single charge (e.g. positive), and the electrons on the wafer surface (especially the oxide layer, dielectric layer) cannot quickly migrate to the surface to neutralize these positive charges, resulting in the accumulation of a large number of positive charges on the wafer surface, forming a surface charge accumulation phenomenon. If not neutralized, the accumulated charges will generate a local electric field, which not only can deflect the subsequent implanted ions (causing ion beam divergence, affecting the doping accuracy), but also can break through the thin dielectric layer (e.g. gate oxide layer) on the wafer surface, causing permanent damage to the device.

[0003] PFG is used to neutralize the positive charges on the wafer surface during ion implantation to prevent potential damage caused by charge accumulation. Specifically, inside the PFG, the working gas (usually inert gas such as Ar, or a small amount of N2, He) is ionized by radio frequency (RF) discharge or electron cyclotron resonance (ECR) to form a plasma containing equal amounts of positive ions (such as Ar⁺) and free electrons. PFG, through ion suppression grid or electric field guiding design, preferentially delivers free electrons in the plasma to the wafer surface; the free electrons delivered to the wafer surface will combine with the positive charges accumulated by previous ion implantation (e.g. positive charges left by implanting B⁺), resulting in charge annihilation, making the net charge on the wafer surface close to zero, and ultimately achieving charge neutralization.

[0004] However, the filament material of PFG (mainly tungsten or molybdenum) will release metal ions while generating hot electrons, and these metal ions may be implanted into the wafer, causing metal contamination. Metal contamination can significantly shorten the lifetime of carriers and affect the performance of semiconductor devices. Therefore, an effective monitoring method is needed to assist in controlling the yield of semiconductor devices.

[0005] In existing technologies, the VPD (vapor phase decomposition) method is commonly used to monitor metal contamination. The VPD method treats the wafer surface with HF vapor, releasing metal contaminants from the oxide layer and altering the wafer's surface properties for easier collection. This is then combined with the powerful detection capabilities of ICP-MS to achieve effective monitoring of trace metal contamination on the wafer surface. However, the VPD method requires a large implantation dose, a thick oxide layer, and a long processing time, which not only increases process complexity but may also affect production efficiency.

[0006] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art. Summary of the Invention

[0007] The purpose of this invention is to provide a method for monitoring metal contamination during ion implantation, which utilizes PFG to efficiently and accurately monitor metal contamination during ion implantation, thereby effectively controlling the wafer defect rate.

[0008] To achieve the above objectives, the present invention provides a method for monitoring metal contamination during ion implantation using PFG, comprising: A P-type semiconductor wafer is provided, wherein the P-type semiconductor wafer is subjected to ion implantation and annealing; in the ion implantation process, a plasma gun is used as an electron source to neutralize the positive charge on the surface of the P-type semiconductor wafer; The diffusion length of charge carriers in the P-type semiconductor wafer is measured, and the carrier lifetime is calculated based on the diffusion length. The PFG metal contamination level is then output.

[0009] Optionally, the diffusion length of the charge carriers is measured using the surface photovoltage method, and the carrier lifetime is calculated using the relationship between the diffusion length and the diffusion coefficient τ=L² / D, where τ represents the carrier lifetime, L represents the diffusion length of the charge carriers, and D represents the diffusion coefficient of the charge carriers.

[0010] Optionally, the output PFG metal contamination level result includes: when the lifetime value is lower than a preset threshold, it is determined that there is excessive PFG metal contamination, and a monitoring signal is output.

[0011] Optionally, the monitoring signal includes a warning signal and / or an adjustment signal for the process parameters of the plasma gun.

[0012] Optionally, the process parameters for plasma gun neutralization include: plasma gas flow rate less than or equal to 2ccm, plasma chamber current less than or equal to 8A, and plasma chamber lead-out voltage less than or equal to 12V.

[0013] Optionally, the filament material of the plasma gun includes at least one of tungsten, molybdenum, titanium, or their alloys.

[0014] Optionally, the ion implantation process parameters include: implantation energy ≥ 50 keV, and implantation dose range of 1 × 10⁻⁶. 13 atoms / cm² to 1×10 15 atoms / cm².

[0015] Optionally, the annealing process parameters include: an annealing temperature of 1000℃ to 1100℃ and an annealing time of 30 seconds to 60 seconds.

[0016] Optionally, the annealing process is carried out in an environment containing a mixture of inert gas and oxygen, wherein the oxygen volume percentage is 1% to 10%, and the inert gas includes at least one of nitrogen or argon.

[0017] Optionally, the material of the P-type semiconductor wafer includes monocrystalline silicon.

[0018] This invention also provides a PFG metal contamination monitoring system for ion implanters, comprising: SPV measurement device, used to detect carrier diffusion length; The control unit includes a readable storage medium storing a computer-readable program for executing the above-described method for monitoring metal contamination during ion implantation using PFG.

[0019] Optionally, the SPV measuring device includes: The light source module is configured to emit pulsed light or continuous light to irradiate the surface of a P-type semiconductor wafer; the voltage probe is configured to collect the photogenerated voltage signal on the surface in a non-contact manner; and the data processing unit is configured to calculate the carrier diffusion length based on the voltage signal and output the PFG metal contamination degree result according to a preset algorithm.

[0020] The present invention also provides a method for manufacturing a semiconductor device, comprising: A semiconductor wafer is provided, wherein the semiconductor wafer is made of monocrystalline silicon; Ion implantation is performed on the semiconductor wafer to obtain a P-type semiconductor wafer; wherein, the plasma gun is turned on during the ion implantation process; An annealing process is performed on the P-type semiconductor wafer; The P-type semiconductor wafer is monitored using the aforementioned method of monitoring metal contamination during ion implantation with PFG, and the PFG metal contamination level is output. The process parameters of the plasma gun are adjusted in real time based on the PFG metal contamination level to ensure that the PFG metal contamination level does not exceed a preset threshold.

[0021] The present invention also provides a semiconductor device manufacturing apparatus, comprising: An ion implantation module is used to perform ion implantation operations and activate a plasma gun to neutralize the charge on the semiconductor wafer during ion implantation; an annealing module is used to perform high-temperature rapid annealing operations on the ion-implanted semiconductor wafer; in the aforementioned ion implanter PFG metal contamination monitoring system, the SPV measurement device is used to detect the carrier diffusion length and convert it into carrier lifetime; the control unit is connected to the ion implantation module, the annealing module, and the SPV measurement device, and is used to control the aforementioned semiconductor device manufacturing method.

[0022] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: To address potential metal contamination during ion implantation, particularly contamination caused by charge neutralization using PFG, this invention innovatively proposes an SPV method. This method measures the carrier diffusion length to calculate the carrier lifetime, thereby enabling quantitative monitoring of the degree of metal contamination on the wafer. The method is simple to operate, highly efficient, accurately reflects the degree of PFG metal contamination, requires no large implantation dose, and is suitable for real-time monitoring of metal contamination.

[0023] Furthermore, the present invention can also adjust the process parameters of the plasma gun in a timely manner based on the real-time output monitoring signal to ensure that the PFG metal contamination level does not exceed the preset threshold, thereby effectively improving product yield and reducing product production costs. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for monitoring metal contamination during ion implantation using PFG according to the present invention.

[0025] Figure 2 This is a simplified structural diagram of a PFG metal contamination monitoring system 20 for an ion implanter according to the present invention.

[0026] Figure 3 This is a simplified structural diagram of an SPV measuring device 21 according to the present invention.

[0027] Figure 4 This is a flowchart of a method for manufacturing a semiconductor device according to the present invention.

[0028] Figure 5 This is a simplified structural diagram of a semiconductor device manufacturing apparatus according to the present invention.

[0029] Figure 6 The diagram shows the test results of an embodiment of the present invention.

[0030] Attached image labels: PFG Metal Contamination Monitoring System for Ion Implanters 20 SPV measuring device 21 Control Unit 22 Light source module 211 Voltage probe 212 Data processing unit 213 Ion implantation module 51 Annealing Module 52 Uncontaminated portion A Pollution part B. Detailed Implementation

[0031] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method for monitoring metal contamination during ion implantation using PFG and a PFG metal contamination monitoring system for ion implanters, based on the present invention. The advantages and features of the present invention will become clearer from the following description. It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions, used only to facilitate and clearly illustrate the embodiments of the present invention. Please refer to the accompanying drawings to make the objectives, features, and advantages of the present invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the present invention, should still fall within the scope of the technical content disclosed in the present invention.

[0032] In semiconductor manufacturing processes, ion implantation equipment such as plasma shower systems (PFS) and plasma guns may be used to perform ion implantation on wafers with grown oxide films. The ion implantation process requires online monitoring of metal contamination to control product yield.

[0033] This invention discovers that when a wafer is contaminated with metal ions, the carrier lifetime within the wafer is shortened, leading to a deterioration in wafer performance. To address this, this invention designs a monitoring method that utilizes the positive correlation between carrier lifetime within the wafer and its diffusion length within the silicon crystal. The diffusion length of the carriers is measured using the surface photovoltage method (SPV), and the carrier lifetime is calculated, thereby achieving quantitative monitoring of the degree of metal contamination on the wafer. The following description, in conjunction with the accompanying drawings, provides a detailed explanation.

[0034] like Figure 1 As shown, the present invention provides a method for monitoring metal contamination during ion implantation using PFG, comprising: Step S1: A P-type semiconductor wafer is provided, which is subjected to ion implantation and annealing. In the ion implantation process, a plasma gun is used as an electron source to neutralize the positive charge on the surface of the P-type semiconductor wafer.

[0035] The material of the P-type semiconductor wafer includes monocrystalline silicon.

[0036] The ion implantation process parameters include: implantation energy ≥ 50 keV, and implantation dose range of 1 × 10⁻⁶. 13 atoms / cm² ~1×10 15 atoms / cm².

[0037] During ion implantation, the power filament generator (PFG) of the ion implanter needs to be turned on (or started) to neutralize the positive charge accumulated on the wafer surface. The PFG filament material contains at least one of tungsten, molybdenum, titanium, or their alloys. Experiments have shown that while generating hot electrons, the PFG filament also releases metal ions (e.g., tungsten or molybdenum ions). These metal ions may be introduced into the wafer by the ion implantation process, leading to metal contamination and affecting product yield. Therefore, effective methods are needed to monitor metal contamination in a timely manner.

[0038] The process parameters for plasma gun neutralization include plasma gas flow rate, plasma chamber current, and plasma chamber output voltage. The amount of electrons generated by the PFG can be controlled by adjusting any one or more of these parameters. For example, the process conditions for plasma gun neutralization include: plasma gas flow rate less than or equal to 2 ccm, plasma chamber current less than or equal to 8 A, and plasma chamber output voltage less than or equal to 12 V.

[0039] In ion implantation processes, implanted ions (such as boron, phosphorus, arsenic, etc.) may reside at electroactive sites (interstitial sites), making it difficult for them to contribute charge carriers. Therefore, annealing can be performed after the ion implantation operation. This invention employs rapid high-temperature annealing of the ion-implanted wafer, where the high temperature allows dopant ions to move to lattice substitution sites, becoming electroactive impurities. Rapid annealing avoids excessive diffusion of dopant ions. As an example, the annealing process parameters include: an annealing temperature of 1000°C to 1100°C and an annealing time of 30 to 60 seconds. In some embodiments, the annealing process is carried out in an environment containing a mixture of inactive gas and oxygen, wherein the oxygen volume percentage is 1% to 10%, and the inactive gas includes at least one of nitrogen or argon.

[0040] Step S2: Measure the diffusion length of the charge carriers in the P-type semiconductor wafer, calculate the charge carrier lifetime based on the diffusion length, and output the PFG metal contamination level result.

[0041] In some embodiments, the diffusion length of charge carriers is measured using the surface photovoltage method, and the carrier lifetime is calculated using the relationship between diffusion length and diffusion coefficient τ=L² / D, where τ represents the carrier lifetime, L represents the diffusion length of charge carriers, and D represents the diffusion coefficient of charge carriers.

[0042] In some embodiments, the output of PFG metal contamination results includes: when the lifetime value is lower than a preset threshold, it is determined that there is excessive PFG metal contamination, and a monitoring signal is output.

[0043] Depending on the process requirements, different thresholds can be set for carrier lifetime in different ion implantation processes. When the calculated carrier lifetime is lower than the process-set threshold, the wafer can be determined to be unqualified and a monitoring signal can be issued so that operators can intervene in the ion implantation process in a timely manner to reduce the product defect rate.

[0044] The monitoring signal can be an alarm signal, such as a display alarm signal or an audible alarm signal. In some embodiments, the monitoring signal can also be an adjustment signal for the process parameters of the plasma gun, which can be output as a display signal or an audible signal. In other embodiments, the monitoring signal can simultaneously include an alarm signal and an adjustment signal, and the signal output can simultaneously include a display signal or an audible signal.

[0045] The measurement method of the present invention can be either offline detection or online monitoring.

[0046] Offline inspection can be sampling, for example, after ion implantation of multiple wafers, the last batch of wafers is inspected to obtain the degree of metal contamination. When the degree of metal contamination increases and approaches that of qualified wafers (i.e., the measured carrier lifetime decreases and approaches that of qualified wafers), intervention is made to the ion implantation equipment or ion implantation process to improve product yield. Initially, n batches of wafers are ion implanted, and the last batch is inspected. If the inspection is qualified, m batches of wafers are then ion implanted, and the last batch is inspected, where m is less than or equal to n, m > 0, and n > 0. During the inspection process, the degree of metal contamination on the wafers tends to increase. When the degree of metal contamination on the tested wafer is slightly lower than or equal to that of qualified wafers, ion implantation is paused to minimize the generation of defective wafers (in this example, wafers with unqualified metal contamination).

[0047] Online monitoring refers to real-time monitoring of the wafer during the ion implantation process. Once the metal contamination level of the wafer is detected to be slightly lower or equivalent to that of a qualified wafer, timely feedback is provided to give a signal in order to minimize the generation of defective wafers (in this case, those with unqualified metal contamination levels).

[0048] like Figure 2 As shown, the present invention also provides a PFG metal contamination monitoring system 20 for ion implanters, comprising: SPV measuring device 21 is used to detect carrier diffusion length; The control unit 22 includes a readable storage medium storing a computer-readable program for executing the above-described method for monitoring metal contamination during ion implantation using PFG.

[0049] The SPV measuring device 21 and the control unit 22 can be connected by signals. The information measured by the SPV measuring device 21 is sent to the control unit 22, and the control unit 22 sends control signals to the SPV measuring device 21 to control the start or stop of the SPV measuring device 21.

[0050] like Figure 3 As shown, the SPV measuring device 21 includes: Light source module 211 is configured to emit pulsed light or continuous light to illuminate the surface of a P-type semiconductor wafer; Voltage probe 212 is configured for non-contact acquisition of surface photogenerated voltage signals; The data processing unit 213 is configured to calculate the carrier diffusion length based on the voltage signal and output the PFG metal contamination degree result according to a preset algorithm.

[0051] The voltage signal collected by the voltage probe 212 is sent to the data processing unit 213. The data processing unit 213 calculates the carrier lifetime according to τ=L² / D, and outputs the PFG metal contamination level result through logical operations. The logical operations include comparing the tested carrier lifetime with a set lifetime threshold.

[0052] like Figure 4 As shown, the present invention also provides a method for manufacturing a semiconductor device, comprising: Step 401: Provide a semiconductor wafer, wherein the semiconductor wafer is made of monocrystalline silicon.

[0053] Step 402: Perform ion implantation on the semiconductor wafer to obtain a P-type semiconductor wafer; wherein, the plasma gun is turned on during the ion implantation process.

[0054] Step 403: Perform an annealing process on the P-type semiconductor wafer.

[0055] Step 404: Measure the diffusion length of the charge carriers in the P-type semiconductor wafer, calculate the charge carrier lifetime based on the diffusion length, and output the PFG metal contamination level result.

[0056] Step 405: Adjust the process parameters of the plasma gun in real time based on the PFG metal contamination level results to ensure that the PFG metal contamination level does not exceed a preset threshold. The process parameters of the plasma gun include plasma gas flow rate, plasma chamber current, and plasma chamber output voltage.

[0057] like Figure 5As shown, the present invention also provides a semiconductor device manufacturing apparatus, comprising: The ion implantation module 51 is used to perform ion implantation operations and to activate the plasma gun to neutralize the charge on the semiconductor wafer during ion implantation; the annealing module 52 is used to perform high-temperature rapid annealing operations on the ion-implanted semiconductor wafer; the PFG metal contamination monitoring system 20 of the ion implanter described above, wherein the SPV measurement device 21 is used to detect the carrier diffusion length and convert it into carrier lifetime; the control unit 22 is connected to the ion implantation module 51, the annealing module 52 and the SPV measurement device 21, and is used to control the semiconductor device manufacturing method described above.

[0058] Example Provide P-type semiconductor wafers: Select P-type single-crystal silicon as the substrate wafer.

[0059] In the ion implantation process, the PFG is activated and used as an electron source to neutralize the positive charge on the wafer surface. The implantation energy is 100 keV and the dose is 5 × 10¹. 4 atoms / cm².

[0060] Annealing: The implanted wafers are subjected to rapid high-temperature annealing at 1050°C for 45 seconds in an atmosphere of nitrogen with 5% oxygen.

[0061] The diffusion length of charge carriers is measured using an SPV (Special Purpose Vehicle) instrument, and the carrier lifetime is calculated using the formula τ = L² / D. Based on the calculated carrier lifetime, the degree of PFG metal contamination is determined. If the lifetime value is lower than a preset threshold, it is determined that PFG metal contamination exceeds the limit, and a monitoring signal is output, prompting an adjustment signal for the plasma gun process parameters. Figure 6 The diagram shows the test results of the method of this invention. In the diagram, A (color gradually changes from yellow-green to red) represents the uncontaminated part, where the charge carriers are not affected by metal ions and have a longer lifetime, with a maximum value of 393.02 μs. B (color is blue) represents the contaminated part, where the charge carriers are affected by metal ions and have a shorter lifetime, with a minimum value of 212.82 μs. Due to the shape of the PFG body, when metal contamination occurs on the wafer, blue cross-shaped patterns will gradually appear in the red wafer. Furthermore, as the metal contamination worsens, the blue cross-shaped patterns become darker. In this embodiment, the threshold value can be set to the lifetime value at which the blue (blue-green or light blue) cross-shaped patterns just begin to appear.

[0062] In summary, this invention employs the SPV method to calculate carrier lifetime by measuring the diffusion length of charge carriers within the silicon crystal, thereby monitoring the degree of PFG metal contamination. This method is applicable to the quantitative monitoring of metal contamination in single-crystal silicon wafers after ion implantation and annealing, particularly for monitoring PFG metal contamination. Using this method, the PFG metal contamination status during ion implantation can be monitored efficiently and accurately, allowing for timely adjustment of process parameters and ensuring the manufacturing quality of semiconductor devices.

[0063] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0064] In the description of this invention, it should be understood that the terms "center," "height," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0065] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0066] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0067] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for monitoring metal contamination during ion implantation using PFG, characterized by, The method comprises the following steps: A P-type semiconductor wafer is provided, and the P-type semiconductor wafer is subjected to ion implantation and annealing treatment; In the ion implantation process, a plasma gun is used as an electron source to neutralize the positive charges on the surface of the P-type semiconductor wafer; The diffusion length of the carriers of the P-type semiconductor wafer is measured, and the carrier lifetime is calculated according to the diffusion length, and a PFG metal contamination degree result is output.

2. The method for monitoring metal contamination during ion implantation using PFG as recited in claim 1, wherein, The surface photovoltage method is used to measure the diffusion length of the carriers, and the carrier lifetime is calculated through the relationship between the diffusion length and the diffusion coefficient τ = L 2 / D, wherein τ represents the carrier lifetime, L represents the diffusion length of the carriers, and D represents the diffusion coefficient of the carriers.

3. The method for monitoring metal contamination during ion implantation using PFG as recited in claim 2, wherein, The output PFG metal contamination degree result includes: when the lifetime value is lower than a preset threshold value, it is determined that the PFG metal contamination exceeds the standard, and a monitoring signal is output.

4. The method for monitoring metal contamination during ion implantation using PFG as recited in claim 3, wherein, The monitoring signal includes a warning signal and / or an adjustment signal of the process parameters of the plasma gun.

5. The method for monitoring metal contamination during ion implantation using PFG as recited in claim 1, wherein, The process parameters of the plasma gun neutralization include: the plasma gas flow is less than or equal to 2 ccm, the plasma cavity current is less than or equal to 8 A, and the plasma cavity extraction voltage is less than or equal to 12 V.

6. The method for monitoring metal contamination during ion implantation using PFG as recited in claim 1, wherein, The filament material of the plasma gun includes at least one of tungsten, molybdenum, titanium or an alloy thereof.

7. The method for monitoring metal contamination during ion implantation using PFG as recited in claim 1, wherein, The process parameters of the ion implantation include: implantation energy > 50 keV, implantation dose in the range of 1 x 10 13 atoms / cm² to 1 x 10 15 atoms / cm².

8. The method for monitoring metal contamination during ion implantation using PFG as recited in claim 1, wherein, The process parameters of the annealing treatment include: the annealing temperature is 1000-1100 DEG C, and the annealing time is 30-60 seconds.

9. The method for monitoring metal contamination during ion implantation using PFG as recited in claim 1, wherein, The annealing treatment is carried out in an environment containing a mixed gas of non-active gas and oxygen, wherein the volume fraction of oxygen is 1-10%, and the non-active gas includes at least one of nitrogen or argon.

10. The method for monitoring metal contamination during ion implantation using PFG as recited in claim 1, wherein, The material of the P-type semiconductor wafer includes monocrystalline silicon.

11. An ion implanter PFG metal contamination monitoring system, comprising: The method comprises the following steps: An SPV measuring device is used to detect the diffusion length of the carriers; A control unit includes a readable storage medium, wherein a computer readable program is stored in the readable storage medium, and the computer readable program is used to execute the method for monitoring the metal contamination in the ion implantation process by using PFG according to any one of claims 1-10.

12. The ion implanter PFG metal contamination monitoring system of claim 11, wherein, The SPV measuring device comprises: A light source module is configured to emit pulsed light or continuous light to irradiate the surface of the P-type semiconductor wafer; a voltage probe is configured to non-contact collect the surface photovoltage signal; and a data processing unit is configured to calculate the diffusion length of the carriers based on the voltage signal, and output the PFG metal contamination degree result according to a preset algorithm.

13. A method of manufacturing a semiconductor device, characterized by The method comprises the following steps: A semiconductor wafer is provided, and the material of the semiconductor wafer includes monocrystalline silicon; An ion implantation operation is performed on the semiconductor wafer to obtain a P-type semiconductor wafer; wherein the plasma gun is turned on during the ion implantation process; An annealing treatment operation is performed on the P-type semiconductor wafer; The P-type semiconductor wafer is monitored by using the method for monitoring the metal contamination in the ion implantation process by using PFG according to any one of claims 1-10, and a PFG metal contamination degree result is output; and the process parameters of the plasma gun are adjusted in real time according to the PFG metal contamination degree result to ensure that the PFG metal contamination level is not higher than a preset threshold value.

14. An apparatus for manufacturing a semiconductor device, characterized by comprising: The method comprises the following steps: An ion implantation module is used to perform an ion implantation operation, and a plasma gun is started to neutralize the charges on the semiconductor wafer during ion implantation. an annealing module for performing a high temperature rapid annealing operation on the ion-implanted semiconductor wafer; the ion implanter PFG metal contamination monitoring system as claimed in claim 11, wherein the SPV measuring device is configured to detect a carrier diffusion length and convert it to a carrier lifetime; and the control unit is connected to the ion implantation module, the annealing module and the SPV measuring device, and configured to control the manufacturing method of the semiconductor device as claimed in claim 13.

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