Wafer conduction type detection equipment and marking equipment

Abstract

The embodiment of the invention discloses wafer conductivity type detection equipment and marking equipment, and the wafer conductivity type detection equipment can comprise a light source module, a voltage detection module and a controller, the light source module can be configured to project a modulated light beam of which the energy is greater than the forbidden bandwidth of a material of the wafer to a detection area of the wafer; the voltage detection module is provided with a capacitance probe, and the capacitance probe is configured in a manner that the end face of the capacitance probe and a detection area of the wafer can form a capacitance structure so as to detect the direction of photovoltage generated by the detection area based on the modulated light beam; the controller can determine the target conduction type of the wafer according to the direction of the photovoltage.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of semiconductor manufacturing technologies, and particularly to a conductive type detection device and a marking device for wafers. Background Art

[0002] During the wafer manufacturing process, rapid and non-destructive detection of the conductive type is a key link to ensure device performance.

[0003] Traditional detection means usually rely on contact probes or low-energy light source excitation, and have significant defects: contact probes are likely to cause scratches or contamination on the wafer surface, especially having a serious impact on the yield of ultra-thin wafers and new compound semiconductor materials; while non-contact detection based on low-energy light sources is difficult to efficiently excite carriers due to insufficient photon energy, resulting in weak opto-voltage signals and being unable to accurately distinguish the conductive type polarity (P-type or N-type), severely restricting the detection accuracy and reliability. Summary of the Invention

[0004] In view of this, embodiments of the present disclosure expect to provide a conductive type detection device and a marking device for wafers; which can solve the technical problem that the existing technology causes damage to wafers during the detection of the conductive type.

[0005] The technical solution of the embodiments of the present disclosure is implemented as follows: In a first aspect, embodiments of the present disclosure provide a conductive type detection device for wafers, including: A light source module configured to project a modulated light beam with an energy greater than the bandgap of the material of the wafer onto the detection area of the wafer; A voltage detection module with a capacitive probe, the capacitive probe being configured such that its end face can form a capacitive structure with the detection area of the wafer to detect the direction of the opto-voltage generated in the detection area based on the modulated light beam; A controller that determines the target conductive type of the wafer according to the direction of the opto-voltage.

[0006] In some examples, the controller is further configured to: Obtain the set conductive type of the wafer in a database; Generate an alarm signal when the target conductive type is different from the set conductive type.

[0007] In some examples, the voltage detection module further includes: A detection resistor, one end of which is connected to the capacitive probe and the other end is grounded; A voltage measurement unit configured to obtain the detection voltage across the detection resistor and use the direction of the detection voltage as the direction of the opto-voltage.

[0008] In some examples, the voltage detection module further includes: A signal amplifier, connected between the detection resistor and the capacitive probe.

[0009] In some examples, the light source module includes: A wavelength selection unit configured to emit visible light or near-infrared light with a wavelength range greater than or equal to 400 nm and less than or equal to 1100 nm; A modulation unit that performs chopping modulation on the light source in a frequency band greater than or equal to 10 kHz and less than or equal to 100 kHz.

[0010] In some examples, the capacitive probe includes: An annular electrode array configured to cover a detection annulus greater than or equal to 3 mm and less than or equal to 5 mm on the edge of the wafer.

[0011] In a second aspect, an embodiment of the present disclosure provides a marking device, including: The conductive type detection device for a wafer according to any one of the first aspect.

[0012] In some examples, the marking device further includes a laser marking unit; The controller is configured to send the target conductive type to the laser marking unit so that the laser marking unit performs marking according to the target conductive type.

[0013] In some examples, the conductive type detection device is integrated on the laser marking unit.

[0014] In some examples, the capacitive probe is arranged along the circumferential direction of the wafer and can move along the radial direction of the wafer.

[0015] An embodiment of the present disclosure provides a conductive type detection device and a marking device for a wafer; a modulated light beam with energy greater than the bandgap of the material of the wafer is projected onto the detection area of the wafer to generate a photocurrent on the wafer surface, and a capacitive detection method is used, without contacting the wafer surface, to avoid damaging or contaminating the wafer and ensure the integrity and measurability of the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. is a schematic diagram of a conductive type detection device for a wafer provided by an embodiment of the present disclosure.

[0017] Figure 2 FIG. is a schematic diagram of another conductive type detection device for a wafer provided by an embodiment of the present disclosure.

[0018] Figure 3 FIG. is a schematic diagram of yet another conductive type detection device for a wafer provided by an embodiment of the present disclosure.

[0019] Figure 4 This is a schematic diagram of yet another conductive type detection device for wafers provided by an embodiment of the present disclosure.

[0020] Figure 5 This is a schematic diagram of a conductive type detection process provided by an embodiment of the present disclosure.

[0021] Figure 6 This is a schematic diagram of a marking device provided by an embodiment of the present disclosure.

[0022] Figure 7 This is a schematic diagram of another marking device provided by an embodiment of the present disclosure.

[0023] Through the above-mentioned accompanying drawings, specific embodiments of the present disclosure have been shown, and more detailed descriptions will be provided hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present disclosure in any way, but to illustrate the concept of the present disclosure to those skilled in the art by referring to specific embodiments. Detailed Embodiments

[0024] Now, example embodiments will be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the present disclosure will be more complete and comprehensive, and will fully convey the concept of the example embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0025] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0026] In the field of semiconductor manufacturing, differentiating the conductivity type of wafers is of crucial significance. Specifically, the conductivity type can be divided into P-type and N-type. From a physical property perspective, the conduction mechanisms of P-type and N-type wafers are completely different. P-type wafers mainly rely on hole conduction, while N-type wafers mainly rely on free electron conduction. This difference in conductivity type directly affects the working principles and performance of semiconductor devices. For example, when designing a diode, the PN junction formed by P-type and N-type wafers is utilized to achieve unidirectional conductivity. If the conductivity type of the wafer cannot be accurately differentiated, the PN junction cannot be correctly constructed, thereby affecting the performance and function of the diode. In addition, different doping elements result in differences in carrier concentration, mobility, and other characteristics between P-type and N-type wafers, and these characteristics are crucial for manufacturing high-performance semiconductor devices.

[0027] From the perspective of device design and application, correctly differentiating P-type and N-type wafers is a prerequisite for realizing the specific functions and performance of devices. Different semiconductor devices have different requirements for P-type and N-type wafers. Take the bipolar transistor as an example. It requires a specific structure formed by P-type and N-type wafers to achieve the current amplification function. In a field-effect transistor, source, drain, and channel regions need to be constructed on an N-type or P-type wafer to control the on and off of the current. In addition, in integrated circuit manufacturing, as the substrate material, the conductivity type of P-type and N-type wafers determines the performance and function of the entire circuit. Different integrated circuit designs may require wafers of different conductivity types to construct various circuit modules such as logic gates and memory cells. Therefore, only by accurately differentiating and selecting the appropriate wafer type can the performance of semiconductor devices and integrated circuits meet the design requirements and satisfy the high-performance and high-reliability needs of various electronic devices.

[0028] All existing conductivity type detection schemes adopt traditional detection means that usually rely on contact probes or low-energy light source excitation, and there are significant defects: contact probes are prone to scratching or contaminating the wafer surface.

[0029] Based on the above disadvantages, the present disclosure first provides a detection device for the conductivity type of wafers. Referring to Figure 1 , it may include a light source module 1, a voltage detection module 2, and a controller 3. Among them, the light source module 1 can be configured to be able to project a modulated light beam with energy greater than the bandgap of the material of the wafer onto the detection area of the wafer; the voltage detection module 2 with a capacitive probe 21, and the capacitive probe 21 is configured such that its end face can form a capacitive structure with the detection area of the wafer to detect the direction of the photocurrent generated in the detection area based on the modulated light beam; the controller 3 can determine the target conductivity type of the wafer according to the direction of the photocurrent.

[0030] In the conductive type detection device for a wafer in the embodiments of the present disclosure, a modulated light beam with energy greater than the bandgap width of the wafer material is projected onto the detection area of the wafer to generate a photovoltage on the wafer surface, and a capacitive detection method is used without contacting the wafer surface, avoiding damage or contamination to the wafer and ensuring the integrity and testability of the wafer.

[0031] The light source module 1 is configured to be able to project a modulated light beam with energy greater than the bandgap width of the wafer material onto the detection area of the wafer. Specifically, the light source module 1 uses a high-brightness light-emitting diode (LED) or a laser diode as the light source. The light source is modulated by a modulation circuit so that the output light beam has a specific frequency and intensity. The energy of the modulated light beam needs to be greater than the bandgap width of the wafer material to ensure that carriers inside the wafer can be excited to generate a photovoltage.

[0032] In some examples, the material of the above-mentioned wafer can be silicon, silicon carbide, etc. When the above-mentioned wafer is a silicon wafer, the bandgap width of silicon is approximately 1.12 electron volts (eV) at room temperature, and the wavelength of the light source projected by the light source module 1 is calculated according to the conversion formula between energy and wavelength of silicon.

[0033] Among them, the conversion formula between energy and wavelength is:

[0034] Among them, is Planck's constant, approximately , is the speed of light, approximately , is the wavelength.

[0035] The calculated wavelength is approximately 1107 nm, but usually the cut-off wavelength of silicon is approximately 1100 nm, so the wavelength corresponding to the light with energy greater than the bandgap width should be shorter, that is, the light with a wavelength less than 1100 nm.

[0036] In some examples, a modulated light beam with a wavelength greater than or equal to 400 nm and less than or equal to 1100 nm can be selected to irradiate the detection area of the wafer.

[0037] In some examples, when the material of the wafer is other materials, the above-mentioned conversion formula between energy and wavelength can be used to calculate the wavelength of the corresponding modulated light beam.

[0038] In some examples, a frequency band greater than or equal to 10 kHz and less than or equal to 100 kHz can be used to perform chopping modulation on the light source. Specifically, the continuous light is converted into square-wave pulsed light by periodically blocking the light source with a perforated disk or a sector blade rotating at high speed. Optionally, the duty cycle can be 50%, or it can be customized according to user requirements. In some other examples, an acousto-optic modulator or an electro-optic modulator can be used to directly perform high-frequency switching control on the driving current of the light source to achieve light intensity modulation without mechanical vibration.

[0039] The 50 / 60 Hz ac power supply and its harmonics will interfere with the low-frequency modulation signal, while the frequency band above 10 kHz can effectively avoid this. Semiconductor detectors have significant 1 / f noise (pink noise) in the low-frequency band, and high-frequency modulation can avoid this noise-dominated region. The response time of a photodiode or an avalanche photodiode (APD) is usually on the order of μs, supporting MHz-level signals, but due to the bandwidth limitation of the subsequent circuit, the actual effective bandwidth is about 100 kHz. Using high-frequency modulation greater than or equal to 10 kHz can reduce the average power density of the light source, avoid local temperature rise caused by continuous light illumination, and reduce the risk of thermal damage to the material. Performing chopping modulation on the light source using a frequency band greater than or equal to 10 kHz and less than or equal to 100 kHz significantly improves the signal-to-noise ratio of the weak light response through high-frequency narrowband signal extraction and synchronous phase-locked detection, while avoiding thermal damage and noise interference. In actual design, a mechanical or electronic modulation scheme needs to be selected according to the detection speed, accuracy, and cost requirements, and the modulation depth, frequency stability, and thermal management parameters need to be optimized.

[0040] In some examples, the voltage detection module 2 can include a capacitive probe 21. The capacitive probe 21 is configured such that its end face can form a capacitive structure with the detection region of the wafer, and is used to detect the direction of the optical voltage generated in the detection region based on the modulated light beam, so as to judge the target conduction type of the wafer.

[0041] In some examples, referring to Figure 2 , the voltage detection module 2 can further include a detection resistor R1 and a voltage measurement unit 22. Among them, one end of the detection resistor R1 is connected to the capacitive probe 21, and the other end is grounded. The voltage detection unit is used to obtain the detection voltage across the detection resistor R1 and use the direction of the detection voltage as the direction of the optical voltage.

[0042] Specifically. The detection resistor R1 (usually a precision low-resistance resistor, such as 1 Ω~1 kΩ) is connected in series between the capacitive probe 21 and the ground, and converts the photocurrent collected by the capacitive probe 21 (generated by the migration of internal carriers in the semiconductor) into a measurable voltage signal; in an N-type semiconductor, the photo-generated carriers (electrons) move towards the capacitive probe 21, and the voltage across the detection resistor R1 is positive; in a P-type semiconductor, holes dominate the migration, and the voltage is negative. The voltage direction directly reflects the material conduction type.

[0043] In some examples, the photocurrent is usually in the nA~μA range, and the voltage directly output by the detection resistor R1 is only in the μV~mV range, which needs to be increased to the effective range (such as 0~5V) through the amplifier gain (such as 100~1000 times). The amplifier bandwidth needs to cover the chopping modulation frequency (10-100kHz) to avoid signal attenuation or phase delay. Therefore, refer to Figure 3 A signal amplifier 23 may be provided, connected between the detection resistor R1 and the capacitance probe 21, and may adopt a same-phase or anti-phase amplification configuration to improve the detection accuracy.

[0044] In some examples, reference Figure 4 The capacitance probe 21 may also be a ring electrode array configured to cover a detection ring zone greater than or equal to 3 mm and less than or equal to 5 mm at the edge of the wafer.

[0045] In some examples, the capacitance probe 21 can be composed of multiple concentric annular electrodes. The optional number of annular electrodes can be two, three or more, which is not repeated in this example embodiment. The spacing between the annular electrodes can be greater than or equal to 0.5 mm and less than or equal to 1 mm, covering an annular area with a width of 3-5 mm on the edge of the wafer, that is, a detection ring zone.

[0046] Optionally, the annular electrode can be made of highly conductive, oxidation-resistant materials such as gold or indium tin oxide (ITO), and the surface can be plated with an insulating layer to prevent direct contact with the wafer. The specific material selection can be customized according to user needs and will not be described in detail in this example implementation.

[0047] Optionally, each circle of annular electrodes can be further divided into a number of sector-shaped units, which can be scanned in time-sharing manner through a multiplexer (MUX) to improve spatial resolution.

[0048] During detection, each annular electrode independently measures the local capacitance signal, and generates a conductivity type distribution map of the edge area through data fusion algorithms (such as weighted average or spatial interpolation). The segmented fan-shaped electrode can detect the circumferential non-uniformity of the wafer edge.

[0049] In some examples, a coverage edge area greater than or equal to 3 mm can ensure coverage of the cutting impact area and the heat diffusion doping transition area at the edge of the wafer, and less than or equal to 5 mm can avoid intrusion into the effective device area (such as the chip graphic area) in the center of the wafer, while suppressing the interference of the central area signal on edge detection.

[0050] In some examples, the controller 3 can be connected to the above-mentioned voltage detection module 2, and can determine the target conductivity type of the wafer according to the direction of the photo-voltage of the voltage detection module 2. Specifically, in an N-type semiconductor, the photo-generated carriers (electrons) move towards the capacitive probe 21, and the voltage across the detection resistor R1 is positive; in a P-type semiconductor, holes dominate the migration and the voltage is negative. The voltage direction directly reflects the material conductivity type.

[0051] After obtaining the target conductivity type, the controller 3 can compare the target conductivity type with the set conductivity type of the wafer in the database. When the two are different, an alarm signal is generated to prevent errors in the subsequent processing caused by the difference between the actual conductivity type and the recorded conductivity type.

[0052] Specifically, referring to Figure 5 , step S510 can be first executed, where the device picks up and aligns the wafer; that is, the wafer is aligned on the detection device, then step S520 is executed to obtain the direction of the photo-voltage in the detection area of the wafer, then step S530 is executed to determine the target conductivity type according to the photo-voltage direction, then step S540 is executed to obtain the set conductivity type, and then step S550 is executed to determine whether the target conductivity type is consistent with the set conductivity type. If they are consistent, step S560 is executed for normal operation. If they are not consistent, step S570 is executed to generate an alarm signal and terminate the processing.

[0053] In the wafer conductivity type detection device in the embodiment of this solution, a modulated light beam with energy greater than the bandgap width of the wafer material is projected onto the detection area of the wafer to generate a photo-voltage on the wafer surface, and a capacitive detection method is used without contacting the wafer surface, avoiding damage or contamination to the wafer, and ensuring the integrity and measurability of the wafer. Through the annular electrode array, high-precision and high-spatial-resolution determination of the wafer conductivity type is achieved.

[0054] The main purpose of wafer marking is to mark specific information on the wafer surface, such as the wafer model, production batch, PN type, etc., for accurate identification and tracking in the subsequent production process. If the PN type is not correctly divided before marking, it may lead to inconsistent marking content with the actual wafer type. For example, mislabeling a P-type wafer as an N-type wafer, or vice versa, which will cause subsequent process steps to be based on incorrect information, and ultimately may lead to performance problems or functional failures in the products of the entire production batch. Therefore, performing PN type division is the basis for ensuring the accuracy of marking content. Only by correctly identifying the PN type of the wafer can the correctness of subsequent processes and the reliability of products be guaranteed.

[0055] Different PN-type wafers have differences in physical and chemical properties, which will affect the process and effect of wafer marking. For example, the doping elements of P-type and N-type wafers are different, resulting in differences in their absorption, reflection and heat conduction characteristics of lasers. Before marking, the PN type of the wafer can be clarified, and the marking process parameters such as laser power, pulse width, scanning speed, etc. can be optimized according to its specific characteristics. This can ensure the efficiency and accuracy of the marking process and avoid marking quality problems caused by mismatched process parameters, such as unclear marking, inconsistent depth, and wafer surface damage. At the same time, reasonable process parameters can also help extend the service life of marking equipment, improve production efficiency and reduce costs.

[0056] The performance and reliability of semiconductor devices depend to a large extent on the accurate grasp of wafer characteristics and precise control of processes during the manufacturing process. PN type division, as a key step before wafer marking, provides important basic information for subsequent manufacturing processes. If the PN type division is inaccurate, it may lead to the use of inappropriate process parameters and conditions in subsequent processes, thereby introducing various defects and potential risks. For example, in processes such as lithography, etching, and doping, the wrong wafer type may lead to problems such as inaccurate pattern transfer and uneven doping concentration, which in turn affects the performance consistency, electrical characteristics, and stability of the device. By accurately dividing the PN type before marking, the pertinence and accuracy of subsequent processes can be ensured, thereby improving the quality and reliability of the final product and reducing the scrap rate and recall risk caused by process errors.

[0057] That is to say, the above-mentioned wafer conductivity type detection device can be directly applied to the marking device. It should be noted that the above-mentioned wafer conductivity type detection device can also be used for re-inspection of processed wafers, or after the epitaxial layer is formed on the wafer, the conductivity type of the epitaxial layer is detected, and it can also be applied to the conductivity type detection in the manufacturing process of MOS tubes. The specific application scenarios can be applied in multiple directions according to user needs, which will not be elaborated here.

[0058] Based on this, the present disclosure also provides a new marking device, which may include the above-mentioned wafer conductivity type detection device.

[0059] In some examples, reference Figure 6 The marking device may include a device body 61, a working platform 62, a laser marking unit 63, and a motion platform, etc., wherein the laser marking unit 63 may include a laser device and a marking head.

[0060] The main body of the device 61 is in the shape of a cuboid and has a frame structure for supporting and installing various functional components to ensure the stability and precision of the device during operation. The working platform 62 is located at the bottom of the device and is used to place the wafers to be marked. The surface of the platform is flat and can accurately adjust the position and angle of the wafers to meet different marking requirements.

[0061] A laser generator is installed on the top of the laser system, which can emit laser with high energy density, stability and precise control. According to different marking requirements, different types of lasers can be selected, such as ultraviolet laser, green laser or fiber laser, etc., to adapt to the wafer marking tasks with different materials and precision requirements.

[0062] The marking head is located below the laser generator and focuses and guides the laser beam to the wafer surface through the optical path system. Precision optical elements, such as focusing lenses and reflecting lenses, are installed inside the marking head, which can accurately control the focusing position, spot size and shape of the laser beam, so as to achieve high-precision marking effects. During the marking process, the marking head can perform fast and accurate scanning movements according to the preset marking patterns and parameters to ensure that each marking point can reach the expected depth and clarity.

[0063] The moving platform is equipped with a high-precision moving mechanism, usually a two-dimensional or three-dimensional motion system, which can realize the precise movement of the wafer under the marking head. The moving platform is driven by a motor and realizes smooth and accurate displacement through transmission components such as lead screws and guide rails. The control system can perform real-time control and monitoring on the displacement speed, acceleration and position of the moving platform to ensure that each position of the wafer can accurately receive laser marking during the marking process.

[0064] In some exemplary embodiments, the detection device can be communicatively connected to the laser marking unit 63, which can ensure the accuracy and real-time nature of the marking content. The detection device can transmit key information such as the conductivity type of the wafer to the marking unit, so as to achieve precise marking according to the target conductivity type. This real-time data transmission mechanism not only improves the marking efficiency, but also reduces production errors caused by information lag or errors.

[0065] Further, referring to Figure 7 , integrating the conductivity type detection device on the laser marking unit 63 can significantly improve the integration and overall performance of the device. The integrated detection and marking system can reduce the space occupied by the device, lower the production cost, and at the same time improve the coordination of the detection and marking processes. For example, integrating the controller 3 of the detection device with the processing unit of the marking device can achieve more efficient resource management and faster data processing, thereby improving the efficiency and quality of the entire production process.

[0066] In addition, the capacitive probe 21 can be integrated with the marking head or separately arranged. This flexibility enables the device to adapt to different detection requirements. For example, by arranging the capacitive probe 21 along the circumferential direction of the wafer and enabling it to move along the radial direction, comprehensive detection of multiple regions of the wafer can be achieved. This design not only improves the detection coverage rate but also can promptly detect minute defects on the wafer surface, ensuring the marking quality.

[0067] Finally, the integrated or separate arrangement of the light source module 1 also provides more possibilities for the optimization of the marking device. Integrating the light source module 1 can enhance the compactness and portability of the device, while the separate arrangement offers greater flexibility and maintainability. According to specific production requirements and environmental conditions, selecting an appropriate layout of the light source module 1 can further improve the performance and applicability of the marking device.

[0068] In summary, by effectively integrating the detection device with the marking unit and optimizing the layouts of the capacitive probe 21 and the light source module 1, the performance and efficiency of the wafer marking device can be significantly improved, thereby meeting the strict requirements for high precision and high efficiency in semiconductor manufacturing.

[0069] In the above embodiments, the descriptions of the respective embodiments have their own focuses. For parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments. The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0070] Those skilled in the art will readily conceive of other embodiments of the present disclosure after considering the specification and practicing the invention herein. The present disclosure is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include known common general knowledge or conventional technical means in the technical field not claimed in the present application.

[0071] It should be understood that the present disclosure is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is only limited by the appended claims.

Claims

1. A conductive type detection device for a wafer, characterized in that, Comprising: A light source module configured to project a modulated light beam with energy greater than the bandgap width of the material of the wafer onto the detection area of the wafer; A voltage detection module with a capacitive probe, the capacitive probe being configured such that its end face can form a capacitive structure with the detection area of the wafer to detect the direction of the photocurrent generated in the detection area based on the modulated light beam; A controller that determines the target conductivity type of the wafer based on the direction of the photocurrent.

2. The conductive type detection device according to claim 1, wherein The controller is further configured to: Obtain the set conductivity type of the wafer in a database; Generate an alarm signal when the target conductivity type is different from the set conductivity type.

3. The conductive type detection device according to claim 1, characterized in that, The voltage detection module further includes: A detection resistor with one end connected to the capacitive probe and the other end grounded; A voltage measurement unit for obtaining the detection voltage across the detection resistor and using the direction of the detection voltage as the direction of the photocurrent.

4. The conductive type detection device according to claim 3, characterized in that The voltage detection module further includes: A signal amplifier connected between the detection resistor and the capacitive probe.

5. The conductive type detection device according to claim 1, characterized in that The light source module includes: A wavelength selection unit configured to emit visible light or near-infrared light with a wavelength range greater than or equal to 400 nm and less than or equal to 1100 nm; A modulation unit that performs chopping modulation on the light source in a frequency band greater than or equal to 10 kHz and less than or equal to 100 kHz.

6. The conductive type detection device according to claim 1, wherein The capacitive probe includes: An annular electrode array configured to cover a detection annulus on the wafer edge greater than or equal to 3 mm and less than or equal to 5 mm.

7. A marking device, characterized in that, Comprising: The conductivity type detection device for a wafer according to any one of claims 1 to 6.

8. The marking device according to claim 7, characterized in that, The marking device further includes a laser marking unit; The controller is configured to send the target conductivity type to the laser marking unit so that the laser marking unit performs marking according to the target conductivity type.

9. The marking device according to claim 8, characterized in that, The conductivity type detection device is integrated on the laser marking unit.

10. The marking device according to claim 8, characterized in that, The capacitive probe is arranged along the circumferential direction of the wafer and can move along the radial direction of the wafer.

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