Photoelectric detection device and monochromatic laser interference end-point detection system

Abstract

The application relates to a photoelectric detection device and a monochromatic laser interference end point detection system. The photoelectric detection device comprises a photoelectric detection unit, a first driving unit, a first processing unit, a first impedance unit, a second impedance unit and a bias control unit. The photoelectric detection unit converts an incident light signal into a photoelectric current signal. The first driving unit converts the photoelectric current signal into a first voltage signal. When the first voltage signal is in a smaller first power range, the first driving unit is connected to a first gear in the first impedance unit. When the first voltage signal is in a larger second power range, the first driving unit is connected to a second gear in the second impedance unit. The bias control unit is used for applying a reverse bias voltage to the photoelectric detection unit when being connected to the second gear. The application can be adapted to large dynamic range light power detection, and the photoelectric detection device can ensure linear output under the condition of large light power.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor process detection, in particular to a photoelectric detection device and a monochromatic laser interference endpoint detection system. BACKGROUND

[0002] In the field of semiconductor manufacturing, dry etching is one of the key processes for forming microstructures of devices. Precise control of etching depth and real-time and accurate determination of etching endpoint are crucial for ensuring the electrical performance of devices and improving product yield. Among them, the monochromatic laser interference endpoint detection system is used for endpoint detection of advanced etching process due to its high precision, non-contact and real-time monitoring advantages.

[0003] The monochromatic laser interference endpoint detection system mainly includes a laser emission module, a photoelectric detection module, and a host computer connected to the photoelectric detection module. The detection principle of the system is as follows: the laser emission module irradiates a laser with good monochromaticity to the etching film on the wafer surface; after the laser penetrates the transparent or semi-transparent film, it will be reflected on the upper and lower interfaces, respectively, and the two reflected lights will interfere due to the difference in optical path; during the etching process, as the thickness of the film uniformly decreases, the reflected light intensity will periodically change (i.e. interference fringes); the period of the light intensity change received by the photoelectric detection module can be used to inversely calculate the etching depth in real time, and when the etching reaches the target interface (endpoint), the host computer will send an etching endpoint signal according to the specific change characteristics of the interference signal.

[0004] When the incident light power is large, the output current of the photoelectric detection module will have obvious nonlinear response problems. This nonlinear problem will introduce measurement errors, seriously reduce the contrast and detection accuracy of the interference signal, and further affect the accuracy of endpoint determination and the overall reliability of the system.

[0005] Therefore, there is a need for a monochromatic laser interference endpoint detection system that can adapt to large dynamic range light power detection. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a photoelectric detection device and a monochromatic laser interference endpoint detection system that can adapt to large dynamic range light power detection, and under the condition of large light power, the photoelectric detection device can ensure linear output, i.e. the photoelectric current signal and the incident light power are linear.

[0007] According to a first aspect of an embodiment of the present application, a photoelectric detection device is provided, which is suitable for a monochromatic laser interference endpoint detection system, and the photoelectric detection device comprises:

[0008] a photoelectric detection unit for converting an incident light signal into a photoelectric current signal;

[0009] The first driving unit is used to convert the photocurrent signal into a corresponding first voltage signal;

[0010] The first processing unit is used to detect the magnitude of the first voltage signal and output a gear switching signal based on the detection result.

[0011] The first impedance unit includes multiple first-level positions with different resistance values;

[0012] The second impedance unit includes at least one second level;

[0013] Wherein, when the first voltage signal is within a first power range, the gear switching signal is used to connect the first drive unit to the corresponding first gear; when the first voltage signal is within a second power range, the gear switching signal is used to connect the first drive unit to the second gear; the first power range is smaller than the second power range;

[0014] The bias control unit is connected to the second impedance unit and the photodetector unit respectively, and is used to apply a reverse bias voltage to the photodetector unit when the first drive unit is connected to the second position, so as to extend the linear response range of the photodetector unit.

[0015] In one embodiment, the first impedance unit includes:

[0016] A multi-channel analog switch has its selection port connected to the first processing unit, and selects the corresponding connection port according to the selection signal output by the first processing unit;

[0017] Multiple resistors and multiple capacitors are provided, wherein a resistor and a capacitor are connected in parallel to form the first gear position; one end of the first gear position is connected to a connection port, and the other end is connected to the input terminal of the first drive unit.

[0018] In one embodiment, the second impedance unit includes:

[0019] The control unit, whose control terminal is connected to the first processing unit, is used to connect the first drive unit to the second gear position according to the strobe signal output by the first processing unit;

[0020] At least one resistor and at least one capacitor, wherein the resistor and the capacitor are connected in parallel to form the second gear;

[0021] One end of the second gear position is connected to the first drive unit through the control unit, and the other end is grounded.

[0022] In one embodiment, the control unit includes an isolation subunit, a current limiting element, a first switch, and a second switch; the isolation subunit is used to receive a gating signal from the first processing unit and unidirectionally transmit the gating signal to the current limiting element; the current limiting element is used to limit the drive current entering the control terminal of the first switch; the first switch is used to adjust the level of the gating signal to be suitable for the second switch; the second switch is used to connect the first driving unit and the second gear position, or disconnect the first driving unit and the second gear position, under the drive of the first switch.

[0023] In one embodiment, the photoelectric detection device further includes:

[0024] The protection unit is connected to the first gear position and the second gear position respectively, and is used to discharge the charge in the first impedance unit or the second impedance unit.

[0025] In one embodiment, the bias control unit includes:

[0026] The linkage drive subunit is used to output a first level signal when the first drive unit is connected to any first gear position; and to output a second level signal when the first drive unit is connected to a second gear position; the first level signal and the second level signal are inverted signals of each other;

[0027] The switching branch includes two mutually exclusive controlled switches, used to clamp the photodetector unit to a reference potential when the first level signal is received; and to connect the photodetector unit to an externally input reverse bias voltage when the second level signal is received.

[0028] The reverse bias branch, connected to the power supply, is used to provide pull-up voltage for the linkage drive subunit.

[0029] In one embodiment, the photoelectric detection device further includes a temperature control unit, which includes a thermoelectric cooler, a temperature sensor, and a temperature controller. The temperature sensor is used to collect the temperature of the photoelectric detection unit in real time and feed the temperature back to the temperature controller. The temperature controller controls the thermoelectric cooler to cool or heat based on the temperature to adjust the temperature of the photoelectric detection unit.

[0030] According to a second aspect of the embodiments of this application, a monochromatic laser interferometry endpoint detection system is provided, which includes a laser emitting device and a photoelectric detection device as described in any of the preceding claims, wherein the laser emitting device includes a laser, and the laser is used to output the incident light signal to the photoelectric detection device.

[0031] In one embodiment, the laser emitting device further includes:

[0032] The second driving unit is used to provide the operating current for driving the laser to emit light, and to detect the magnitude of the operating current in real time so that the operating current is maintained within a preset range.

[0033] In one embodiment, the laser emitting device further includes:

[0034] A backlight detection unit is used to collect the backlight of the laser and convert it into a power value;

[0035] The second processing unit is configured to output a feedback signal to the second driving unit according to the magnitude of the power value, so that the second driving unit adjusts the magnitude of the operating current.

[0036] In one embodiment, the backlight detection unit includes:

[0037] A backlight detector, whose photosensitive surface receives the backlight and converts the backlight into a photocurrent signal;

[0038] The transimpedance amplifier circuit converts the photocurrent signal into a second voltage signal;

[0039] The signal conditioning circuit biases, filters, or adjusts the gain of the second voltage signal, and outputs a third voltage signal suitable for analog-to-digital conversion.

[0040] An analog-to-digital converter circuit converts the third voltage signal into the power value.

[0041] Compared with the prior art, the beneficial effects of this application are as follows: the first processing unit switches the gear according to the magnitude of the first voltage signal corresponding to the incident light signal. When the first voltage corresponding to the incident light signal is detected to be large, the gear is switched to the second gear, and at the same time, the bias control unit applies a reverse bias voltage to the photodetector unit, so that the photodetector unit can still achieve linear output when detecting high-power light incident, which can improve the detection accuracy of the monochromatic laser interference endpoint detection system using this photodetector device. In addition, when the first voltage signal of the incident light signal is greater than the threshold, the gear is switched down to the second gear, and when the first voltage signal of the incident light signal is less than the threshold, the gear is switched up to the first gear. Moreover, the first gear can automatically realize transimpedance adjustment, realizing optical power dynamic range detection of up to 90dB or more, improving detection accuracy. Attached Figure Description

[0042] Figure 1 This is a schematic block diagram of a photoelectric detection device according to an exemplary embodiment;

[0043] Figure 2 This is a schematic block diagram of a photoelectric detection device according to another exemplary embodiment;

[0044] Figure 3 This is a circuit connection diagram of the photoelectric detection device;

[0045] Figure 4 This is a schematic diagram of a monochromatic laser interferometry endpoint detection system according to an exemplary embodiment.

[0046] In the picture,

[0047] 1. Photoelectric detection unit; 2. First driving unit; 3. First processing unit; 4. First impedance unit; 5. Second impedance unit; 6. Bias control unit; 7. Temperature control unit; 8. Protection unit;

[0048] 21, Second processing unit; 22, Backlight detection unit; 23, Laser; 24, Second driving unit;

[0049] 71, thermostat; 72, thermoelectric cooler; 73, temperature sensor;

[0050] 100, photoelectric detection device; 200, laser emitting device. Detailed Implementation

[0051] Unless otherwise defined, the technical or scientific terms used in this specification and claims shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. Specific embodiments of this application will be described below in conjunction with the accompanying drawings. It should be noted that, in order to provide a concise description, this specification cannot exhaustively describe all features of the actual embodiments. Without departing from the spirit and scope of this application, those skilled in the art can modify and substitute the embodiments of this application, and the resulting embodiments are also within the protection scope of this application.

[0052] In monochromatic laser interferometry systems used for semiconductor etching endpoint detection, the designed optical power range is typically low, generally between tens of microwatts (µW) and a few milliwatts (mW), with typical operating power in the range of 0.1 mW to 5 mW. This design aims to ensure a sufficient signal-to-noise ratio while avoiding saturation of the photodetector module, unnecessary thermal or photochemical effects on the tested wafer (especially photosensitive materials), and ensuring long-term stable system operation. However, when the incident light power is high, exceeding 10 mW, the output current of the photodetector module exhibits a significant nonlinear response. This is because the photoelectric conversion process within the photodetector module tends to saturate under strong light irradiation, leading to an imbalance between the generation and recombination rates of photogenerated carriers, thus disrupting the linear relationship between the output current and the incident light power. This nonlinear effect introduces measurement errors, severely reducing the contrast and detection accuracy of the interference signal, and consequently affecting the accuracy of endpoint determination and the overall reliability of the system. Therefore, in practical applications, it is necessary to optimize the control of the optical power or employ nonlinear correction techniques to ensure that the detector operates within the linear range.

[0053] To solve the above technical problems, refer to Figure 1 This application provides a photoelectric detection device suitable for a monochromatic laser interferometric endpoint detection system. The photoelectric detection device includes:

[0054] Photoelectric detection unit 1 is used to convert incident light signals into photocurrent signals;

[0055] The first driving unit 2 is used to convert the photocurrent signal into a corresponding first voltage signal;

[0056] The first processing unit 3 is used to detect the magnitude of the first voltage signal and output a gear switching signal according to the detection result;

[0057] The first impedance unit 4 includes multiple first-level positions with different resistance values;

[0058] The second impedance unit 5 includes at least one second position, specifically, the resistance value of the second position is a fixed value.

[0059] Wherein, when the first voltage signal is within the first power range, the gear shifting signal is used to connect the first drive unit 2 to the corresponding first gear; when the first voltage signal is within the second power range, the gear shifting signal is used to connect the first drive unit 2 to the second gear; the first power range is smaller than the second power range;

[0060] The bias control unit 6 is connected to the second impedance unit 5 and the photodetector unit 1 respectively, and is used to apply a reverse bias voltage to the photodetector unit 1 when the first drive unit 2 is connected to the second position, so as to extend the linear response range of the photodetector unit 1.

[0061] This application uses a first processing unit 3 to switch gear levels based on the magnitude of a first voltage signal corresponding to the incident light signal. For example, the real-time first voltage signal is compared with a preset threshold. When the detected first voltage corresponding to the incident light signal is larger, i.e., greater than the preset threshold, the gear level is switched to the second gear level. At the same time, the bias control unit 6 applies a reverse bias voltage to the photodetector unit 1, so that the photodetector unit 1 can still achieve linear output when detecting high-power light incident, which can improve the detection accuracy of the monochromatic laser interference endpoint detection system using this photodetector device. In addition, when the first voltage signal of the incident light signal is greater than the preset threshold, the gear level is switched down to the second gear level, i.e., the resistance value of the second gear level is fixed and less than the resistance value of each of the first gear levels. When the first voltage signal of the incident light signal is less than the preset threshold, the gear level is switched up to the first gear level. The first gear level can also automatically adjust the transimpedance according to the magnitude of the first voltage signal. In this way, the photodetector device of this application can achieve a dynamic range of up to 90dB or more, improving the dynamic detection range of optical power.

[0062] In one implementation, see Figure 3 As shown, the first impedance unit 4 includes:

[0063] The multi-channel analog switch U2 has its selection port connected to the first processing unit 3, and selects the corresponding connection port according to the selection signal output by the first processing unit 3;

[0064] Multiple resistors (R2-R7) and multiple capacitors (C2-C7) are provided. One resistor and one capacitor are connected in parallel to form the first gear position. One end of the first gear position is connected to a connection port of the multiplex analog switch, and the other end is connected to the input terminal of the first drive unit 2.

[0065] In this embodiment, the automatic adjustment of multi-stage transresistance can be achieved through the multi-channel analog switch U2, specifically including...

[0066] The six first-level positions are: parallel resistor R2 and capacitor C2, parallel resistor R3 and capacitor C3, parallel resistor R4 and capacitor C4, parallel resistor R5 and capacitor C5, parallel resistor R6 and capacitor C6, and parallel resistor R7 and capacitor C7. In this embodiment, when the first processing unit determines that the first voltage signal is within the first power range, it can further divide it into multiple levels according to its magnitude, corresponding to different resistance values ​​for the first-level positions. Automatic cross-resistance adjustment can be achieved through the multi-channel analog switch U2.

[0067] In one implementation, see Figure 3 As shown, the second impedance unit 5 includes:

[0068] The control unit, whose control terminal is connected to the first processing unit 3, is used to connect the first driving unit 2 to the second gear position according to the selection signal output by the first processing unit 3; at least one resistor and at least one capacitor, wherein a resistor and a capacitor connected in parallel constitute the second gear position. In this embodiment, a second gear position is included, which is formed by a resistor R1 and a capacitor C1 connected in parallel. Its resistance value is fixed and less than the resistance value of each first gear position; one end of the second gear position is connected to the first driving unit 2 through the control unit, and the other end is grounded.

[0069] In this embodiment, the first processing unit 3 determines that the first voltage signal is within the second power range, that is, the current photoelectric sensor detects a high-power optical signal input. At this time, it outputs a gating signal (such as a high-level signal) to the control unit to realize the connection between the second position and the first driving unit 2, so that the first driving unit 2 outputs at a fixed resistance value. This avoids the use of a multi-channel analog switch to achieve cross-resistance adjustment when a high-power optical signal is input, as the internal resistance of the multi-channel analog switch is too large and affects the linearity of the measurement results.

[0070] Furthermore, see Figure 3 As shown, the control unit includes an isolation subunit (including diodes D1, D2, and D3), a current-limiting element (i.e., resistor R13), a first switch (i.e., transistor Q5), and a second switch (i.e., transistor Q25). The isolation subunit is used to receive the gating signal from the first processing unit 3 (such as a microcontroller), such as a high-level signal represented by A0A1A2, and to transmit the gating signal unidirectionally to the current-limiting element. The current-limiting element is used to limit the drive current entering the control terminal of the first switch. The first switch is used to adjust the level of the gating signal to be suitable for the second switch. The second switch is used to connect the first driving unit and the second gear, or disconnect the first driving unit and the second gear, under the drive of the first switch.

[0071] In this embodiment, the first processing unit 3 can be a microcontroller. It outputs a high-level gating signal to the isolation subunit. This high level causes the isolation subunit to output a drive current to the first switch through a current-limiting element, making the first switch conduct. This, in turn, causes the power supply DVDD to provide a drive current to the second switch, making the second switch conduct. This, in turn, connects the first drive unit and the second gear. When a low-level gating signal is output to the isolation subunit, the low level cannot make the first switch conduct, thus the second switch is in the off state. At this time, the first drive unit is off from the second gear, but conducts to the first gear. The control unit in this embodiment improves the electrical isolation between each impedance unit and the microcontroller, ensuring stable conduction and cutoff of the second switch and avoiding high losses caused by being in a semi-conducting state. In addition, when a high-power optical signal is input, the first drive unit and the second gear are directly connected, avoiding nonlinearity problems caused by using multiple analog switches.

[0072] In one implementation, see Figure 2 As shown, the photoelectric detection device further includes a protection unit 8, which is connected to the first and second positions respectively, and is used to discharge the charge in the first or second impedance unit. Specifically, see... Figure 3 As shown, resistors R17 and R9, capacitor C9, and transistor Q6 constitute the protection unit 8. When the first processing unit 3 outputs a selection signal to switch gears, it simultaneously controls the switching device in the protection unit 8, namely transistor Q6, to conduct with the current-limiting resistor R9. This allows the charge in the capacitor corresponding to the previous gear (i.e., one of capacitors C1 to C7) to be grounded through resistor R17 and current-limiting resistor R9, thereby discharging the charge and improving voltage stability during gear switching. This gear switching includes switching between the second gear and the first gear, switching between different first gears, and switching between different second gears.

[0073] In one implementation, see Figure 3 As shown, the bias control unit 6 includes:

[0074] The linkage drive subunit is used to output a first level signal when the first drive unit 2 is connected to any first gear position; and to output a second level signal when the first drive unit 2 is connected to a second gear position; the first level signal and the second level signal are inverse signals of each other;

[0075] The switching branch includes two mutually exclusive controlled switches, used to clamp the photodetector unit to a reference potential when the first level signal is received; and to connect the photodetector unit to an externally input reverse bias voltage when the second level signal is received.

[0076] The reverse bias branch, connected to the power supply, is used to provide pull-up voltage for the linkage drive subunit.

[0077] See Figure 3 The figure shows a schematic diagram of the specific circuit connections inside the photoelectric detection device. The operational amplifier U1 serves as the first driving unit. The input terminal of the operational amplifier U1 is connected to the output terminal PD1 of the photoelectric detection unit 1. The input terminal of the operational amplifier U1 is also connected to the feedback loop formed by the above-mentioned first impedance unit 4 and second impedance unit 5. Transistors Q1 to Q4 and resistors R13 to R15 constitute the above-mentioned bias control unit 6. Among them, transistors Q3 and Q4 form a linkage driving sub-unit, and resistors R14 to R15 form a reverse bias branch to connect the linkage driving sub-unit to the power supply AVDD. Transistors Q1 and Q2 are two mutually exclusive controlled switches in the switching branch, used to receive the first level signal and the second level signal output by the linkage driving sub-unit. In this way, when transitor Q1 is turned on under the first level signal, the photoelectric detection unit is grounded, and when transitor Q2 is turned on under the second level signal, a reverse bias voltage is provided to the anode of the photoelectric detection unit through resistor R13.

[0078] In one embodiment, see Figure 2 As shown, the photoelectric detection device further includes a temperature control unit 7. The temperature control unit 7 includes a thermoelectric cooler 72, a temperature sensor 73, and a temperature controller 71. The temperature sensor 73 is used to collect the temperature of the photoelectric detection unit 1 in real time and feed the temperature back to the temperature controller 71. The temperature controller 71 controls the thermoelectric cooler 72 to cool or heat based on the magnitude of the temperature to adjust the temperature of the photoelectric detection unit 1. In this embodiment, the temperature control unit 7 ensures the stability of the working temperature of the photoelectric detection unit 1 and further improves the detection accuracy of the photoelectric detection unit 1.

[0079] According to the second aspect of the embodiments of the present application, see Figure 4 As shown, a monochromatic laser interference end point detection system is provided, which includes a laser emission device 200 and the photoelectric detection device 100 as described in any one of the above. The laser emission device 200 includes a laser 23. The laser 23 is used to output the incident light signal to the photoelectric detection device 100. The end point detection system of this embodiment uses the photoelectric detection device 100 with a large dynamic range of optical power detection, which improves the end point detection accuracy of the semiconductor etching process. In addition, the output power of the laser can be adjusted according to the magnitude of the first voltage signal detected by the photoelectric detection device 100, so as to achieve the linkage control of the laser and the photoelectric detection device and further improve the end point detection accuracy.

[0080] Specifically, see Figure 4 As shown, the laser emission device further includes:

[0081] The second driving unit 24 is used to provide the operating current for driving the laser 23 to emit light, and to detect the magnitude of the operating current in real time so that the operating current is maintained within a preset range.

[0082] In this embodiment, the second driving unit 24 provides a constant current to the laser 23, thereby improving the stability of the laser's output power. Specifically, the second driving unit 24 includes a constant current source circuit and a current detection circuit. The required set voltage is output to the second driving unit 24, controlling the constant current source circuit to output the required current to drive the laser 23 to emit light. The current detection circuit collects the current operating current of the laser in real time and uses feedback to control the laser current, thereby achieving automatic current control.

[0083] In one implementation, see Figure 4 As shown, the laser emitting device further includes:

[0084] The backlight detection unit 22 is used to collect the backlight of the laser 23 and convert it into a power value;

[0085] The second processing unit 21 is used to output a feedback signal to the second driving unit 24 according to the magnitude of the power value, so that the second driving unit adjusts the magnitude of the operating current.

[0086] Specifically, the backlight detection unit includes:

[0087] A backlight detector, whose photosensitive surface receives the backlight and converts the backlight into a photocurrent signal;

[0088] The transimpedance amplifier circuit converts the photocurrent signal into a second voltage signal;

[0089] The signal conditioning circuit biases, filters, or adjusts the gain of the second voltage signal, and outputs a third voltage signal suitable for analog-to-digital conversion.

[0090] An analog-to-digital converter circuit converts the third voltage signal into a power value.

[0091] In this embodiment, a backlight detector is used to monitor the backlight of the laser 23 in real time and convert it into a photocurrent signal. A transimpedance amplifier circuit, a signal conditioning circuit, and an analog-to-digital converter circuit are used to convert the photocurrent signal into the current power value in real time. The second processing unit 21, such as a microcontroller, can control the second driving unit according to the feedback of the current power value, thereby further realizing closed-loop control of the laser output power, improving the stability of the laser operation, further improving the detection accuracy of the photoelectric detection device, and improving the accuracy of the etching process endpoint detection.

[0092] The above description of the embodiments is intended to enable those skilled in the art to understand and apply this application. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, this application is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. A photoelectric detection device, suitable for a monochromatic laser interferometric endpoint detection system, for receiving interference light signals reflected from a wafer surface, characterized in that, The photoelectric detection device includes: The photoelectric detection unit is used to convert the incident light signal into a photocurrent signal; The first driving unit is used to convert the photocurrent signal into a corresponding first voltage signal; The first processing unit is used to detect the magnitude of the first voltage signal in real time and output a gear switching signal based on the detection result. The first impedance unit includes multiple first-level positions with different resistance values; The second impedance unit includes at least one second position, the resistance value of which is fixed. Wherein, when the first voltage signal is within a first power range, the gear switching signal is used to connect the first drive unit to the corresponding first gear; when the first voltage signal is within a second power range, the gear switching signal is used to connect the first drive unit to the second gear; the first power range is smaller than the second power range; The bias control unit is connected to the second impedance unit and the photodetector unit respectively. When the first drive unit is connected to the second position, the bias control unit applies a reverse bias voltage to the photodetector unit to extend the linear response range of the photodetector unit.

2. The photoelectric detection device as described in claim 1, characterized in that, The first impedance unit includes: A multi-channel analog switch has its selection port connected to the first processing unit, and selects the corresponding connection port according to the selection signal output by the first processing unit; Multiple resistors and multiple capacitors are provided, wherein a resistor and a capacitor are connected in parallel to form the first gear position; one end of the first gear position is connected to a connection port, and the other end is connected to the input terminal of the first drive unit.

3. The photoelectric detection device as described in claim 1, characterized in that, The second impedance unit includes: The control unit, whose control terminal is connected to the first processing unit, is used to connect the first drive unit to the second gear position according to the strobe signal output by the first processing unit; At least one resistor and at least one capacitor, wherein the resistor and the capacitor are connected in parallel to form the second gear; One end of the second gear position is connected to the first drive unit through the control unit, and the other end is grounded.

4. The photoelectric detection device as described in claim 3, characterized in that, The control unit includes an isolation subunit, a current limiting element, a first switch, and a second switch; The isolation subunit is used to receive the gating signal from the first processing unit and transmit the gating signal unidirectionally to the current limiting element; The current limiting element is used to limit the drive current entering the first switch control terminal; The first switch is used to adjust the level of the gating signal to be suitable for the second switch; The second switch is used to connect the first drive unit and the second gear position or disconnect the first drive unit and the second gear position when driven by the first switch.

5. The photoelectric detection device as described in claim 1, characterized in that, The photoelectric detection device also includes: The protection unit is connected to the first gear position and the second gear position respectively, and is used to discharge the charge in the first impedance unit or the second impedance unit.

6. The photoelectric detection device as described in claim 1, characterized in that, The bias control unit includes: The linkage drive subunit is used to output a first level signal when the first drive unit is connected to any first gear position; and to output a second level signal when the first drive unit is connected to a second gear position; the first level signal and the second level signal are inverted signals of each other; The switching branch includes two mutually exclusive controlled switches, used to clamp the photodetector unit to a reference potential when the first level signal is received; and to connect the photodetector unit to an externally input reverse bias voltage when the second level signal is received. The reverse bias branch, connected to the power supply, is used to provide pull-up voltage for the linkage drive subunit.

7. The photoelectric detection device as described in claim 1, characterized in that, The photoelectric detection device also includes a temperature control unit, which includes a thermoelectric cooler, a temperature sensor, and a temperature controller. The temperature sensor is used to collect the temperature of the photoelectric detection unit in real time and feed the temperature back to the temperature controller. The temperature controller controls the thermoelectric cooler to cool or heat based on the temperature to adjust the temperature of the photoelectric detection unit.

8. A monochromatic laser interferometry endpoint detection system, characterized in that, It includes a laser emitting device and a photoelectric detection device as described in any one of claims 1 to 7, wherein the laser emitting device includes a laser for outputting the incident light signal to the photoelectric detection device.

9. The monochromatic laser interferometry endpoint detection system as described in claim 8, characterized in that, The laser emitting device also includes: The second driving unit is used to provide the operating current for driving the laser to emit light, and to detect the magnitude of the operating current in real time so that the operating current is maintained within a preset range.

10. The monochromatic laser interferometry endpoint detection system as described in claim 9, characterized in that, The laser emitting device also includes: A backlight detection unit is used to collect the backlight of the laser and convert it into a power value; The second processing unit is configured to output a feedback signal to the second driving unit according to the magnitude of the power value, so that the second driving unit adjusts the magnitude of the operating current.

11. The monochromatic laser interferometry endpoint detection system as described in claim 10, characterized in that, The backlight detection unit includes: A backlight detector, whose photosensitive surface receives the backlight and converts the backlight into a photocurrent signal; The transimpedance amplifier circuit converts the photocurrent signal into a second voltage signal; The signal conditioning circuit biases, filters, or adjusts the gain of the second voltage signal, and outputs a third voltage signal suitable for analog-to-digital conversion. An analog-to-digital converter circuit converts the third voltage signal into the power value.

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