Photoelectric detector gain regulation and control method, optical detection module and in-situ detection device

Abstract

The invention provides a photoelectric detector gain regulation and control method, an optical detection module and an in-situ detection device.The photoelectric detector gain regulation and control method comprises the steps that the set gain value of a photoelectric detector and the environment temperature of the environment where the photoelectric detector is located are obtained; inputting the environment temperature and the set gain value into a gain regulation and control model to output reverse bias voltage; and transmitting the reverse bias voltage to the photoelectric detector so as to regulate and control the current gain value of the photoelectric detector and enable the current gain value to return to the set gain value, so that the reverse bias voltage and the gain of the APD detector have the same non-linear relationship through the method, and further the APD detector is not influenced by the ambient temperature any more. Meanwhile, the in-situ detection device provided by the invention adopts the optical detection module based on the regulation and control method, so that a wider temperature detection range is realized.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor detection technology, and in particular to an in-situ detection device. Background Art

[0002] Epitaxy (Epi) refers to the process of precisely growing a layer of single crystal material with the same lattice arrangement on a single crystal substrate (usually a wafer). Since the new single crystal layer strictly follows the extension growth of the substrate crystal phase, it is called an epitaxial layer. The epitaxial layer can be a homoepitaxial layer (Si / Si) or a heteroepitaxial layer (SiGe / Si or SiC / Si, etc.); there are also many ways to achieve epitaxial growth, including molecular beam epitaxy (MBE), ultra-high vacuum chemical vapor deposition (UHV / CVD), atmospheric and reduced pressure epitaxy (ATM&RP EPI), etc. According to the growth method, the epitaxy process can be divided into two categories: full epitaxy and selective epitaxy.

[0003] During the epitaxial growth process, the in-situ detection device can detect the sample (substrate or epitaxial growth layer) in real time, that is, obtain relevant information while growing, without taking the sample out of the reaction chamber. This is achieved through special design and technical means, such as coaxial beam design, high temperature and corrosion resistant window materials, high-precision signal transmission and processing, etc., so that the detection device can work stably in complex growth environments such as high temperature, high pressure, and chemical atmosphere, and timely reflect the growth dynamics and changes of the epitaxial growth layer. In this way, the operator can adjust the machine's process parameters, such as temperature, gas flow, pressure, etc., at any time according to the real-time monitored data to optimize the epitaxial growth process and thus improve the quality of the epitaxial growth layer.

[0004] Traditional in-situ detection devices rely on silicon detectors to detect infrared radiation signals and reflection signals on the sample surface. The surface temperature of the wafer or epitaxial growth layer can be obtained through the infrared radiation signal, and the growth dynamics and changes of the epitaxial growth layer can be obtained through the reflection signal. However, since the silicon detector itself is not very sensitive, its ability to detect weak infrared radiation signals is limited. During the process, when the sample temperature is low, traditional silicon detectors are often unable to detect the weak infrared radiation on the sample surface, and thus are unable to obtain the sample surface temperature under low temperature conditions. This drawback as a whole results in the traditional in-situ detection device having a small temperature measurement range and a high lower temperature measurement limit for the sample, which in turn results in one in-situ detection device being unable to meet the requirements of different epitaxial growth processes for temperature detection of epitaxial growth samples. It is often necessary to use in-situ detection devices of different specifications for different epitaxial growth processes. Summary of the invention

[0005] In view of the shortcomings of the prior art mentioned above, the purpose of the present invention is to provide a photodetector gain control method, an optical detection module and an in-situ detection device, which are used to solve the problems in the prior art that the in-situ detection device has a small temperature measurement range, a high lower temperature measurement limit, and one in-situ detection device cannot meet the different measurement temperature ranges required for different types of epitaxial growth processes.

[0006] In order to solve the above technical problems, the first aspect of the present invention provides a photodetector gain control method, comprising: Obtaining a set gain value of the photodetector and an ambient temperature of an environment where the photodetector is located; The ambient temperature and the set gain value are input into a gain control model to output a reverse bias voltage; the gain control model is constructed using a neural network algorithm and trained using sample ambient temperatures, sample reverse bias voltages and sample gain values; The reverse bias voltage is transmitted to the photodetector to adjust the current gain value of the photodetector to return it to the set gain value.

[0007] The gain control model includes: an input layer, an intermediate hidden layer and an output layer; The step of inputting the ambient temperature and the set gain value into a gain control model to output a reverse bias voltage includes: Inputting the ambient temperature and the set gain value into the input layer to obtain input layer data; The intermediate hidden layer processes the data of the input layer to obtain an intermediate value; The output layer processes the intermediate value to obtain the reverse bias voltage.

[0008] The technical effect achieved by the above technical scheme is as follows: the photodetector gain control method in this scheme is used to solve the problem that the internal gain of some photodetectors (such as ADP detectors) is easily affected by the ambient temperature. In this scheme, by referring to the gain control model, according to the ambient temperature of the photodetector, the relationship between the reverse bias voltage and the gain of the photodetector at different ambient temperatures is quantified by machine learning, and the APD detector gain drift caused by the ambient temperature is compensated by adjusting the reverse bias voltage, so that the signal output is not affected by the ambient temperature.

[0009] Furthermore, in this solution, by constructing a gain control model, the ambient temperature and the set gain value are used as input layer data, the input layer data is processed by the intermediate hidden layer, and the intermediate value is processed by the output layer, and finally a reverse bias voltage for adjusting the gain value of the photodetector is obtained. The reverse bias voltage acts on the photodetector to compensate for the gain drift caused by the ambient temperature, thereby making the detection signal output unaffected by the ambient temperature.

[0010] Preferably, the training using the sample environment temperature, the sample reverse bias voltage and the sample gain value includes: Constructing a data set with a plurality of known sets of sample ambient temperatures, sample reverse bias voltages and sample gain values; Dividing the data set into a training set and a validation set; using the training set to train the gain control model, and using the validation set to verify the accuracy of the gain control model; The stochastic gradient descent algorithm is used as the optimization algorithm in the training process to adjust the parameters of the gain control model.

[0011] Through the above technical scheme, the technical effect achieved is: in this scheme, the gain control model is trained by making a data set composed of the sample ambient temperature, the sample reverse bias voltage and the sample gain value, so that the optimal parameters of the gain control model can be obtained, thereby making the model more targeted and accurate, and obtaining a more accurate prediction value (reverse bias voltage).

[0012] A second aspect of the present invention provides an optical detection module, comprising: a photoelectric detector and an ambient temperature sensing module; The photodetector comprises a variable gain unit, and the variable gain unit has a set gain value; the photodetector is used to receive a light signal and convert the light signal into an amplified electrical signal according to the set gain value; The ambient temperature sensing module includes a temperature sensor and a microprocessor. The temperature sensor is used to obtain ambient temperature data of the environment where the photodetector is located. The microprocessor is electrically connected to the temperature sensor. The microprocessor is used to input the ambient temperature data and the set gain value into a gain control model to output a reverse bias voltage for controlling the photodetector. The reverse bias voltage is used to adjust the current gain value to return it to the set gain value.

[0013] The gain control model includes: Input layer, used to input ambient temperature and set gain value; An intermediate hidden layer, used for processing the data of the input layer to obtain an intermediate value; The output layer is used to process the intermediate value to obtain the reverse bias voltage.

[0014] The technical effect achieved by the above technical solution is: the optical detection module in the technical solution uses a photoelectric detector with variable gain, which can adapt to the detection of light signals of different intensities. For example, when the surface temperature of the sample to be tested is low, the infrared radiation light is relatively weak, and the gain value can be increased at this time to obtain a stronger signal; when the surface temperature of the sample to be tested is high, the infrared radiation light is relatively strong, and the gain value can be appropriately lowered to obtain a stable signal strength.

[0015] Furthermore, in order to prevent the gain value of the photodetector from being affected by the ambient temperature, the ambient temperature sensing module is introduced. The ambient temperature sensing module can detect the ambient temperature of the photodetector in real time, and output in real time the reverse bias voltage for regulating the photodetector based on the ambient temperature and the set gain value of the photodetector. By adjusting the reverse bias voltage, the gain drift of the photodetector caused by the ambient temperature can be compensated, so that the signal output is not affected by the ambient temperature.

[0016] Furthermore, by constructing a gain control model, the ambient temperature and the set gain value are used as input layer data, the input layer data is processed by the intermediate hidden layer, and the intermediate value is processed by the output layer, and finally a reverse bias voltage for adjusting the gain value of the photodetector is obtained. The reverse bias voltage acts on the photodetector to compensate for the gain drift caused by the ambient temperature, thereby making the detection signal output unaffected by the ambient temperature.

[0017] The third aspect of the present invention provides an in-situ detection device, including the optical detection module provided by the second aspect of the present invention, and further comprising: A signal collection module, disposed above the sample in the process chamber for epitaxial growth, for collecting optical signals from the surface of the sample; A receiving optical module, which is connected to the signal acquisition module through an optical fiber and is used to receive the optical signal and collimate, split and focus the optical signal; the optical detection module is arranged on the optical path of the optical signal and is used to convert the optical signal into an amplified electrical signal; The process control module is used to send process information; in this embodiment, the process information includes machine rotation speed and wafer layout.

[0018] a signal processing module, electrically connected to the optical detection module and the process control module respectively, for receiving the electrical signal and the process information, and generating corresponding data information according to the process information and the electrical signal; The display module is electrically connected to the signal processing module and is used to receive and display the data information in real time.

[0019] Through the above technical scheme, the technical effect achieved is: the in-situ detection device in this scheme can effectively improve the detection of lower temperature signals on the sample surface by the in-situ detection device by using the optical detection module provided by the second aspect of the present invention, thereby greatly broadening the temperature detection range of the in-situ detection device, so that one in-situ detection device can meet the detection requirements of sample temperature in various epitaxial growth processes. It effectively solves the problem of the high lower limit and small temperature measurement range of the in-situ detection device in the prior art for detecting the surface temperature of the sample (wafer or epitaxial growth layer) in the epitaxial growth equipment.

[0020] Preferably, it also includes a signal transmission module, the signal transmission module is connected to the signal collection module via an optical fiber, the signal transmission module is used to generate an emission light signal, and the emission light signal irradiates the sample to generate a reflected light signal; The optical signal includes the reflected light signal and the infrared radiation signal of the sample surface.

[0021] The technical effect achieved by the above technical solution is: by setting the signal transmission module, a stable, reliable and appropriately strong signal is provided for the detection process to meet the requirement of the in-situ detection device for accurate measurement of the temperature of the epitaxial growth layer.

[0022] Preferably, the signal transmission module includes: A light source electronic module, used for generating the emission light signal; The transmitting optical module is arranged on the optical path of the transmitting optical signal, and is used for receiving the transmitting optical signal and performing collimation, splitting and focusing processing on the transmitting optical signal.

[0023] The technical effect achieved by the above technical solution is: the light source electronic module, as the energy source of the entire signal emission, can provide a stable, reliable and appropriately strong optical signal for the detection process, so as to meet the requirements of the in-situ detection device for accurately measuring the optical properties of the epitaxial growth layer. The emission optical module can collimate, split and focus the light emitted by the light source electronic module, so that the optical signal can be vertically irradiated to the detection area of ​​the epitaxial growth layer, improve the spatial resolution and accuracy of the detection, and ensure that the acquired optical signal can accurately reflect the local characteristics of the epitaxial growth layer.

[0024] Preferably, the signal acquisition module includes a probe, the probe includes a signal transmitting end and a signal collecting end, and the optical fiber includes a transmitting optical fiber and a collecting optical fiber; The signal transmitting end of the probe is connected to the transmitting optical module through the transmitting optical fiber, and the receiving optical module is connected to the signal collecting end of the probe through the collecting optical fiber.

[0025] Through the above technical solution, the technical effect achieved is: the signal transmitting end and the signal collecting end are arranged on one probe, which effectively improves the structural integration of the probe and saves the installation space of the probe.

[0026] Preferably, the signal processing module includes: A signal amplifier, used for receiving the electrical signal and amplifying the electrical signal; A signal converter, used for converting the electrical signal processed by the signal amplifier into a digital signal; The central processor is used to receive the electrical signal and the process information, generate corresponding data information according to the process information and the electrical signal, and transmit the data information to the display module for display.

[0027] Through the above technical scheme, the technical effect achieved is: by setting the signal amplifier, the received electrical signal can be amplified; by setting the signal converter, the electrical signal processed by the signal amplifier can be converted into a digital signal, thereby facilitating processing by the central processor. The central processor generates corresponding data information based on the process information and the electrical signal, and transmits the data information to the display module for display.

[0028] Preferably, the display module includes a graphics processing system, and the graphics processing system receives the data information and displays the data information as a curve image.

[0029] Through the above technical solution, the technical effect achieved is: the display module can display the received data information as a curve image, thereby improving the readability of the data information. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the process of the photodetector gain control method according to the first embodiment of the present invention; Figure 2 Schematic diagram of a specific flow of step 300 in the photodetector gain control method according to the first embodiment of the present invention; Figure 3 4 is a schematic diagram of a specific flow of step 400 in the photodetector gain control method according to the first embodiment of the present invention; Figure 4 Schematic diagram of the relationship between the gain and reverse bias voltage of the APD detector in the prior art of the present invention at different ambient temperatures (from left to right, -20°C, 0°C, 20°C, 40°C and 60°C); Figure 5 It is a schematic diagram of the nonlinear relationship between the reverse bias voltage and the gain of the APD detector under the control of the gain control model in the first embodiment of the present invention; Figure 6 This is a schematic diagram of the module structure of the optical detection module in the second embodiment of the present invention; Figure 7 This is a schematic diagram of the module structure of the in-situ detection device in the third embodiment of the present invention; Figure 8 Schematic diagram of the connection relationship between the in-situ detection device, the process chamber and the display in the third embodiment of the present invention.

[0031] Reference numerals: 1-Main chassis; 2-probe; 21-transmitting optical fiber; 22-collecting optical fiber; 3-process chamber; 31-machine platform; 32-wafer; 4- Display. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the usual meanings understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Unless otherwise specified, the "connection" described in this article can be a direct connection or an indirect connection, that is, a connection through an intermediate.

[0033] Embodiment 1: See also Figure 1 The first embodiment of the present invention provides a photodetector gain control method, the method comprising the following steps: Step 100: obtaining a set gain value of the photoelectric detector and an ambient temperature of an environment where the photoelectric detector is located; Step 200: constructing a gain control model using a neural network algorithm.

[0034] Step 300, training the gain control model using sample ambient temperature, sample reverse bias voltage and sample gain value; Step 400: inputting the ambient temperature and the set gain value into a gain control model to output a reverse bias voltage; Step 500: Transmit the reverse bias voltage to the photodetector to adjust the current gain value of the photodetector to return it to the set gain value.

[0035] In this embodiment, the photodetector is an APD (Avalanche Photo – Diode) detector. The APD detector is a highly sensitive photodetector. Its working principle is to apply a reverse bias voltage on the basis of a photodiode to cause an avalanche multiplication effect of photogenerated carriers in a strong electric field region. When the electron-hole pairs generated by photons accelerate under a high electric field, they collide with lattice atoms and stimulate new electron-hole pairs. This process is like an avalanche, amplifying the photocurrent. Due to the avalanche multiplication effect, the APD detector can detect weak light signals, but its internal gain is easily affected by the external ambient temperature. For example, Figure 4 The relationship between the gain and reverse bias voltage of the APD detector at different ambient temperatures (-20°C, 0°C, 20°C, 40°C and 60°C from left to right) is shown. It can be seen that at different ambient temperatures, the gain and reverse bias voltage of the APD detector maintain different nonlinear relationships, which can easily cause inaccurate temperature measurements at different ambient temperatures.

[0036] In this scheme, by referencing the gain control model, according to the ambient temperature of the photodetector, the relationship between the reverse bias voltage and gain of the photodetector at different ambient temperatures is quantified through machine learning. The gain drift of the APD detector caused by the ambient temperature is compensated by adjusting the reverse bias voltage to ensure that the reverse bias voltage and gain of the APD detector have the same nonlinear relationship at different ambient temperatures (such as the attached Figure 5 As shown in the figure), the APD detector is no longer affected by the ambient temperature.

[0037] In this embodiment, the gain control model includes: an input layer, an intermediate hidden layer and an output layer; wherein the input layer is used to input the ambient temperature and set the gain value; the intermediate layer includes three layers of neurons, and the number of neurons in each layer is 8, 16 and 4 respectively. After each layer of neurons, an activation function is added to introduce nonlinear factors into the model to enhance the expression ability; specifically, in this embodiment, the activation function adopts the Relu function; in some embodiments, the activation function can adopt the Sigmoid function or the Tanh function, and the appropriate activation function can be selected according to actual needs. The output layer is a single fully connected layer, and the output layer is used to process the intermediate value to obtain the reverse bias voltage.

[0038] See also Figure 2 In step 300, the process of training using the sample ambient temperature, the sample reverse bias voltage and the sample gain value includes: Step 310 , making a data set from multiple sets of known sample ambient temperatures, sample reverse bias voltages, and sample gain values.

[0039] Step 320, divide the data set into a training set and a validation set; use the training set to train the gain control model, and use the validation set to verify the accuracy of the gain control model. Further, in this step, the data set is divided using a K-fold crossover method.

[0040] Step 330: Use the stochastic gradient descent algorithm as the optimization algorithm in the training process to adjust the parameters of the gain control model.

[0041] Through the above technical scheme, the technical effect achieved is: in this scheme, the gain control model is trained by making a data set composed of the sample ambient temperature, the sample reverse bias voltage and the sample gain value, so that the optimal parameters of the gain control model can be obtained, thereby making the model more targeted and accurate, and obtaining a more accurate prediction value (reverse bias voltage).

[0042] Furthermore, this model uses the root mean square error function as the loss function; in terms of hyperparameter settings, the learning rate is set to 0.0001, the batch size is set to 64, and the number of training times is set to 50.

[0043] See also Figure 3 In step 400, the step of inputting the ambient temperature and the set gain value into a gain control model to output a reverse bias voltage includes: Step 410: Input the ambient temperature and the set gain value into the input layer to obtain input layer data.

[0044] Step 420: The intermediate hidden layer processes the data of the input layer to obtain an intermediate value.

[0045] Step 430: The output layer processes the intermediate value to obtain the reverse bias voltage.

[0046] In this embodiment, by constructing the gain control model, the ambient temperature and the set gain value are used as input layer data, the input layer data is processed by the intermediate hidden layer, and the intermediate value is processed by the output layer, and finally a reverse bias voltage for adjusting the gain value of the photodetector is obtained. The reverse bias voltage acts on the photodetector to compensate for the gain drift caused by the ambient temperature, thereby making the output of the detection signal unaffected by environmental factors.

[0047] Embodiment 2: See also Figure 6 A second embodiment of the present invention provides an optical detection module, including: a photoelectric detector and an ambient temperature sensing module.

[0048] The photodetector includes a variable gain unit, and the variable gain unit has a set gain value; the photodetector is used to receive a light signal and convert the light signal into an amplified electrical signal according to the set gain value; specifically, in this embodiment, the photodetector is an APD detector. The variable gain unit is a variable gain amplifier (PGA).

[0049] The ambient temperature sensing module includes a temperature sensor and a microprocessor. The temperature sensor is used to obtain the ambient temperature data of the environment where the photodetector is located; the microprocessor is electrically connected to the temperature sensor, and the microprocessor is used to input the ambient temperature data and the set gain value into a gain control model to output a reverse bias voltage for controlling the photodetector, and the reverse bias voltage is used to adjust the current gain value to return it to the set gain value.

[0050] The optical detection module in this embodiment uses a PAD detector with variable gain, which can adapt to the detection of light signals of different intensities. For example, when the surface temperature of the sample to be tested is low, the infrared radiation light is relatively weak, and the gain value can be increased at this time to obtain a stronger signal; when the surface temperature of the sample to be tested is high, the infrared radiation light is relatively strong, and the gain value can be appropriately lowered to obtain a stable signal strength.

[0051] In this embodiment, the temperature sensor is a prior art and will not be described in detail here; the microprocessor may be a MCU (micro control unit).

[0052] In this embodiment, the gain control model includes: an input layer, an intermediate hidden layer and an output layer.

[0053] The input layer is used to input the ambient temperature and set the gain value; the intermediate hidden layer is used to process the data of the input layer to obtain the intermediate value; the output layer is used to process the intermediate value to obtain the reverse bias voltage.

[0054] Embodiment three: See also Figure 7 The third embodiment of the present invention provides an in-situ detection device, including an optical detection module provided in the second embodiment of the present invention, and also including: a signal acquisition module, a receiving optical module, a process control module, a signal processing module and a display module.

[0055] The signal acquisition module is disposed above a sample in a process chamber for epitaxial growth, and is used to collect optical signals from the surface of the sample; in this embodiment, the sample is a wafer or an epitaxial growth layer.

[0056] The receiving optical module is connected to the signal acquisition module via an optical fiber, and is used to receive the optical signal and collimate, split and focus the optical signal; the optical detection module is arranged on the optical path of the optical signal, and is used to convert the optical signal into an amplified electrical signal.

[0057] The process control module is used to send process information. In this embodiment, the process information includes process type, machine speed and wafer layout. The process information is formulated according to different types of epitaxial growth processes. This embodiment is applied to in-situ detection in GaAs (gallium arsenide) process.

[0058] The signal processing module is electrically connected to the optical detection module and the process control module respectively, and is used for receiving the electrical signal and the process information, and generating corresponding data information according to the process information and the electrical signal.

[0059] The display module is electrically connected to the signal processing module and is used for receiving and displaying the data information in real time.

[0060] The in-situ detection device in this embodiment can effectively improve the detection of lower temperature signals on the sample surface by the in-situ detection device by using the optical detection module provided by the second aspect of the present invention, thereby greatly broadening the temperature detection range of the in-situ detection device, so that one in-situ detection device can meet the detection requirements of sample temperature in various epitaxial growth processes. The problem of the high lower limit and small temperature measurement range of the in-situ detection device in the prior art for detecting the surface temperature of the sample (wafer or epitaxial growth layer) in the epitaxial growth equipment is effectively solved.

[0061] In this embodiment, a signal transmitting module is also included. The signal transmitting module is connected to the signal collecting module via an optical fiber. The signal transmitting module is used to generate an emission light signal. When the emission light signal is irradiated onto the sample, a reflected light signal is generated.

[0062] The optical signal includes the reflected light signal and the infrared radiation signal of the sample surface. The temperature of the sample surface can be obtained by collecting the infrared radiation signal, and the growth condition of the epitaxial growth layer can be obtained by collecting the reflected light signal.

[0063] Furthermore, the signal transmission module includes: a light source electronic module and a transmission optical module. The light source electronic module is used to generate the transmission light signal; the transmission optical module is arranged on the optical path of the transmission light signal, and is used to receive the transmission light signal and perform collimation, splitting and focusing processing on the transmission light signal.

[0064] Specifically, the light source electronic module, as the energy source for the entire signal emission, can provide a stable, reliable and appropriately intensive optical signal for the detection process, so as to meet the requirements of the in-situ detection device for accurately measuring the optical properties of the epitaxial growth layer. In addition, the light source electronic module can also accurately control the wavelength, frequency, pulse width and other parameters of the light it emits, so that it can emit a specific optical signal adapted to different detection requirements (such as detecting the epitaxial growth of different materials or different growth stages), thereby achieving more targeted and accurate detection. In this embodiment, the frequency range of the signal light that the light source electronic module can provide is 3-1000Hz, and the pulse width range is 1.6-5ms. The light source electronic module can provide three types of light, and the wavelength ranges of the three types of light are 390-410nm, 610-630nm, and 940-960nm, respectively.

[0065] The emission optical module enables the optical signal to accurately illuminate the detection area of ​​the epitaxial growth layer in a specific shape and spot size, thereby improving the spatial resolution and accuracy of the detection and ensuring that the acquired optical signal can accurately reflect the local characteristics of the epitaxial growth layer.

[0066] In this embodiment, the signal collection module includes a probe, the probe includes a signal transmitting end and a signal collection end, and the optical fiber includes a transmitting optical fiber and a collecting optical fiber. The signal transmitting end of the probe is connected to the transmitting optical module through the transmitting optical fiber, and the transmitting optical signal enters the signal transmitting end through the transmitting optical fiber, and is emitted from the signal transmitting end to irradiate the sample.

[0067] The receiving optical module is connected to the signal collection end of the probe through the collection optical fiber. After being received by the signal collection end, the reflected light signal or the infrared radiation signal enters the receiving optical module through the collection optical fiber.

[0068] In this embodiment, the signal transmitting end and the signal collecting end are arranged on one probe, which effectively improves the structural integration of the probe and saves the installation space of the probe.

[0069] In this embodiment, the signal processing module includes: a signal amplifier, a signal converter and a central processor. The signal amplifier is used to receive the electrical signal and amplify the electrical signal; the signal converter is used to convert the electrical signal processed by the signal amplifier into a digital signal, thereby facilitating the processing of the central processor; in this embodiment, the signal converter is an A / D converter.

[0070] The central processor is used to receive the electrical signal and the process information, generate corresponding data information according to the process information and the electrical signal, and transmit the data information to the display module for display.

[0071] In this embodiment, the display module includes a graphics processing system, which receives the data information and displays the data information as a curve image, thereby improving the readability of the data information. In this embodiment, the display module is a display. The curve image is displayed on the screen of the display.

[0072] See also Figure 8 Further, the in-situ detection device also includes a mainframe box 1, the signal transmission module, the signal collection module, the receiving optical module, the process control module and the signal processing module are all arranged in the mainframe box 1, and the probe 2 is connected to the corresponding interface of the mainframe box 1 through the transmission optical fiber 21 and the collection optical fiber 22. The process chamber 3 and the display 4 are respectively connected to the corresponding interfaces on the mainframe box 1 through cables.

[0073] A rotating machine table 31 is provided in the process chamber 3 for epitaxial growth, and a plurality of wafers 32 are placed on the upper surface of the machine table 31 at equal intervals around the circumference and rotate under the drive of the machine table 31; the epitaxial growth layer grows on the surface of the wafer 32, and the probe 2 is arranged directly above the process chamber 3 to receive the optical signal from the surface of the wafer 32 or the epitaxial growth layer in real time. The process information (machine rotation speed and wafer layout) is transmitted to the process control module in real time through a cable.

[0074] In this embodiment, the in-situ detection device has two detection scenarios. In the first scenario, the in-situ detection device detects the temperature of the surface of the wafer or epitaxial growth layer. At this time, the signal transmitting end of the probe does not work, and the signal acquisition end receives the infrared radiation signal. After the infrared radiation signal is processed by the signal processing module, a temperature image of the surface of the wafer or epitaxial growth layer is displayed on the display screen of the display.

[0075] In the second scenario, the in-situ detection device detects the reflected light signal of the epitaxial growth layer. At this time, the signal transmitting end of the probe is working, and the transmitted light signal transmitted by the signal transmitting module is transmitted from the signal transmitting end to the wafer or the epitaxial growth layer, and generates a reflected light signal after reflection. The reflected light signal is received by the signal receiving end of the probe and transmitted back to the main box through the collection optical fiber. After the reflected light signal is finally processed by the signal processing module, an image of the reflectivity is displayed on the display screen of the display. Furthermore, in this embodiment, the reflectivity is reflected by a voltage value.

[0076] In summary, the present invention proposes a photodetector gain control method, an optical detection module, and an in-situ detection device, which adjust the gain of the APD detector in the in-situ detection device in real time through a gain control model, so that the reverse bias voltage and gain of the APD detector have the same nonlinear relationship, and the APD detector is no longer affected by the ambient temperature. At the same time, since the APD detector has a high sensitivity and can detect weak light signals, the in-situ detection device in the present invention has a larger temperature measurement range. The present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0077] The above is only a specific implementation of the embodiment of the present application, but the protection scope of the embodiment of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed in the embodiment of the present application should be included in the protection scope of the embodiment of the present application. Therefore, the protection scope of the embodiment of the present application should be based on the protection scope of the claims.

Claims

1. A photodetector gain control method, characterized in that: include: Obtaining a set gain value of the photodetector and an ambient temperature of an environment where the photodetector is located; Inputting the ambient temperature and the set gain value into a gain control model to output a reverse bias voltage; The gain control model is constructed using a neural network algorithm and trained using sample ambient temperature, sample reverse bias voltage and sample gain value; Transmitting the reverse bias voltage to the photodetector to adjust the current gain value of the photodetector to return it to the set gain value; The gain control model includes: an input layer, an intermediate hidden layer and an output layer; The step of inputting the ambient temperature and the set gain value into a gain control model to output a reverse bias voltage includes: Inputting the ambient temperature and the set gain value into the input layer to obtain input layer data; The intermediate hidden layer processes the data of the input layer to obtain an intermediate value; The output layer processes the intermediate value to obtain the reverse bias voltage.

2. The photodetector gain control method according to claim 1, characterized in that: The training using the sample ambient temperature, the sample reverse bias voltage and the sample gain value includes: Constructing a data set with a plurality of known sets of sample ambient temperatures, sample reverse bias voltages and sample gain values; Dividing the data set into a training set and a validation set; using the training set to train the gain control model, and using the validation set to verify the accuracy of the gain control model; The stochastic gradient descent algorithm is used as the optimization algorithm in the training process to adjust the parameters of the gain control model.

3. An optical detection module, characterized in that: include: A photodetector comprising a variable gain unit having a set gain value; The photodetector is used to receive the optical signal and convert the optical signal into an amplified electrical signal according to the set gain value; The ambient temperature sensing module includes a temperature sensor and a microprocessor, wherein the temperature sensor is used to obtain ambient temperature data of the environment where the photodetector is located; the microprocessor is electrically connected to the temperature sensor, and the microprocessor is used to input the ambient temperature data and the set gain value into a gain control model to output a reverse bias voltage for controlling the photodetector, wherein the reverse bias voltage is used to adjust the current gain value to return it to the set gain value; The gain control model includes: Input layer, used to input ambient temperature and set gain value; An intermediate hidden layer, used for processing the data of the input layer to obtain an intermediate value; The output layer is used to process the intermediate value to obtain the reverse bias voltage.

4. An in-situ detection device, characterized in that: The optical detection module according to claim 3 further comprises: A signal collection module, disposed above the sample in the process chamber for epitaxial growth, for collecting optical signals from the surface of the sample; A receiving optical module, which is connected to the signal acquisition module through an optical fiber and is used to receive the optical signal and collimate, split and focus the optical signal; the optical detection module is arranged on the optical path of the optical signal and is used to convert the optical signal into an amplified electrical signal; Process control module, used to send process information; a signal processing module, electrically connected to the optical detection module and the process control module respectively, for receiving the electrical signal and the process information, and generating corresponding data information according to the process information and the electrical signal; The display module is electrically connected to the signal processing module and is used to receive and display the data information in real time.

5. The in-situ detection device according to claim 4, characterized in that: It also includes a signal transmission module, which is connected to the signal collection module through an optical fiber, and is used to generate an emission light signal, and the emission light signal irradiates the sample to generate a reflected light signal; The optical signal includes the reflected light signal and the infrared radiation signal of the sample surface.

6. The in-situ detection device according to claim 5, characterized in that: The signal transmission module comprises: A light source electronic module, used for generating the emission light signal; The transmitting optical module is arranged on the optical path of the transmitting optical signal, and is used for receiving the transmitting optical signal and performing collimation and focusing processing on the transmitting optical signal.

7. The in-situ detection device according to claim 6, characterized in that: The signal acquisition module includes a probe, the probe includes a signal transmitting end and a signal collecting end, and the optical fiber includes a transmitting optical fiber and a collecting optical fiber; The signal transmitting end of the probe is connected to the transmitting optical module through the transmitting optical fiber, and the receiving optical module is connected to the signal collecting end of the probe through the collecting optical fiber.

8. The in-situ detection device according to claim 7, characterized in that: The signal processing module comprises: A signal amplifier, used for receiving the electrical signal and amplifying the electrical signal; A signal converter, used for converting the electrical signal processed by the signal amplifier into a digital signal; The central processor is used to receive the electrical signal and the process information, generate corresponding data information according to the process information and the electrical signal, and transmit the data information to the display module for display.

9. The in-situ detection device according to claim 8, characterized in that: The display module includes a graphics processing system, which receives the data information and displays the data information as a curve image.

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