Method and detection system for detecting growth state of epitaxial film

Abstract

The present application provides a method for detecting the growth state of an epitaxial film and a detection system for performing the method for detecting the growth state of an epitaxial film. During the execution of the epitaxial process, the method for detecting the growth state of the epitaxial film in the present application controls an optical detection device to emit light in a specific wavelength range to the epitaxial film for optical detection, obtains the light intensity information of the epitaxial film and sends it to a main control device, and the main control device calculates according to the light intensity information of the epitaxial film, the specific wavelength range and the crystal form correspondence data pre-stored in the main control device, so as to realize real-time monitoring and evaluation of the crystal form situation on the film surface during the growth process of the epitaxial film.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor material growth, and particularly to a method and a detection system for detecting the growth state of an epitaxial film. Background Art

[0002] Some semiconductor materials, such as aluminum gallium nitride (AlGaN), are suitable for manufacturing high-temperature-resistant high-frequency high-power devices due to characteristics such as a wider bandgap width, a higher thermal conductivity coefficient, and a dielectric constant. However, some of these semiconductor materials have a high bond energy and are difficult to form a high-quality substrate through the crystal pulling process or cutting.

[0003] The epitaxial process is a technology for growing an epitaxial film along a specific crystal orientation on a substrate with a crystal orientation, and the fabrication of a device is continued on the epitaxial film. The epitaxial film can be a homoepitaxial film, that is, the substrate and the epitaxial film have the same material, or a heteroepitaxial film, that is, the constituent materials of the substrate and the epitaxial film are different. Thus, through the epitaxial process, a high-quality heteroepitaxial film of a semiconductor material with a high bond energy can be formed on the substrate, which is beneficial to the fabrication of high-frequency high-power devices.

[0004] However, for a heteroepitaxial film, due to the mismatch between the lattice and the thermal expansion coefficient between the substrate material and the epitaxial film material, the structure of the epitaxial film is prone to generating high-density defects. Therefore, the requirements for the heteroepitaxial process are high, and it is necessary to monitor and evaluate the crystal form on the surface of the epitaxial film in real time during the heteroepitaxial process. Summary of the Invention

[0005] The present application provides a method for detecting the growth state of an epitaxial film and a detection system for performing the growth state detection method, so as to realize real-time monitoring and evaluation of the crystal form on the surface of the film during the growth process of the epitaxial film.

[0006] The method for detecting the growth state of the epitaxial film in the present application at least includes the following steps:

[0007] S0: Provide a semiconductor growth device, an optical detection device, and a main control device. The semiconductor growth device carries a substrate, the optical detection device is arranged in the semiconductor growth device, the main control device is communicatively connected with the optical detection device, the main control device prestores crystal form correspondence data of the semiconductor material at different wavelengths and the corresponding absorption coefficients, and each of the absorption coefficients is different;

[0008] S1: Control the semiconductor growth device to perform an epitaxial process on the substrate, so that an epitaxial film composed of the semiconductor material and having a constituent material different from that of the substrate is formed on the exposed surface of the substrate;

[0009] S2: During the process of performing the epitaxial process, control the optical detection device to emit light within a specific wavelength range towards the epitaxial film for optical detection, and acquire and send the light intensity information of the epitaxial film to the main control device;

[0010] S3: The main control device calculates based on the light intensity information of the epitaxial film, the specific wavelength, and the crystal form correspondence data to obtain the real-time crystal form information on the surface of the epitaxial film.

[0011] The detection system of the present application is used to execute the method for detecting the growth state of the epitaxial film. The detection system includes an optical detection device configured to be disposed on a semiconductor growth device, and a main control device communicatively connected to the optical detection device. The semiconductor growth device is configured to perform an epitaxial process on a substrate to form an epitaxial film whose constituent material is different from that of the substrate.

[0012] The beneficial effects of the method for detecting the growth state of the epitaxial film and the detection system of the present application are both as follows: During the process of performing the epitaxial process, control the optical detection device to emit light within a specific wavelength range towards the epitaxial film for optical detection, and acquire and send the light intensity information of the epitaxial film to the main control device, and calculate through the main control device based on the light intensity information of the epitaxial film, the specific wavelength, and the crystal form correspondence data, so as to realize real-time monitoring and evaluation of the crystal form situation on the film surface during the growth process of the epitaxial film.

[0013] Optionally, the main control device also pre-stores empirical reflectivity correspondence data related to the reflectivity, thickness, phase difference, absorption coefficient, and refractive index of the semiconductor material. In step S3, the step of the main control device calculating based on the light intensity information, the specific wavelength, and the crystal form correspondence data includes:

[0014] S31: The main control device obtains real-time reflectivity correspondence data between the real-time reflectivity of the epitaxial film and the growth time based on the light intensity information of the epitaxial film;

[0015] S32: The main control device calculates the real-time absorption coefficient of the epitaxial film based on the real-time reflectivity correspondence data and the empirical reflectivity correspondence data, and obtains the real-time crystal form information on the surface of the epitaxial film according to the real-time absorption coefficient, the specific wavelength, and the crystal form correspondence data.

[0016] Optionally, the empirical reflectivity correspondence data includes:

[0017]

[0018] Wherein:

[0019] R is the empirical reflectivity, ni n is the refractive index of the reaction space medium located above the epitaxial film j n is the refractive index of the semiconductor material k a is the refractive index of the substrate material, a is the absorption coefficient of a specific crystal plane of the semiconductor material at the specific wavelength, γ is the phase difference d is the optical thickness of the epitaxial film

[0020] λ is the specific wavelength, i is the incident angle of light in the specific wavelength range incident from the reaction space medium to the epitaxial film, j is the refraction angle of the outgoing light exiting from the bottom surface of the epitaxial film, k is the refraction angle of the outgoing light exiting from the bottom surface of the substrate

[0021] Optionally, the real-time reflectivity correspondence data is the periodic oscillation curve data of the real-time reflectivity of the epitaxial film and the growth time

[0022] Optionally, the real-time reflectivity of the epitaxial film shows a decaying trend with the extension of the growth time

[0023] Optionally, before performing the step S1, it further includes performing the step of obtaining the specific wavelength:

[0024] Obtain single crystal samples of different crystal forms of the semiconductor material

[0025] Perform optical test and analysis on each single crystal sample under light in different wavelength ranges to obtain absorption spectrum group data

[0026] In the absorption spectrum data, obtain the wavelength data group formed by the wavelengths corresponding to the highest absorption coefficient values of each single crystal sample, and obtain the crystal form correspondence data

[0027] Select any wavelength in the wavelength data group as the specific wavelength

[0028] Optionally, the step of obtaining single crystal samples of different crystal forms of the semiconductor material includes:

[0029] Obtain a single crystal sample to be cut of the semiconductor material

[0030] Perform crystal plane cutting on the single crystal sample to be cut to form each single crystal sample

[0031] Optionally, the semiconductor growth equipment includes a carrying device to carry the substrate

[0032] The process of performing the step S1 includes controlling the carrying device to drive the substrate to rotate

[0033] The process of executing step S2 further includes controlling the optical detection device to emit light within the specific wavelength range to the carrier device, so as to obtain and send the received light intensity information of the carrier device to the main control device;

[0034] In step S3, after the main control device performs subtraction processing based on the light intensity information of the epitaxial film and the light intensity information of the carrier device to subtract the background information including thermal radiation information, calculations are performed based on the obtained light intensity information, the specific wavelength, and the crystal form correspondence data.

[0035] Optionally, after step S32 is executed, the following steps are further included:

[0036] S33: The main control device calculates the real-time optical thickness increment of the epitaxial film based on the empirical reflectivity correspondence data, the real-time reflectivity correspondence data, and the real-time crystal form information;

[0037] S34: The main control device obtains the growth rate change data of the epitaxial film based on the real-time optical thickness increment.

[0038] Optionally, step S33 includes:

[0039] S331: The main control device obtains the real-time optical thickness increment Δd of the epitaxial film within the time period Δt based on the real-time reflectivity values within the i-th cycle of the periodic oscillation curve, the empirical reflectivity correspondence values, and the real-time crystal form information i ; i ;

[0040] S332: The main control device obtains the real-time optical thickness increment Δd of the epitaxial film within the time period Δt based on the real-time reflectivity values within the (i + n)-th cycle of the periodic oscillation curve, the empirical reflectivity correspondence values, and the real-time crystal form information (i+n) ; (i+n) ;

[0041] S333: Repeat step S332 until the epitaxial process ends or until

[0042] Where:

[0043] i is a positive integer greater than or equal to 1, and n is a positive integer greater than or equal to 1 and takes sequential values.

[0044] Optionally, the energy of the light within the specific wavelength range is greater than the bandgap of the semiconductor material.

[0045] Optionally, the epitaxial film is an epitaxial doped film. Description of the Drawings

[0046] Figure 1 Flow chart of the epitaxial film growth state detection method provided by the embodiment of the present invention;

[0047] Figure 2 Schematic diagram of the working state of the detection device provided by the embodiment of the present invention;

[0048] Figure 3 Schematic diagram of the structure of the detection device provided by the embodiment of the present invention;

[0049] Figure 4 Schematic diagram of the optical path of light incident on the film formed on the substrate provided by the embodiment of the present invention;

[0050] Figure 5 Schematic diagram of the periodic oscillation of the reflectivity with the optical thickness provided by the embodiment of the present invention;

[0051] Figure 6 Schematic diagram of the periodic attenuation oscillation of the reflectivity with the optical thickness provided by the embodiment of the present invention;

[0052] Figure 7 Graph of the corresponding relationship between the absorption coefficient and wavelength of different doped epitaxial films provided by the embodiment of the present invention.

[0053] Explanation of reference numerals:

[0054] 1, 500 Substrate

[0055] 2 Film

[0056] 3 Medium

[0057] 100 Reaction chamber

[0058] 200 Main control device

[0059] 300 Detection device

[0060] 310 Light emitter

[0061] 320 Light emitter adjustment part

[0062] 330 Connection seat

[0063] 340 Light propagation part

[0064] 400 Carrying device Detailed implementation manners

[0065] For semiconductor materials with very high bond energy that are difficult to form high-quality substrates through crystal pulling or cutting processes, corresponding heteroepitaxial films can be grown on hetero-substrates through heteroepitaxial processes. Since the substrates used in the epitaxial process have specific crystal orientation characteristics (which are determined according to the requirements of semiconductor device manufacturing), what the epitaxial process requires to control is that the epitaxial film extends and grows following the crystal orientation characteristics of the substrate, thereby ensuring a high degree of consistency in crystal orientation with the substrate and a high degree of integrity of the lattice structure. However, due to the different constituent materials of the substrate and the epitaxial film, the mismatch in lattice and thermal expansion coefficients between the two makes the structure of the epitaxial film prone to high-density defects. Therefore, it is necessary to monitor and evaluate the crystal form on the surface of the epitaxial film in real time during the epitaxial process.

[0066] It can be understood that the technical solution provided in this embodiment is also applicable to the thin film deposition process where the substrate and the epitaxial layer are made of the same material or the material deposition process in the preparation of other semiconductor functional layers. There is no excessive limitation here to expand the application scope of the technical solution provided in this embodiment.

[0067] The embodiments of the present invention provide a method for detecting the growth state of an epitaxial film and a detection system for performing the growth detection method, so as to monitor and evaluate the lattice growth situation during the growth process of the epitaxial film through a non-contact optical detection method, which is non-destructive, fast, and real-time. At the same time, the optical thickness of the heteroepitaxial film and the change in growth rate can also be obtained.

[0068] The detection system provided by the embodiments of the present invention includes an optical detection device and a main control device that are communicatively connected to each other, and the optical detection device is arranged in the semiconductor growth equipment.

[0069] The method for detecting the growth state of the epitaxial film according to the embodiments of the present invention refers to Figure 1 , including:

[0070] S1: Control the semiconductor growth equipment to perform an epitaxial process on the substrate, so that an epitaxial film composed of the semiconductor material and having a different constituent material from the substrate is formed on the exposed surface of the substrate;

[0071] S2: During the execution of the epitaxial process, control the optical detection device to emit light within a specific wavelength range to the epitaxial film for optical detection, and obtain and send the received light intensity information of the epitaxial film to the main control device;

[0072] S3: The main control device calculates according to the light intensity information, the specific wavelength, and the crystal form correspondence data to obtain the real-time crystal form information on the surface of the epitaxial film.

[0073] The technical solutions of the present application will be described in detail below in conjunction with the accompanying drawings in the embodiments of the present invention. Those skilled in the art can understand other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific implementation manners, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application.

[0074] Embodiment 1:

[0075] The semiconductor growth equipment for performing the epitaxial process provided in this embodiment is an MOCVD equipment. Refer to Figure 2 , which includes a reaction chamber 100. A carrying device 400 is disposed inside the reaction chamber 100. A substrate 500 is carried on the top surface of the carrying device 400. A gas injection device (not shown in the figure) opposite to the top surface of the carrying device 400 is provided at the top of the reaction chamber 100 to supply process gas toward the substrate 500.

[0076] In step S1, control the semiconductor growth equipment to perform an epitaxial process on the substrate, so that an epitaxial film composed of the semiconductor material and having a composition different from that of the substrate is formed on the exposed surface of the substrate. Specifically:

[0077] In the semiconductor growth equipment provided in this embodiment, a heating device is further disposed below the carrying device 400 to adjust the temperature inside the reaction chamber 100. Specifically, the heating device transfers heat to the substrate 500 through the carrying device 400. In the semiconductor growth equipment provided in this embodiment, a pressure control system including a pumping system and an exhaust system is also provided to adjust the pressure inside the process chamber. The specific implementation manners of the heating device and the pressure control system are conventional technical means for those skilled in the art.

[0078] In this embodiment, control the semiconductor growth equipment to perform an epitaxial process on the substrate. Specifically, by controlling the heating device, the process temperature condition required for the epitaxial process is satisfied inside the reaction chamber 100. After the pressure inside the reaction chamber 100 satisfies the process pressure condition required for the epitaxial process by controlling the pressure control system, control the carrying device 400 to drive the substrate 500 to rotate around the axis of the reaction chamber 100 at a certain rate. By controlling the gas injection device to supply process gas for the epitaxial process to the top surface of the carrying device 400, the process gas grows epitaxially on the surface of the substrate 500 to form an epitaxial film composed of semiconductor material and having a composition different from that of the substrate 500, that is, a heteroepitaxial film. The rotation of the carrying device 400 enables the process gas above the top surface of the carrying device 400 to be uniformly mixed, which is beneficial to improving the quality of the epitaxial film.

[0079] In some embodiments, it is possible to select whether to adjust the rotation of the carrying device 400 according to the requirements of the epitaxial process.

[0080] In some embodiments, the heteroepitaxial film is an aluminum gallium nitride (Al (1-x) Ga x As) epitaxial film. The semiconductor growth equipment is an MOCVD equipment, the carrier device 400 is a graphite base, and the corresponding substrate 500 is a silicon substrate. Specifically, the growth temperature is controlled at 1100 degrees Celsius, the process pressure is controlled at 50 Torr, and the source gases used are trimethylaluminum, trimethylgallium, and ammonia. The specific epitaxial process is a conventional technical means in the art.

[0081] In some embodiments, the epitaxial process includes any one of epitaxial film preparation processes such as metalorganic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), pulsed laser deposition (PLD), or atomic layer deposition (ALD). Correspondingly. As an example, the epitaxial film in this embodiment is obtained by the metalorganic chemical vapor deposition (MOCVD) process.

[0082] For facilitating the optical detection of the epitaxial film formed on the substrate, referring to Figure 2 , a transparent window (not marked in the figure) is provided at the top of the reaction chamber 100, and the optical detection device 300 is arranged above the transparent window. The optical detection device 300 is electrically connected to the main control device 200 to transmit the light intensity information of the reflected light.

[0083] Furthermore, the specific setting manner of the transparent window and the optical detection device 300 is necessary so as not to affect the normal operation of the gas injection device and not to affect the pressure in the reaction chamber 100.

[0084] The optical detection device 300 is arranged at the top of the reaction chamber 100. During the execution of the epitaxial process, the optical detection device 300 emits light in a specific wavelength range to the area where the substrate is located in the reaction chamber 100, can receive the reflected light of the specific wavelength range, and transmits the obtained light intensity information to the main control device 200.

[0085] The main control device 200 is used to receive the light intensity information from the optical detection device 300 and perform data processing on the light intensity information, and can obtain the growth state of the heteroepitaxial film in the reaction chamber 100 in real time, such as the surface crystal form, optical thickness, and growth rate change of the epitaxial film. The provision of the above information enables the process personnel to timely know the process growth situation of the epitaxial film, which can be used as a reference for optimizing and adjusting the growth process of the epitaxial film, and can also discover abnormal situations in the growth process at the first time, such as abnormal crystal form, uneven thickness, too fast or too slow growth rate, etc., so as to timely adjust the process parameters, ensure that the deposition quality of the epitaxial film meets the requirements, and also helps to reduce the trial and error and waiting time in the epitaxial process, providing valuable reference for subsequent large-scale production.

[0086] In one embodiment, referring toFigure 3 , the detection device 300 at least includes:

[0087] A light emitter 310;

[0088] A light emitter adjustment unit 320, connected to the light emitter 310, for driving the light emitter 310 to move to adjust the position and direction of the light emitter 310;

[0089] A connection base 330, connected to the light emitter adjustment unit 320. The connection base 330 is provided with a light passing hole (not marked in the figure), and the light passing hole is used for the light emitted by the light emitter 310 to pass through, and also for the light reflected by the epitaxial film to pass through;

[0090] A light propagation unit 340, located between the light emitter 310 and the light passing hole of the connection base 330, for transmitting and / or condensing the light emitted by the light emitter 310 to the surface of the thin film to be measured, and receiving the light reflected by the epitaxial film and passing through the light passing hole. Further, the light propagation unit 340 includes a photodetector, and the photodetector receives the reflected light to obtain optical information and sends the optical information to the main control device 200.

[0091] In step S2, during the execution of the epitaxial process, control the optical detection device to emit light in a specific wavelength range to the epitaxial film for optical detection, and obtain and send the received light intensity information to the main control device. Specifically:

[0092] The optical detection device 300 is arranged on the top of the transparent window of the reaction chamber 100 through the connection base 330. Before detection, adjust the light emitter adjustment unit 320 so that the light emitted by the light emitter 310, after being processed by the light propagation unit 340, enters the substrate or the epitaxial film through the light passing hole of the connection base 330 and the transparent window of the reaction chamber 100. Subsequently, the light is reflected back to the light propagation unit 340 of the detection device 300 after passing through the substrate or the epitaxial film, and is processed into optical information by the light propagation unit 340 and sent to the main control device 200 for calculation and analysis.

[0093] In one embodiment, the main control device 200 pre-stores the data of the crystal form correspondence relationship between the semiconductor material and the corresponding absorption coefficient at different wavelengths.

[0094] In one embodiment, the main control device 200 pre-stores the empirical reflectivity correspondence relationship data between the reflectivity, thickness, phase difference, absorption coefficient and refractive index of the semiconductor material.

[0095] Embodiment 2:

[0096] This embodiment provides a method for obtaining a specific wavelength λ.

[0097] In step S3, the main control device calculates according to the light intensity information, the specific wavelength, and the crystal form correspondence data to obtain the real-time crystal form information on the surface of the epitaxial film.

[0098] In this embodiment, step S3 includes:

[0099] S31: The main control device obtains the real-time reflectivity correspondence data between the real-time reflectivity of the epitaxial film and the growth time according to the light intensity information.

[0100] Refer to Figure 4 , a heterogeneous epitaxial film 2 is covered on the substrate 1, light is incident from the medium to the epitaxial film 2, and one reflection and one refraction occur at the medium / epitaxial film interface. The refracted light continues to have a secondary reflection at the substrate / epitaxial film interface. After the epitaxial film growth starts, as its optical thickness increases, the reflectivity and refractive index change. For example, in the case of normal incidence, the reflectivity shows a Figure 5 periodic oscillation characteristic as shown. The maximum and minimum values of the reflectivity appear at integer multiples of 1 / 4 of the incident wavelength of the film's optical thickness. Therefore, it is possible to judge whether the optical thickness of the film has reached 1 / 4 of the incident wavelength thickness by judging the maximum and minimum values of the reflectivity. More importantly, due to the increase in thickness caused by the growth of the thin film during the epitaxial process, the periodic oscillation characteristic of the reflectivity with the increase in optical thickness is also the theoretical basis for this application to monitor the real-time crystal form information on the surface of the epitaxial film.

[0101] However, since the epitaxial film has an absorption effect on light of certain wavelengths, its reflectivity R will also show a decay trend with time. For example Figure 6 the real-time reflectivity correspondence data of this embodiment shown is a periodic decay oscillation curve of the real-time reflectivity of the epitaxial film and the growth time. If the incident wavelength is not selected properly, the decay of R is significant, making its periodic change with time not significant or even showing a linear trend. Therefore, it is necessary to select appropriate light with a specific wavelength λ so that the real-time reflectivity correspondence data between the real-time reflectivity R obtained by the main control device according to the light intensity information and the growth time has a significant periodic change.

[0102] In some embodiments, the energy of the specific wavelength is greater than the bandgap width of the semiconductor material. If the energy of the specific wavelength is lower than the bandgap width, the incident light exiting to the epitaxial film will be completely absorbed by the semiconductor material, or fluorescence excitation will occur, so that the optical detection device cannot detect the corresponding reflected light.

[0103] In this embodiment, before performing step S1, the step of obtaining the specific wavelength includes:

[0104] S01: Obtain single crystal samples of different crystal forms of the semiconductor material;

[0105] S02: Perform optical test and analysis on each of the single crystal samples under light of different wavelength ranges to obtain absorption spectrum group data;

[0106] S03: From the absorption spectrum group data, obtain the wavelengths corresponding to the highest absorption coefficient values of each single crystal sample to form a wavelength data group, and obtain the crystal form correspondence data;

[0107] S04: Select any wavelength from the wavelength data group as the specific wavelength.

[0108] In step S01 of this embodiment, the epitaxial film is an epitaxial doped film, and the corresponding composition is Al(1-x)GaxAs. When the value of x is different, it correspondingly shows different crystal form epitaxial films. After designing the required composition of the epitaxial film according to the requirements of the semiconductor device function, select the corresponding epitaxial process, and it is necessary to monitor the crystal form during the epitaxial process to determine whether the composition of the epitaxial film meets the device requirements.

[0109] In some embodiments, the steps of obtaining single crystal samples of different crystal forms of the semiconductor material include: obtaining a single crystal sample to be cut of the semiconductor material; performing crystal plane cutting on the single crystal sample to be cut to form each of the single crystal samples. This method requires that the single crystal sample is suitable for crystal plane cleavage by crystal plane cutting, and it is necessary to select an appropriate crystal orientation angle and ensure that the cutting process does not damage the cutting crystal plane characteristics as much as possible. For example, taking silicon carbide as an example, the crystal planes in its (0001) and (11-20) directions are cut from a 4H-SiC single crystal sample grown along (000-1)C, and the cutting inclination angle is 4 degrees off the [11-20] crystal orientation. The (11-22) and (11-2-2) oriented wafers are cut from 4H-SiC with the same orientation. The (11-22) oriented 4H-SiC crystal is cut from the (000-1)C crystal plane at an angle of 73° relative to the basal plane.

[0110] In step S02 of this embodiment, the instrument used for optical test and analysis is a VERTEX 80 Fourier transform infrared (FTIR) spectrometer. The sample to be measured is placed on the measurement platform of the instrument and measured and analyzed at room temperature. Transmission and reflection measurements are performed at the same point of the sample, and the light incident angle is selected to be close to the normal direction of the corresponding sample. The probe beam is polarized by a linear polarizer, and the sample under study is rotated to change the angle between the optical axis of crystal c and the electric field vector of the incident electromagnetic wave e. The specific implementation method of the test and analysis is the conventional operation of those skilled in the art.

[0111] In step S03 of this embodiment, obtained through step S02 Figure 7 The corresponding relationship diagram of the absorption coefficient and wavelength of each single crystal sample shown. From Figure 7As can be seen, the wavelengths corresponding to the maximum absorption coefficients of each single-crystal sample all fall within a narrow range of 0.23 μm - 0.26 μm. This narrow range is the wavelength data set of the light within the specific wavelength range, that is, ultraviolet light can be used as the specific wavelength light.

[0112] Embodiment 3:

[0113] This embodiment provides a step of deducting background information including thermal radiation information through the optical detection device 300 during the epitaxial process to ensure accurate detection results.

[0114] Since the reaction space of the epitaxial process is filled with a thermal medium (thermal process gas atmosphere), such as Al (1-x) Ga x For the As epitaxial process with a process temperature of 1100 °C, the epitaxial film itself will generate significant thermal radiation. This part of the thermal radiation enters the optical detection device along with the reflected light, making its radiation information included in the light intensity information, and this part of the radiation information needs to be deducted.

[0115] Since the carrier device drives the carrier substrate of the epitaxial film to rotate synchronously, and the carrier device and the epitaxial film are in the same process environment and can be considered to have the same temperature, therefore, during the execution of step S2, it further includes controlling the optical detection device to emit the light within the specific wavelength range to the carrier device, so as to obtain and send the light intensity information of the carrier device to the main control device. In this embodiment, the carrier device significantly absorbs most or even all of the light within the specific wavelength range, and the real-time reflectivity of the carrier device hardly changes with the growth time. The light intensity information of the carrier device is the information reflected to the optical detection device due to thermal radiation. Specifically, the constituent material of the carrier device in this embodiment is different from that of the epitaxial film and is a light-absorbing material that absorbs the light within the specific wavelength range, such as graphite. More specifically, the optical detection device at a fixed position can collect the light intensity information of the epitaxial film and the light intensity information of the carrier device when detecting the rotating carrier device. The main control device can distinguish and process these two types of information, and the specific processing method is a conventional technical means for those skilled in the art.

[0116] In some embodiments, the carrier device has a certain reflection of the light within the specific wavelength range. In the light intensity information of the carrier device, in addition to including thermal radiation information, it also includes the real-time reflection information of the carrier device. The main control device further deducts the real-time reflection information of the carrier device, and the specific processing method is a conventional technical means for those skilled in the art.

[0117] Further, in step S3, the main control device performs a deduction process on the received light intensity information. After deducting the background information including the thermal radiation information, calculations are performed based on the obtained light intensity information, the specific wavelength, and the crystal form correspondence data.

[0118] Embodiment 4:

[0119] This embodiment provides a method for obtaining the real-time crystal form of an epitaxial film.

[0120] After step S31 of Embodiment 2 ends, S32 is executed: The main control device calculates the real-time absorption coefficient of the epitaxial film based on the real-time reflectivity correspondence data and the empirical reflectivity correspondence data, and obtains the real-time crystal form information on the surface of the epitaxial film based on the real-time absorption coefficient, the specific wavelength, and the crystal form correspondence data.

[0121] The main control device pre-stores empirical reflectivity correspondence data related to the reflectivity, thickness, phase difference, absorption coefficient, and refractive index of the semiconductor material. The empirical reflectivity is R.

[0122] Specifically,

[0123]

[0124] Where:

[0125] n i is the refractive index of the reaction space medium above the epitaxial film, n j is the refractive index of the semiconductor material, n k is the refractive index of the substrate material, which are constants pre-stored in the main control device.

[0126] a is the absorption coefficient of a specific crystal plane of the semiconductor material at the specific wavelength, γ is the phase difference, d is the optical thickness of the epitaxial film, λ is the specific wavelength, i is the incident angle of light from the reaction space medium to the epitaxial film in the specific wavelength range, j is the refraction angle of the light exiting from the bottom surface of the epitaxial film, and k is the refraction angle of the light exiting from the bottom surface of the substrate.

[0127] During the process of performing an epitaxial process to prepare an Al (1-x) Ga x As epitaxial film, the optical detection device vertically emits light to the epitaxial film, so that the values of cosi, cosj, and cosk can all be approximated as 1. The main control device obtains from the light intensity information of the epitaxial film acquired and sent by the optical detection device Figure 6The periodic oscillation decay curve of the real-time reflectivity versus the growth time as shown. The real-time reflectivities corresponding to the adjacent d sampled growth times of the curve are R1 and R2 respectively. By solving the following equation, the real-time absorption coefficient a can be calculated, and then referring to Figure 7 According to the absorption coefficient a, the value of x in Al (1-x) Ga x As can be obtained, and the crystal form corresponding to the composition of this Al (1-x) Ga x As can be obtained.

[0128]

[0129] Example 5:

[0130] This example provides a method for obtaining the real-time optical thickness and growth rate change data of the epitaxial film.

[0131] After S32 of Example 5 ends, S33 is executed: The main control device calculates the real-time optical thickness of the epitaxial film according to the empirical reflectivity correspondence data, the real-time reflectivity correspondence data, and the real-time crystal form information. Specifically:

[0132] S331: The main control device obtains the real-time optical thickness d of the epitaxial film within the Δt i time period according to the adjacent real-time reflectivity values within the i-th period of the periodic oscillation curve, the empirical reflectivity correspondence value, and the real-time crystal form information. i .

[0133] Specifically, since the time of one period is very short, the absorption coefficient a can take the value determined in step S32. Referring to Figure 6 , within the Δt1 time period from t1 to t2 (the first period), referring to the above, the absorption coefficient a can be calculated at adjacent time nodes. According to the adjacent real-time reflectivity peak values R max1 and R max2 , the optical thickness increment Δd1 = d2 - d1 within the Δt1 time period is calculated:

[0134]

[0135] After step S331 ends, S332 is executed: The main control device obtains the real-time optical thickness increment Δd of the epitaxial film within the Δt (i+n) time period according to the adjacent real-time reflectivity values within the (i + n)-th period of the periodic oscillation curve, the theoretical reflectivity correspondence value, and the real-time crystal form information. (i+n) .

[0136] Specifically, referring to Figure 6, within the time period Δt2 from t2 to t3 (the second cycle), based on the adjacent real-time reflectivity peak values R max3 and R max4 calculate the average optical thickness increment Δd2 = d3 - d4 within the time period Δt2:

[0137]

[0138] Similarly, in step S333, for the next cycle within the time period Δt3, based on the adjacent real-time reflectivity peak values, the average optical thickness increment Δd3 within the time period Δt3 can be calculated. By analogy, the average optical thickness increments Δd1, Δd2....Δd for each of the n cycles are obtained n until the epitaxial process ends, or until the real-time reflectivity satisfies In this case, it indicates that the decay oscillation trend of the real-time reflectivity R with the growth time has tended to a linear relationship.

[0139] Furthermore, based on the average optical thickness increments Δd1, Δd2....Δd for each of the n cycles n and the corresponding time periods Δt1, Δt2....Δt n , by which can be obtained calculate the growth rate change of the epitaxial film for each cycle.

[0140] In some embodiments, the corresponding optical thickness increment can also be calculated based on the adjacent real-time reflectivity trough values within the cycle.

[0141] The technical solution provided by this application is particularly applicable to the on-line optical detection method for the growth of heteroepitaxial films. It can not only measure the growth rate and the change of optical thickness with time, but also evaluate the crystal form characteristics of the epitaxial film. Under the guidance of the real-time detection data of the heteroepitaxial growth situation, the epitaxial process can be further adjusted to precisely control the growth parameters of the epitaxial layer, which is of great significance for manufacturing semiconductor devices with excellent performance.

[0142] The above embodiments merely illustrate the principles and effects of this application, rather than limiting this application. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by this application should still be covered by the claims of this application.

Claims

1. A method for detecting the growth state of an epitaxial film, characterized in that: At least the following steps are included: S0: Provide a semiconductor growth device, an optical detection device and a main control device, wherein the semiconductor growth device carries a substrate, the optical detection device is arranged in the semiconductor growth device, the main control device is in communication connection with the optical detection device, and the main control device pre-stores empirical reflectivity correspondence data with the reflectivity, thickness, phase difference, absorption coefficient and refractive index of the semiconductor material, and crystal form correspondence data of the semiconductor material at different wavelengths and the corresponding absorption coefficient, and each of the absorption coefficients is different; S1: controlling the semiconductor growth device to perform an epitaxial process on the substrate, so that an epitaxial film composed of the semiconductor material and having a composition material different from that of the substrate is formed on the exposed surface of the substrate; S2: During the execution of the epitaxial process, controlling the optical detection device to emit light in a specific wavelength range to the epitaxial film for optical detection, and acquiring and sending light intensity information of the epitaxial film to the main control device; S3: The main control device performs calculations according to the light intensity information of the epitaxial film, the specific wavelength and the crystal form correspondence data, the steps comprising: S31: the main control device obtains real-time reflectivity correspondence data between the real-time reflectivity of the epitaxial film and the growth time according to the light intensity information of the epitaxial film; S32: The main control device calculates the real-time absorption coefficient of the epitaxial film according to the real-time reflectivity correspondence data and the empirical reflectivity correspondence data, and obtains the real-time crystal type information of the epitaxial film surface according to the real-time absorption coefficient, the specific wavelength and the crystal type correspondence data.

2. The epitaxial film growth state detection method according to claim 1, characterized in that: The empirical reflectivity correspondence data includes: in: R is the empirical reflectivity, n i is the refractive index of the reaction space medium above the epitaxial film, n j is the refractive index of the semiconductor material, n k is the refractive index of the substrate material, a is the absorption coefficient of a specific crystal plane of the semiconductor material at the specific wavelength, γ is the phase difference, d is the optical thickness of the epitaxial film; λ is the specific wavelength, i is the incident angle of the light in the specific wavelength range from the reaction space medium to the epitaxial film, j is the refraction angle of the outgoing light emitted from the bottom surface of the epitaxial film, and k is the refraction angle of the outgoing light emitted from the bottom surface of the substrate.

3. The epitaxial film growth state detection method according to claim 1, characterized in that: The real-time reflectivity correspondence data is periodic oscillation curve data of the real-time reflectivity and growth time of the epitaxial film.

4. The epitaxial film growth state detection method according to claim 3, characterized in that: The real-time reflectivity of the epitaxial film shows a decaying trend as the growth time increases.

5. The epitaxial film growth state detection method according to claim 4, characterized in that: Before executing the step S1, the method further includes executing the step of obtaining the specific wavelength: Obtaining single crystal samples of different crystal forms of the semiconductor material; Performing optical testing and analysis on each of the single crystal samples under light of different wavelength ranges to obtain absorption spectrum group data; Acquire the wavelength corresponding to the maximum value of the absorption coefficient of each single crystal sample in the absorption spectrum group data to form a wavelength data group, and acquire the crystal form corresponding relationship data; Any wavelength in the wavelength data group is selected as the specific wavelength.

6. The epitaxial film growth state detection method according to claim 5, characterized in that: The steps of obtaining single crystal samples of different crystal forms of the semiconductor material include: Obtaining a single crystal sample of the semiconductor material to be cut; The single crystal samples to be cut are subjected to crystal plane cutting to form the single crystal samples.

7. The epitaxial film growth state detection method according to claim 1, characterized in that: The semiconductor growth equipment comprises a carrying device for carrying the substrate; The process of executing the step S1 includes controlling the carrying device to drive the substrate to rotate; The process of executing step S2 further includes controlling the optical detection device to emit the light in the specific wavelength range to the carrier device, so as to obtain and send the received light intensity information of the carrier device to the main control device; In step S3, the main control device performs subtraction processing based on the light intensity information of the epitaxial film and the light intensity information of the carrier device to deduct background information including thermal radiation information, and then performs calculation based on the obtained light intensity information, the specific wavelength and the crystal type correspondence data.

8. The epitaxial film growth state detection method according to claim 1, characterized in that: After the step S32 is completed, the following steps are also performed: S33: the main control device calculates the real-time optical thickness increment of the epitaxial film according to the empirical reflectivity correspondence data, the real-time reflectivity correspondence data and the real-time crystal type information; S34: The main control device obtains the growth rate change data of the epitaxial film according to the real-time optical thickness increment.

9. The epitaxial film growth state detection method according to claim 8, characterized in that: The step S33 comprises: S331: The main control device obtains the real-time reflectivity value in the ith period of the periodic oscillation curve, the empirical reflectivity correspondence data and the real-time crystal type information at Δt i The real-time optical thickness increment Δd of the epitaxial film within a time period i ; S332: The main control device obtains the real-time reflectivity value in the (i+n)th period of the periodic oscillation curve, the empirical reflectivity correspondence data and the real-time crystal type information. (i+n) The real-time optical thickness increment Δd of the epitaxial film within a time period (i+n) ; S333: Repeat step S332 until the epitaxial process is completed or until the in: i is a positive integer greater than or equal to 1, n is a positive integer greater than or equal to 1 and the values ​​are taken sequentially.

10. The epitaxial film growth state detection method according to claim 1, characterized in that: The energy of light in the specific wavelength range is greater than the bandgap width of the semiconductor material.

11. The epitaxial film growth state detection method according to claim 1, characterized in that: The epitaxial film is an epitaxial doped film.

12. A detection system, characterized in that: Used to execute the epitaxial film growth state detection method described in any one of claims 1-11, the detection system includes an optical detection device for being arranged on a semiconductor growth device, and a main control device communicatively connected to the optical detection device, and the semiconductor growth device is configured to perform an epitaxial process on a substrate to form an epitaxial film whose composition material is different from that of the substrate.

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