Device and method for measuring geometric parameters and performance parameters of sample

Abstract

The invention discloses a device and a method for measuring geometric parameters and performance parameters of a sample, the device comprises a white light interference measurement module, a Raman spectrum measurement module and an ellipsometry measurement module, and the white light interference measurement module and the Raman spectrum measurement module adopt a partial common-path design. Common-optical-path measurement of Raman spectrum data and interference fringe images is achieved, the surface appearance and material composition information of the same measurement point position can be obtained at the same time, and in-situ high-precision obtaining of geometric parameters and material composition information in ellipsometry modeling is achieved. The condition of analysis errors caused by inconsistent information carried by different measurement points of the heterogeneous film is avoided, and the precision and the reliability of an ellipsometry measurement result can be greatly improved. According to the method for measuring the geometric parameters and the performance parameters of the film layer on the surface of the wide bandgap semiconductor wafer, the morphological information and the performance parameters of the heterogeneous film can be comprehensively and accurately measured and represented by combining the ellipsometric spectrum, the white light interference, the Raman spectrum and other technologies.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical measurement technology, and in particular to a sample geometric parameter and performance parameter measurement device and a measurement method. BACKGROUND

[0002] Wide bandgap semiconductors are ideal materials for manufacturing high-frequency and high-power devices due to their high-voltage, high-frequency and high-temperature characteristics, and are widely used in 5G communication, new energy vehicles, aerospace and other fields. High-precision characterization and measurement of the geometric morphology and performance parameters of wide bandgap semiconductors at high temperatures are of great significance to the study of their high-temperature service performance and temperature-dependent mechanisms. Traditional measurement methods such as AFM and SEM are difficult to simultaneously characterize the geometric features and performance parameters of semiconductor materials in situ, especially in high-temperature environments. Ellipsometry has the advantages of high precision, non-contact, wide measurement parameters, and high-temperature measurement capability, and has been widely used in the measurement of film thickness and key dimensions in the semiconductor industry. It is the only potential effective means to solve the above problems.

[0003] The measurement results of ellipsometry are strongly dependent on the prior knowledge of the measurement parameters. The more sufficient the prior knowledge is, the higher the reliability of the measured parameters will be. The prior knowledge used by existing ellipsometers often comes from other auxiliary instruments. However, in a high-temperature environment, the performance of the material form changes all the time, and it is necessary to ensure the unity of the measurement reference and position to achieve high-precision and high-reliability measurement of the measurement system.

[0004] The measurement device and method for measuring the change of thin film optical constants with temperature disclosed in patent CN 109883956A measure the ellipsometric parameters of the substrate and the film surface of the same sample with temperature change by turning over the sample, and use the measured optical constants of the substrate at the same temperature as the initial conditions for fitting the optical constants of the film layer to realize the measurement of the change of thin film optical constants with temperature. This method ignores the influence of turning over the sample on the measurement point, and cannot realize the simultaneous measurement of the geometric and performance parameters of the wafer during temperature change. When the substrate of the wide bandgap semiconductor wafer and the thin film material are different, the measurement of the geometric and performance parameters of the wafer cannot be realized.

[0005] The device and method for measuring thin film optical constants and topographic parameters under high-temperature loading disclosed in patent CN 110376136B can calibrate the ellipsometric parameter deviation introduced by the quartz glass window at different heating temperatures within a wide temperature range, and can more accurately measure the optical constants and topographic parameters of the sample to be measured. This method directly uses the ellipsometric model to inversely solve the thin film surface topographic parameters, but in the measurement of wide bandgap semiconductor wafer ultra-thin film, since the roughness and thickness are in the same order of magnitude, the surface roughness value needs to be fixed first to improve the accuracy and precision of the performance parameters.

[0006] Currently, the methods for measuring the morphology and performance of wide-bandgap semiconductor heterojunction thin films include Raman spectroscopy, X-ray diffraction, transmission electron microscopy, and atomic force microscopy, etc. These methods have their own characteristics, but usually only provide a single morphology or performance parameter of the hetero thin film, leading to the lack of comprehensive morphology and performance parameters in the analysis process, which cannot accurately and comprehensively evaluate the influence of the hetero thin film on the device performance. For example, Raman spectroscopy can provide molecular vibration information of the material, but the analytical ability of the layer number and thickness is limited; X-ray diffraction can reveal the crystal structure, but it is difficult to directly obtain the surface topography information; transmission electron microscopy can analyze the atomic level structure, but the sample preparation is complex and may change the original state of the thin film; atomic force microscopy can provide high-resolution surface topography images, but the measurement speed is slow and limited by the scanning area.

[0007] Therefore, it is necessary to develop more advanced measurement and characterization methods that can comprehensively consider multiple morphology and performance parameters to accurately evaluate and optimize the morphology and performance of wide-bandgap semiconductor heterojunction thin films. These new methods should have the ability of high resolution, high sensitivity and multi-parameter synchronous measurement, so as to better reveal the structure-performance relationship of the thin film and promote its application in high-performance electronic and optoelectronic devices. SUMMARY

[0008] In view of the above technical problems, the purpose of the embodiments of the present application is to provide a sample geometric parameter and performance parameter measurement device and a measurement method to solve the technical problems mentioned in the background section.

[0009] In a first aspect, embodiments of the present application provide a sample geometric parameter and performance parameter measuring device, comprising an ellipsometry module, a white light interferometry module, a Raman spectroscopy module and a data processing module, the white light interferometry module and the Raman spectroscopy module share the same objective lens and beam splitter in the optical path structure to realize partial common optical path, the white light interferometry module and the Raman spectroscopy module detect the interference fringe image and the Raman spectrum data of the same measurement point on the surface of the sample respectively; the light emitted by the ellipsometry module and the light emitted by the white light interferometry module and the Raman spectroscopy module form coincident spots on the surface of the sample, the ellipsometry module measures the ellipsometric spectrum data of the same measurement point on the surface of the sample; the data processing module comprises a surface three-dimensional topography recovery unit, a Raman spectrum processing unit and an ellipsometric spectrum data analysis unit; the surface three-dimensional topography recovery unit is connected with the white light interferometry module and obtains the initial value of the geometric parameter according to the interference fringe image collected by the white light interferometry module; the Raman spectrum processing unit is connected with the Raman spectroscopy module and extracts the material composition information and the initial value of the performance parameter according to the Raman spectrum data collected by the Raman spectroscopy module; the ellipsometric spectrum data analysis unit is connected with the ellipsometry module to collect the ellipsometric spectrum data, the ellipsometric spectrum data analysis unit establishes the optical model and the oscillator model of the sample according to the material characteristics of the sample, the material composition information, the initial value of the geometric parameter and the initial value of the performance parameter, and combines the ellipsometric spectrum data to perform fitting analysis, thereby obtaining the geometric parameter and the performance parameter of the sample.

[0010] As preferred, the white light interferometry module comprises a first light source, a collimating lens, a relay lens group, an imaging tube lens, a photodetector, a first beam splitter, a second beam splitter, a first objective lens and a second objective lens, the first beam splitter is arranged between the second objective lens and the second beam splitter, and the second beam splitter is arranged between the first beam splitter and the imaging tube lens; the incident light path of the first objective lens is arranged parallel to the sample surface; the incident light path of the second objective lens is arranged perpendicular to the sample surface, the first objective lens is controlled to move along a direction parallel to the sample surface by a first driving mechanism, a reference plane is arranged in the focal plane of the first objective lens, and the second objective lens is controlled to move along a direction perpendicular to the sample surface by a second driving mechanism; the light emitted by the first light source is converted into parallel light after passing through the collimating lens, and the parallel light is split into two coherent light waves, i.e. reference light and measurement light, after passing through the first beam splitter after uniform illumination by the relay lens group, the reference light and the measurement light are irradiated on the sample surface and then enter the first objective lens and the second objective lens respectively, the two coherent light waves return to the first beam splitter after the original route, and interference is generated after superposition, and then the interference is entered into the photodetector through the second beam splitter and the imaging tube lens, and an interference fringe image is obtained by the photodetector; the Raman spectrum measurement module comprises a second light source, a first beam splitter, a dichroic mirror, a second beam splitter, a confocal lens group, a second objective lens and a spectrometer, monochromatic light emitted by the second light source sequentially passes through the dichroic mirror, the second beam splitter and the first beam splitter, and then enters the second objective lens, the second objective lens converges the monochromatic light, and then projects the monochromatic light onto the surface of the sample, collects Raman scattered light containing sample substance component information, and then returns the Raman scattered light to the second beam splitter through the first beam splitter, the Raman scattered light is reflected by the second beam splitter and then passes through the dichroic mirror to enter the confocal lens group, the confocal lens group filters out stray light in the Raman scattered light, and then transmits the required Raman spectrum information to the spectrometer, and Raman spectrum data is obtained by the spectrometer.

[0011] As preferred, the white light interferometry module comprises a first light source, a collimating lens, a relay lens group, an imaging tube lens, a photodetector, a first beam splitter, a second beam splitter, a third beam splitter, a first objective lens and a second objective lens; the incident light path of the first objective lens is arranged parallel to the sample surface, and the incident light path of the second objective lens is arranged perpendicular to the sample surface; the second beam splitter is arranged between the first beam splitter and the second objective lens, and the third beam splitter is arranged between the first beam splitter and the first objective lens; the first objective lens is controlled to move along a direction parallel to the sample surface by a first driving mechanism, and a reference plane is arranged in the focal plane of the first objective lens, and the second objective lens is controlled to move along a direction perpendicular to the sample surface by a second driving mechanism; the light emitted by the first light source is converted into parallel light after passing through the collimating lens, and the parallel light is split into two coherent light waves, i.e. reference light and measurement light, after passing through the first beam splitter after uniform illumination by the relay lens group; the reference light and the measurement light are incident into the first objective lens and the second objective lens respectively after irradiating the sample surface, and the two coherent light waves return to the original path and pass through the second beam splitter and the third beam splitter respectively, and then the interference is generated after superposition at the first beam splitter, and the interference fringe image is obtained by the photodetector through the imaging tube lens; the Raman spectrum measurement module comprises a second light source, a dichroic mirror, a second beam splitter, a confocal lens group, a second objective lens and a spectrometer; the dichroic mirror is arranged between the second beam splitter and the confocal lens group; the monochromatic light emitted by the second light source is reflected by the dichroic mirror and the second beam splitter in sequence and then enters the second objective lens; the second objective lens converges the monochromatic light and projects it onto the surface of the sample, collects the Raman scattered light containing the sample substance composition information and returns it to the second beam splitter, and the Raman scattered light passes through the dichroic mirror and enters the confocal lens group after being reflected by the second beam splitter; the confocal lens group filters out the stray light in the Raman scattered light and transmits the required Raman spectrum information to the spectrometer, and the Raman spectrum data is obtained by the spectrometer.

[0012] As preferred, the ellipsometry module comprises a wide-spectrum light source, a polarizer, a first rotation compensator, a second rotation compensator, an analyzer and a detection unit; the light emitted by the wide-spectrum light source is transmitted to the polarizer through an optical fiber; the light transmitted by the optical fiber is converted into polarized light with a certain characteristic through the polarizer and the first rotation compensator and is obliquely incident on the surface of the sample; the polarized light reflected by the surface of the sample passes through the second rotation compensator and the analyzer in sequence and is transmitted to the detection unit through the optical fiber; and the ellipsometric spectrum data of the sample is obtained by the detection unit.

[0013] As preferred, the sample stage is further provided below with a six-degree-of-freedom motion displacement stage for adjusting the measurement point position or achieving sample stage leveling according to the interference fringe image; the polarizer is provided below with a first rotating stage for adjusting the included angle between the polarizer and the sample stage; the analyzer is provided below with a second rotating stage for adjusting the included angle between the analyzer and the sample stage; the sample stage comprises a normal-temperature sample stage and a high-temperature sample stage, and when the sample stage is the high-temperature sample stage, the high-temperature sample stage further comprises a high-temperature heating cavity, a first optical window, a second optical window and a third optical window; the high-temperature sample stage is installed inside the high-temperature heating cavity, the high-temperature heating cavity can be evacuated or filled with inert gas; the first optical window and the third optical window are respectively installed on the two sides of the high-temperature heating cavity and can transmit the incident light and the reflected light of the ellipsometric measurement module; the second optical window is installed on the surface of the high-temperature heating cavity and is perpendicular to the high-temperature sample stage; the temperature control range on the high-temperature sample stage is 300-1200K.

[0014] As preferred, the geometric parameters include film thickness and surface roughness; the performance parameters include one or more of crystal structure, crystal orientation, dielectric constant, optical band gap, optical constant, residual stress, conductivity, doping concentration, impurity and defect, carrier concentration, carrier mobility and electron relaxation time, the dielectric constant includes real part and imaginary part, and the optical constant includes refractive index and extinction coefficient.

[0015] As preferred, the oscillator model includes an empirical Cauchy model, a Gaussian model, a Drude model, a Tauc-Lorentz model or a Drude-Lorentz model.

[0016] In the second aspect, the embodiments of the present application provide a method for measuring geometric parameters and performance parameters of a film layer on a wide-bandgap semiconductor wafer surface, which uses the sample geometric parameter and performance parameter measurement device in any one of the first aspect, wherein the sample includes a wafer and a film layer on the wafer surface, and the method comprises the following steps:

[0017] 1) selecting a measurement point position on the surface of the film layer on the wafer surface, and obtaining an interference fringe image corresponding to the measurement point position on the surface of the film layer on the wafer surface through the white light interference measurement module;

[0018] 2) keeping the position of the film layer on the wafer surface unchanged, switching to the Raman spectrum measurement module, adjusting the second objective lens to be located at the focal position of the Raman spectrum measurement module, and collecting Raman spectrum data corresponding to the measurement point position on the surface of the film layer on the wafer surface;

[0019] 3) According to the state of the interference fringes in the interference fringe image, adjust the sample stage to make it level, the sample surface is perpendicular to the entrance surface of the first objective; switch to the ellipsometric measurement module, the light emitted in the ellipsometric measurement module coincides with the light emitted in the white light interferometric measurement module and the Raman spectrum measurement module to form a spot on the surface of the sample, and the ellipsometric spectrum data corresponding to the measurement point on the surface of the wafer surface film layer is obtained through the ellipsometric measurement module;

[0020] 4) Extract the initial value of the geometric parameter according to the interference fringe image, and determine the initial value of the material composition information and the performance parameter according to the Raman spectrum data;

[0021] 5) Determine the material characteristics according to the material composition information, establish the optical model and the oscillator model of the wafer surface film layer according to the material characteristics, the initial value of the geometric parameter, the initial value of the performance parameter, and the ellipsometric spectrum data for fitting analysis to obtain the geometric parameter and the performance parameter of the sample.

[0022] As preferred, the wafer surface film layer includes at least one hetero film, the outermost hetero film is a rough surface layer, the geometric parameter includes the surface roughness and the film thickness, the wafer surface film layer includes multiple film layers, and the performance parameter includes one or more of the crystal structure, the crystal orientation, the dielectric constant, the optical band gap, the optical constant, the residual stress, the conductivity, the doping concentration, the impurity and defect, the carrier concentration, the carrier mobility, and the electron relaxation time.

[0023] The optical model of the wafer and at least one hetero film on the surface thereof is established in combination with the surface roughness and the material composition information, the material characteristics are determined according to the material composition information measured by the Raman spectrum measurement module, and the corresponding oscillator model is selected according to the material characteristics;

[0024] The initial value of the thickness of the rough surface layer and the initial value of the surface roughness are estimated based on the interference fringe image;

[0025] The incident depth of the second light source in the Raman spectrum measurement module is adjusted to obtain Raman spectrum data of different intensities, and the number of layers of the intermediate hetero film and the initial value of the thickness of each layer of the intermediate hetero film are estimated according to the Raman spectrum data of different intensities;

[0026] The optical model and the oscillator model of the wafer surface film layer are established according to the material characteristics, the initial value of the surface roughness, the initial value of the thickness of the rough surface layer, the initial value of the thickness of each layer of the intermediate hetero film, and the material composition information, and the fitting analysis is performed in combination with the ellipsometric spectrum data to obtain the thickness of each layer of the hetero film and the surface roughness.

[0027] As preferred, when the wafer surface film layer includes multiple film layers, and the sample stage is a high-temperature sample stage, the method further includes:

[0028] Place the sample on the high-temperature sample table, vacuumize or fill nitrogen into the high-temperature heating cavity, slowly heat to the preset temperature and keep;

[0029] The interference fringe image, the Raman spectrum data and the ellipsometric spectrum data are measured at room temperature and the preset temperature respectively;

[0030] The surface topography of the sample surface at room temperature and the preset temperature is extracted by the centroid algorithm according to the interference fringe image, and the change of the surface topography with temperature is analyzed;

[0031] The baseline correction is performed on the Raman spectrum data, the background noise and the fluorescence interference are removed, the peak fitting is performed on the corrected Raman spectrum data, the position, the intensity and the full width at half maximum of the characteristic peak are accurately determined by using the Gaussian or Lorentzian function, the characteristic peak position at the preset temperature and room temperature is analyzed, the offset of the characteristic peak position is determined, the intensity change of the characteristic peak is analyzed, the material composition information of the wafer surface film layer and the crystalline quality at high temperature are determined, the stress coefficient is determined according to the material composition information, and the initial value of the residual stress at room temperature and the preset temperature is calculated by the offset and the stress coefficient;

[0032] The size of the preset temperature is adjusted, and the above steps are repeated to obtain the initial value of the residual stress under different temperature conditions;

[0033] The optical model and the oscillator model of the wafer surface film layer are established according to the material characteristics, the initial value of the residual stress under different temperature conditions and the material composition information, and the fitting analysis is performed in combination with the ellipsometric spectrum data at the corresponding temperature to obtain the change of the residual stress of the multi-layer film under different temperature conditions;

[0034] The initial value of the remaining performance parameter is determined according to the material composition information and the temperature, and the above step is repeated to obtain the remaining performance parameter under high temperature conditions through fitting analysis.

[0035] Compared with the prior art, the beneficial effects of the present application are as follows:

[0036] (1) The sample geometric parameter and performance parameter measuring device proposed in the present application combines the white light interference measurement module and the Raman spectrum measurement module of the partial common path design with the ellipsometric measurement module, uses special wavelength monochromatic light and a dichroic mirror, and shares the objective lens and the beam splitter in the white light interference measurement module and the Raman spectrum measurement module, realizes the common path measurement of the Raman spectrum data and the interference fringe image, can obtain the surface topography and the material composition information of the same measurement point at the same time, realizes the in-situ high-precision acquisition of the geometric parameters and the material composition information in the ellipsometric modeling, avoids the situation that the information carried by different measurement points of the heterogeneous film is inconsistent and then leads to analysis errors, and can greatly improve the precision and reliability of the ellipsometric measurement results.

[0037] (2) The geometric parameter and performance parameter measurement method of the surface film layer of the wide bandgap semiconductor wafer provided by the present application can comprehensively and accurately measure and characterize the morphological information and performance parameters of the hetero film by combining ellipsometric spectroscopy, white light interference and Raman spectroscopy. The method provides important technical support for the research and development of wide bandgap semiconductor heterojunction thin films, and helps to further improve the performance and reliability of the device.

[0038] (3) The geometric parameter and performance parameter measurement method of the surface film layer of the wide bandgap semiconductor wafer provided by the present application can obtain Raman spectrum data of different intensities by adjusting the incident depth of the second light source in the Raman spectrum measurement module. Since different material layers exhibit unique vibration frequencies in Raman spectroscopy, the material of each film layer can be distinguished by these characteristic peaks to further obtain the number of layers and thickness information of the multi-layer hetero film. In addition, the optical model and oscillator model can be combined to perform fitting analysis on the thickness, surface roughness and other geometric parameters of each film layer in the multi-layer hetero film, as well as the carrier concentration, mobility and other performance parameters. BRIEF DESCRIPTION OF DRAWINGS

[0039] The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and serve to explain principles of the present application. Other embodiments and many of the intended advantages of the present application will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.

[0040] Figure 1 A structural schematic diagram of a sample geometric parameter and performance parameter measurement device of embodiment one of the present application is shown;

[0041] Figure 2 A high-temperature sample stage and its corresponding device schematic diagram of a sample geometric parameter and performance parameter measurement device of embodiment one of the present application is shown;

[0042] Figure 3 A structural schematic diagram of a sample geometric parameter and performance parameter measurement device of embodiment two of the present application is shown;

[0043] Reference numerals: 101, wide spectrum light source; 102, polarizer; 103, first rotation compensator; 104, second rotation compensator; 105, analyzer; 106, detection unit; 211, first light source; 212, collimating lens; 213, relay lens group; 214, imaging tube lens; 215, photodetector; 216, first beam splitter; 217, first driving mechanism; 218, first objective lens; 219, reference plane; 220, second driving mechanism; 221, second objective lens; 231, second beam splitter; 232, dichroic mirror; 233, second light source; 234, confocal lens group; 235, spectrometer; 236, third beam splitter; 310, high-temperature heating cavity; 320, first optical window; 330, second optical window; 340, third optical window; 350, high-temperature sample stage; 400, sample. DETAILED DESCRIPTION

[0044] The application will be further described below in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the application and are not intended to limit the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for the convenience of description. It should be noted that the sizes and dimensions of the components in the drawings are not in proportion, and the sizes of some components may be highlighted for the purpose of illustration.

[0045] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0046] The embodiment of the present application is a sample geometric parameter and performance parameter measuring device, comprising an ellipsometry module, a white light interference measuring module, a Raman spectrum measuring module and a data processing module, the white light interference measuring module and the Raman spectrum measuring module share the same objective lens and beam splitter in the optical path structure to realize partial common optical path, the white light interference measuring module and the Raman spectrum measuring module respectively detect the interference fringe image and the Raman spectrum data of the same measuring point on the surface of the sample 400; the light emitted by the ellipsometry module and the light emitted by the white light interference measuring module and the Raman spectrum measuring module are coincident on the light spot formed on the surface of the sample 400, and the ellipsometry module measures the ellipsometric spectrum data of the same measuring point on the surface of the sample 400; the data processing module comprises a surface three-dimensional topography recovery unit, a Raman spectrum processing unit and an ellipsometric spectrum data analysis unit; the surface three-dimensional topography recovery unit is connected with the white light interference measuring module, and obtains the initial value of the geometric parameter according to the interference fringe image collected by the white light interference measuring module; the Raman spectrum processing unit is connected with the Raman spectrum measuring module, and extracts the material composition information and the initial value of the performance parameter of the surface of the sample 400 according to the Raman spectrum data collected by the Raman spectrum measuring module; the ellipsometric spectrum data analysis unit is connected with the ellipsometry module to collect the ellipsometric spectrum data, and the ellipsometric spectrum data analysis unit establishes the optical model and the oscillator model of the sample 400 according to the material characteristics of the sample 400, the material composition information, the initial value of the geometric parameter and the initial value of the performance parameter, and combines the ellipsometric spectrum data to perform fitting analysis, so as to obtain the geometric parameter and the performance parameter of the sample 400.

[0047] The sample geometric parameter and performance parameter measuring device mentioned in the present application will be described in detail below by using specific embodiments.

[0048] Embodiment one

[0049] In the first embodiment of the present application, the white light interferometry module comprises a first light source 211, a collimating lens 212, a relay lens group 213, an imaging tube lens 214, a photodetector 215, a first beam splitter 216, a second beam splitter 231, a first objective lens 218, and a second objective lens 221. The first beam splitter 216 is arranged between the second objective lens 221 and the second beam splitter 231, and the second beam splitter 231 is arranged between the first beam splitter 216 and the imaging tube lens 214. The incident light path of the first objective lens 218 is arranged parallel to the surface of the sample 400. The incident light path of the second objective lens 221 is arranged perpendicular to the surface of the sample 400. A first driving mechanism 217 is connected to the first objective lens 218 for controlling the movement of the first objective lens 218 in a direction parallel to the surface of the sample 400. A reference plane 219 is arranged in the focal plane of the first objective lens 218. A second driving mechanism 220 is connected to the second objective lens 221 for controlling the movement of the second objective lens 221 in a direction perpendicular to the surface of the sample 400. The light emitted by the first light source 211 is converted into parallel light by the collimating lens 212. After uniform illumination by the relay lens group 213, the parallel light is split into two coherent light waves, i.e. reference light and measurement light, by the first beam splitter 216. After irradiating the surface of the sample 400, the reference light and the measurement light enter the first objective lens 218 and the second objective lens 221, respectively. The two coherent light waves return to the first beam splitter 216, superimpose to generate interference, and then enter the photodetector 215 through the second beam splitter 231 and the imaging tube lens 214. The interference fringe image is obtained by the photodetector 215.

[0050] In a specific embodiment, the Raman spectrum measurement module comprises a second light source 233, a first beam splitter 216, a dichroic mirror 232, a second beam splitter 231, a second objective lens 221, a confocal lens group 234, and a spectrometer 235. The monochromatic light emitted by the second light source 233 is sequentially reflected by the dichroic mirror 232, the second beam splitter 231, and the first beam splitter 216, and then enters the second objective lens 221. After the second objective lens 221 converges the monochromatic light and projects it onto the surface of the sample 400, the Raman scattered light containing the material composition information of the sample 400 is collected and returned to the second beam splitter 231 through the first beam splitter 216. The Raman scattered light is reflected by the second beam splitter 231 and then transmitted through the dichroic mirror 232 to enter the confocal lens group 234. The confocal lens group 234 filters out the stray light in the Raman scattered light and transmits the required Raman spectrum information to the spectrometer 235. The Raman spectrum data is obtained by the spectrometer 235.

[0051] In a specific embodiment, the ellipsometry module includes a wide-spectrum light source 101, a polarizer 102, a first rotation compensator 103, a second rotation compensator 104, an analyzer 105, and a detection unit 106. The light emitted by the wide-spectrum light source 101 is transmitted to the polarizer 102 through an optical fiber. The light transmitted by the optical fiber is converted into polarized light with a certain characteristic and is obliquely incident on the surface of the sample 400 through the polarizer 102 and the first rotation compensator 103. Then, the polarized light is sequentially transmitted through the second rotation compensator 104 and the analyzer 105 to collect the reflected polarized light from the surface of the sample 400 and transmit it to the detection unit 106 through the optical fiber. The ellipsometric spectral data of the sample 400 are obtained by the detection unit 106.

[0052] Specifically, referring to Figure 1 The sample geometric parameter and performance parameter measuring device provided in the embodiments of the present application includes an ellipsometry module, a white light interferometry module, a Raman spectrum measuring module, and a data processing module. The white light interferometry module and the Raman spectrum measuring module can detect the interference fringe image and the Raman spectrum data of the same measurement point on the surface of the sample 400 in a common optical path. Further, the initial value of the surface roughness and the material composition information can be obtained through the surface three-dimensional topography recovery unit and the Raman spectrum processing unit. Specifically, the same second objective lens 221, the first beam splitter 216, and the second beam splitter 231 can be used for co-site measurement. The second objective lens 221 simultaneously collects the detection light beam emitted by the white light interferometry module and the Raman scattered light containing the sample 400 information emitted by the Raman spectrum measuring module. The second beam splitter 231, the dichroic mirror 232, the confocal lens group 234, and the spectrometer 235 in the Raman spectrum measuring module are arranged above the first beam splitter 216 and the first objective lens 218 of the white light interferometry module. At the same time, the detection light emitted by the ellipsometry module and the detection light emitted by the second objective lens 221 are adjusted to be at the same measurement point on the surface of the sample 400. Thus, the interference fringe image, the Raman spectrum data, and the ellipsometric spectral data at the same measurement point can be obtained, which avoids the situation that different measurement points carry inconsistent information and thus cause analysis errors. The optical model and the oscillator model are established through the ellipsometric spectral data analysis unit. The ellipsometric parameters, the Mueller matrix, the reflection coefficient, and the transmission coefficient can be calculated using the ellipsometric spectral data. Further, the geometric parameters and the performance parameters of the sample 400 are obtained through fitting analysis.

[0053] Specifically, the first objective 218 and the second objective 221 in the white light interferometry module have the same optical parameters and the same distance from the first beam splitter 216. The incident light path of the first objective 218 is arranged parallel to the surface of the sample 400; the incident light path of the second objective 221 is arranged perpendicular to the surface of the sample 400. The first objective 218 and the second objective 221 are respectively driven by the first driving mechanism 217 and the second driving mechanism 220, and the first driving mechanism 217 and the second driving mechanism 220 both include a piezoelectric ceramic, which drives the first objective 218 or the second objective 221 to move. The first beam splitter 216 is arranged between the second objective 221 and the second beam splitter 231, and the second beam splitter 231 is arranged between the first beam splitter 216 and the imaging tube lens 214. The first beam splitter 216 not only can transmit the white light wavelength and reflect the monochromatic light wavelength, but also can avoid the optical path difference of the reference light and the measurement light when returning to the first beam splitter 216, so that the surface roughness measurement effect is good.

[0054] In specific embodiments, the sample stage is further provided below the six-degree-of-freedom motion displacement stage for adjusting the measurement point position or achieving sample stage leveling according to the interference fringe image; the first rotary stage is arranged below the polarizer 102, and the first rotary stage is used for adjusting the included angle between the polarizer 102 and the sample stage; the second rotary stage is arranged below the analyzer 105, and the second rotary stage is used for adjusting the included angle between the analyzer 105 and the sample stage; the sample stage includes a normal-temperature sample stage and a high-temperature sample stage 350, and the reference Figure 2 When the sample stage is the high-temperature sample stage 350, the high-temperature heating cavity 310, the first optical window 320, the second optical window 330 and the third optical window 340 are further included; the high-temperature sample stage 350 is installed inside the high-temperature heating cavity 310, and the high-temperature heating cavity 350 can be vacuumized or filled with inert gas; the first optical window 320 and the third optical window 340 are respectively installed on the two sides of the high-temperature heating cavity 310, and can transmit the incident light and the reflected light of the ellipsometry module; the second optical window 330 is installed on the surface of the high-temperature heating cavity 310 and is perpendicular to the high-temperature sample stage 350; and the temperature control range of the high-temperature sample stage 350 is 300-1200K.

[0055] Further, the sample stage on which the sample 400 is placed in the embodiments of the present application can be the high-temperature sample stage 350, the high-temperature sample stage 350 has a high-temperature heating function, the temperature control range is 300-1200K, and the geometric parameters and performance parameters of the sample 400 at different temperatures can be tested, and the high-temperature heating cavity 310, the first optical window 320, the second optical window 330 and the third optical window 340 are used to ensure that the optical path is not affected during the test. The six-degree-of-freedom motion displacement stage is arranged below the high-temperature sample stage 350, and is used for adjusting different measurement point positions.

[0056] In specific embodiments, the geometric parameters include film thickness and surface roughness; the performance parameters include one or more of crystal structure, crystal orientation, dielectric constant, optical band gap, optical constants, residual stress, electrical conductivity, doping concentration, impurities and defects, carrier concentration, carrier mobility, and electron relaxation time, the dielectric constant includes real and imaginary parts, and the optical constants include refractive index and extinction coefficient.

[0057] In specific embodiments, the oscillator model includes an empirical Cauchy model, a Gaussian model, a Drude model, a Tauc Lorentz model, or a Drude Lorentz model.

[0058] Specifically, to avoid the occurrence of local optimal solution in the regression analysis process, it is necessary to set good initial values for each unknown parameter. Taking the surface roughness in the geometric parameters as an example, the initial value of the surface roughness can be directly calculated from the interference fringe image, the optical model is constructed by using the combined parameters, the material properties are determined by using the material composition information, and the category of the oscillator model is selected by using the material properties. If the sample 400 is transparent and non-absorbing, the Cauchy model is selected; if the sample 400 is absorbing, the Lorentz model can be selected; if the sample 400 is a metal material, the Drude model is selected, and the specific model corresponds to the existing calculation formula, which is not described here; the oscillator model is substituted into the optical model for regression analysis, and the surface roughness of the sample 400 can be obtained. In one embodiment, the LM algorithm is used for regression analysis.

[0059] In the calculation process of other geometric parameters and performance parameters, the corresponding model calculation initial value can be selected according to specific needs, for example, the initial thickness can be obtained by using the equivalent medium approximation model and the surface roughness approximation, or it can be estimated by using Raman spectrum, or it can be guessed by the shape of ellipsometric spectrum data. The ellipsometric spectrum of a thick film with a wavelength comparable to the thickness will have multiple oscillation peaks. The more oscillation peaks, the thicker the film, and vice versa. The initial value of the residual stress can be described by using a uniaxial anisotropic model, or it can be obtained by using Raman spectrum data. There are two methods to obtain the initial value of the optical constant: one is to query the existing database (such as RefractiveIndex.INFO, Palik), which contains the optical constant values of similar materials, and the other is to generate ellipsometric spectrum data by simulation, and compare it with the test obtained ellipsometric spectrum data to estimate the approximate range.

[0060] Further, the parameters that can be calculated from the ellipsometric spectral data include the complete 16 elements of the Mueller matrix or 4 elements of the Jones matrix or the reflection and transmission coefficients (rp, rs, tp, ts) in the wavelength range from 210 nm to 1650 nm. The surface topography of the sample 400 can also be recovered from the interference fringe image. The phase change of the interference fringe image is analyzed, the relative height of each point on the surface of the sample 400 is calculated, the phase information at different wavelengths is integrated, and the three-dimensional topography image of the surface of the sample 400 is obtained by a phase unwrapping algorithm and a height reconstruction algorithm. The characteristic peaks in the Raman spectrum are fitted using Gaussian or Lorentzian functions to accurately determine the position, intensity, frequency shift, and full width at half maximum, etc. The physical information of the sample 400 can be extracted, including crystal structure, crystal orientation, residual stress, impurities, and defects, etc.

[0061] Embodiments of the present application also propose a method for measuring geometric parameters and performance parameters of a wide-bandgap semiconductor wafer surface film layer, which uses the above-mentioned sample geometric parameter and performance parameter measuring device. The sample 400 includes a wafer and a wafer surface film layer, and includes the following steps:

[0062] 1) Select a measurement point on the surface of the wafer surface film layer, and obtain the interference fringe image corresponding to the measurement point on the surface of the wafer surface film layer by the white light interference measurement module;

[0063] 2) The position of the wafer surface film layer remains unchanged, switch to the Raman spectrum measurement module, adjust the second objective lens 221 to be located at the focal position of the Raman spectrum measurement module, and collect the Raman spectrum data corresponding to the measurement point on the surface of the wafer surface film layer;

[0064] 3) According to the interference fringe state in the interference fringe image, adjust the sample stage to be leveled, so that the surface of the sample 400 is perpendicular to the entrance surface of the first objective lens 218; switch to the ellipsometric measurement module, the light emitted in the ellipsometric measurement module coincides with the light spots formed on the surface of the sample 400 by the light emitted in the white light interference measurement module and the Raman spectrum measurement module, the light emitted by the wide-spectrum light source 101 in the ellipsometric measurement module is transmitted to the polarizer 102 through the optical fiber, the light transmitted by the optical fiber is converted into polarized light with a certain characteristic through the polarizer 102 and the first rotation compensator 103, and is obliquely incident on the surface of the wafer surface film layer, and then passes through the second rotation compensator 104 and the analyzer 105 in turn, so as to collect the polarized light reflected by the wafer surface film layer and transmitted to the detection unit 106 through the optical fiber, and the ellipsometric spectral data corresponding to the measurement point on the surface of the wafer surface film layer is obtained by the detection unit 106;

[0065] 4) Extract the initial value of the geometric parameter according to the interference fringe image, and determine the initial value of the material composition information and the performance parameter according to the Raman spectrum data;

[0066] 5) According to the material composition information, the material properties are determined, and the optical model and the oscillator model of the wafer surface film layer are established according to the material properties, the initial values of the geometric parameters and the initial values of the performance parameters, and the ellipsometric spectrum data are combined for fitting analysis to obtain the geometric parameters and the performance parameters of the sample 400.

[0067] Specifically, step 1 specifically includes: turning on the first light source 211 in the white light interference measurement module, and adjusting the collimating lens 212 and the relay lens group 213 in the white light interference measurement module to ensure that the image illuminance obtained by the photodetector 215 in the white light interference measurement module is uniform;

[0068] Adjusting the distance between the second objective lens 221 in the white light interference measurement module and the wafer surface film layer to make the photodetector 215 collect a clear image of the measurement point on the wafer surface film layer surface;

[0069] Driving the first driving mechanism 217 in the white light interference measurement module and driving the first objective lens 218 to move to adjust the distance between the first objective lens 218 and the reference plane 219, so that the photodetector 215 collects an interference fringe image.

[0070] Specifically, taking the surface roughness in the geometric parameters as an example, the method for measuring the geometric parameters and the performance parameters of the wide-bandgap semiconductor wafer surface film layer proposed by the embodiments of the present application is explained, which includes the following steps:

[0071] S1, turn on the first light source 211 of the white light interference measurement module and the second light source 233 of the Raman spectrum measurement module, adjust the light source power to ensure that the image in the photodetector 215 is neither overexposed nor overdark, ensure that the detected light intensity in the spectrometer 235 is maximum, adjust the collimating lens 212 and the relay lens group 213 to ensure that the image illuminance obtained by the photodetector 215 is uniform;

[0072] S2, adjust the distance between the sample 400 and the second objective lens 221 so that a clear image of the to-be-measured region of the sample 400 can be collected in the photodetector 215, control the first driving mechanism 217 to move, adjust the distance between the first objective lens 218 and the reference plane 219 until clear interference fringe images appear in the image;

[0073] S3, control the second driving mechanism 220 to move, adjust the second objective lens 221 to perform axial scanning, find the focal point position of the Raman spectrum measurement module, control the second driving mechanism 220 to move to the focal point position, and the spectrometer 235 records the spectrum data at this time.

[0074] S4, adjust the surface of the sample 400 on the sample stage to be perpendicular to the incident surface of the first objective 218 according to the state of the interference fringes in the interference fringe image; turn on the broadband light source 101 of the ellipsometry module, the light emitted by the broadband light source 101 is transmitted to the polarizer 102 through the optical fiber, the polarizer 102 converts the light transmitted by the optical fiber into polarized light with a certain characteristic and obliquely irradiates the surface of the sample 400. The polarized light reflected by the surface of the sample 400 is collected by the analyzer 105 and transmitted to the detection unit 106 through the optical fiber, and the ellipsometric spectrum data is collected by the detection unit 106. Wherein, the light spot irradiated by the polarizer 102 in the ellipsometry module on the surface of the sample 400 coincides with the light spot converged on the surface by the second objective 221;

[0075] S5, extract the initial value Sa or Sq of the surface roughness according to the interference fringe image collected in step S2;

[0076] S6, extract the material composition information of the surface according to the Raman spectrum data collected in step S3, and calculate the ellipsometric parameters, Mueller matrix, reflection coefficient and transmission coefficient, etc. by using the ellipsometric spectrum data collected in step S4;

[0077] S7, establish the optical model and the oscillator model of the sample 400 according to the material characteristics and the initial value Sa or Sq of the surface roughness and the material composition information extracted in steps S5 and S6, perform fitting analysis according to the measured Mueller matrix, and explain the Mueller matrix by using the optical model and the oscillator model to obtain the surface roughness of the sample 400.

[0078] Further, other geometric parameters and performance parameters can be obtained by using the same regression analysis method. At present, the regression analysis method is the classical nonlinear regression algorithm Levenberg-Marquardt algorithm (LM algorithm), the independent variable is the calculated physical quantity (such as refractive index, extinction coefficient, surface roughness, thickness, etc.), and the regression dependent variable is the measured ellipsometric parameters, Mueller matrix, reflection coefficient and transmission coefficient, etc. These calculated physical quantities can be parameterized by the oscillator model in the wavelength range, so the actual independent variable is the parameter of each oscillator model (such as carrier concentration and carrier mobility in the Drude model).

[0079] The oscillator model can be selected according to the material characteristics. If the sample 400 is transparent and non-absorbing, the empirical Cauchy model is selected; if the sample 400 is absorbing, the Lorentz model is selected; if the sample 400 is a metal material, the Drude model is selected.

[0080] In specific embodiments, the wafer surface film layer includes at least one heterogeneous film, the outermost heterogeneous film is a rough surface layer, the geometric parameters include surface roughness and film thickness, the wafer surface film layer includes multiple layers of films, and the performance parameters include one or more of crystal structure, crystal orientation, dielectric constant, optical band gap, optical constant, residual stress, electrical conductivity, doping concentration, impurities and defects, carrier concentration, carrier mobility, and electron relaxation time, and further include:

[0081] An optical model of the wafer and at least one heterogeneous film on the surface of the wafer is established in combination with the surface roughness and the material composition information, the material characteristics are determined according to the material composition information measured by the Raman spectrum measurement module, and the corresponding oscillator model is selected according to the material characteristics;

[0082] The initial value of the thickness of the rough surface layer and the initial value of the surface roughness are estimated based on the interference fringe image;

[0083] The depth of incidence of the second light source 233 in the Raman spectrum measurement module is adjusted to obtain Raman spectrum data of different intensities, and the number of layers of the intermediate heterogeneous film and the initial value of the thickness of each layer of the intermediate heterogeneous film are estimated according to the Raman spectrum data of different intensities;

[0084] The optical model and the oscillator model of the wafer surface film layer are established according to the material characteristics, the initial value of the surface roughness, the initial value of the thickness of the rough surface layer, the initial value of the thickness of each layer of the intermediate heterogeneous film, and the material composition information, and fitting analysis is performed in combination with the ellipsometric spectrum data to obtain the thickness of each layer of the heterogeneous film and the surface roughness.

[0085] In specific embodiments, when the wafer surface film layer includes multiple layers of films, and the sample 400 table is a high-temperature sample table 350, when the sample 400 table is a high-temperature sample table 350, further comprising:

[0086] The sample 400 is placed on the high-temperature sample table 350, the high-temperature heating cavity 310 is evacuated or filled with nitrogen, and the temperature is slowly raised to a preset temperature and then maintained;

[0087] The interference fringe image, the Raman spectrum data, and the ellipsometric spectrum data are measured at room temperature and at the preset temperature, respectively;

[0088] The surface topography of the sample 400 at room temperature and at the preset temperature is extracted by the centroid algorithm according to the interference fringe image, and the change of the surface topography with temperature is analyzed;

[0089] The Raman spectrum data is baseline corrected to remove background noise and fluorescence interference, the corrected Raman spectrum data is peak fitted, Gaussian or Lorentzian function is used to accurately determine the position, intensity and half-width of the characteristic peak, the characteristic peak position at the preset temperature and room temperature is analyzed, the offset of the characteristic peak position is determined, the intensity change of the characteristic peak is analyzed, the material composition information of the wafer surface film layer and the crystalline quality at high temperature are determined, the stress coefficient is determined according to the material composition information, and the initial value of the residual stress at room temperature and the preset temperature is calculated through the offset and the stress coefficient;

[0090] The size of the preset temperature is adjusted, and the above steps are repeated to obtain the initial value of the residual stress under different temperature conditions;

[0091] The optical model and the oscillator model of the wafer surface film layer are established according to the material properties, the initial value of the residual stress under different temperature conditions and the material composition information, and the fitting analysis is performed combined with the ellipsometric spectrum data at the corresponding temperature to obtain the change of the residual stress of the multi-layer film under different temperature conditions;

[0092] The initial value of the remaining performance parameters is determined according to the material composition information and the temperature, and the above step is repeated to obtain the remaining performance parameters under high temperature conditions through fitting analysis.

[0093] Further, the sample 400 in the embodiments of the present application can be a wafer and a multi-layer hetero film on the surface thereof, that is, a multi-layer hetero film is deposited on a wide bandgap semiconductor wafer substrate layer, and the wafer substrate layer and the hetero film include but are not limited to gallium nitride / aluminum gallium nitride, silicon carbide / silicon dioxide, zinc oxide / gallium nitride, gallium oxide / aluminum gallium nitride, aluminum nitride / silicon carbide, diamond / aluminum nitride or indium gallium nitride / gallium nitride.

[0094] The ellipsometric spectrum data, the interference image sequence and the Raman spectrum data of the wide bandgap semiconductor wafer hetero film are measured. The ellipsometric spectrum data includes complete 16 Mueller matrix elements or 4 Jones matrix elements or reflection and transmission coefficients (r p ,r s ,t p ,t s ) in the wavelength range of 210 nm to 1650 nm; the interference image sequence includes a plurality of interference fringe images, and the Raman spectrum data includes Raman scattering spectrum excited by a 785 nm wavelength;

[0095] The surface topography of the hetero film is recovered through the interference fringe images, the phase change of the interference fringe images is analyzed, the relative height of each point on the surface of the sample 400 is calculated, the phase information at different wavelengths is integrated, and the three-dimensional topography image of the surface of the sample 400 is obtained through the phase unwrapping algorithm and the height reconstruction algorithm;

[0096] The characteristic peaks in the Raman spectrum data are fitted using Gaussian or Lorentzian functions to accurately determine the peak position, intensity, frequency shift and half-width, etc., and the physical property information of the hetero film is extracted, including crystal structure, crystal orientation, initial value of residual stress, impurities and defects, etc.

[0097] The optical model and oscillator model of the wide-bandgap semiconductor wafer multilayer hetero film are established in combination with the surface topography information and physical property information of the sample 400, and the construction process of the optical model is as follows: the transfer matrix of the rough surface layer, the intermediate film layer and the wafer substrate layer is established based on the transfer matrix method, and the isotropic transfer matrix formula is as follows:

[0098] X p =X 0,p P p X sub,p ;

[0099] X s =X 0,s P s X sub,s ;

[0100] Wherein, X p and X s represent the total transfer matrix of horizontal p light and vertical s light, X 0,p and X 0,s represent the transfer matrix of horizontal p light and vertical s light in the rough surface layer, X sub,p and X sub,s represent the transfer matrix of horizontal p light and vertical s light in the substrate; P p and P s represent the transfer matrix of horizontal p light and vertical s light in the intermediate film layer, and the expression is as follows:

[0101] P p =ΠP j,p ;

[0102] P s =ΠP j,s ;

[0103] Wherein, P j,p and P j,s represent the transfer matrix of horizontal p light and vertical s light in the jth intermediate film layer, and the expression is as follows:

[0104]

[0105] Wherein, n j represents the optical constant (including refractive index and extinction coefficient) of the jth intermediate film layer, and the phase retardation of each layer is d jrepresents the thickness of the jthintermediate film layer, λ represents the wavelength, and φ represents the angle of refraction. j represents the angle of refraction of the jthintermediate film layer. X 0,p represents the angle of refraction of the jthintermediate film layer. X sub,p represents the angle of refraction of the jthintermediate film layer. X 0,s represents the angle of refraction of the jthintermediate film layer. X sub,s The expressions of X

[0106]

[0107] wherein N0and N sub represents the refractive index of the wafer substrate layer and the rough surface layer;

[0108] The transmission coefficient and the reflection coefficient in the main diagonal of the final Jones matrix can be calculated:

[0109]

[0110] wherein X p,00 and X p,10 represent the first element in the first row and the first element in the second row in X p , respectively; X s,00 and X s,10 represent the first element in the first row and the first element in the second row in X s , respectively; r p , r s , t p , t s represent the reflection coefficient and the transmission coefficient.

[0111] Therefore, the optical constants can be fitted by fitting analysis of the reflection coefficient and the transmission coefficient calculated from the ellipsometric spectrum data obtained by testing;

[0112] The initial value of the thickness of the rough surface layer is determined according to the statistical data of the rough surface obtained from the interference fringe image, as shown in the following formula:

[0113] d EMA = σ + 0.80h;

[0114] wherein d EMA represents the initial value of the thickness of the rough surface layer, σ represents the root mean square height of the surface, and h represents the average height, and σ and h can be calculated according to the thickness calculation used in the surface roughness calculation process. The thickness of the intermediate film layer can be obtained by adjusting the incident depth of the second light source 233 in the Raman spectrum measurement module to obtain Raman spectrum data of different intensities, so as to estimate the initial value of the thickness of each intermediate film layer and the number of intermediate film layers. After the initial value of the thickness of the rough surface layer and the initial value of the thickness of each intermediate film layer are determined, the thickness of the rough surface layer and the thickness of each intermediate film layer can be obtained by fitting processing in combination with the optical model.

[0115] Further, the oscillator model is reconstructed, and the performance parameters such as residual stress, dielectric constant, optical band gap, conductivity, doping concentration, impurities and defects, carrier concentration, carrier mobility, and electron relaxation time are extracted from the oscillator model by regression analysis of the measured reflection coefficients (rp, rs).

[0116] In another embodiment, when the wafer surface film layer is a multilayer film, i.e., the number of layers is greater than or equal to 3, the multilayer film sample is prone to stress concentration during film formation. The accumulated tensile stress or compressive stress in the film layer exceeds the material limit, which can cause local microcracks to form, affecting the mechanical stability and electrical insulation. The volume expansion of the material during heating can also introduce additional thermal stress, so the presence of stress in the multilayer film and the high-temperature evolution process need to be considered.

[0117] Therefore, taking sample 400 as an example, which is a silicon carbide semiconductor wafer with three layers of thin films on the surface, the measurement method of its geometric parameters and performance parameters under high-temperature conditions is as follows:

[0118] Place sample 400 on high-temperature sample stage 350, fill nitrogen gas or vacuum in the high-temperature heating cavity to avoid oxidation or contamination of sample 400 during heating, slowly warm up to the preset temperature, the preset dimension can be 900℃, ensure uniform temperature distribution and maintain stable for a period of time, so that sample 400 reaches thermal equilibrium;

[0119] Measure the ellipsometric spectrum data, interference fringe image, and Raman spectrum data of the wide-bandgap semiconductor wafer surface film layer under high-temperature conditions; the ellipsometric spectrum data, interference fringe image, and Raman spectrum data are sampled at the same time and come from the same area on the surface of sample 400;

[0120] According to the collected interference fringe image on the surface of sample 400, the surface topography of sample 400 is extracted by the centroid algorithm, and the surface roughness parameters Sq or Sa are extracted;

[0121] Use software to perform baseline correction on the collected Raman spectrum data to remove background noise and fluorescence interference, perform peak fitting on the corrected Raman spectrum data, use Gaussian or Lorentzian function to accurately determine the position, intensity, and full width at half maximum of the characteristic peak, analyze the characteristic peak position of the Raman spectrum under high-temperature conditions, compared with the characteristic peak position under room temperature conditions, determine the shift amount, analyze the intensity change of the characteristic peak, understand the material composition information of the thin film, the crystalline quality under high temperature, and calculate the initial value of the residual stress σ through the shift amount Δω and the stress coefficient k of the material, as shown in the following formula:

[0122] Δω=k·σ;

[0123] The surface topography information and physical property information of the wafer are combined to establish an optical model and a phonon model of the multi-layer thin film on the silicon carbide wafer under high temperature conditions, and ellipsometric parameters, Mueller matrix, reflection coefficient and transmission coefficient obtained by fitting analysis of ellipsometric spectrum data are combined to obtain geometric parameters including film thickness, surface roughness and the like and performance parameters including residual stress, optical constant, dielectric constant, carrier concentration, carrier mobility, electron relaxation time and the like.

[0124] Embodiment Two

[0125] Embodiment Two of the present application is different from Embodiment One in that the layout and structure of the ellipsometric measurement module and the white light interferometric measurement module are different. In Embodiment Two of the present application, the ellipsometric measurement module and the white light interferometric measurement module can be specifically implemented by using the same second objective lens 221 and second beam splitter 231 to realize co-site measurement.

[0126] Specifically, referring to Figure 3The white light interference measurement module comprises a first light source 211, a collimating lens 212, a relay lens group 213, an imaging tube lens 214, a photodetector 215, a first beam splitter 216, a second beam splitter 231, a third beam splitter 236, a first objective lens 218, and a second objective lens 221; the incident light path of the first objective lens 218 is arranged parallel to the surface of the sample 400, and the incident light path of the second objective lens 221 is arranged perpendicular to the surface of the sample 400; the second beam splitter 231 is arranged between the first beam splitter 216 and the second objective lens 221, and the third beam splitter 236 is arranged between the first beam splitter 216 and the first objective lens 218; the first objective lens 218 is controlled to move along a direction parallel to the surface of the sample 400 by a first driving mechanism 217, a reference plane 219 is arranged in the focal plane of the first objective lens 218, and the second objective lens 221 is controlled to move along a direction perpendicular to the surface of the sample 400 by a second driving mechanism 220; the light emitted by the first light source 211 is converted into parallel light after passing through the collimating lens 212, and the parallel light is divided into two coherent light waves, i.e., reference light and measurement light, after passing through the first beam splitter 216 after uniform illumination by the relay lens group 213; the reference light and the measurement light are incident into the first objective lens 218 and the second objective lens 221, respectively, after being irradiated on the surface of the sample 400; the two coherent light waves return along the original path, pass through the second beam splitter 231 and the third beam splitter 236, respectively, and then superimpose to generate interference at the first beam splitter 216, and then enter the photodetector 215 through the imaging tube lens 214; the interference fringe image is obtained by the photodetector 215; the Raman spectrum measurement module comprises a second light source 233, a dichroic mirror 232, the second beam splitter 231, a confocal lens group 234, the second objective lens 221, and a spectrometer 235; the dichroic mirror 232 is arranged between the second beam splitter 231 and the confocal lens group 234; monochromatic light emitted by the second light source 233 is reflected by the dichroic mirror 232 and the second beam splitter 231 in sequence, and then enters the second objective lens 221; the second objective lens 221 converges the monochromatic light, projects it onto the surface of the sample 400, collects Raman scattered light containing sample composition information, and returns the Raman scattered light to the second beam splitter 231; the Raman scattered light is reflected by the second beam splitter 231, and then passes through the dichroic mirror 232 to enter the confocal lens group 234; the confocal lens group 234 filters out stray light in the Raman scattered light, and then transmits the required Raman spectrum information to the spectrometer 235; the Raman spectrum data is obtained by the spectrometer 235.

[0127] The second beam splitter 231, the dichroic mirror 232, the confocal lens group 234, and the spectrometer 235 in the Raman spectrum measurement module are arranged in the space below the first beam splitter 216, the third beam splitter 236, and the first objective lens 218 of the white light interference measurement module.

[0128] Those skilled in the art should understand that the application scope of the application involved in the present application is not limited to the technical solutions formed by the specific combinations of the technical features described above, and should also cover other technical solutions formed by any combinations of the technical features described above or their equivalent features without departing from the application concept described above. For example, the technical solutions formed by mutually replacing the technical features described above and the technical features disclosed in the present application (but not limited to) having similar functions.

Claims

1. A sample geometry and performance parameter measuring device, characterized by, The ellipsometry module, the white light interferometry module, the Raman spectrum measurement module and the data processing module are included, and the same objective lens and beam splitter are shared in the optical path structure of the white light interferometry module and the Raman spectrum measurement module to realize partial common optical path, and the interference fringe image and the Raman spectrum data of the same measurement point on the surface of the sample are detected by the white light interferometry module and the Raman spectrum measurement module respectively; the light emitted by the ellipsometry module and the light emitted by the white light interferometry module and the Raman spectrum measurement module are coincident on the light spot formed on the surface of the sample, and the ellipsometric spectrum data of the same measurement point on the surface of the sample is measured by the ellipsometry module; the data processing module includes a surface three-dimensional topography recovery unit, a Raman spectrum processing unit and an ellipsometric spectrum data analysis unit; The surface three-dimensional topography recovery unit is connected with the white light interferometry module, and the initial value of the geometric parameter is obtained according to the interference fringe image collected by the white light interferometry module; the Raman spectrum processing unit is connected with the Raman spectrum measurement module, and the initial value of the material composition information and the performance parameter of the sample surface is extracted according to the Raman spectrum data collected by the Raman spectrum measurement module; the ellipsometric spectrum data analysis unit is connected with the ellipsometry module to collect the ellipsometric spectrum data, and the ellipsometric spectrum data analysis unit establishes the optical model and the oscillator model of the sample according to the material characteristics, the material composition information, the initial value of the geometric parameter and the initial value of the performance parameter, and combines the ellipsometric spectrum data for fitting analysis to obtain the geometric parameter and the performance parameter of the sample.

2. The sample geometry and performance parameter measuring apparatus according to claim 1, characterized by, The white light interferometry module includes a first light source, a collimating lens, a relay lens group, an imaging tube lens, a photodetector, a first beam splitter, a second beam splitter, a first objective lens and a second objective lens, the first beam splitter is arranged between the second objective lens and the second beam splitter, the second beam splitter is arranged between the first beam splitter and the imaging lens tube; the incident light path of the first objective lens is arranged parallel to the surface of the sample; The incident light path of the second objective lens is arranged perpendicularly to the sample surface, the first objective lens is controlled to move in a direction parallel to the sample surface by a first driving mechanism, a reference plane is arranged in the focal plane of the first objective lens, and the second objective lens is controlled to move in a direction perpendicular to the sample surface by a second driving mechanism; the light emitted by the first light source is converted into parallel light after passing through the collimating lens, and the parallel light is divided into two coherent light waves, namely reference light and measurement light, after passing through the relay lens group and the first beam splitter; the reference light and the measurement light irradiate the sample surface and then enter the first objective lens and the second objective lens respectively, the two coherent light waves return to the first beam splitter after the original route, and then the interference is generated after the two coherent light waves are superimposed, and then the interference is generated after the two coherent light waves are superimposed; the second beam splitter and the imaging tube lens enter the photodetector, and the interference fringe image is obtained by the photodetector; the Raman spectrum measurement module comprises a second light source, a first beam splitter, a dichroic mirror, a second beam splitter, a confocal lens group, a second objective lens and a spectrometer; the monochromatic light emitted by the second light source sequentially passes through the dichroic mirror, the second beam splitter, the first beam splitter, and then enters the second objective lens; the second objective lens converges the monochromatic light, projects it onto the surface of the sample, collects the Raman scattered light containing the sample substance composition information, and returns the Raman scattered light to the second beam splitter through the first beam splitter; the Raman scattered light is reflected by the second beam splitter and then passes through the dichroic mirror to enter the confocal lens group; the confocal lens group filters out stray light in the Raman scattered light and then transmits the required Raman spectrum information to the spectrometer; and the Raman spectrum data is obtained by the spectrometer.

3. The sample geometry and performance parameter measuring apparatus according to claim 1, wherein The white light interference measurement module comprises a first light source, a collimating lens, a relay lens group, an imaging tube lens, a photodetector, a first beam splitter, a second beam splitter, a third beam splitter, a first objective lens and a second objective lens; the incident light path of the first objective lens is arranged parallel to the sample surface, and the incident light path of the second objective lens is arranged perpendicularly to the sample surface; The second beam splitter is arranged between the first beam splitter and the second objective lens, and the third beam splitter is arranged between the first beam splitter and the first objective lens; the first objective lens is controlled to move along a direction parallel to the sample surface by a first driving mechanism, and a reference plane is arranged in the focal plane of the first objective lens; the second objective lens is controlled to move along a direction perpendicular to the sample surface by a second driving mechanism; the light emitted by the first light source is converted into parallel light after passing through the collimating lens, and the parallel light is divided into two coherent light waves, namely reference light and measurement light, after passing through the first beam splitter after uniform illumination by the relay lens group; the reference light and the measurement light are irradiated on the sample surface and then enter the first objective lens and the second objective lens respectively, and the two coherent light waves return along the original path and then pass through the second beam splitter and the third beam splitter respectively, and then the interference is generated after superposition at the first beam splitter and then enters the imaging tube lens and the photodetector, and the interference fringe image is obtained by the photodetector; the Raman spectrum measurement module includes a second light source, a dichroic mirror, a second beam splitter, a confocal lens group, a second objective lens and a spectrometer, the dichroic mirror is arranged between the second beam splitter and the confocal lens group, the monochromatic light emitted by the second light source sequentially passes through the dichroic mirror and the second beam splitter and then enters the second objective lens, the second objective lens converges the monochromatic light and then projects it onto the surface of the sample, collects the Raman scattered light containing the sample substance composition information and returns it to the second beam splitter, the Raman scattered light is reflected by the second beam splitter and then passes through the dichroic mirror and enters the confocal lens group, the confocal lens group filters out the stray light in the Raman scattered light and then transmits the required Raman spectrum information to the spectrometer, and the Raman spectrum data is obtained by the spectrometer.

4. The sample geometry and performance parameter measuring apparatus according to claim 1, wherein, The ellipsometry measurement module includes a wide-spectrum light source, a polarizer, a first rotation compensator, a second rotation compensator, an analyzer and a detection unit, the light emitted by the wide-spectrum light source is transmitted to the polarizer through an optical fiber, the light transmitted by the optical fiber is converted into polarized light with a certain characteristic through the polarizer and the first rotation compensator and is obliquely incident on the surface of the sample, and then sequentially passes through the second rotation compensator and the analyzer to collect the polarized light reflected by the sample surface and then transmit the polarized light to the detection unit through the optical fiber, and the ellipsometry spectrum data of the sample is obtained by the detection unit.

5. The sample geometry and performance parameter measuring apparatus according to claim 4, wherein, The sample stage is provided with a six-degree-of-freedom motion displacement stage below the sample stage, which is used for adjusting a measurement point position or realizing sample stage leveling according to an interference fringe image; a first rotating stage is arranged below the polarizer, which is used for adjusting an included angle between the polarizer and the sample stage; a second rotating stage is arranged below the analyzer, which is used for adjusting an included angle between the analyzer and the sample stage; the sample stage comprises a normal-temperature sample stage and a high-temperature sample stage; when the sample stage is the high-temperature sample stage, the high-temperature sample stage further comprises a high-temperature heating cavity, a first optical window, a second optical window and a third optical window; the high-temperature sample stage is installed inside the high-temperature heating cavity, the high-temperature heating cavity can be evacuated or filled with inert gas; the first optical window and the third optical window are respectively installed on two sides of the high-temperature heating cavity, and can transmit incident light and reflected light of the ellipsometric measurement module; the second optical window is installed on the surface of the high-temperature heating cavity and is perpendicular to the high-temperature sample stage; the temperature control range of the high-temperature sample stage is 300-1200K.

6. The sample geometry and performance parameter measuring apparatus according to claim 1, wherein, The geometric parameters include film thickness and surface roughness; the performance parameters include one or more of crystal structure, crystal orientation, dielectric constant, optical band gap, optical constant, residual stress, conductivity, doping concentration, impurity and defect, carrier concentration, carrier mobility and electron relaxation time, the dielectric constant includes real part and imaginary part of dielectric constant, and the optical constant includes refractive index and extinction coefficient.

7. The sample geometry and performance parameter measuring apparatus according to claim 1, wherein, The oscillator model includes an empirical Cauchy model, a Gaussian model, a Drude model, a Tauc Lorentz model or a Drude Lorentz model.

8. A method for measuring geometric and performance parameters of a surface film layer of a wide bandgap semiconductor wafer, characterized by, The sample geometric parameter and performance parameter measurement device of any one of claims 1-7 is adopted, wherein the sample includes a wafer and a wafer surface film layer, and the method comprises the following steps: 1) selecting a measurement point position on the wafer surface film layer surface, and obtaining an interference fringe image corresponding to the measurement point position on the wafer surface film layer surface by the white light interference measurement module; 2) the position of the wafer surface film layer remains unchanged, switching to the Raman spectrum measurement module, adjusting the second objective lens to be located at the focal point position of the Raman spectrum measurement module, and collecting Raman spectrum data corresponding to the measurement point position on the wafer surface film layer surface; 3) adjusting the sample stage to be leveled according to the interference fringe state in the interference fringe image, so that the sample surface is perpendicular to the incident surface of the first objective lens; switching to the ellipsometric measurement module, the light emitted in the ellipsometric measurement module and the light emitted in the white light interference measurement module and the Raman spectrum measurement module coincide on the spot formed on the surface of the sample, and ellipsometric spectrum data corresponding to the measurement point position on the wafer surface film layer surface is obtained by the ellipsometric measurement module; 4) extracting initial values of geometric parameters according to the interference fringe image, and determining initial values of material composition information and performance parameters according to the Raman spectrum data; 5) determining material properties according to the substance composition information, establishing an optical model and a phonon model of the wafer surface film layer according to the material properties, the substance composition information, the initial value of the geometric parameters and the initial value of the performance parameters, and combining the ellipsometric spectrum data for fitting analysis to obtain the geometric parameters and the performance parameters of the sample.

9. The method of claim 8, wherein: The wafer surface film layer includes at least one hetero film, and the outermost hetero film is a rough surface layer. The geometric parameters include surface roughness and film thickness. The wafer surface film layer includes multiple film layers. The performance parameters include one or more of crystal structure, crystal orientation, dielectric constant, optical band gap, optical constant, residual stress, conductivity, doping concentration, impurities and defects, carrier concentration, carrier mobility and electron relaxation time, and further include: establishing an optical model of the wafer and at least one hetero film on the surface thereof in combination with the surface roughness and the substance composition information, determining material properties according to the substance composition information measured by the Raman spectrum measurement module, and selecting a corresponding phonon model according to the material properties; estimating the initial value of the thickness and the initial value of the surface roughness of the rough surface layer based on the interference fringe image; adjusting the depth of incidence of the second light source in the Raman spectrum measurement module to obtain Raman spectrum data of different intensities, and estimating the number of layers of the intermediate hetero film and the initial value of the thickness of each intermediate hetero film according to the Raman spectrum data of different intensities; establishing an optical model and a phonon model of the wafer surface film layer according to the material properties, the initial value of the surface roughness, the initial value of the thickness of the rough surface layer, the initial value of the thickness of each intermediate hetero film, and the substance composition information, and combining the ellipsometric spectrum data for fitting analysis to obtain the thickness of each hetero film and the surface roughness.

10. The method of claim 8 or 9, wherein the method further comprises: When the wafer surface film layer includes multiple film layers, and the sample stage is a high-temperature sample stage, the method further includes: placing the sample on the high-temperature sample stage, evacuating the high-temperature heating cavity or filling it with nitrogen, slowly warming it to a preset temperature, and then keeping it at the preset temperature; measuring the interference fringe image, the Raman spectrum data and the ellipsometric spectrum data at room temperature and the preset temperature, respectively; extracting the surface topography of the sample surface at room temperature and the preset temperature by the centroid algorithm according to the interference fringe image, and analyzing the change of the surface topography with temperature; performing baseline correction on the Raman spectrum data to remove background noise and fluorescence interference, performing peak fitting on the corrected Raman spectrum data, accurately determining the position, intensity and full width at half maximum of the characteristic peak using Gaussian or Lorentzian function, analyzing the characteristic peak position of the Raman spectrum at the preset temperature and room temperature, determining the shift amount of the characteristic peak position, analyzing the intensity change of the characteristic peak, determining the substance composition information of the wafer surface film layer and the crystalline quality at high temperature, determining the stress coefficient according to the substance composition information, and calculating the initial value of the residual stress at room temperature and the preset temperature through the shift amount and the stress coefficient; adjusting the size of the preset temperature, and repeating the above steps to obtain the initial value of the residual stress under different temperature conditions; According to the material characteristics, the initial value of the residual stress under different temperature conditions and the substance composition information, an optical model and a vibrator model of the wafer surface film layer are established, and fitting analysis is performed in combination with ellipsometric spectrum data under the corresponding temperature to obtain the change of the residual stress of the multi-layer film under different temperature conditions; According to the substance composition information and the temperature, the initial value of the remaining performance parameters is determined, the previous step is repeated, and fitting analysis is performed to obtain the remaining performance parameters under high temperature conditions.

Images