CN117109455A - Film thickness measurement device and method - Google Patents

Abstract

The application provides a film thickness measuring device, which comprises a sample stage, wherein the film thickness measuring device further comprises: the emission end is used for emitting incident light to a sample on the sample table, the incident light is formed by converging four lasers with different wavelengths, and the emission end can adjust the incident light into linearly polarized light; the receiving end is used for receiving emergent light formed by sample reflection, comprises a polarization detection component and a detection component, realizes detection of emergent light intensity under different azimuth angles by adjusting the polarization detection component, and obtains a group of light intensity values corresponding to the wavelengths of four lasers under each azimuth angle; and the processing component is used for respectively adopting an ellipsometry calculation method and a spectroscopic measurement calculation method according to the azimuth angle and the light intensity value to obtain the film thickness and the optical parameters of the sample, and comparing the film thicknesses calculated by the ellipsometry calculation method and the spectroscopic measurement calculation method to determine the film thickness value of the sample. The measuring device provided by the application can completely cover the measuring range of the film thickness.

Description

Film thickness measurement device and method

Technical field

The present application relates to the field of optical measurement technology, and in particular to a film thickness measurement device and method.

Background technique

The detection of optical films mainly consists of two aspects, film thickness and optical constants; in actual production preparation, the uniformity of the thickness distribution of the film also needs to be detected. In the measurement of film thickness and optical constants, ellipsometry and spectrometry are currently the most widely used technologies. However, they have different measurement ranges and accuracy of film thickness. Currently, different methods need to be used to measure different film thicknesses. , the measurement steps are more complicated.

In related technologies, spectrophotometers are often used for spectral measurement. The reflection (or transmission) spectrum of the film is measured by the spectrophotometer, and then the reflectivity and transmittance of the film are calculated, as well as the thickness and optical constants of the film. Ellipsometry measurement can use lasers, LED lamps, halogen lamps, etc. as light sources to measure the thickness and optical constants of the film by modulating the polarized light incident on the film and reflected by the film. Among them, the measurement range of spectral measurement is relatively large, but the measurement accuracy of measuring films of several hundred nanometers is poor and cannot meet the measurement needs; and for ellipsometry, due to the periodicity problem of film thickness, it is impossible to measure films with multiple periodic thicknesses. There will be multiple solutions to the problem of measurement. Although there are currently wide-spectrum film thickness measurement devices using Mueller matrices, each device needs to be calibrated, and errors such as installation will have a greater impact on the measurement results.

Therefore, it is necessary to propose a technical solution to solve the problem of limited measurement range when measuring film thickness using film thickness measurement methods in related technologies.

Contents of the invention

The purpose of this application is to propose a technical solution to solve the problem of limited measurement range when measuring film thickness using film thickness measurement methods in related technologies.

Based on the above problems, this application provides a film thickness measurement device, which includes a sample stage. The sample stage is used to carry the sample. The film thickness measurement device is used to detect the film thickness and optical constants of the sample. The film thickness measurement device includes:

The emission end is used to emit incident light to the sample on the sample stage. The incident light is formed by the convergence of four lasers with different wavelengths, and the emission end can adjust the incident light into linearly polarized light;

The receiving end is used to receive the outgoing light formed by the reflection of the sample. The receiving end includes an analyzer component and a detection component. By adjusting the analyzer component, the detection of the outgoing light intensity at different azimuth angles is achieved. At each azimuth angle, Obtain the light intensity values corresponding to the wavelengths of a set of four lasers;

The processing component uses the calculation methods of ellipsometry and spectral measurement to obtain the film thickness and optical parameters of the sample based on the azimuth angle and light intensity value, respectively, and compares the film thickness calculated by the two methods to determine the film thickness of the sample. Thickness value.

Further, the transmitter includes:

The light source assembly includes four laser transmitters, each of which emits laser light with different wavelengths;

A beam splitter group, including a cascade of beam splitters, combines the lasers emitted by each laser transmitter into a common beam;

The polarizing component includes a first polarizer, the first polarizer can rotate the azimuth angle, and is used to convert the common light beam into linearly polarized light, and use the common light beam converted into linearly polarized light as incident light.

Further, the receiving end includes:

The analyzer component includes a second polarizer and a third polarizer. The incident light is reflected by the surface of the sample to form outgoing light. The outgoing light passes through the second polarizer and the third polarizer in sequence, and the second polarizer and the third polarizer. Azimuth angle adjustable;

Dichroic mirror group. The dichroic mirror group includes three dichroic mirrors. Each dichroic mirror is arranged on the same optical axis. When the outgoing light passes through the dichroic mirror, it is partially reflected and partially transmitted to separate the light of different wavelengths. ;

The detection component includes four detectors, three of which receive the light beam reflected by each dichroic mirror respectively, and the remaining one receives the light beam transmitted from the last dichroic mirror. The detector is used to detect the light of the received light beam. powerful.

Further, the second polarizer adopts a magneto-optical modulation device.

Further, the processing component calculates the ellipsometric parameters ψ and Δ through the following formulas:

2ψ＝arccos(-s ₁ /s ₀ )

Δ＝arccos(s ₂ /s ₀ ·sin2ψ)

In the formula, s ₀ , s ₁ , and s ₂ represent Stokes parameters, which are calculated by the following formula:

s _0-i =4×(a _0-i -a _4-i )

In the formula, a _0-i , a _2-i , b _2-i , a _4-i , and b _4-i are Fourier coefficients, which are calculated by the following formula:

In the formula, i represents the detector serial number, N represents the total number of azimuth angles detected, I _j represents the light intensity value obtained by detector i in the j-th detection, and W _j represents the orientation of the second polarizer in the j-th detection. horn;

The processing component obtains the ellipsometric measurement value of the sample film thickness and the corresponding optical constants through numerical inversion calculation based on the ellipsometric parameters ψ and Δ.

Further, the processing component also calculates the total reflection coefficient of the P light component and the S light component based on the light intensity of the S polarized light and P polarized light. The total reflection coefficient of the P light component and the S light component is expressed by the following formula:

Among them, r _1p and r _1s are respectively the reflection coefficient of the P component and the S component that are reflected once at the air/film interface. r _2p and r _2s are the reflection coefficients of the P component that is reflected once at the film/substrate interface. coefficient and the reflection coefficient of the S component, 2δ is the phase difference between adjacent reflected light beams, expressed by the following formula:

In the formula, λ is the wavelength of light, n is the complex refractive index of the film, is the refraction angle in the film;

The processing component also calculates spectral measurements of film thickness and corresponding optical constants based on the calculated reflectivity of the film at four wavelengths.

Further, the processing component processes the light intensity data according to the ellipsometry principle to obtain the ellipsometry parameters, and obtains the ellipsometry measurement results based on the ellipsometry parameters. The ellipsometry measurement results include the ellipsometry measurement value of the film thickness of the sample and the corresponding optical constants;

The processing component also processes the light intensity data according to the principle of spectral measurement, calculates the reflectivity of the sample film to light beams of different wavelengths, and obtains spectral measurement results based on the reflectivity. The spectral measurement results include the spectral measurement value of the film thickness of the sample and the corresponding optical constant;

The processing component also compares the ellipsometry measurement results with the spectrum measurement results. When the ellipsometry measurement value and the spectrum measurement value are both within a thickness period range, the measurement result outputs the ellipsometry measurement value. If the difference between the two measurement results is greater than one thickness period, the spectrum measurement value is output as the measurement result.

Furthermore, the sample stage includes:

The loading plane is used to carry the sample;

The five-dimensional adjustment platform is used to ensure that the plane of the sample to be measured is perpendicular to the incident plane, and is adjusted so that the center of the carrier plane coincides with the incident optical axis;

The electric rotating platform drives the load plane to rotate, thereby rotating the sample to be measured and achieving circumferential measurement.

This application also provides a film thickness measurement method, which is based on the film thickness measurement device as described above. The method includes the following steps:

S1. Set the incident angle of the incident light according to the refractive index range of the film on the sample;

S2. Place the sample substrate on the sample stage, adjust the polarization axes of the first to third polarizers to the P component and S component successively, adjust the sample stage and the receiving end, obtain a suitable signal, and record it as the baseline;

S3. Place the sample on the sample stage and align the center of the sample with the center of the sample stage;

S4. Adjust the first to third polarizers, collect light intensity data, process the light intensity data according to the ellipsometry principle, obtain ellipsometry parameters, and obtain ellipsometry measurement results based on the ellipsometry parameters. The ellipsometry measurement results include the sample Ellipsometric measurement values of film thickness and corresponding optical constants;

S5. Adjust the first to third polarizers, collect light intensity data, process the light intensity data according to the principle of spectral measurement, calculate the reflectivity of the sample film to light beams of different wavelengths, and obtain the spectral measurement results based on the reflectance. The spectral measurement results Includes spectral measurements of film thickness of the sample and corresponding optical constants;

S6. Compare the ellipsometry measurement results with the spectrum measurement results. When the ellipsometry measurement value and the spectrum measurement value are both within a thickness period range, output the ellipsometry measurement value as the measurement result. If the difference between the two measurement results is greater than one thickness period, the spectrum measurement value is output as the measurement result.

Further, step S4 includes the following steps:

S41. Control the polarization axis of the first polarizer to form an angle of 45° with the incident surface of the incident light, and the polarization axis of the third polarizer to form an angle of 0° with the incident surface;

S42. Adjust the second polarizer so that the initial polarization axis position of the second polarizer forms an angle of 0° with the incident surface;

S43. Use magneto-optical modulation to change the azimuth angle of the second polarizer. Every time the azimuth angle changes θ, record the light intensity data;

S44. Process the light intensity data according to the ellipsometry principle to obtain the ellipsometry parameters, and obtain the ellipsometry measurement value of the film thickness of the sample and the corresponding optical constants based on the ellipsometry parameters.

According to the above description, the present invention combines spectral measurement and ellipsometry, which can completely cover the range of film thickness measurement, and can realize self-calibration based on the results of ellipsometry and spectrum measurement, improving the accuracy of film thickness measurement. An automatic displacement structure is introduced into the design of the stage. After measuring the thickness at a point, the distribution of the film can be quickly obtained based on the light intensity at different positions and the uniformity of the film can be judged.

Description of drawings

Figure 1 is a schematic diagram of a film thickness measurement device provided by an embodiment of the present application;

Figure 2 is a schematic structural diagram of the transmitting end and receiving end of the film thickness measuring device provided by the embodiment of the present application;

Figure 3 is a schematic structural diagram of the second polarizer in the film thickness measuring device provided by the embodiment of the present application;

Figure 4 is a schematic diagram of the sample stage provided by the embodiment of the present application;

Figure 5 is a flow chart of a film thickness measurement method provided by an embodiment of the present application.

Film thickness measuring device 100, sample stage 11, transmitting end 12, receiving end 13, processing component 14, load plane 111, five-dimensional adjustment platform 112, electric rotation platform 113, electric X-axis displacement platform 114, light source assembly 121, minute Beam set 122, polarizing component 123, analyzer component 131, dichroic mirror group 132, detection component 133, first polarizer 1231, second polarizer 1311, third polarizer 1312, magneto-optical crystal 1311a, control Device 1311b.

Detailed ways

The present application will be described in detail below with reference to the specific embodiments shown in the drawings. However, these embodiments do not limit the present application. Those of ordinary skill in the art may make structural, method, or functional changes based on these embodiments. are included in the protection scope of this application.

As shown in Figure 1, this application provides a film thickness measurement device 100, which includes a sample stage 11. The sample stage 11 is used to carry a sample, and the film thickness measurement device 100 is used to detect the film thickness and optical constants of the sample. The film thickness measuring device 100 also includes:

Emitting end 12. The emitting end 12 is used to emit incident light to the sample on the sample stage 11. The incident light is formed by the convergence of four lasers with different wavelengths, and the emitting end 12 can transmit the incident light. The light is adjusted to linearly polarized light;

Receiving end 13. The receiving end 13 is used to receive the outgoing light formed by reflection of the sample. The receiving end 13 includes an analyzer component 131 and a detection component 133. By adjusting the analyzer component 131, it is possible to detect different azimuth angles. Detect the outgoing light intensity, and obtain a set of four light intensity values corresponding to the wavelengths of the laser at each azimuth angle;

The processing component 14, according to the azimuth angle and the light intensity value, uses the calculation methods of ellipsometry and spectral measurement respectively to obtain the film thickness and optical parameters of the sample, and calculates the film thickness calculated by the two methods. Compare to determine the film thickness value of the sample.

According to the above description, embodiments of the present application provide a thin film measurement device that combines ellipsometry and spectrum measurement. Using the device provided by the embodiment of the present application, the parameters required for the two measurement methods of ellipsometry and spectrum measurement can be measured at the same time, ensuring that the calculation parameters used in the two measurement methods are measured under the same conditions. Therefore, by comparing the calculation results of ellipsometry and spectral measurement, the film thickness range can be automatically determined and the measurement results can be independently verified, thereby solving the problem of multiple solutions when ellipsometry measures films with multiple periodic thicknesses. To solve the problem, the film thickness measurement device 100 provided by the present application can completely cover the range of film thickness measurement, and can realize self-calibration based on the results of ellipsometry and spectrum measurement, thereby improving the accuracy of film thickness measurement.

As shown in FIG. 2 , as an optional implementation manner, the emission end 12 includes a light source component 121 , a beam splitter group 122 and a polarizing component 123 .

The light source component 121 includes four laser emitters, and the laser wavelengths emitted by each laser emitter are different. The film thickness measurement device 100 provided in the embodiment of the present application uses laser as the light source, has good collimation characteristics, does not need to use structures such as lenses, reduces the impact of dispersion on detection, and improves detection accuracy.

The beam splitter group 122 includes cascaded beam splitters that combine the lasers emitted by the individual laser emitters into a common beam.

The polarizing component 123 includes a first polarizer 1231. The first polarizer 1231 can rotate the azimuth angle and is used to convert the common light beam into linearly polarized light. The linearly polarized light is irradiated on the surface of the sample as incident light.

As an optional implementation, the receiving end 13 includes an analysis component 131 , a dichroic mirror group 132 and a detection component 133 .

Among them, the analyzer component 131 includes a second polarizer 1311 and a third polarizer 1312. The incident light is reflected by the sample surface to form outgoing light. The outgoing light passes through the second polarizer 1311 and the third polarizer 1312 in sequence. The second polarizer The azimuth angles of 1311 and the third polarizer 1312 are adjustable;

The dichroic mirror group 132 includes three dichroic mirrors. Each dichroic mirror is arranged on the same optical axis. When the emitted light passes through the dichroic mirror, it is partially reflected and partially transmitted to separate the light of different wavelengths;

The detection component 133 includes four detectors, three of which receive the light beam reflected by each dichroic mirror respectively, and the remaining one receives the light beam transmitted from the last dichroic mirror, and the detector is used to detect the light of the received light beam. powerful.

The processing component 14 can obtain the film thickness and optical parameters of the sample using calculation methods of ellipsometry and spectrum measurement respectively based on the azimuth angle and light intensity value, and compare the film thickness calculated by the two methods to determine the thickness of the sample. The film thickness value and the optical parameter corresponding to the film thickness value.

Specifically, for ellipsometry, the change in polarization state of the reflected light is measured through the same spectrum. If linearly polarized light with a known polarization direction is reflected from the sample surface, the reflected light will become elliptically polarized light. The polarization of the elliptically polarized light The state depends on the incident angle, the incident direction of linearly polarized light and the reflection characteristics of the sample surface. Two ellipsometric parameters ψ and Δ can be determined in ellipsometry measurement. The ellipsometric parameters ψ and Δ are used to obtain the optical constants of the material and the sample. membrane thickness. Among them, for the ellipsometric parameter ψ, tanψ represents the ratio of the amplitude after reflection of p light and s light, and Δ represents the change in the phase difference between p light and s light.

As an optional implementation manner, the processing component 14 can calculate and obtain the ellipse parameters ψ and Δ according to the following manner.

S11. Adjust the azimuth angle of the second polarizer 1311 to the j-th preset angle W _j . Each detector obtains the corresponding light intensity value I _j at this azimuth angle. Each detector detects N different azimuths. The light intensity under the corner is obtained, and N light intensity values are obtained.

S12. Construct a light intensity expression formula. The light intensity expression formula is as follows:

I _i =a _0-i +a _2-i cos 2A+b _2-i sin2A+a _4-i cos4A+b _4-i sin4A

In the formula, I _i is the light intensity obtained by different detectors, a _0-i , a _2-i , b _2-i , a _4-i , b _4-i are Fourier coefficients;

S13. For the i-th detector, according to the corresponding light intensity values at N different azimuth angles obtained by its detection, calculate the Fourier coefficient according to the discrete periodic function Fourier coefficient formula, which is expressed by the discrete periodic function Fourier coefficient formula. as follows:

In the formula, i represents the detector serial number, N represents the total number of azimuth angles detected, I _j represents the light intensity value obtained by detector i in the j-th detection, and W _j represents the intensity value of the second polarizer 1311 in the j-th detection. Azimuth.

S14. Calculate Stokes parameters based on Fourier coefficients. Stokes parameters can be calculated by the following formula:

s _0-i =4×(a _0-i -a _4-i )

S15. According to the Stokes parameters, calculate the ellipse parameters ψ and Δ.

The ellipsometric parameters ψ and Δ can be calculated by the following formulas:

2ψ＝arccos(-s ₁ /s ₀ )

Δ＝arccos(s ₂ /s ₀ ·sin2ψ)

When there is only a single wavelength, it is an incomplete polarizer, and only three Stokes parameters can be obtained, and the positive and negative of Δ cannot be judged. At the same time, considering the corresponding errors of measurement and photodetector, the optical constants cannot be solved. This application uses four wavelengths of incident light composed of four lasers. For each wavelength, a set of ellipsometric parameters ψ and Δ can be obtained, so four sets of elliptical parameters ψ and Δ can be obtained. According to each set of ellipsometric parameters ψ and Δ, parameters such as film thickness and optical constants of the sample to be measured can be obtained through numerical inversion calculation. The film thickness calculated based on the numerical inversion of the four sets of ellipsometric parameters is averaged, and the average value of the film thickness is used as the measurement result of the sample film thickness. Similarly, the optical constants calculated based on the numerical inversion of the four sets of ellipsometric parameters were averaged, and the average of the optical constants was used as the optical constant measurement result of the sample film.

According to the above description, it can be seen that the film thickness measurement device 100 provided in the embodiment of the present application can obtain parameters such as film thickness and optical constants of the sample using ellipsometry.

The film thickness measurement device 100 provided in the embodiment of the present application can also use spectral measurement to obtain parameters such as film thickness and optical constants of the sample.

As an optional implementation method, in spectral measurement, the film substrate needs to be measured and calibrated first. During calibration, the optical axis of the polarizing device is located on the same plane, and the light intensity of S-polarized light and P-polarized light is measured respectively, and then Place the film sample to obtain the corresponding light intensity information. According to the multi-beam plate interference theory, the total reflection coefficient of the P light component and S light component is:

Among them, r _1p and r _1s are respectively the reflection coefficient of the P component and the S component that are reflected once at the air/film interface. r _2p and r _2s are the reflection coefficients of the P component that is reflected once at the film/substrate interface. coefficient and the reflection coefficient of the S component. 2δ is the phase difference between adjacent reflected light beams, which can be expressed by the following formula:

In the formula, λ is the wavelength of light, n is the complex refractive index of the film, is the refraction angle in the film, and the thickness and optical constants of the film can be calculated by bringing in the reflectivity of the four wavelengths calculated by measurement.

According to the above description, it can be seen that the film thickness measurement device 100 provided by the embodiment of the present application can calculate and obtain the film thickness and optical constants of the sample by using ellipsometry and spectrum measurement in one measurement, and perform the measurement results based on both. Verification improves the accuracy of measurement while improving the simplicity of measurement. Moreover, in this way, the film thickness measurement device 100 provided by the embodiment of the present application can cover the thickness range of the complete film measurement, and can meet the film measurement requirements.

Specifically, for measuring the thickness of a film above several hundred nanometers, the thickness of the film can be determined based on the results of spectral measurement. For measuring film thickness below a few hundred nanometers, the results of ellipsometry can be used as the thickness of the sample film.

As for ellipsometry, there are multiple solutions due to film periodicity issues. This application combines spectral measurement with ellipsometry to achieve self-calibration. Since the period number of thickness is known, when the measured value of ellipsometry (hereinafter referred to as ellipsometric measurement value) and the measured value of spectral measurement (hereinafter referred to as spectral measurement value) are both within a thickness period range, the measurement result output ellipsometry Offset measurement value, if the difference between the two measurement results is greater than one thickness period, the spectrum measurement value will be output as the measurement result. In this way, the uncertain value of film thickness can be eliminated and the accuracy of film thickness measurement can be improved.

As an optional implementation manner, in the film thickness measurement device 100 provided by the embodiment of the present application, the second polarizer 1311 may use a magneto-optical modulation device.

Specifically, the magneto-optical modulation device is shown in Figure 3. The magneto-optical modulation device includes a magneto-optical crystal 1311a and a controller 1311b.

The working principle of the magneto-optical modulation device is: if a beam of linearly polarized light propagates along the axis of the magneto-optical crystal, the controller is used to adjust the voltage wound on the magneto-optical crystal, thereby generating a DC magnetic field along the direction of the optical axis. The polarization plane will rotate by an angle W. This phenomenon is called the magneto-optical effect. The magneto-optical effect satisfies the following rules:

W＝VLB

Among them, W is the angle of rotation of the light wave polarization plane, V is the Verdet constant, L is the length of the magneto-optical crystal, and B is the magnetic induction intensity. The controller changes the current on the coil to change the intensity B of the magnetic induction, thereby causing the rotation angle W of the light wave polarization plane.

According to the above description, this application uses magneto-optical modulation to control the second polarizer 1311, which reduces moving components, thereby increasing the stability of operation and improving measurement accuracy. In addition, the use of magneto-optical modulation makes the adjustment of azimuth angle more convenient and faster, which can improve measurement efficiency.

As an optional implementation method, in the embodiment of the present application, the design of the sample stage 11 introduces an automatically controlled X-axis (or Y-axis) and rotation structure. In the actual test, by controlling the X-axis (or Y-axis) ) displacement and rotation of the carrier plane 111 move each point of the film to the incident surface to achieve film thickness measurement at each position.

The structure of the sample stage 11 is shown in Figure 4. The sample stage 11 includes: a load plane 111, a five-dimensional adjustment platform 112, an electric rotation platform 113, and an electric X-axis displacement platform 114.

Among them, the loading plane 111 is used to carry the sample.

The five-dimensional adjustment platform 112 is used to ensure that the plane of the sample to be measured is perpendicular to the incident plane, and is adjusted so that the center of the object plane 111 coincides with the incident optical axis.

The electric rotating platform 113 drives the load plane 111 to rotate, thereby rotating the sample to be measured and achieving circumferential measurement.

The electric X-axis displacement platform 114 drives the load plane 111 to move forward and backward (or left and right) to achieve measurements at different positions from the center.

As an optional implementation, the film thickness measurement device 100 provided by the embodiment of the present application includes a film uniformity test mode. In the film uniformity test mode, the zero position is automatically adjusted first. After setting the detection area, the five-dimensional adjustment platform 112, the electric rotation platform 113, the electric X-axis displacement platform 114 and other devices cooperate with each other to drive the sample stage 11 to move, so that the film The thickness measurement device 100 can scan every point in the detection area, record data, display film thickness distribution and calculate uniformity.

As an optional implementation method, the polarization axes of the rotating first, second, and third polarizers 1312 can all be adjusted to the S light plane. According to the total reflection coefficient formula of the S light component, in the optical constant (generally When the optical constants of the same sample remain unchanged by default) and the wavelength is known, the total reflectance is only related to the thickness of the film, so the thickness distribution of the film can be quickly obtained based on changes in reflectivity.

In order to further illustrate the film thickness measurement device 100 provided by the embodiment of the present application, as shown in FIG. 5 , the present application also provides a film thickness measurement method, which is based on the film thickness measurement device 100 as described above.

First, define the plane formed by the incident light and the normal vector of the contact surface as the incident surface, and the plane formed by the reflected light and the normal vector of the contact surface as the reflective surface. In the discussion of polarized light, the vertical component S and the horizontal component P of the electric field are both directed to these two planes.

The film thickness measurement method includes the following steps:

S1. Set the incident angle of the incident light according to the refractive index range of the film on the sample.

S2. Place the sample substrate on the sample stage 11, adjust the polarization axes of the first to third polarizers 1312 to the P component and S component successively, adjust the sample stage 11 and the receiving end 13, obtain a suitable signal, and record it as the baseline .

S3. Place the sample on the sample stage 11, and align the center of the sample with the center of the sample stage 11.

S4. Adjust the first to third polarizers 1312, collect light intensity data, process the light intensity data according to the ellipsometry principle, obtain ellipsometry parameters, and obtain ellipsometry measurement results based on the ellipsometry parameters. The ellipsometry measurement results include Ellipsometric measurements of the film thickness of the sample and the corresponding optical constants.

Step S4 includes the following steps:

S41. Control the polarization axis of the first polarizer 1231 to form an angle of 45° with the incident surface of the incident light, and control the polarization axis of the third polarizer 1312 to form an angle of 0° with the incident surface.

S42. Adjust the second polarizer 1311 so that the initial polarization axis position of the second polarizer 1311 forms an angle of 0° with the incident surface.

S43. Use magneto-optical modulation to change the azimuth angle of the second polarizer 1311. Each time the azimuth angle changes θ, light intensity data is recorded.

S44. Process the light intensity data according to the ellipsometry principle to obtain the ellipsometry parameters, and obtain the ellipsometry measurement value of the film thickness of the sample and the corresponding optical constants based on the ellipsometry parameters.

S5. Adjust the first to third polarizers 1312, collect light intensity data, process the light intensity data according to the principle of spectral measurement, calculate the reflectivity of the sample film to light beams of different wavelengths, and obtain spectral measurement results based on the reflectance. Spectral measurement Results include spectral measurements of the sample's film thickness and corresponding optical constants.

Step S5 includes the following steps:

S51. Adjust the polarization axes of the first to third polarizers 1312 to the p component and the s component successively.

S52. Record and process the light intensities corresponding to the four wavelengths. Based on the light intensity, the reflectivity of the film to the four wavelength beams is calculated based on the multi-beam plate interference theory.

S53 calculates the spectral measurement value of the film thickness and the corresponding optical constants based on the reflectivity of the four wavelength beams.

S6. Compare the ellipsometry measurement results with the spectrum measurement results. When the ellipsometry measurement value and the spectrum measurement value are both within a thickness period, the measurement results output the ellipsometry measurement value. If the difference between the two measurement results is greater than one thickness. period, the spectrum measurement value is output as the measurement result.

What is disclosed above is only the preferred embodiment of the present application, but it is not used to limit the scope of rights of the present application. Those of ordinary skill in the art can understand that: without departing from the spirit and scope of the present application and the appended claims, Within the scope of the invention, changes, modifications, substitutions, combinations, and simplifications should all be equivalent substitutions and still fall within the scope of the invention.

Claims (10)

1. A film thickness measurement device, comprising a sample stage, the sample stage is used to carry a sample, and the film thickness measurement device is used to detect the film thickness and optical constants of the sample, characterized in that the film thickness measurement Devices include: The emission end is used to emit incident light to the sample on the sample stage. The incident light is formed by the convergence of four lasers with different wavelengths, and the emission end can adjust the incident light into a line. polarized light; The receiving end is used to receive the outgoing light formed by the reflection of the sample. The receiving end includes an analyzer component and a detection component. By adjusting the analyzer component, the detection of the outgoing light intensity at different azimuth angles is achieved. , at each azimuth angle, obtain a set of four light intensity values corresponding to the wavelengths of the laser; The processing component, according to the azimuth angle and the light intensity value, uses the calculation methods of ellipsometry and spectral measurement respectively to obtain the film thickness and optical parameters of the sample, and compares the film thickness calculated by the two methods. , to determine the film thickness value of the sample. 2. The film thickness measuring device according to claim 1, characterized in that, The transmitter includes: The light source component includes four laser emitters, and the laser wavelengths emitted by each of the laser emitters are different; A beam splitter group, including a cascade of beam splitters, combines the lasers emitted by each of the laser transmitters into a common beam; A polarizing component, including a first polarizer, the first polarizer can rotate the azimuth angle, and is used to convert the common light beam into linearly polarized light, and use the common light beam converted into the linearly polarized light as the incident light. Light. 3. The film thickness measuring device according to claim 1, characterized in that, The receiving end includes: An analyzer component, including a second polarizer and a third polarizer, the incident light is reflected by the sample surface to form outgoing light, and the outgoing light passes through the second polarizer and the third polarizer in sequence, The azimuth angles of the second polarizer and the third polarizer are adjustable; Dichroic mirror group, the dichroic mirror group includes three dichroic mirrors, each of the dichroic mirrors is arranged on the same optical axis, and the outgoing light is partially reflected and partially transmitted when passing through the dichroic mirror. , to separate light of different wavelengths; The detection component includes four detectors, three of which respectively receive the light beams reflected by each of the dichroic mirrors, and the remaining one of the detectors receives the light beams transmitted from the last dichroic mirror, so The detector is used to detect the light intensity of the received light beam. 4. The film thickness measuring device according to claim 3, characterized in that, The second polarizer uses a magneto-optical modulation device. 5. The film thickness measuring device according to claim 1, characterized in that, The processing component calculates the ellipsometric parameters ψ and Δ through the following formulas: 2ψ＝arccos(-s ₁ /s ₀ ) Δ＝arccos(s ₂ /s ₀ ·sin 2ψ) In the formula, s ₀ , s ₁ , and s ₂ represent Stokes parameters, which are calculated by the following formula: s _0-i =4×(a _0-i -a _4-i ) In the formula, a _0-i , a _2-i , b _2-i , a _4-i , and b _4-i are Fourier coefficients, which are calculated by the following formula: In the formula, i represents the detector serial number, N represents the total number of azimuth angles detected, I _j represents the light intensity value obtained by detector i in the j-th detection, and W _j represents the orientation of the second polarizer in the j-th detection. horn; The processing component obtains the ellipsometry measurement value of the sample film thickness and the corresponding optical constants through numerical inversion calculation based on the ellipsometric parameters ψ and Δ. 6. The film thickness measuring device according to claim 1, characterized in that, The processing component also calculates the total reflection coefficient of the P light component and the S light component based on the light intensity of the S polarized light and the P polarized light. The total reflection coefficient of the P light component and the S light component is expressed by the following formula: Among them, r _1p and r _1s are respectively the reflection coefficient of the P component and the S component that are reflected once at the air/film interface. r _2p and r _2s are the reflection coefficients of the P component that is reflected once at the film/substrate interface. coefficient and the reflection coefficient of the S component, 2δ is the phase difference between adjacent reflected light beams, expressed by the following formula: In the formula, λ is the wavelength of light, n is the complex refractive index of the film, is the refraction angle in the film; The processing component also calculates the spectral measurement value of the film thickness and the corresponding optical constant based on the calculated reflectivity of the film at four wavelengths. 7. The film thickness measuring device according to claim 1, characterized in that, The processing component processes the light intensity data according to the ellipsometry principle to obtain ellipsometry parameters, and obtains ellipsometry measurement results based on the ellipsometry parameters. The ellipsometry measurement results include the ellipsometry measurement value of the film thickness of the sample and the corresponding optical constants; The processing component also processes the light intensity data according to the principle of spectral measurement, calculates the reflectivity of the sample film to light beams of different wavelengths, and obtains spectral measurement results based on the reflectance. The spectral measurement results include spectral measurement values of the film thickness of the sample. and corresponding optical constants; The processing component also compares the ellipsometry measurement result with the spectrum measurement result. When the ellipsometry measurement value and the spectrum measurement value are both within a thickness period range, the measurement result outputs the ellipsometry measurement value. If the two If the interval between measurement results is greater than one thickness period, the spectrum measurement value will be output as the measurement result. 8. The film thickness measuring device according to claim 1, wherein the sample stage includes: The loading plane is used to carry the sample; The five-dimensional adjustment platform is used to ensure that the plane of the sample to be measured is perpendicular to the incident plane, and is adjusted so that the center of the carrier plane coincides with the incident optical axis; The electric rotating platform drives the load plane to rotate, thereby rotating the sample to be measured and achieving circumferential measurement. 9. A method for measuring film thickness, characterized in that the method is based on the film thickness measuring device according to any one of claims 1 to 8, and the method includes the following steps: S1. Set the incident angle of the incident light according to the refractive index range of the film on the sample; S2. Place the sample substrate on the sample stage, adjust the polarization axes of the first to third polarizers to the P component and S component successively, adjust the sample stage and the receiving end, obtain a suitable signal, and record it as the baseline; S3. Place the sample on the sample stage and align the center of the sample with the center of the sample stage; S4. Adjust the first to third polarizers, collect light intensity data, process the light intensity data according to the ellipsometry measurement principle, obtain ellipsometry parameters, and obtain ellipsometry measurement results according to the ellipsometry parameters. The ellipsometry measurement results include the ellipsometry measurement value of the film thickness of the sample and the corresponding optical constants; S5. Adjust the first to third polarizers, collect light intensity data, process the light intensity data according to the principle of spectral measurement, calculate the reflectivity of the sample film to light beams of different wavelengths, and obtain spectral measurement results based on the reflectance. , the spectral measurement results include the spectral measurement value of the film thickness of the sample and the corresponding optical constant; S6. Compare the ellipsometry measurement result with the spectrum measurement result. When the ellipsometry measurement value and the spectrum measurement value are both within a thickness period range, output the ellipsometry measurement value as the measurement result, If the difference between the two measurement results is greater than one thickness period, the spectrum measurement value is output as the measurement result. 10. The film thickness measurement method according to claim 9, characterized in that, The step S4 includes the following steps: S41. Control the polarization axis of the first polarizer to form an angle of 45° with the incident surface of the incident light, and the polarization axis of the third polarizer to form an angle of 0° with the incident surface; S42. Adjust the second polarizer so that the initial polarization axis position of the second polarizer forms an angle of 0° with the incident surface; S43. Use magneto-optical modulation to change the azimuth angle of the second polarizer. Every time the azimuth angle changes θ, record the light intensity data; S44. Process the light intensity data according to the ellipsometry principle to obtain the ellipsometry parameters, and obtain the ellipsometry measurement value of the film thickness of the sample and the corresponding optical constants based on the ellipsometry parameters.