CN112964647B - Method and device for detecting ultrathin metal film by using spectroscopic ellipsometer - Google Patents

Abstract

The invention provides a method and a device for detecting an ultrathin metal film by using a spectroscopic ellipsometer. Wherein, the method comprises the following steps: constructing a first system consisting of a silicon substrate and a natural silicon oxide layer, measuring an ellipsometry parameter of the first system, and determining an optical constant and a thickness corresponding to the first system; constructing a second system consisting of a silicon substrate, a natural silicon oxide layer and a non-absorption dielectric layer, measuring an ellipsometry parameter of the second system, and determining an optical constant and a thickness of the non-absorption dielectric layer according to the ellipsometry parameter and optical constant and thickness data corresponding to the first system; and constructing a third system consisting of a silicon substrate, a natural silicon oxide layer, a non-absorption dielectric layer and a metal film layer, measuring an ellipsometric parameter of the third system, and determining the optical constant and the thickness data of the metal film layer according to the ellipsometric parameter, the optical constant and the thickness data corresponding to the first system and the optical constant and the thickness data of the non-absorption dielectric layer. By adopting the method disclosed by the invention, the detection precision and sensitivity of the ultrathin metal film can be improved.

Description

A method and device for detecting ultra-thin metal film using spectroscopic ellipsometer

technical field

The invention relates to the technical field of optical measurement, in particular to a method and a device for detecting an ultra-thin metal film by using a spectroscopic ellipsometer. In addition, it also relates to an optical characterization method and device of an ultra-thin metal film using a spectroscopic ellipsometer.

Background technique

Spectroscopic ellipsometer is a general-purpose optical measuring instrument that uses the polarization characteristics of light to obtain information about the sample to be measured. The basic principle is to project special elliptically polarized light onto the surface of the sample to be measured through a polarizer, and measure the reflected light (or transmitted light) of the sample to obtain the polarization state change of the polarized light before and after reflection (or transmission) (including amplitude ratio and phase difference), so as to extract the relevant physical (such as optical parameters, film thickness, etc.) information of the sample to be tested. Ellipsometry technology has the characteristics of non-destructive testing, high sensitivity, high precision, and can be used for real-time monitoring of ultra-thin films and their preparation process. It is one of the important means of accurate measurement and has an irreplaceable position in the field of thin film research. The ellipsometry of the spectroscopic ellipsometer can obtain the optical properties such as the refractive index, extinction coefficient and complex dielectric function of the material, and can also be further calculated to obtain the reflectivity, absorption rate, transmittance, and optical bandgap of the material. related optical parameters. At the same time, ellipsometry can also be used to obtain comprehensive information such as material composition, interface layer properties and roughness. However, there are still many limitations in using the conventional ellipsometry method to measure material parameters/properties, such as: when measuring ultra-thick (or ultra-thin) metal films, due to the serious attenuation (almost no change) of ultra-thick (or ultra-thin) metal films The ellipsometric signal makes it difficult for conventional methods to accurately measure the optical parameters and physical thickness of ultra-thick (or ultra-thin) metal films. Establish a physical model and then determine the parameters in the model by inversion method, which is the so-called trial and error method. Therefore, due to the increase of unknown quantities and the lack of limiting conditions in the fitting process, the film thickness and optical constants often appear to be non-unique. Generally, there are three growth modes in thin films, namely island growth, layer growth and island-layer mixed growth. Conventional films or bulk materials have completely different shapes and/or properties. Using ellipsometry to analyze such films (such as films with rough surfaces and a large number of defects such as interfaces and holes) often requires careful selection of appropriate dispersion equations. The lack of constraint equations And the complexity of the selection of the dispersion equation makes it difficult for conventional ellipsometry to accurately measure optical and physical parameters under weak signal conditions.

In recent years, with the miniaturization and integration of various devices, nanometer-thick metal films have become more and more important in the manufacture of semiconductor chips and various devices. Nano-thick metal thin films are widely used in microelectronics, integrated optics, solar cells, biomedicine, chemistry and aerospace technology due to their unique properties different from their corresponding materials, and they are indispensable for exhibiting specific new functions . At present, the methods for detecting thin films with nanometer thickness include atomic force microscope, scanning electron microscope, transmission electron microscope, scanning tunneling microscope, spectrophotometer and various film thickness meters, etc. These methods may be able to achieve sub-nanometer resolution detection, but due to their It is destructive to devices, complicated to operate, and low in detection efficiency, so it cannot be applied in actual production lines. Therefore, it cannot meet the rapidly developing advanced process control and optimized detection requirements. In order to better solve the problem that the thickness of nanometer films cannot be accurately measured quickly, non-destructively and efficiently, especially for the problem that conventional ellipsometry cannot accurately measure ultra-thin metal films (such as thickness below 10nm), people have proposed Some improvement measures include the development of some technologies and methods, such as multi-angle measurement, interference enhancement, dielectric function parametric modeling, and the combination of ellipsometric parameters and transmittance measurements, ellipsometric parameters and reflectivity measurements, etc. For example: using the method of synergy analysis of ellipsometric parameters and reflectivity to realize the determination of the thickness of metal Cu nano-film with a thickness of 2.86-12.6nm; the thickness measured by the above method is 3.9nm, while the thickness measured by AFM technology is 2.86nm nm, the thickness deviation between the two is as high as 36.4% (|Thickness measured by ellipsometry-Thickness measured by AFM|/Thickness measured by AFM×100). Therefore, the thickness measured by the currently used method has a large deviation.

It can be seen that the development of a new method for accurately measuring ultra-thin metal films with a thickness below 10nm is not only very important for scientific research, but also has important practical significance and value for industrial production.

Contents of the invention

To this end, the present invention provides a method and device for detecting ultra-thin metal films using a spectroscopic ellipsometer to solve the problem of large deviations in measurement data and poor sensitivity in the existing measurement methods in the prior art, resulting in failure to meet actual use requirements. question.

The invention provides a method for detecting an ultra-thin metal film by using a spectroscopic ellipsometer, comprising: constructing a first system composed of a silicon substrate and a natural silicon oxide layer, and measuring the silicon substrate in the first system by using a spectroscopic ellipsometer and the ellipsometric parameters of the natural silicon oxide layer; according to the ellipsometric parameters, determine the optical constants corresponding to the silicon substrate and the optical constants and thickness data corresponding to the natural silicon oxide layer;

Prepare a non-absorbing medium layer on the first system, construct a second system consisting of a silicon substrate, a natural silicon oxide layer and a non-absorbing medium layer, and measure the non-absorbing medium layer in the second system by using a spectroscopic ellipsometer Ellipsometric parameter; determine the optical constant of the non-absorbing medium layer according to the ellipsometric parameter of the non-absorbing medium layer, the corresponding optical constant of the silicon substrate, and the corresponding optical constant and thickness data of the natural silicon oxide layer and thickness data;

Prepare a metal film layer on the second system, construct a third system composed of a silicon substrate, a natural silicon oxide layer, a non-absorbing medium layer and a metal film layer, and measure the metal film in the third system by using a spectroscopic ellipsometer Layer ellipsometric parameters; according to the ellipsometric parameters of the metal film layer, the corresponding optical constants of the silicon substrate, the corresponding optical constants and thickness data of the natural silicon oxide layer, and the optical constants of the non-absorbing medium layer and thickness data to determine the optical constant and thickness data of the metal film layer.

Further, the preparation of the non-absorbing medium layer on the first system specifically includes: using any one of chemical vapor deposition, magnetron sputtering deposition and electron beam evaporation deposition on the natural silicon oxide layer or The non-absorbing medium layer was prepared in two ways.

Further, the non-absorbing medium layer is a medium material that is non-absorbing to light within the spectral range of the ellipsometer measurement, and the non _- absorbing medium layer includes any one _{of SiO2} film, Si3N4 film and _MgF2 film ; The thickness data of the non-absorbing medium layer is 500nm-2um.

Further, in the process of measuring the ellipsometric parameters by using the spectroscopic ellipsometer, it is determined that the wavelength range parameter of the incident light of the spectroscopic ellipsometer is 190nm-2500nm and the parameter of the incident angle of the incident light is 45°-70°.

Further, according to the ellipsometric parameters, determining the optical constants corresponding to the silicon substrate and the optical constants and thickness data corresponding to the natural silicon oxide layer, specifically includes:

Constructing a first ellipsometric fitting model corresponding to the first system, using the first ellipsometric fitting model to fit the ellipsometric parameters of the silicon substrate and the natural silicon oxide layer in the first system, to obtain and recording the optical constants corresponding to the silicon substrate and the optical constants and thickness data corresponding to the natural silicon oxide layer;

Determining the optical constant and thickness of the non-absorbing medium layer according to the ellipsometric parameters of the non-absorbing medium layer, the corresponding optical constant of the silicon substrate, and the corresponding optical constant and thickness data of the natural silicon oxide layer Data, specifically:

Construct a second ellipsometric fitting model corresponding to the second system, use the second ellipsometric fitting model to fit the ellipsometric parameters of the non-absorbing medium layer in the second system, obtain and record the Optical constants and thickness data of the non-absorbing dielectric layer;

According to the ellipsometric parameters of the metal film layer, the optical constants corresponding to the silicon substrate, the optical constants and thickness data corresponding to the natural silicon oxide layer, and the optical constants and thickness data of the non-absorbing medium layer, Determine the optical constants and thickness data of the metal film layer, specifically including:

Constructing a third ellipsometric fitting model corresponding to the third system, using the third ellipsometric fitting model to fit the ellipsometric parameters of the metal film layer in the third system, to obtain the metal film layer Optical constants and thickness data for .

Further, the metal film layer includes any metal element among gold, platinum, palladium and titanium, and the thickness data of the metal film layer is less than 10 nm.

The invention provides an optical characterization method of an ultra-thin metal film using a spectroscopic ellipsometer, comprising:

Setting the operating parameters of the spectroscopic ellipsometer;

Build an ellipsometric fitting model for measuring the metal film layer;

Using the spectroscopic ellipsometer to measure the ellipsometric parameters corresponding to the structural layers of the ellipsometric fitting model; the structural layers include a silicon substrate layer, a natural silicon oxide layer, a non-absorbing medium layer, a transition layer, and a metal film layer, air roughness layer, and air layer;

Wherein, the ellipsometric parameter corresponding to the second non-absorbing medium layer in the transition layer is the same as the ellipsometric parameter corresponding to the non-absorbing medium layer;

Fitting the ellipsometric parameters corresponding to the structural layer with the ellipsometric fitting model to obtain the optical constant and thickness data of the metal film layer.

Further, the operating parameters include: at least one of an incident angle parameter, a measurement wavelength range parameter, a measurement wavelength interval parameter, and a reference characteristic wavelength parameter;

The transition layer is composed of a second non-absorbing medium layer and a second metal film layer;

The rough air layer is composed of the third metal film layer and the second air layer.

The invention provides a device for detecting an ultra-thin metal film using a spectroscopic ellipsometer, comprising:

The first system parameter determination unit is used to construct a first system composed of a silicon substrate and a natural silicon oxide layer, and use a spectroscopic ellipsometer to measure the ellipsometric parameters of the silicon substrate and the natural silicon oxide layer in the first system; according to The ellipsometric parameters determine the optical constants corresponding to the silicon substrate and the optical constants and thickness data corresponding to the natural silicon oxide layer;

The second system parameter determination unit is used to prepare a non-absorbing medium layer on the first system, construct a second system composed of a silicon substrate, a natural silicon oxide layer and a non-absorbing medium layer, and use a spectroscopic ellipsometer to measure the The ellipsometric parameter of the non-absorbing medium layer in the second system; determined according to the ellipsometric parameter of the non-absorbing medium layer, the corresponding optical constant of the silicon substrate, and the corresponding optical constant and thickness data of the natural silicon oxide layer Optical constants and thickness data of the non-absorbing medium layer;

The third system parameter determination unit is used to prepare a metal film layer on the second system, construct a third system composed of a silicon substrate, a natural silicon oxide layer, a non-absorbing medium layer and a metal film layer, and use a spectroscopic ellipsometer Measuring the ellipsometric parameter of the metal film layer in the third system; according to the ellipsometric parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant and thickness data corresponding to the natural silicon oxide layer, and The optical constant and thickness data of the non-absorbing medium layer determine the optical constant and thickness data of the metal film layer.

Further, the second system parameter determination unit is specifically used to: prepare non-metallic silicon dioxide on the natural silicon oxide layer by any one or two methods of chemical vapor deposition, magnetron sputtering deposition and electron beam evaporation deposition. absorbent layer.

Further, the non-absorbing medium layer is a medium material that is non-absorbing to light within the spectral range of the ellipsometer measurement, and the non _- absorbing medium layer includes any one _{of SiO2} film, Si3N4 film and _MgF2 film ; The thickness data of the non-absorbing medium layer is 500nm-2um.

Further, in the process of measuring the ellipsometric parameters by using the spectroscopic ellipsometer, it is determined that the wavelength range parameter of the incident light of the spectroscopic ellipsometer is 190nm-2500nm and the parameter of the incident angle of the incident light is 45°-70°.

Further, the first system parameter determination unit is specifically configured to: construct a first ellipsometric fitting model corresponding to the first system, and use the first ellipsometric fitting model to Fitting the ellipsometric parameters of the substrate and the natural silicon oxide layer, obtaining and recording the optical constants corresponding to the silicon substrate and the optical constants and thickness data corresponding to the natural silicon oxide layer;

The second system parameter determination unit is specifically configured to: construct a second ellipsometric fitting model corresponding to the second system, and use the second ellipsometric fitting model to analyze the non-absorbing medium layer in the second system The ellipsometric parameters are fitted, and the optical constant and thickness data of the non-absorbing medium layer are obtained and recorded;

The third system parameter determination unit is specifically configured to: construct a third ellipsometric fitting model corresponding to the third system, and use the third ellipsometric fitting model to analyze the metal film layer in the third system The ellipsometric parameters are fitted to obtain the optical constant and thickness data of the metal film layer.

Further, the metal film layer includes any metal element among gold, platinum, palladium and titanium, and the thickness data of the metal film layer is less than 10 nm.

The invention provides an optical characterization device using a spectroscopic ellipsometer for an ultra-thin metal film, comprising:

An operating parameter setting unit, used for setting the operating parameters of the spectroscopic ellipsometer;

An ellipsometric fitting model building unit for constructing an ellipsometric fitting model for measuring metal film layers;

The ellipsometric parameter measurement unit is used to measure the ellipsometric parameters corresponding to the structural layers of the ellipsometric fitting model by using the spectroscopic ellipsometer; the structural layers include a silicon substrate layer, a natural silicon oxide layer, a non-absorbing A medium layer, a transition layer, a metal film layer, an air roughness layer, and an air layer; wherein, the ellipsometric parameter corresponding to the second non-absorbing medium layer in the transition layer is the same as the ellipsometric parameter corresponding to the non-absorbing medium layer;

The metal film layer data acquisition unit is configured to fit the ellipsometric parameters corresponding to the structural layer with the ellipsometric fitting model to obtain the optical constant and thickness data of the metal film layer.

Further, the operating parameters include: at least one of an incident angle parameter, a measurement wavelength range parameter, a measurement wavelength interval parameter, and a reference characteristic wavelength parameter;

The transition layer is composed of a second non-absorbing medium layer and a second metal film layer;

The rough air layer is composed of the third metal film layer and the second air layer.

Adopting the method for detecting ultra-thin metal films using spectroscopic ellipsometry described in the present invention can perform non-destructive, high-precision and high-sensitivity detection of ultra-thin metal films, and the instrument configuration is simple and has good reproducibility sex. It can be integrated into the integrated circuit production line, adapt to the process control and optimized detection requirements of integrated circuits, and expand the ellipsometric measurement range of the limit metal film.

Adopting the optical characterization method of the ultra-thin metal film using a spectroscopic ellipsometer according to the present invention can carry out non-destructive, high-precision and high-sensitivity detection on a metal film with a film thickness lower than 10 nm; the instrument configuration is simple and easy to operate , has good reproducibility; at the same time, it will not damage the sample, avoiding the damage of the sample by the traditional measurement method, which leads to the non-repeatability of the experiment; in addition, it can be integrated into the integrated circuit production line, adapting to the process control and The optimized detection requirements expand the ellipsometric measurement range of the limit metal film.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

Fig. 1 is a schematic flow chart of a method for detecting an ultra-thin metal film using a spectroscopic ellipsometer provided by an embodiment of the present invention;

Fig. 2 is a schematic structural diagram of a device for detecting ultra-thin metal films using a spectroscopic ellipsometer provided by an embodiment of the present invention;

3 is a schematic flow diagram of an optical characterization method using a spectroscopic ellipsometer for an ultra-thin metal film provided by an embodiment of the present invention;

4 is a schematic structural view of an optical characterization device using a spectroscopic ellipsometer for an ultra-thin metal film provided by an embodiment of the present invention;

Fig. 5a is an AFM topography image of steps formed by evaporating an ultra-thin Pt film and an unevaporated ultra-thin Pt film on a silicon substrate, a natural silicon oxide layer, and a non-absorbing dielectric layer by electron beam evaporation provided by an embodiment of the present invention. ;

Figure 5b is the vertical height curve of steps formed by evaporating ultra-thin Pt films and non-evaporated ultra-thin Pt films on a system composed of silicon substrate, natural silicon oxide layer and non-absorbing dielectric layer by electron beam evaporation provided by the embodiment of the present invention picture;

Fig. 6 is a fitting diagram of ellipsometric parameters for evaporating an ultra-thin Pt film on a system composed of a silicon substrate, a natural silicon oxide layer and a non-absorbing medium layer provided by an embodiment of the present invention;

7 is a structural diagram of the first ellipsometric fitting model provided by the embodiment of the present invention;

Figure 8a is the AFM morphology of steps formed by evaporating an ultra-thin Pt film and an unevaporated ultra-thin Pt film on a system composed of a silicon substrate, a natural silicon oxide layer and a silicon oxide _SiO2 layer by electron beam evaporation provided by an embodiment of the present invention picture;

Figure 8b is the vertical height of steps formed by evaporating an ultra-thin Pt film and an unevaporated ultra-thin Pt film on a system composed of a silicon substrate, a natural silicon oxide layer and a silicon oxide _SiO2 layer by electron beam evaporation provided by an embodiment of the present invention Graph;

Fig. 9 is an ellipsometric fitting diagram of evaporating an ultra-thin Pt film on a system composed of a silicon substrate, a natural silicon oxide layer and a silicon oxide _SiO2 layer provided by an embodiment of the present invention;

Fig. 10 is a structural diagram of the second ellipsometric fitting model provided by the embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

This application proposes a method for accurately measuring the optical parameters and thickness data of ultra-thin metal films based on optical ellipsometry technology, thereby overcoming the limitations of conventionally used ellipsometry and realizing ultra-thin metal films with a thickness of less than 10nm Measured precisely. This not only expands the range of measurement objects of the ellipsometer, but also enriches the measurement methods of ellipsometry, which will actively promote and promote the development and progress of ultra-thin metal film measurement technology required in scientific research and industrial production. The following is a detailed description of the embodiment of the method for detecting an ultra-thin metal film using a spectroscopic ellipsometer according to the present invention. As shown in Figure 1, it is a schematic flow chart of a method for detecting an ultra-thin metal film using a spectroscopic ellipsometer provided by an embodiment of the present invention. The specific implementation process includes the following steps:

Step 101: Construct a first system consisting of a silicon substrate and a natural silicon oxide layer, and use a spectroscopic ellipsometer to measure the ellipsometric parameters of the silicon substrate and the natural silicon oxide layer in the first system; according to the ellipsometric parameters, The optical constant corresponding to the silicon substrate and the optical constant and thickness data corresponding to the natural silicon oxide layer are determined.

In this step, in the process of measuring the ellipsometric parameters of the silicon substrate (Si substrate) and the natural silicon oxide layer in the first system using the spectroscopic ellipsometer, it is necessary to first determine the ratio of the incident light of the spectroscopic ellipsometer The wavelength range parameter is 190nm-2500nm and the incident angle parameter of the incident light is 45°-70°.

Specifically, according to the ellipsometric parameters, the optical constants corresponding to the silicon substrate and the optical constants and thickness data corresponding to the natural silicon oxide layer are determined, and the implementation process includes: constructing the first ellipsoid corresponding to the first system A partial fitting model, using the first ellipsometric fitting model to fit the ellipsometric parameters of the silicon substrate and the natural silicon oxide layer in the first system, to obtain the optical constants corresponding to the silicon substrate and the Describe the optical constant and thickness data corresponding to the natural silicon oxide layer, and record and store the data;

Step 102: Prepare a non-absorbing medium layer on the first system, construct a second system consisting of a silicon substrate, a natural silicon oxide layer, and a non-absorbing medium layer, and measure the non-absorbing medium layer in the second system using a spectroscopic ellipsometer. The ellipsometric parameter of the medium layer; according to the ellipsometric parameter of the non-absorbing medium layer, the optical constant corresponding to the silicon substrate, and the optical constant and thickness data corresponding to the natural silicon oxide layer, determine the non-absorbing medium layer Optical constants and thickness data for .

In this step, the specific implementation of preparing the non-absorbing medium layer on the first system includes: using any of chemical vapor deposition, magnetron sputtering deposition and electron beam evaporation deposition on the silicon substrate and the natural silicon oxide layer. The non-absorbing medium layer is prepared in one or both ways. Wherein, the non-absorbing medium layer is a medium material that is non-absorbing to light within the spectral range of the ellipsometer measurement, and the non _- absorbing medium layer includes any one _{of SiO2} film, Si3N4 film and _MgF2 film, etc. ; The thickness data of the non-absorbing medium layer is 500nm-2um.

In the specific implementation process, in the process of using the spectroscopic ellipsometer to measure the ellipsometric parameters of the non-absorbing medium layer in the second system, it is necessary to pre-determine that the wavelength range parameter of the incident light of the spectroscopic ellipsometer is 190nm-2500nm And the incident angle parameter of the incident light is 45°-70°.

Specifically, according to the ellipsometric parameters of the non-absorbing medium layer, the optical constants corresponding to the silicon substrate, and the optical constants and thickness data corresponding to the natural silicon oxide layer, the optical constants and the thickness of the non-absorbing medium layer are determined. Thickness data, the implementation process includes: constructing a second ellipsometric fitting model corresponding to the second system, using the second ellipsometric fitting model to simulate the ellipsometric parameters of the non-absorbing medium layer in the second system combined to obtain the optical constant and thickness data of the non-absorbing medium layer, and record and store the data;

Step 103: Prepare a metal film layer on the second system, construct a third system consisting of a silicon substrate, a natural silicon oxide layer, a non-absorbing medium layer, and a metal film layer, and measure the third system using a spectroscopic ellipsometer The ellipsometric parameters of the metal film layer; according to the ellipsometric parameters of the metal film layer, the corresponding optical constants of the silicon substrate, the corresponding optical constants and thickness data of the natural silicon oxide layer, and the non-absorbing medium layer The optical constant and thickness data of the metal film layer are determined.

In this step, the specific implementation of preparing the metal film layer on the second system includes: using chemical vapor deposition, magnetron sputtering deposition and electron beam evaporation on the silicon substrate, natural silicon oxide layer and non-absorbing medium layer Either one or two methods of deposition are used to prepare metal film layers.

In the specific implementation process, in the process of using the spectroscopic ellipsometer to measure the ellipsometric parameters of the metal film layer in the third system, it is also necessary to predetermine that the wavelength range parameter of the incident light of the spectroscopic ellipsometer is 190nm-2500nm And the incident angle parameter of the incident light is 45°-70°.

Specifically, according to the ellipsometric parameters of the metal film layer, the optical constants corresponding to the silicon substrate, the optical constants and thickness data corresponding to the natural silicon oxide layer, and the optical constants and Thickness data, determining the optical constant and thickness data of the metal film layer, the implementation process includes: constructing a third ellipsometric fitting model corresponding to the third system, using the third ellipsometric fitting model to The ellipsometric parameters of the metal film layer in the three systems are fitted to obtain the optical constant and thickness data of the metal film layer, and the data are recorded and stored. Wherein, the metal film layer includes any metal element among gold, platinum, palladium, titanium, etc., and the thickness data of the metal film layer is less than 10 nm.

In a specific embodiment, a spectroscopic ellipsometer is used to detect the metal film layer Pt (thickness is about 3nm), wherein, the incident angle of the spectroscopic ellipsometer can be set to 70°, and the wavelength range can be set to 380nm to 930nm, The non-absorbing medium layer is a silicon nitride (Si ₃ N ₄ ) film, and the specific method is as follows:

(1) Construct the first system composed of Si substrate and natural silicon oxide layer: n-Si(100) substrate can be selected as the first system (system 1) composed of Si substrate and natural silicon oxide layer, and the spectral The ellipsometer measures the first system, obtains the ellipsometric parameters of the Si substrate and the natural silicon oxide layer in the first system, and calculates and records the optical constants and the obtained values of the Si substrate and the natural silicon oxide layer in the first system. The thickness data of the natural silicon oxide layer in the first system. In the specific implementation process, the calculated thickness data of the natural silicon oxide layer is 1.27 nm; when the wavelength is 633 nm, the calculated refractive index of the natural silicon oxide layer is 1.5274 and the extinction coefficient is 0.

(2) Construct the second system consisting of Si substrate, natural silicon oxide layer and non-absorbing dielectric layer (such as silicon nitride (Si ₃ N ₄ ) layer or silicon nitride (Si ₃ N ₄ ) film): available A silicon nitride (Si ₃ N ₄ ) film with a thickness of 1um was prepared on the first system by chemical vapor deposition to obtain the second system (i.e. system 2), and the silicon nitride in the second system ( Si ₃ N ₄ ) film's ellipsometric parameter, brought into the recorded optical constant and thickness of the natural silicon oxide layer, thereby calculating and recording the optical constant and the optical constant of the silicon nitride (Si ₃ N ₄ ) film in the second system thickness. Among them, the calculated thickness of the silicon nitride (Si ₃ N ₄ ) film is 947.66nm; when the wavelength is 633nm, the calculated refractive index of the silicon nitride (Si ₃ N ₄ ) film is 1.9722 and the extinction coefficient is 0 .

(3) Prepare a third system (system 3) consisting of Si substrate, natural silicon oxide layer, non-absorbing medium layer system and metal film layer (such as platinum Pt layer or platinum Pt film). The third system was obtained by evaporating a platinum Pt film with a thickness of about 3nm above the second system by high vacuum electron beam evaporation method. The ellipsometric parameters of the platinum Pt film in the third system were measured by spectroscopic ellipsometer, and the recorded first The optical constant and thickness of the natural silicon oxide layer in one system and the optical constant and the thickness of the silicon nitride (Si ₃ N ₄ ) film in the second system, so as to calculate and record the platinum in the third system Optical constants and thickness of the Pt film. Wherein, the calculated thickness of the platinum Pt film is 3.15 nm; when the wavelength is 633 nm, the calculated refractive index of the platinum Pt film is 2.2818 and the extinction coefficient is 4.77632.

As shown in Figure 5(a), the left side of the dotted line is the ultra-thin platinum Pt film evaporated on the silicon substrate, natural silicon oxide layer, and silicon nitride (Si ₃ N ₄ ) layer system, and the right side of the dotted line is not An ultra-thin Pt film was evaporated on a second system composed of a silicon substrate, a natural silicon oxide layer and a silicon nitride (Si ₃ N ₄ ) layer. As shown in Figure 5(b), electron beam evaporation was used to evaporate ultra-thin Pt film and non-evaporated ultra-thin Pt film on the second system composed of Si substrate, natural silicon oxide layer and silicon nitride (Si ₃ N ₄ ) layer Vertical height plot of film-forming steps. It can be seen from Figures 5(a) and 5(b) that the thickness of the platinum Pt film evaporated by the high vacuum electron beam evaporation system is about 2.954nm. The thickness of the metal film (dAFM) was measured by an atomic force microscope (AFM), and compared with the thickness (dEI) fitted by the ellipsometer, the calculated thickness deviation (|dEl-dAFM|/dAFM×100) was 6.9%.

As shown in FIG. 7 , it is a structural diagram of the first ellipsometric fitting model provided by the embodiment of the present invention. The structural layers corresponding to the first ellipsometric fitting model include: Si substrate layer (Si Lengosci), natural silicon oxide layer (SiO ₂ (native)), non-absorbing dielectric layer (Si ₃ N ₄ -TL), transition layer ( Pt/Si ₃ N ₄ ), metal film layer (Pt(platiunum)-DL#1), air roughness layer (Roughness-Air/Pt(Platiunu...)), and air layer (Air). Among them, a silicon _nitride (Si ₃ N ₄ ) film was prepared _on a Si substrate by chemical vapor deposition with a thickness of 1000 nm; a high vacuum electron beam evaporation method was used to evaporate a thickness of about 3nm platinum Pt film. The Si substrate layer is the Leng Oscilator dispersion model; the natural silicon oxide layer is the Cauchy dispersion model; the non-absorbing medium layer is the Tauc-Lorentz dispersion model of the Si ₃ N ₄ film; the transition layer is a mixed layer of the Si ₃ N ₄ layer and the Pt layer, It is a Bruggeman effective approximation model; the platinum Pt film is a Drude-Lorentz Oscilator dispersion model; the air rough layer is a mixed layer of Pt layer and air layer, which is a Bruggeman effective approximation model.

In another specific embodiment, a spectroscopic ellipsometer is used to detect the metal film Pt (thickness is about 3nm), wherein, the incident angle of the spectroscopic ellipsometer is set to 70°, the wavelength range is set to 380nm-930nm, and the non-absorbing The dielectric layer is silicon oxide (SiO ₂ ), and the specific method is as follows:

(1) Construct the first system composed of Si substrate and natural silicon oxide layer: n-Si (100) substrate can be selected as the first system (system 1) composed of Si substrate and natural silicon oxide layer, and use spectral ellipsometry The polarimeter measures the first system, obtains the ellipsometric parameters of the Si substrate and the natural silicon oxide layer in the first system, and calculates and records the optical constants and the described optical constants of the Si substrate and the natural silicon oxide layer in the first system. Thickness data of the native silicon oxide layer in the first system. Wherein, the calculated thickness of the natural silicon oxide layer is 1.27 nm; when the wavelength is 633 nm, the calculated refractive index of the natural silicon oxide layer is 1.5274 and the extinction coefficient is 0.

(2) Construct the second system consisting of Si substrate, natural silicon oxide layer and non-absorbing dielectric layer: use chemical vapor deposition to prepare a silicon oxide (SiO ₂ ) film with a thickness of 1um above the first system to obtain the second system, The ellipsometric parameters of the silicon oxide (SiO ₂ ) film in the second system are measured by spectroscopic ellipsometer, and the optical constants and thicknesses of the recorded natural silicon oxide layer are taken into account to calculate and record the oxidation rate in the second system. Optical constants and thicknesses of silicon (SiO ₂ ) films. Wherein, the calculated thickness of the silicon oxide (SiO ₂ ) film is 1033.85 nm; when the wavelength is 633 nm, the calculated refractive index of the silicon oxide (SiO ₂ ) film is 1.4699 and the extinction coefficient is 0.

(3) Preparation of Si substrate, natural silicon oxide layer, non-absorbing medium layer system and metal film layer system: a platinum Pt film with a thickness of 3nm can be evaporated on the second system by high vacuum electron beam evaporation method to obtain the third system , using spectroscopic ellipsometer to measure the ellipsometric parameters of the platinum Pt film in the third system, the optical constant and thickness of the native silicon oxide layer in the first system and the silicon oxide (SiO ₂ ) in the second system film the optical constant and the thickness, so as to calculate and record the optical constant and thickness of the platinum Pt film in the third system. Wherein, the calculated thickness of the platinum Pt film is 3.815 nm; when the wavelength is 633 nm, the calculated refractive index of the platinum Pt film is 2.3426 and the extinction coefficient is 4.20478.

As shown in Figure 8(a), the difference between the steps formed by evaporating ultra-thin Pt film and non-evaporated ultra-thin Pt film on the Si substrate and the first system composed of natural silicon oxide layer silicon oxide (SiO ₂ ) by electron beam evaporation AFM topography. The left side of the dotted line is the ultra-thin Pt film evaporated on the Si substrate, natural silicon oxide layer and silicon oxide (SiO ₂ ) layer system, and the right side of the dotted line is the ultra-thin Pt film that was not evaporated on the Si substrate, natural silicon oxide layer and silicon oxide (SiO 2 ) layer system. An ultrathin Pt film was evaporated on the second system composed of SiO ₂ ) layer. As shown in Fig. 8(b), electron beam evaporation was used to evaporate ultra-thin Pt film and non-evaporated ultra-thin Pt film on the second system composed of Si substrate, natural silicon oxide layer and silicon oxide (SiO ₂ ) layer. Vertical height graph of steps. From Figure 8(a) and (b), it can be seen that the thickness of the platinum Pt film evaporated by the high vacuum electron beam evaporation system is about 2.99nm. The thickness of the metal film (dAFM) was measured by an atomic force microscope (AFM), and compared with the thickness (dEI) fitted by the ellipsometer, the calculated thickness deviation (|dEl-dAFM|/dAFM×100) was 27%.

As shown in FIG. 10 , it is a structural diagram of the second ellipsometric fitting model. The structural layers of the second ellipsometric fitting model include: Si substrate layer (Si Leng osci), natural silicon oxide layer (SiO ₂ (native)), non-absorbing dielectric layer (Cau-SiO (CVD)), transition layer ( Pt/SiO ₂ ), metal film layer (Pt(platiunum)-DL#1), air roughness layer (Roughness-Air/Pt(Platiunu...)), and air layer (Air). Among them, a silicon oxide (SiO ₂ ) film was prepared on a Si substrate by chemical vapor deposition, with a thickness of 1000 nm; a platinum Pt film with a thickness of about 3 nm was evaporated on the silicon oxide (SiO ₂ ) film by high vacuum electron beam evaporation. . The Si substrate layer is the Leng Oscilator dispersion model; the natural silicon oxide layer is the Cauchy dispersion model; the non-absorbing medium layer is the Cauchy dispersion model of the silicon oxide (SiO ₂ ) film; the transition layer is a mixed layer of SiO ₂ layer and Pt layer, which is The Bruggeman effective approximation model; the platinum Pt film is the Drude-Lorentz Oscilator dispersion model; the air rough layer is the mixed layer of the Pt layer and the air layer, which is the Bruggeman effective approximation model.

As shown in FIG. 6 , it is an ellipsometric fitting diagram of an ultra-thin Pt film evaporated on a second system composed of a Si substrate, a natural silicon oxide layer and a silicon nitride (Si ₃ N ₄ ) layer. As shown in FIG. 9 , it is an ellipsometric fitting diagram of an ultra-thin Pt film evaporated on a Si substrate/natural silicon oxide layer/silicon oxide (SiO ₂ ) layer system. It can be seen from Figure 6 and Figure 9 that one or more calculation steps have an excellent mathematical fit, that is, the mean square error EMA is extremely low, so it can be shown that the calculation results are more in line with the real morphology of the platinum Pt film .

Using the method for detecting ultra-thin metal films using spectroscopic ellipsometry described in the embodiments of the present invention, non-destructive, high-precision and high-sensitivity detection can be performed on metal films with a film thickness lower than 10 nm, and the measured metal thickness and The actual thickness deviation is very small, and enables the spectroscopic ellipsometer to detect and fit metal films with a thickness less than 10nm, greatly improving the accuracy and sensitivity of ultra-thick metal film detection, and expanding the thickness range of measurable metal films . The instrument configuration is simple, easy to operate, the measurement results are stable and reliable, the application range is wide, and it has good reproducibility; at the same time, it will not damage the sample, avoiding the damage to the sample caused by the traditional measurement method, which leads to the non-repeatability of the experiment; in addition, It can be integrated into the integrated circuit production line, adapt to the process control and optimized detection requirements of integrated circuits, and expand the ellipsometric measurement range of the limit metal film.

Corresponding to the method for detecting the ultra-thin metal film by using the spectroscopic ellipsometer provided above, the present invention also provides a device for detecting the ultra-thin metal film by using the spectroscopic ellipsometer. Since the embodiment of the device is similar to the above-mentioned method embodiment, it is relatively simple to describe, please refer to the description of the above-mentioned method embodiment part for relevant points, and the device for detecting ultra-thin metal films using a spectroscopic ellipsometer described below The examples are illustrative only. Please refer to FIG. 2 , which is a schematic structural diagram of a device for detecting an ultra-thin metal film using a spectroscopic ellipsometer according to an embodiment of the present invention.

A kind of device that utilizes spectroscopic ellipsometer to detect ultra-thin metal film according to the present invention specifically comprises the following parts:

The first system parameter determination unit 201 is configured to construct a first system composed of a silicon substrate and a natural silicon oxide layer, and use a spectroscopic ellipsometer to measure the ellipsometric parameters of the silicon substrate and the natural silicon oxide layer in the first system; According to the ellipsometric parameters, determine the optical constants corresponding to the silicon substrate and the optical constants and thickness data corresponding to the natural silicon oxide layer;

The second system parameter determination unit 202 is used to prepare a non-absorbing medium layer on the first system, construct a second system consisting of a silicon substrate, a natural silicon oxide layer and a non-absorbing medium layer, and measure the obtained by using a spectroscopic ellipsometer. The ellipsometric parameter of the non-absorbing medium layer in the second system; according to the ellipsometric parameter of the non-absorbing medium layer, the corresponding optical constant of the silicon substrate, and the corresponding optical constant and thickness data of the natural silicon oxide layer, determining optical constants and thickness data for said non-absorbing medium layer;

The third system parameter determination unit 203 is used to prepare a metal film layer on the second system, construct a third system composed of a silicon substrate, a natural silicon oxide layer, a non-absorbing medium layer and a metal film layer, and use spectral ellipsometry The instrument measures the ellipsometric parameter of the metal film layer in the third system; according to the ellipsometric parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant corresponding to the natural silicon oxide layer and the thickness data As well as the optical constant and thickness data of the non-absorbing medium layer, determine the optical constant and thickness data of the metal film layer.

Using the device for detecting ultra-thin metal films with a spectroscopic ellipsometer described in the embodiments of the present invention, non-destructive, high-precision and high-sensitivity detection can be performed on metal films with a film thickness lower than 10 nm, and the measured metal thickness is consistent with The actual thickness deviation is very small, and enables the spectroscopic ellipsometer to detect and fit metal films with a thickness less than 10nm, greatly improving the accuracy and sensitivity of ultra-thin metal film detection, and expanding the thickness range of measurable metal films . The instrument configuration is simple, easy to operate, the measurement results are stable and reliable, the application range is wide, and it has good reproducibility; at the same time, it will not damage the sample, avoiding the damage to the sample caused by the traditional measurement method, which leads to the non-repeatability of the experiment; in addition, It can be integrated into the integrated circuit production line, adapt to the process control and optimized detection requirements of integrated circuits, and expand the ellipsometric measurement range of the limit metal film.

Based on the optical characterization method of ultra-thin metal film using spectroscopic ellipsometer according to the present invention, its embodiment will be described in detail below. As shown in FIG. 3 , it is a schematic flowchart of an optical characterization method using a spectroscopic ellipsometer for an ultra-thin metal film provided by an embodiment of the present invention. The specific implementation process includes the following steps:

Step 301: Setting the operating parameters of the spectroscopic ellipsometer. Wherein, the operating parameters include: at least one of an incident angle parameter, a measurement wavelength range parameter, a measurement wavelength interval parameter, and a reference characteristic wavelength parameter.

Step 302: Construct an ellipsometric fitting model for measuring the metal film layer.

Step 303: Use the spectroscopic ellipsometer to measure the ellipsometric parameters corresponding to the structural layers of the ellipsometric fitting model; the structural layers include a silicon substrate layer, a natural silicon oxide layer, a non-absorbing medium layer, and a transition layer , a metal film layer, an air rough layer, and an air layer; wherein, the ellipsometric parameter corresponding to the second non-absorbing medium layer in the transition layer is the same as the ellipsometric parameter corresponding to the non-absorbing medium layer.

Step 304: Fitting the ellipsometric parameters corresponding to the structural layer with the ellipsometric fitting model to obtain the optical constant and thickness data of the metal film layer.

Wherein, the transition layer is composed of a second non-absorbing medium layer and a second metal film layer, and the transition layer is a Bruggeman effective approximate model. It should be noted that, in a specific implementation process, the transition layer is not limited to the Bruggeman effective approximation model, and may also be other fitting models, which are not specifically limited here.

The rough air layer is composed of a third metal film layer and a second air layer, and the transition layer is a Bruggeman effective approximation model. It should be noted that, in the specific implementation process, the rough air layer is not limited to the Bruggeman effective approximation model, but can also be other fitting models, which are not specifically limited here.

Using the optical characterization method of the ultra-thin metal film using spectroscopic ellipsometer described in the embodiment of the present invention, it is possible to perform non-destructive, high-precision and high-sensitivity optical property characterization of the metal film with a film thickness of less than 10 nm; instrument configuration Simple, easy to operate, and has good reproducibility; at the same time, it will not damage the sample, avoiding the damage to the sample caused by the traditional measurement method, which leads to the unrepeatability of the experiment; in addition, it can be integrated into the integrated circuit production line, suitable for integrated circuit The process control and optimized detection requirements have expanded the ellipsometric measurement range of the limit metal film.

Corresponding to the optical characterization method of the ultra-thin metal film using the spectroscopic ellipsometer provided above, the present invention also provides an optical characterization device of the ultra-thin metal film using the spectroscopic ellipsometer. Since the embodiment of the device is similar to the above-mentioned method embodiment, the description is relatively simple. Please refer to the description of the above-mentioned method embodiment for the relevant parts. The optical characterization of the ultra-thin metal film using the spectroscopic ellipsometer described below The embodiments of the device are illustrative only. Please refer to FIG. 4 , which is a schematic structural diagram of an optical characterization device using a spectroscopic ellipsometer for an ultra-thin metal film provided by an embodiment of the present invention.

An optical characterization device of an ultra-thin metal film using a spectroscopic ellipsometer according to the present invention specifically includes the following parts:

An operating parameter setting unit 401, configured to set operating parameters of the spectroscopic ellipsometer.

The ellipsometric fitting model construction unit 402 is configured to construct an ellipsometric fitting model for measuring the metal film layer.

The ellipsometric parameter measurement unit 403 is used to measure the ellipsometric parameters corresponding to the structural layers of the ellipsometric fitting model by using the spectroscopic ellipsometer; the structural layers include a silicon substrate layer, a natural silicon oxide layer, a Absorbing medium layer, transition layer, metal film layer, rough air layer and air layer; wherein, the ellipsometric parameter corresponding to the second non-absorbing medium layer in the transition layer is the same as the ellipsometric parameter corresponding to the non-absorbing medium layer .

The metal film layer data obtaining unit 404 is configured to fit the ellipsometric parameters corresponding to the structural layer with the ellipsometric fitting model to obtain the optical constant and thickness data of the metal film layer.

Using the optical characterization device for ultra-thin metal films using spectroscopic ellipsometer described in the embodiments of the present invention, it is possible to perform non-destructive, high-precision and high-sensitivity optical property characterization of metal films with a film thickness of less than 10 nm; instrument configuration Simple, easy to operate, and has good reproducibility; at the same time, it will not damage the sample, avoiding the damage to the sample caused by the traditional measurement method, which leads to the unrepeatability of the experiment; in addition, it can be integrated into the integrated circuit production line, suitable for integrated circuit The process control and optimized detection requirements have expanded the ellipsometric measurement range of the limit metal film.

Above embodiment is only in order to illustrate technical scheme of the present invention and is not limited to it, and this method aims at utilizing optical ellipsometer to improve the measurement accuracy and the sensitivity of various weak signal ultra-thin films (comprising ultra-thin films such as sub-nanometer thickness metals Weak signal systems such as films or other film systems), without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and All deformations should belong to the protection scope of the appended claims of the present invention.

It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks of the illustrated figures, or portions thereof.

Although various arrow types and line types may be employed in flowcharts and/or block diagrams, it should be understood that they do not limit the scope of the corresponding embodiments. In fact, some arrows or other connectors may merely be used to indicate the logical flow of the depicted embodiments. For example, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted embodiment. It will also be noted that each block of the block diagrams and/or flowcharts, and combinations of blocks in the block diagrams and/or flowcharts, can be implemented by a dedicated hardware-based system that performs the specified function or operation, or by a combination of dedicated hardware and code. combination to achieve.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any inventions or of what may be claimed, but rather as descriptions of features that are specific to particular implementations of particular inventions. Certain features that are described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Furthermore, although features above may be described as functioning in certain combinations and even initially claimed as such, one or more features from a claimed combination may in some cases be deleted from that combination and the claimed combination Can target subgroups or variations of subgroups.

Various modifications to the implementations described in this disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of the disclosure. Thus, the claims are not intended to be limited to the implementations shown herein but are to be accorded the widest scope consistent with the teachings, principles and novel features disclosed herein.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (7)

1. A method utilizing spectroscopic ellipsometer to detect ultra-thin metal film, is characterized in that, comprising: Constructing a first system consisting of a silicon substrate and a natural silicon oxide layer, using a spectroscopic ellipsometer to measure the ellipsometric parameters of the silicon substrate and the natural silicon oxide layer in the first system; according to the ellipsometric parameters, determining the Optical constants corresponding to the silicon substrate and optical constants and thickness data corresponding to the natural silicon oxide layer; Prepare a non-absorbing medium layer on the first system, construct a second system consisting of a silicon substrate, a natural silicon oxide layer and a non-absorbing medium layer, and measure the non-absorbing medium layer in the second system by using a spectroscopic ellipsometer Ellipsometric parameter; determine the optical constant of the non-absorbing medium layer according to the ellipsometric parameter of the non-absorbing medium layer, the corresponding optical constant of the silicon substrate, and the corresponding optical constant and thickness data of the natural silicon oxide layer and thickness data; the non-absorbing dielectric layer is a dielectric material that is non-absorbing to light within the spectral range of the ellipsometer measurement, and includes any one _{of SiO2} film, Si3N4 film and _MgF2 film _; Prepare a metal film layer on the second system, construct a third system composed of a silicon substrate, a natural silicon oxide layer, a non-absorbing medium layer and a metal film layer, and measure the metal film in the third system by using a spectroscopic ellipsometer Layer ellipsometric parameters; according to the ellipsometric parameters of the metal film layer, the corresponding optical constants of the silicon substrate, the corresponding optical constants and thickness data of the natural silicon oxide layer, and the optical constants of the non-absorbing medium layer and thickness data, determine the optical constants and thickness data of the metal film layer; the metal film layer includes any metal element in gold, platinum, palladium, titanium, and the thickness data of the metal film layer is less than 10nm. 2. the method for utilizing spectroscopic ellipsometer to detect ultra-thin metal film according to claim 1, is characterized in that, described preparing non-absorbing medium layer on described first system, specifically comprises: in described natural silicon oxide The non-absorbing medium layer is prepared by any one or two methods of chemical vapor deposition, magnetron sputtering deposition and electron beam evaporation deposition on the layer. 3. the method utilizing spectroscopic ellipsometer to detect ultra-thin metal film according to claim 1, is characterized in that, utilizes spectroscopic ellipsometer to measure in the process of ellipsometric parameter, determines the value of the incident light of described spectroscopic ellipsometer The wavelength range parameter is 190nm-2500nm and the incident angle parameter of the incident light is 45°-70°. 4. the method for utilizing spectroscopic ellipsometer to detect ultra-thin metal film according to claim 1, is characterized in that, described according to described ellipsometric parameter, determine the corresponding optical constant of described silicon substrate and described natural oxidation Optical constants and thickness data corresponding to the silicon layer, including: Constructing a first ellipsometric fitting model corresponding to the first system, using the first ellipsometric fitting model to fit the ellipsometric parameters of the silicon substrate and the natural silicon oxide layer in the first system, to obtain and recording the optical constants corresponding to the silicon substrate and the optical constants and thickness data corresponding to the natural silicon oxide layer; Determining the optical constant and thickness of the non-absorbing medium layer according to the ellipsometric parameters of the non-absorbing medium layer, the corresponding optical constant of the silicon substrate, and the corresponding optical constant and thickness data of the natural silicon oxide layer Data, specifically: Construct a second ellipsometric fitting model corresponding to the second system, use the second ellipsometric fitting model to fit the ellipsometric parameters of the non-absorbing medium layer in the second system, obtain and record the Optical constants and thickness data of the non-absorbing dielectric layer; According to the ellipsometric parameters of the metal film layer, the optical constants corresponding to the silicon substrate, the optical constants and thickness data corresponding to the natural silicon oxide layer, and the optical constants and thickness data of the non-absorbing medium layer, Determine the optical constants and thickness data of the metal film layer, specifically including: Constructing a third ellipsometric fitting model corresponding to the third system, using the third ellipsometric fitting model to fit the ellipsometric parameters of the metal film layer in the third system, to obtain the metal film layer Optical constants and thickness data for . 5. An optical characterization method utilizing a spectroscopic ellipsometer for an ultra-thin metal film, characterized in that it comprises: Setting the operating parameters of the spectroscopic ellipsometer; the operating parameters include: at least one of an incident angle parameter, a measurement wavelength range parameter, a measurement wavelength interval parameter, and a reference characterization wavelength parameter; Build an ellipsometric fitting model for measuring the metal film layer; Using the spectroscopic ellipsometer to measure the ellipsometric parameters corresponding to the structural layers of the ellipsometric fitting model; the structural layers include a silicon substrate layer, a natural silicon oxide layer, a non-absorbing medium layer, a transition layer, and a metal film layer, an air rough layer and an air layer; the transition layer is composed of a second non-absorbing medium layer and a second metal film layer; the air rough layer is composed of a third metal film layer and a second air layer; the non-absorbing The dielectric layer is a non-absorbing dielectric material for light within the spectral range measured by the ellipsometer, including any one of SiO ₂ film, Si ₃ N ₄ film and MgF ₂ film; Wherein, the ellipsometric parameter corresponding to the second non-absorbing medium layer in the transition layer is the same as the ellipsometric parameter corresponding to the non-absorbing medium layer; Fitting the ellipsometric parameters corresponding to the structural layer with the ellipsometric fitting model to obtain optical constants and thickness data of the metal film layer; the metal film layer includes gold, platinum, palladium, titanium For any metal element, the thickness data of the metal film layer is less than 10nm. 6. A device utilizing spectroscopic ellipsometry to detect ultra-thin metal films, characterized in that it comprises: The first system parameter determination unit is used to construct a first system composed of a silicon substrate and a natural silicon oxide layer, and use a spectroscopic ellipsometer to measure the ellipsometric parameters of the silicon substrate and the natural silicon oxide layer in the first system; according to The ellipsometric parameters determine the optical constants corresponding to the silicon substrate and the optical constants and thickness data corresponding to the natural silicon oxide layer; The second system parameter determination unit is used to prepare a non-absorbing medium layer on the first system, construct a second system composed of a silicon substrate, a natural silicon oxide layer and a non-absorbing medium layer, and use a spectroscopic ellipsometer to measure the The ellipsometric parameter of the non-absorbing medium layer in the second system; determined according to the ellipsometric parameter of the non-absorbing medium layer, the corresponding optical constant of the silicon substrate, and the corresponding optical constant and thickness data of the natural silicon oxide layer The optical constant and thickness data of the non-absorbing medium layer; the non-absorbing medium layer is a medium material that is non-absorbing to light in the spectral range of ellipsometer measurement, including SiO ₂ film, Si ₃ N ₄ film and MgF ₂ film any of The third system parameter determination unit is used to prepare a metal film layer on the second system, construct a third system composed of a silicon substrate, a natural silicon oxide layer, a non-absorbing medium layer and a metal film layer, and use a spectroscopic ellipsometer Measuring the ellipsometric parameter of the metal film layer in the third system; according to the ellipsometric parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant and thickness data corresponding to the natural silicon oxide layer, and The optical constant and thickness data of the non-absorbing medium layer determine the optical constant and thickness data of the metal film layer; the metal film layer includes any metal element in gold, platinum, palladium, titanium, and the metal The thickness data of the film layer is less than 10nm. 7. An optical characterization device utilizing a spectroscopic ellipsometer for an ultra-thin metal film, characterized in that it comprises: The operating parameter setting unit is used to set the operating parameters of the spectroscopic ellipsometer; the operating parameters include: at least one of the incident angle parameter, the measurement wavelength range parameter, the measurement wavelength interval parameter and the reference wavelength parameter; Partial fitting model construction unit, used for constructing the ellipsometric fitting model of measuring metal film layer; The ellipsometric parameter measurement unit is used to measure the ellipsometric parameters corresponding to the structural layers of the ellipsometric fitting model by using the spectroscopic ellipsometer; the structural layers include a silicon substrate layer, a natural silicon oxide layer, a non-absorbing medium layer, transition layer, metal film layer, air rough layer and air layer; the transition layer is composed of the second non-absorbing medium layer and the second metal film layer; the air rough layer is composed of the third metal film layer and the second Air layer composition; Wherein, the ellipsometric parameter corresponding to the second non-absorbing medium layer in the transition layer is the same as the ellipsometric parameter corresponding to the non-absorbing medium layer; Dielectric materials that are non-absorbing to light within the scope, including any one of SiO ₂ film, Si ₃ N ₄ film and MgF ₂ film; The metal film layer data acquisition unit is used to fit the ellipsometric parameters corresponding to the structural layer with the ellipsometric fitting model to obtain the optical constant and thickness data of the metal film layer; the metal film layer includes Any metal element in gold, platinum, palladium, titanium, the thickness data of the metal film layer is less than 10nm.

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