CN112964647A - Method and device for detecting ultrathin metal film by using spectroscopic ellipsometer - Google Patents
Method and device for detecting ultrathin metal film by using spectroscopic ellipsometer Download PDFInfo
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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
Technical Field
The invention relates to the technical field of optical measurement, in particular to a method and a device for detecting an ultrathin metal film by using a spectroscopic ellipsometer. In addition, the invention also relates to an optical characterization method and device of the ultrathin metal film by using the spectroscopic ellipsometer.
Background
The spectroscopic ellipsometer is a general optical measuring instrument for obtaining information of a sample to be measured by using polarization characteristics of light. The method is based on the basic principle that special elliptically polarized light is projected to the surface of a sample to be measured through a polarizer, and the change of the polarization state (including amplitude ratio and phase difference) of the polarized light before and after reflection (or transmission) is obtained by measuring the reflected light (or transmitted light) of the sample to be measured, so that the related physical (such as optical parameters, film thickness and the like) information of the sample to be measured is extracted. The ellipsometry measurement technology belongs to nondestructive detection, has the characteristics of high sensitivity and high precision, can be used for real-time monitoring of ultrathin films and the preparation process of the ultrathin films, has incomparable advantages of other thickness measuring instruments, becomes one of important means for accurately measuring the thickness and the optical constant of the ultrathin films, and has irreplaceable status in the field of thin film research. The spectroscopic ellipsometer is used for ellipsometry measurement, so that the optical properties such as the refractive index, the extinction coefficient, the complex dielectric function and the like of the material can be obtained, and the relevant optical parameters including the reflectivity, the absorptivity, the transmissivity and the optical band gap of the material can be further calculated. Meanwhile, the ellipsometry technology can also be used for acquiring comprehensive information such as material components, interface layer properties, roughness and the like. However, there are many limitations to measuring material parameters/properties using conventional ellipsometry methods, including for example: when measuring an ultra-thick (or ultra-thin) metal film, it is difficult for the conventional method to accurately determine optical parameters, physical thicknesses, etc. of the ultra-thick (or ultra-thin) metal film due to the severe attenuation (almost no change) of an ellipsometric signal by the ultra-thick (or ultra-thin) metal film; an ellipsometry equation based on the conventional ellipsometry method is a set of transcendental equations, cannot obtain an analytic solution, a physical model must be established first, and then parameters in the model are determined by an inversion method, namely a so-called trial and error method, so that the thickness and optical constants of a film often appear non-uniqueness in the fitting process due to the increase of unknown quantity and the shortage of limiting conditions; generally, three growth modes of a film exist, namely island-shaped growth, layered growth and island-layer mixed growth, for a nano-scale metal film, the film morphology is greatly influenced by the substrate surface, structure and morphology, and is often completely different from the morphology or/and properties of a conventional film or a body material, a proper dispersion equation is required to be carefully selected when an ellipsometer is used for analyzing the film (such as a film with rough surface and defects of a large number of interfaces, holes and the like), and the optical parameters, the physical parameters and the like are difficult to accurately measure under the weak signal condition in the conventional ellipsometry due to the defects of the constraint equation and the complexity of the selection of the dispersion equation.
In recent years, with the miniaturization and the improvement of integration of various devices, a metal film of a nanometer thickness is increasingly important in the manufacture of semiconductor chips and various devices. Due to the unique properties of the nano-thick metal film different from the corresponding body material, the nano-thick metal film is increasingly widely applied in the fields of microelectronics, integrated optics, solar cells, biomedicine, chemistry, aerospace technology and the like, and shows specific novel functions, so that the nano-thick metal film is indispensable. At present, means for detecting a nano-thickness thin film include an atomic force microscope, a scanning electron microscope, a transmission electron microscope, a scanning tunneling microscope, a spectrophotometer, various film thickness meters and the like, and these means may be capable of realizing detection with sub-nanometer resolution, but cannot be applied to an actual production line due to the destructiveness of devices, complex operation and low detection efficiency. Therefore, the detection requirements for advanced process control and optimization, which are rapidly developed, cannot be satisfied. In order to better solve the problem that the thickness of the nano-film cannot be measured accurately and rapidly without damage, especially the problem that the conventional ellipsometry cannot measure the ultra-thin metal film (for example, the thickness is below 10 nm), some improvements have been proposed, including the development of techniques and methods, such as multi-angle measurement, interference enhancement, parametric modeling of dielectric function, combination of ellipsometry parameter and transmittance measurement and ellipsometry parameter and reflectance measurement. Such as: the measurement of the thickness of the metal Cu nano film with the thickness of 2.86-12.6nm is realized by utilizing an ellipsometric parameter and reflectivity collaborative analysis method; the thickness measured by the above method is 3.9nm, while the thickness measured by AFM technique is 2.86nm, and the thickness deviation between the two is as high as 36.4% (| ellipsometric thickness-AFM measurement thickness |/AFM measurement thickness × 100). Therefore, the thickness deviation measured by the currently used method is large.
Therefore, the development of a new method for accurately measuring the ultrathin metal film with the thickness of less than 10nm is very important for scientific research and has important practical significance and value for industrial production.
Disclosure of Invention
Therefore, the invention provides a method and a device for detecting an ultrathin metal film by using a spectroscopic ellipsometer, which aim to solve the problem that the measurement method in the prior art has large measurement data deviation and poor sensitivity, so that the actual use requirement cannot be met.
The invention provides a method for detecting an ultrathin metal film by using a spectroscopic ellipsometer, which comprises the following steps of: constructing a first system consisting of a silicon substrate and a natural silicon oxide layer, and measuring ellipsometry parameters of the silicon substrate and the natural silicon oxide layer in the first system by using a spectroscopic ellipsometer; determining an optical constant corresponding to the silicon substrate and an optical constant and thickness data corresponding to the natural silicon oxide layer according to the ellipsometry parameter;
preparing a non-absorption dielectric layer on the first system, constructing a second system consisting of a silicon substrate, a natural silicon oxide layer and the non-absorption dielectric layer, and measuring an ellipsometry parameter of the non-absorption dielectric layer in the second system by using a spectroscopic ellipsometer; determining the optical constant and the thickness data of the non-absorption dielectric layer according to the ellipsometry parameter of the non-absorption dielectric layer, the optical constant corresponding to the silicon substrate and the optical constant and the thickness data corresponding to the natural silicon oxide layer;
preparing a metal film layer on the second system, constructing a third system consisting of a silicon substrate, a natural silicon oxide layer, a non-absorption dielectric layer and the metal film layer, and measuring an ellipsometry parameter of the metal film layer in the third system by using a spectroscopic ellipsometer; and determining the optical constant and the thickness data of the metal film layer according to the ellipsometry parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant and the thickness data corresponding to the natural silicon oxide layer and the optical constant and the thickness data of the non-absorption dielectric layer.
Further, the preparing a non-absorbing medium layer on the first system specifically includes: and preparing a non-absorption dielectric layer on the natural silicon oxide layer by adopting any one or two modes of chemical vapor deposition, magnetron sputtering deposition and electron beam evaporation deposition.
Further, the non-absorption medium layer is a medium material which is non-absorption to light in the spectrum measuring range of the ellipsometer, and the non-absorption medium layer comprises SiO2Film, Si3N4Film and MgF2Any one of the films; the thickness data of the non-absorption dielectric layer is 500 nm-2 um.
Further, in the process of measuring the ellipsometric parameter by using the spectroscopic ellipsometer, the wavelength range parameter of the incident light of the spectroscopic ellipsometer is determined to be 190nm to 2500nm and the incident angle parameter of the incident light is determined to be 45 to 70 degrees.
Further, the determining an optical constant corresponding to the silicon substrate and an optical constant and thickness data corresponding to the natural silicon oxide layer according to the ellipsometry parameter specifically includes:
constructing a first ellipsometry fitting model corresponding to the first system, fitting ellipsometry parameters of a silicon substrate and a natural silicon oxide layer in the first system by using the first ellipsometry fitting model, and obtaining and recording an optical constant corresponding to the silicon substrate and optical constant and thickness data corresponding to the natural silicon oxide layer;
determining the optical constant and the thickness data of the non-absorption dielectric layer according to the ellipsometry parameter of the non-absorption dielectric layer, the optical constant corresponding to the silicon substrate and the optical constant and the thickness data corresponding to the natural silicon oxide layer, specifically comprising:
constructing a second ellipsometry fitting model corresponding to the second system, fitting the ellipsometry parameters of the non-absorption medium layer in the second system by using the second ellipsometry fitting model, and obtaining and recording optical constants and thickness data of the non-absorption medium layer;
determining the optical constant and the thickness data of the metal film layer according to the ellipsometry parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant and the thickness data corresponding to the natural silicon oxide layer and the optical constant and the thickness data of the non-absorption dielectric layer, and specifically comprises the following steps:
and constructing a third ellipsometry fitting model corresponding to the third system, and fitting the ellipsometry parameters of the metal film layer in the third system by using the third ellipsometry fitting model to obtain the optical constant and the thickness data of the metal film layer.
Further, the metal film layer comprises any one metal element of 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 ultrathin metal film by using a spectroscopic ellipsometer, which comprises the following steps:
setting the operating parameters of the spectrum ellipsometer;
constructing an ellipsometry fitting model for measuring the metal film layer;
respectively measuring ellipsometry parameters corresponding to the structural layers of the ellipsometry fitting model by using the spectroscopic ellipsometer; the structure layer comprises a silicon substrate layer, a natural silicon oxide layer, a first non-absorption medium layer, a transition layer, a first metal film layer, an air rough layer and a first air layer;
the ellipsometry parameter corresponding to the second non-absorption dielectric layer in the transition layer is the same as the ellipsometry parameter corresponding to the first non-absorption dielectric layer;
and fitting the ellipsometry parameters corresponding to the structural layer with the ellipsometry fitting model to obtain the optical constant and the thickness data of the metal film layer.
Further, the operating parameters include: at least one of an incident angle parameter, a measured wavelength range parameter, a measured wavelength interval parameter, and a reference characterization wavelength parameter;
the transition layer consists of a second non-absorption medium layer and a second metal film layer;
the air rough layer consists of a third metal film layer and a second air layer.
The invention provides a device for detecting an ultrathin metal film by using a spectroscopic ellipsometer, which comprises:
the first system parameter determination unit is used for constructing a first system consisting of a silicon substrate and a natural silicon oxide layer, and measuring ellipsometry parameters of the silicon substrate and the natural silicon oxide layer in the first system by using a spectroscopic ellipsometer; determining an optical constant corresponding to the silicon substrate and an optical constant and thickness data corresponding to the natural silicon oxide layer according to the ellipsometry parameter;
the second system parameter determining unit is used for preparing a non-absorption dielectric layer on the first system, constructing a second system consisting of a silicon substrate, a natural silicon oxide layer and the non-absorption dielectric layer, and measuring the ellipsometry parameter of the non-absorption dielectric layer in the second system by using a spectroscopic ellipsometer; determining the optical constant and the thickness data of the non-absorption dielectric layer according to the ellipsometry parameter of the non-absorption dielectric layer, the optical constant corresponding to the silicon substrate and the optical constant and the thickness data corresponding to the natural silicon oxide layer;
a third system parameter determination unit, configured 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 dielectric layer, and the metal film layer, and measure an ellipsometry parameter of the metal film layer in the third system by using a spectroscopic ellipsometer; and determining the optical constant and the thickness data of the metal film layer according to the ellipsometry parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant and the thickness data corresponding to the natural silicon oxide layer and the optical constant and the thickness data of the non-absorption dielectric layer.
Further, the second system parameter determining unit is specifically configured to: and preparing a non-absorption dielectric layer on the natural silicon oxide layer by adopting any one or two modes of chemical vapor deposition, magnetron sputtering deposition and electron beam evaporation deposition.
Further, the non-absorption medium layer is a medium material which is non-absorption to light in the spectrum measuring range of the ellipsometer, and the non-absorption medium layer comprises SiO2Film, Si3N4Film and MgF2Any one of the films; the thickness data of the non-absorption dielectric layer is 500 nm-2 um.
Further, in the process of measuring the ellipsometric parameter by using the spectroscopic ellipsometer, the wavelength range parameter of the incident light of the spectroscopic ellipsometer is determined to be 190nm to 2500nm and the incident angle parameter of the incident light is determined to be 45 to 70 degrees.
Further, the first system parameter determining unit is specifically configured to: constructing a first ellipsometry fitting model corresponding to the first system, fitting ellipsometry parameters of a silicon substrate and a natural silicon oxide layer in the first system by using the first ellipsometry fitting model, and obtaining and recording an optical constant corresponding to the silicon substrate and optical constant and thickness data corresponding to the natural silicon oxide layer;
the second system parameter determination unit is specifically configured to: constructing a second ellipsometry fitting model corresponding to the second system, fitting the ellipsometry parameters of the non-absorption medium layer in the second system by using the second ellipsometry fitting model, and obtaining and recording optical constants and thickness data of the non-absorption medium layer;
the third system parameter determining unit is specifically configured to: and constructing a third ellipsometry fitting model corresponding to the third system, and fitting the ellipsometry parameters of the metal film layer in the third system by using the third ellipsometry fitting model to obtain the optical constant and the thickness data of the metal film layer.
Further, the metal film layer comprises any one metal element of gold, platinum, palladium and titanium, and the thickness data of the metal film layer is less than 10 nm.
The present invention provides an optical characterization device for an ultra-thin metal film using a spectroscopic ellipsometer, comprising:
the operating parameter setting unit is used for setting the operating parameters of the spectroscopic ellipsometer;
the ellipsometry fitting model building unit is used for building an ellipsometry fitting model for measuring the metal film layer;
the ellipsometry parameter measuring unit is used for measuring the ellipsometry parameters corresponding to the structural layers of the ellipsometry fitting model by using the spectroscopic ellipsometer; the structure layer comprises a silicon substrate layer, a natural silicon oxide layer, a first non-absorption medium layer, a transition layer, a first metal film layer, an air rough layer and a first air layer; the ellipsometry parameter corresponding to the second non-absorption dielectric layer in the transition layer is the same as the ellipsometry parameter corresponding to the first non-absorption dielectric layer;
and the metal film layer data obtaining unit is used for fitting the ellipsometric parameters corresponding to the structural layer with the ellipsometric fitting model to obtain the optical constant and the thickness data of the metal film layer.
Further, the operating parameters include: at least one of an incident angle parameter, a measured wavelength range parameter, a measured wavelength interval parameter, and a reference characterization wavelength parameter;
the transition layer consists of a second non-absorption medium layer and a second metal film layer;
the air rough layer consists of a third metal film layer and a second air layer.
The method for detecting the ultrathin metal film by using the spectroscopic ellipsometer can perform nondestructive, high-precision and high-sensitivity detection on the ultrathin metal film, and has simple instrument configuration and better reproducibility. The method can be integrated into an integrated circuit production line, meets the process control and optimized detection requirements of the integrated circuit, and enlarges the ellipsometry measurement range of the limit metal film.
By adopting the optical characterization method of the ultrathin metal film by using the spectroscopic ellipsometer, the nondestructive, high-precision and high-sensitivity detection can be carried out on the metal film with the film thickness of less than 10 nm; the device is simple in configuration, easy to operate and good in reproducibility; meanwhile, the sample cannot be damaged, so that the problem that the traditional measurement method damages the sample to cause unrepeatability of the experiment is avoided; in addition, the method can be integrated into an integrated circuit production line, meets the detection requirements of process control and optimization of the integrated circuit, and enlarges the ellipsometry measurement range of the limit metal film.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic flow chart of a method for detecting an ultra-thin metal film by using a spectroscopic ellipsometer according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an apparatus for detecting an ultra-thin metal film by using a spectroscopic ellipsometer according to an embodiment of the present invention;
FIG. 3 is a schematic flow chart of a method for optically characterizing an ultra-thin metal film using a spectroscopic ellipsometer according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of an apparatus for optical characterization of an ultra-thin metal film using a spectroscopic ellipsometer according to an embodiment of the present invention;
FIG. 5a is an AFM profile of steps formed by evaporating an ultra-thin Pt film and an un-evaporated ultra-thin Pt film on a system consisting of a silicon substrate, a natural silicon oxide layer and a non-absorbing dielectric layer by electron beam evaporation according to an embodiment of the present invention;
FIG. 5b is a vertical height profile of a step formed by evaporating an ultra-thin Pt film and an un-evaporated ultra-thin Pt film on a system consisting of a silicon substrate, a natural silicon oxide layer and a non-absorbing dielectric layer by electron beam evaporation according to an embodiment of the present invention;
FIG. 6 is an ellipsometric parameter-fitted graph of an ultra-thin Pt film evaporated on a system composed of a silicon substrate, a native silicon oxide layer and a non-absorbing dielectric layer according to an embodiment of the present invention;
FIG. 7 is a block diagram of a first ellipsometric fitting model according to an embodiment of the present invention;
FIG. 8a shows an embodiment of the present invention using electron beam evaporation on a silicon substrate, a native silicon oxide layer and a silicon oxide SiO2Forming an AFM (atomic force microscopy) topography of a step by the evaporated ultrathin Pt film and the unevaporated ultrathin Pt film on the system consisting of the layers;
FIG. 8b shows an embodiment of the present invention using electron beam evaporation on a silicon substrate, a native silicon oxide layer and a silicon oxide SiO2A vertical height curve graph of a step formed by an evaporated ultrathin Pt film and an unevaporated ultrathin Pt film on a system consisting of the layers;
FIG. 9 shows an embodiment of the present invention in a silicon substrate, a native silicon oxide layer and a silicon oxide SiO2Evaporating an ellipsometric parameter fitting graph of the ultrathin Pt film on a system consisting of the layers;
fig. 10 is a structural diagram of a second ellipsometric fitting model according to an embodiment of the present invention.
Detailed Description
In order to make the objects, 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 with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The application provides a method for accurately measuring optical parameters and thickness data of an ultrathin metal film based on an optical ellipsometry technology, so that the limitation of conventional ellipsometry is overcome, and the accurate measurement of the ultrathin metal film with the thickness of less than 10nm is realized. This not only expands the measurement object range of the ellipsometer, but also enriches the ellipsometry measurement method, and will actively promote and promote the development and progress of the ultra-thin metal film measurement technology required in scientific research and industrial production. Hereinafter, an embodiment of the method for inspecting an ultra-thin metal film using a spectroscopic ellipsometer according to the present invention will be described in detail. As shown in fig. 1, which is a schematic flow chart of a method for detecting an ultra-thin metal film by using a spectroscopic ellipsometer according to an embodiment of the present invention, the specific implementation process includes the following steps:
step 101: constructing a first system consisting of a silicon substrate and a natural silicon oxide layer, and measuring ellipsometry parameters of the silicon substrate and the natural silicon oxide layer in the first system by using a spectroscopic ellipsometer; and determining the optical constant corresponding to the silicon substrate and the optical constant and thickness data corresponding to the natural silicon oxide layer according to the ellipsometry parameter.
In this step, in the process of measuring the ellipsometry parameters of the silicon substrate (Si substrate) and the natural silicon oxide layer in the first system by using the spectroscopic ellipsometer, it is required to first determine that the wavelength range parameter of incident light of the spectroscopic ellipsometer is 190nm to 2500nm and the incident angle parameter of the incident light is 45 ° to 70 °.
Specifically, the determining, according to the ellipsometry parameter, an optical constant corresponding to the silicon substrate and an optical constant and thickness data corresponding to the natural silicon oxide layer includes: constructing a first ellipsometry fitting model corresponding to the first system, fitting ellipsometry parameters of a silicon substrate and a natural silicon oxide layer in the first system by using the first ellipsometry fitting model to obtain an optical constant corresponding to the silicon substrate and optical constant and thickness data corresponding to the natural silicon oxide layer, and recording and storing the data;
step 102: preparing a non-absorption dielectric layer on the first system, constructing a second system consisting of a silicon substrate, a natural silicon oxide layer and the non-absorption dielectric layer, and measuring an ellipsometry parameter of the non-absorption dielectric layer in the second system by using a spectroscopic ellipsometer; and determining the optical constant and the thickness data of the non-absorption dielectric layer according to the ellipsometry parameter of the non-absorption dielectric layer, the optical constant corresponding to the silicon substrate and the optical constant and the thickness data corresponding to the natural silicon oxide layer.
In this step, the specific implementation manner of preparing the non-absorbing medium layer on the first system includes: on a silicon substrate and a native silicon oxide layerThe non-absorption dielectric layer is prepared by adopting any one or two modes of chemical vapor deposition, magnetron sputtering deposition and electron beam evaporation deposition. Wherein the non-absorption dielectric layer is a dielectric material which is non-absorption to light in the spectrum measurement range of the ellipsometer and comprises SiO2Film, Si3N4Film and MgF2A film, etc.; the thickness data of the non-absorption dielectric layer is 500 nm-2 um.
In the specific implementation process, in the process of measuring the ellipsometry parameter of the non-absorption medium layer in the second system by using the spectroscopic ellipsometer, it is required to determine in advance that the wavelength range parameter of incident light of the spectroscopic ellipsometer is 190nm to 2500nm and the incident angle parameter of the incident light is 45 ° to 70 °.
Specifically, the determining of the optical constant and the thickness data of the non-absorbing dielectric layer according to the ellipsometry parameter of the non-absorbing dielectric layer, the optical constant corresponding to the silicon substrate, and the optical constant and the thickness data corresponding to the natural silicon oxide layer includes: constructing a second ellipsometry fitting model corresponding to the second system, fitting the ellipsometry parameters of the non-absorption medium layer in the second system by using the second ellipsometry fitting model to obtain optical constants and thickness data of the non-absorption medium layer, and recording and storing the data;
step 103: preparing a metal film layer on the second system, constructing a third system consisting of a silicon substrate, a natural silicon oxide layer, a non-absorption dielectric layer and the metal film layer, and measuring an ellipsometry parameter of the metal film layer in the third system by using a spectroscopic ellipsometer; and determining the optical constant and the thickness data of the metal film layer according to the ellipsometry parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant and the thickness data corresponding to the natural silicon oxide layer and the optical constant and the thickness data of the non-absorption dielectric layer.
In this step, the specific implementation manner of preparing the metal film layer on the second system includes: and preparing a metal film layer on the silicon substrate, the natural silicon oxide layer and the non-absorption dielectric layer by adopting any one or two modes of chemical vapor deposition, magnetron sputtering deposition and electron beam evaporation deposition.
In the specific implementation process, in the process of measuring the ellipsometry parameter of the metal film layer in the third system by using the spectroscopic ellipsometer, it is also required to determine in advance that the wavelength range parameter of the incident light of the spectroscopic ellipsometer is 190nm to 2500nm and the incident angle parameter of the incident light is 45 ° to 70 °.
Specifically, the determining of the optical constant and the thickness data of the metal film layer according to the ellipsometry parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant and the thickness data corresponding to the natural silicon oxide layer, and the optical constant and the thickness data of the non-absorption dielectric layer includes: and constructing a third ellipsometry fitting model corresponding to the third system, fitting the ellipsometry parameters of the metal film layer in the third system by using the third ellipsometry fitting model to obtain the optical constant and thickness data of the metal film layer, and recording and storing the data. The metal film layer comprises any one metal element of gold, platinum, palladium, titanium and the like, and the thickness data of the metal film layer is less than 10 nm.
In one embodiment, the metal film layer Pt (with a thickness of about 3nm) is detected by a spectroscopic ellipsometer, wherein the incident angle of the spectroscopic ellipsometer can be set to 70 °, the wavelength range can be set to 380nm to 930nm, and the non-absorption medium layer is silicon nitride (Si) (Si is a silicon nitride) layer3N4) The specific method of the membrane is as follows:
(1) constructing a first system consisting of a Si substrate and a native silicon oxide layer: an n-Si (100) substrate can be selected as a first system (system 1) consisting of a Si substrate and a natural silicon oxide layer, an spectroscopic ellipsometer is utilized to measure the first system, ellipsometry parameters of the Si substrate and the natural silicon oxide layer in the first system are obtained, and optical constants of the Si substrate and the natural silicon oxide layer in the first system and thickness data of the natural silicon oxide layer in the first system are calculated and recorded. In a specific implementation, the calculated thickness data of the native silicon oxide layer is 1.27 nm; the calculated refractive index of the native silicon oxide layer is 1.5274 and the extinction coefficient is 0 at a wavelength of 633 nm.
(2) Construction of a Si substrate, a native silicon oxide layer and a non-absorbing dielectric layer (such as silicon nitride (Si)3N4) Layer or silicon nitride (Si)3N4) Film) of a second system consisting of: silicon nitride (Si) with a thickness of 1um can be prepared on the first system by chemical vapor deposition3N4) The film is formed to provide a second system (i.e., system 2) in which silicon nitride (Si) is measured using a spectroscopic ellipsometer3N4) Ellipsometric parameters of the film were taken into account in the optical constants and thickness of the native silicon oxide layer recorded, thereby calculating and recording the silicon nitride (Si) in the second system3N4) Optical constants and thickness of the film. Wherein the calculated silicon nitride (Si)3N4) The thickness of the film was 947.66 nm; calculated silicon nitride (Si) at a wavelength of 633nm3N4) The film had a refractive index of 1.9722 and an extinction coefficient of 0.
(3) A third system (i.e., system 3) of a Si substrate, a native silicon oxide layer, a non-absorbing dielectric layer system, and a metal film layer (e.g., a platinum Pt layer or a platinum Pt film) is prepared. Evaporating a platinum Pt film with the thickness of about 3nm above a second system by using a high vacuum electron beam evaporation method to obtain a third system, measuring an ellipsometry parameter of the platinum Pt film in the third system by using a spectroscopic ellipsometer, and bringing the ellipsometry parameter into the recorded optical constant and thickness of the natural silicon oxide layer of the first system and the silicon nitride (Si) in the second system3N4) The optical constants and the thicknesses of the films were calculated and recorded, thereby calculating and recording the optical constants and the thicknesses of the platinum Pt films in the third system. Wherein the calculated thickness of the platinum Pt film is 3.15 nm; the calculated refractive index of the platinum Pt film was 2.2818 and the extinction coefficient was 4.77632 at a wavelength of 633 nm.
As shown in fig. 5(a), the left side of the dotted line is on the silicon substrate, the natural silicon oxide layer, and the silicon nitride (Si)3N4) An ultra-thin Pt film is evaporated on the layer system, and the silicon substrate, the natural silicon oxide layer and the silicon nitride (Si) are not on the right side of the dotted line3N4) Evaporating the ultra-thin Pt film on the second system of layers. As shown in fig. 5(b), electron beam evaporation is performed on the Si substrate, the natural silicon oxide layer, and silicon nitride (Si)3N4) The vertical height profile of the step formed by the evaporated ultrathin Pt film and the unevaporated ultrathin Pt film on the second system of the layer composition. It can be seen from fig. 5(a) and 5(b) that the thickness of the platinum Pt film evaporated by the high vacuum electron beam evaporation system is about 2.954 nm. The thickness of the metal film (dAFM) was measured using an Atomic Force Microscope (AFM) and compared to the thickness fitted with an ellipsometer (dEI), the thickness deviation (| dEl-dAFM |/dAFM × 100) was calculated to be 6.9%.
Fig. 7 is a structural diagram of a first ellipsometric fitting model according to an embodiment of the present invention. The structural layer corresponding to the first ellipsometric fitting model comprises: si substrate layer (Si Leng osci) and natural silicon oxide layer (SiO)2(native)), non-absorbing dielectric layer (Si)3N4-TL), transition layer (Pt/Si)3N4) The Air-purifying film comprises a metal film layer (Pt) (plain) -DL #1), an Air rough layer (Roughness-Air/Pt (plain …)), and an Air layer (Air). Wherein silicon nitride (Si) is prepared on a Si substrate by chemical vapor deposition3N4) A film having a thickness of 1000 nm; application of high vacuum electron beam evaporation method to silicon nitride (Si)3N4) A platinum Pt film with a thickness of about 3nm was evaporated over the film. The Si substrate layer is a Leng oscillor dispersion model; the natural silicon oxide layer is a Cauchy dispersion model; the non-absorbing medium layer is Si3N4Tauc-Lorentz dispersion model of the film; the transition layer is Si3N4A mixed layer of layers and a Pt layer, which is a Bruggeman effective approximation model; the platinum Pt film is a Drude-Lorentz Oscillator dispersion model; the air rough layer is a mixed layer of a Pt layer and an air layer, and is a Bruggeman effective approximate model.
In another embodiment, the metal film Pt (thickness of about 3nm) is detected by a spectroscopic ellipsometer with an incident angle of 70 °, a wavelength range of 380nm to 930nm, and a non-absorbing dielectric layer of silicon oxide (SiO)2) The specific method comprises the following steps:
(1) constructing a first system consisting of a Si substrate and a natural silicon oxide layer: an n-Si (100) substrate can be selected as a first system (system 1) consisting of a Si substrate and a natural silicon oxide layer, an spectroscopic ellipsometer is utilized to measure the first system, ellipsometry parameters of the Si substrate and the natural silicon oxide layer in the first system are obtained, and optical constants of the Si substrate and the natural silicon oxide layer in the first system and thickness data of the natural silicon oxide layer in the first system are calculated and recorded. Wherein the calculated thickness of the native silicon oxide layer is 1.27 nm; the calculated refractive index of the native silicon oxide layer is 1.5274 and the extinction coefficient is 0 at a wavelength of 633 nm.
(2) Constructing a second system consisting of the Si substrate, the natural silicon oxide layer and the non-absorption dielectric layer: preparing silicon oxide (SiO) with thickness of 1um above the first system by chemical vapor deposition2) The film was formed into a second system, and the silicon oxide (SiO) in the second system was measured using a spectroscopic ellipsometer2) Ellipsometry parameters of the film were taken into the optical constants and thickness of the native silicon oxide layer recorded, thereby calculating and recording the silicon oxide (SiO) in the second system2) Optical constants and thickness of the film. Wherein the calculated silicon oxide (SiO)2) The thickness of the film was 1033.85 nm; calculated silicon oxide (SiO) at a wavelength of 633nm2) The film had a refractive index of 1.4699 and an extinction coefficient of 0.
(3) Preparing a Si substrate, a natural silicon oxide layer, a non-absorption dielectric layer system and a metal film layer system: evaporating a platinum Pt film with the thickness of 3nm above a second system by using a high vacuum electron beam evaporation method to obtain a third system, measuring an ellipsometry parameter of the platinum Pt film in the third system by using a spectroscopic ellipsometer, and bringing the ellipsometry parameter into the recorded optical constant and thickness of the natural silicon oxide layer of the first system and the silicon oxide (SiO) in the second system2) The optical constants and the thicknesses of the films were calculated and recorded, thereby calculating and recording the optical constants and the thicknesses of the platinum Pt films in the third system. Wherein the calculated thickness of the platinum Pt film is 3.815 nm; the calculated refractive index of the platinum Pt film was 2.3426 and the extinction coefficient was 4.20478 at a wavelength of 633 nm.
As shown in FIG. 8(a), silicon oxide (SiO) is deposited on a Si substrate or a native silicon oxide layer by electron beam evaporation2) AFM topography of steps formed by the evaporated ultrathin Pt film and the unevaporated ultrathin Pt film on the first system of composition. Wherein the left side of the dotted line is on the Si substrate, the natural silicon oxide layer and the silicon oxide (SiO)2) An ultra-thin Pt film was evaporated on the layer system, and the Si substrate, the native silicon oxide layer and the silicon oxide (SiO) were not present on the right side of the dotted line2) Evaporating the ultra-thin Pt film on the second system of layers. As shown in fig. 8(b), electron beam evaporation was used to form a silicon oxide layer on a Si substrate, a natural silicon oxide layer, and silicon oxide (SiO)2) Vertical height profile of the step formed by the evaporated ultrathin Pt film and the unevaporated ultrathin Pt film on the second system of layer composition. It can be seen from fig. 8(a) and (b) that the thickness of the platinum Pt film evaporated by the high vacuum electron beam evaporation system is about 2.99 nm. The thickness of the metal film (dAFM) was measured using an Atomic Force Microscope (AFM) and compared to the thickness fitted with an ellipsometer (dEI), the thickness deviation (| dEl-dAFM |/dAFM × 100) was calculated to be 27%.
As shown in fig. 10, which is a block diagram of a second ellipsometric fitting model. The structural layer of the second helioelliptic ellipsometric fitting model includes: si substrate layer (Si Leng osci) and natural silicon oxide layer (SiO)2(native)), non-absorbing dielectric layer (Cau-SiO (CVD)), transition layer (Pt/SiO)2) The Air-purifying film comprises a metal film layer (Pt) (plain) -DL #1), an Air rough layer (Roughness-Air/Pt (plain …)), and an Air layer (Air). Wherein silicon oxide (SiO) is prepared on a Si substrate by chemical vapor deposition2) A film having a thickness of 1000 nm; on silicon oxide (SiO) by high vacuum electron beam evaporation2) A platinum Pt film with a thickness of about 3nm was evaporated over the film. The Si substrate layer is a Leng oscillor dispersion model; the natural silicon oxide layer is a Cauchy dispersion model; the non-absorption medium layer is silicon oxide (SiO)2) (ii) a Cauchy dispersion model of the film; the transition layer is SiO2A mixed layer of layers and a Pt layer, which is a Bruggeman effective approximation model; the platinum Pt film is a Drude-Lorentz Oscillator dispersion model; the air rough layer is a mixed layer of a Pt layer and an air layer, and is a Bruggeman effective approximate model.
As shown in FIG. 6, the silicon nitride layer is formed on a Si substrate, a natural silicon oxide layer and silicon nitride (Si)3N4) Ellipsometric parametric fit of evaporated ultrathin Pt films on the second system of layer compositions. As shown in fig. 9, it is formed on a Si substrate/native silicon oxide layer/silicon oxide (SiO)2) Ellipsometric parameter fitting graph of evaporated ultrathin Pt film on the layer system. As can be seen from FIGS. 6 and 9, one or more of the calculation stepsThe fitting degree in mathematics is extremely good, namely the mean square error EMA is extremely low, so that the calculation result can be shown to be more consistent with the real morphology of the platinum Pt film.
By adopting the method for detecting the ultrathin metal film by using the spectroscopic ellipsometer, the nondestructive, high-precision and high-sensitivity detection can be carried out on the metal film with the film thickness of less than 10nm, the deviation between the measured metal thickness and the actual thickness is very small, the spectroscopic ellipsometer can realize the detection and fitting of the metal film with the thickness of less than 10nm, the detection precision and sensitivity of the ultrathin metal film are greatly improved, and the thickness range of the detectable metal film is expanded. The device has the advantages of simple configuration, easy operation, stable and reliable measurement result, wide application range and better reproducibility; meanwhile, the sample cannot be damaged, so that the problem that the traditional measurement method damages the sample to cause unrepeatability of the experiment is avoided; in addition, the method can be integrated into an integrated circuit production line, meets the detection requirements of process control and optimization of the integrated circuit, and enlarges the ellipsometry measurement range of the limit metal film.
Corresponding to the method for detecting the ultrathin metal film by using the spectroscopic ellipsometer, the invention also provides a device for detecting the ultrathin metal film by using the spectroscopic ellipsometer. Since the embodiment of the apparatus is similar to the above method embodiment, it is relatively simple to describe, and please refer to the description of the above method embodiment, and the following embodiment of the apparatus for detecting an ultra-thin metal film by using an spectroscopic ellipsometer is only exemplary. Fig. 2 is a schematic structural diagram of an apparatus for detecting an ultra-thin metal film by using a spectroscopic ellipsometer according to an embodiment of the present invention.
The device for detecting the ultrathin metal film by using the spectroscopic ellipsometer specifically comprises the following parts:
a first system parameter determining unit 201, configured to construct a first system composed of a silicon substrate and a natural silicon oxide layer, and measure ellipsometry parameters of the silicon substrate and the natural silicon oxide layer in the first system by using a spectroscopic ellipsometer; determining an optical constant corresponding to the silicon substrate and an optical constant and thickness data corresponding to the natural silicon oxide layer according to the ellipsometry parameter;
a second system parameter determining unit 202, configured to prepare a non-absorbing dielectric layer on the first system, construct a second system composed of a silicon substrate, a natural silicon oxide layer, and the non-absorbing dielectric layer, and measure an ellipsometry parameter of the non-absorbing dielectric layer in the second system by using a spectroscopic ellipsometer; determining the optical constant and the thickness data of the non-absorption dielectric layer according to the ellipsometry parameter of the non-absorption dielectric layer, the optical constant corresponding to the silicon substrate and the optical constant and the thickness data corresponding to the natural silicon oxide layer;
a third system parameter determining unit 203, configured 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 dielectric layer, and the metal film layer, and measure an ellipsometry parameter of the metal film layer in the third system by using a spectroscopic ellipsometer; and determining the optical constant and the thickness data of the metal film layer according to the ellipsometry parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant and the thickness data corresponding to the natural silicon oxide layer and the optical constant and the thickness data of the non-absorption dielectric layer.
The device for detecting the ultrathin metal film by using the spectroscopic ellipsometer can perform nondestructive, high-precision and high-sensitivity detection on the metal film with the film thickness of less than 10nm, has small deviation between the measured metal thickness and the actual thickness, and enables the spectroscopic ellipsometer to realize detection and fitting of the metal film with the film thickness of less than 10nm, thereby greatly improving the detection precision and sensitivity of the ultrathin metal film and expanding the thickness range of the detectable metal film. The device has the advantages of simple configuration, easy operation, stable and reliable measurement result, wide application range and better reproducibility; meanwhile, the sample cannot be damaged, so that the problem that the traditional measurement method damages the sample to cause unrepeatability of the experiment is avoided; in addition, the method can be integrated into an integrated circuit production line, meets the detection requirements of process control and optimization of the integrated circuit, and enlarges the ellipsometry measurement range of the limit metal film.
Hereinafter, embodiments of the method for optically characterizing an ultra-thin metal film using a spectroscopic ellipsometer according to the present invention will be described in detail. As shown in fig. 3, which is a schematic flow chart of an optical characterization method for an ultra-thin metal film using a spectroscopic ellipsometer according to an embodiment of the present invention, the specific implementation process includes the following steps:
step 301: the operating parameters of the spectroscopic ellipsometer are set. Wherein the operating parameters include: at least one of an incident angle parameter, a measured wavelength range parameter, a measured wavelength interval parameter, and a reference characterizing wavelength parameter.
Step 302: and constructing an ellipsometry fitting model for measuring the metal film layer.
Step 303: respectively measuring ellipsometry parameters corresponding to the structural layers of the ellipsometry fitting model by using the spectroscopic ellipsometer; the structure layer comprises a silicon substrate layer, a natural silicon oxide layer, a first non-absorption medium layer, a transition layer, a first metal film layer, an air rough layer and a first air layer; the ellipsometry parameter corresponding to the second non-absorption dielectric layer in the transition layer is the same as the ellipsometry parameter corresponding to the first non-absorption dielectric layer.
Step 304: and fitting the ellipsometry parameters corresponding to the structural layer with the ellipsometry fitting model to obtain the optical constant and the thickness data of the metal film layer.
The transition layer is composed of a second non-absorption medium layer and a second metal film layer, and 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 herein.
The air rough layer consists of a third metal film layer and a second air layer, and the transition layer is a Bruggeman effective approximate model. It should be noted that, in the specific implementation process, the air roughness layer is not limited to the Bruggeman effective approximation model, but may also be other fitting models, which is not specifically limited herein.
By adopting the optical characterization method of the ultrathin metal film by using the spectroscopic ellipsometer, the nondestructive, high-precision and high-sensitivity optical property characterization can be carried out on the metal film with the film thickness of less than 10 nm; the device is simple in configuration, easy to operate and good in reproducibility; meanwhile, the sample cannot be damaged, so that the problem that the traditional measurement method damages the sample to cause unrepeatability of the experiment is avoided; in addition, the method can be integrated into an integrated circuit production line, meets the detection requirements of process control and optimization of the integrated circuit, and enlarges the ellipsometry measurement range of the limit metal film.
Corresponding to the above-mentioned method for optically characterizing an ultra-thin metal film using a spectroscopic ellipsometer, the present invention also provides an apparatus for optically characterizing an ultra-thin metal film using a spectroscopic ellipsometer. Since the embodiment of the apparatus is similar to the above method embodiment, it is relatively simple to describe, and please refer to the description of the above method embodiment, and the following embodiment of the apparatus for optical characterization of ultra-thin metal films using spectroscopic ellipsometer is only illustrative. Fig. 4 is a schematic structural diagram of an optical characterization device for an ultra-thin metal film using a spectroscopic ellipsometer according to an embodiment of the present invention.
The optical characterization device for the ultrathin metal film by using the spectroscopic ellipsometer specifically comprises the following parts:
an operation parameter setting unit 401 for setting the operation parameters of the spectroscopic ellipsometer.
An ellipsometry fitting model constructing unit 402, configured to construct an ellipsometry fitting model for measuring the metal film layer.
An ellipsometry parameter measuring unit 403, configured to measure ellipsometry parameters corresponding to the structural layers of the ellipsometry fitting model by using the spectroscopic ellipsometer; the structure layer comprises a silicon substrate layer, a natural silicon oxide layer, a first non-absorption medium layer, a transition layer, a first metal film layer, an air rough layer and a first air layer; the ellipsometry parameter corresponding to the second non-absorption dielectric layer in the transition layer is the same as the ellipsometry parameter corresponding to the first non-absorption dielectric layer.
The metal film data obtaining unit 404 is configured to fit the ellipsometry parameter corresponding to the structural layer with the ellipsometry fitting model to obtain an optical constant and thickness data of the metal film.
By adopting the optical characterization device for the ultrathin metal film by using the spectroscopic ellipsometer, the nondestructive, high-precision and high-sensitivity optical property characterization can be carried out on the metal film with the film thickness of less than 10 nm; the device is simple in configuration, easy to operate and good in reproducibility; meanwhile, the sample cannot be damaged, so that the problem that the traditional measurement method damages the sample to cause unrepeatability of the experiment is avoided; in addition, the method can be integrated into an integrated circuit production line, meets the detection requirements of process control and optimization of the integrated circuit, and enlarges the ellipsometry measurement range of the limit metal film.
The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to be limiting, and the present method is intended to improve the measurement accuracy and sensitivity of various weak signal ultrathin films (including ultrathin films such as metal films with sub-nanometer thickness or other weak signal systems) by using an optical ellipsometer, and those skilled in the art can make various corresponding changes and modifications according to the present invention without departing from the spirit and essence of the present invention, but these corresponding changes and modifications should fall within the protection scope of the appended claims.
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, or portions thereof, of the illustrated figure.
Although various arrow types and line types may be employed in the flow chart diagrams and/or block diagram block diagrams, they are understood not to limit the scope of the corresponding embodiments. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the depicted embodiment. For instance, 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 flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and code.
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 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 may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
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 disclosure, principles and novel features disclosed herein.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for detecting an ultra-thin metal film using a spectroscopic ellipsometer, comprising:
constructing a first system consisting of a silicon substrate and a natural silicon oxide layer, and measuring ellipsometry parameters of the silicon substrate and the natural silicon oxide layer in the first system by using a spectroscopic ellipsometer; determining an optical constant corresponding to the silicon substrate and an optical constant and thickness data corresponding to the natural silicon oxide layer according to the ellipsometry parameter;
preparing a non-absorption dielectric layer on the first system, constructing a second system consisting of a silicon substrate, a natural silicon oxide layer and the non-absorption dielectric layer, and measuring an ellipsometry parameter of the non-absorption dielectric layer in the second system by using a spectroscopic ellipsometer; determining the optical constant and the thickness data of the non-absorption dielectric layer according to the ellipsometry parameter of the non-absorption dielectric layer, the optical constant corresponding to the silicon substrate and the optical constant and the thickness data corresponding to the natural silicon oxide layer;
preparing a metal film layer on the second system, constructing a third system consisting of a silicon substrate, a natural silicon oxide layer, a non-absorption dielectric layer and the metal film layer, and measuring an ellipsometry parameter of the metal film layer in the third system by using a spectroscopic ellipsometer; and determining the optical constant and the thickness data of the metal film layer according to the ellipsometry parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant and the thickness data corresponding to the natural silicon oxide layer and the optical constant and the thickness data of the non-absorption dielectric layer.
2. The method for detecting an ultra-thin metal film using a spectroscopic ellipsometer of claim 1, wherein the preparing of the non-absorbing dielectric layer on the first system specifically comprises: and preparing a non-absorption dielectric layer on the natural silicon oxide layer by adopting any one or two modes of chemical vapor deposition, magnetron sputtering deposition and electron beam evaporation deposition.
3. The method of claim 1, wherein the non-absorbing dielectric layer is a dielectric material that is non-absorbing to light in the spectroscopic range of ellipsometry, and comprises SiO2Film, Si3N4Film and MgF2Any one of the films; the thickness data of the non-absorption dielectric layer is 500 nm-2 um.
4. The method for inspecting an ultra-thin metal film using a spectroscopic ellipsometer as set forth in claim 1, wherein the wavelength range parameter of incident light of the spectroscopic ellipsometer is determined to be 190nm to 2500nm and the incident angle parameter of the incident light is determined to be 45 ° to 70 ° in the process of measuring the ellipsometric parameter using the spectroscopic ellipsometer.
5. The method for detecting an ultra-thin metal film using a spectroscopic ellipsometer as claimed in claim 1, wherein the determining the optical constant corresponding to the silicon substrate and the optical constant and thickness data corresponding to the natural silicon oxide layer according to the ellipsometry parameters specifically comprises:
constructing a first ellipsometry fitting model corresponding to the first system, fitting ellipsometry parameters of a silicon substrate and a natural silicon oxide layer in the first system by using the first ellipsometry fitting model, and obtaining and recording an optical constant corresponding to the silicon substrate and optical constant and thickness data corresponding to the natural silicon oxide layer;
determining the optical constant and the thickness data of the non-absorption dielectric layer according to the ellipsometry parameter of the non-absorption dielectric layer, the optical constant corresponding to the silicon substrate and the optical constant and the thickness data corresponding to the natural silicon oxide layer, specifically comprising:
constructing a second ellipsometry fitting model corresponding to the second system, fitting the ellipsometry parameters of the non-absorption medium layer in the second system by using the second ellipsometry fitting model, and obtaining and recording optical constants and thickness data of the non-absorption medium layer;
determining the optical constant and the thickness data of the metal film layer according to the ellipsometry parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant and the thickness data corresponding to the natural silicon oxide layer and the optical constant and the thickness data of the non-absorption dielectric layer, and specifically comprises the following steps:
and constructing a third ellipsometry fitting model corresponding to the third system, and fitting the ellipsometry parameters of the metal film layer in the third system by using the third ellipsometry fitting model to obtain the optical constant and the thickness data of the metal film layer.
6. The method for detecting an ultra-thin metal film using an spectroscopic ellipsometer as set forth in claim 1, wherein the metal film layer comprises any one metal element selected from the group consisting of gold, platinum, palladium, and titanium, and the thickness data of the metal film layer is less than 10 nm.
7. A method for optical characterization of an ultra-thin metal film using a spectroscopic ellipsometer, comprising:
setting the operating parameters of the spectrum ellipsometer;
constructing an ellipsometry fitting model for measuring the metal film layer;
respectively measuring ellipsometry parameters corresponding to the structural layers of the ellipsometry fitting model by using the spectroscopic ellipsometer; the structure layer comprises a silicon substrate layer, a natural silicon oxide layer, a first non-absorption medium layer, a transition layer, a first metal film layer, an air rough layer and a first air layer;
the ellipsometry parameter corresponding to the second non-absorption dielectric layer in the transition layer is the same as the ellipsometry parameter corresponding to the first non-absorption dielectric layer;
and fitting the ellipsometry parameters corresponding to the structural layer with the ellipsometry fitting model to obtain the optical constant and the thickness data of the metal film layer.
8. The method of claim 7, wherein the operating parameters comprise: at least one of an incident angle parameter, a measured wavelength range parameter, a measured wavelength interval parameter, and a reference characterization wavelength parameter;
the transition layer consists of a second non-absorption medium layer and a second metal film layer;
the air rough layer consists of a third metal film layer and a second air layer.
9. An apparatus for inspecting ultra-thin metal films using a spectroscopic ellipsometer, comprising:
the first system parameter determination unit is used for constructing a first system consisting of a silicon substrate and a natural silicon oxide layer, and measuring ellipsometry parameters of the silicon substrate and the natural silicon oxide layer in the first system by using a spectroscopic ellipsometer; determining an optical constant corresponding to the silicon substrate and an optical constant and thickness data corresponding to the natural silicon oxide layer according to the ellipsometry parameter;
the second system parameter determining unit is used for preparing a non-absorption dielectric layer on the first system, constructing a second system consisting of a silicon substrate, a natural silicon oxide layer and the non-absorption dielectric layer, and measuring the ellipsometry parameter of the non-absorption dielectric layer in the second system by using a spectroscopic ellipsometer; determining the optical constant and the thickness data of the non-absorption dielectric layer according to the ellipsometry parameter of the non-absorption dielectric layer, the optical constant corresponding to the silicon substrate and the optical constant and the thickness data corresponding to the natural silicon oxide layer;
a third system parameter determination unit, configured 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 dielectric layer, and the metal film layer, and measure an ellipsometry parameter of the metal film layer in the third system by using a spectroscopic ellipsometer; and determining the optical constant and the thickness data of the metal film layer according to the ellipsometry parameter of the metal film layer, the optical constant corresponding to the silicon substrate, the optical constant and the thickness data corresponding to the natural silicon oxide layer and the optical constant and the thickness data of the non-absorption dielectric layer.
10. An apparatus for optical characterization of ultra-thin metal films using a spectroscopic ellipsometer, comprising:
the operating parameter setting unit is used for setting the operating parameters of the spectroscopic ellipsometer;
the ellipsometry fitting model building unit is used for building an ellipsometry fitting model for measuring the metal film layer;
the ellipsometry parameter measuring unit is used for measuring the ellipsometry parameters corresponding to the structural layers of the ellipsometry fitting model by using the spectroscopic ellipsometer; the structure layer comprises a silicon substrate layer, a natural silicon oxide layer, a first non-absorption medium layer, a transition layer, a first metal film layer, an air rough layer and a first air layer; the ellipsometry parameter corresponding to the second non-absorption dielectric layer in the transition layer is the same as the ellipsometry parameter corresponding to the first non-absorption dielectric layer;
and the metal film layer data obtaining unit is used for fitting the ellipsometric parameters corresponding to the structural layer with the ellipsometric fitting model to obtain the optical constant and the thickness data of the metal film layer.
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