CN111435123A

CN111435123A - Metal TiN measurementxMethod for film absorption coefficient

Info

Publication number: CN111435123A
Application number: CN201910042818.2A
Authority: CN
Inventors: 胡德霖; 胡醇; 谷承艳; 赵杰; 闫敏; 杨星琦
Original assignee: Suzhou Electrical Appliance Science Research Institute Co ltd
Current assignee: Suzhou Electrical Appliance Science Research Institute Co ltd
Priority date: 2019-01-11
Filing date: 2019-01-11
Publication date: 2020-07-21

Abstract

The invention relates to a method for measuring metallic TiN_xMethod of absorption coefficient of thin film. Firstly, a P-GaN substrate and a metallic TiN coating layer with the thickness of about 50nm are coated_xPerforming cathode fluorescence test (C L) at different voltages on the same position of the thin film P-GaN to obtain corresponding cathode fluorescence intensity, and obtaining TiN at different voltages according to Lambert's law_xThe absorption coefficient of the film, and further obtaining the average absorption coefficient value; finally, the square resistance of the film is tested by utilizing the four-probe technology to further determine the TiN_xMetallic thin film the present invention utilizes SEM in combination with C L to obtain metallic TiN_xAbsorption coefficient of the film, thereby providing a semi-conductivityA novel method for measuring the absorption coefficient of a metallic thin film having a thickness of several tens of nanometers on a bulk substrate.

Description

Metal TiN measurementxMethod for film absorption coefficient

Technical Field

The invention relates to a method for measuring the absorption coefficient of a film, in particular to a metallic TiN film_xA method for measuring the absorption coefficient of the film.

Background

Titanium nitride (TiN)_x) Is a refractory non-stoichiometric transition metal nitride, has a melting point as high as 2930 ℃, metallic TiNx is golden yellow, and exhibits plasma excitation behavior in the visible and near infrared spectral ranges. Compared with conventional plasma materials, e.g. gold and silver, TiN_xHas the advantages of high melting point, good chemical stability, high mechanical strength, corrosion resistance, biocompatibility, easy integration with standard silicon-based technology, and TiN_xHas tunability with variations of growth parameters, and thus, TiN_xBecomes a plasma ceramic material for replacing the traditional noble metal material gold, marks a new technical start of a plasma device and is TiN with nanometer size_xThe film comprises a nano-sized film, a nano antenna, nano particles, a super surface and a nano pattern structure, and has wide application prospects in the aspects of solar thermal photovoltaic systems (S/TPV), biological medical treatment, heat-assisted magnetic recording (HAMR), High-temperature sensors (High-T sensors), planar photonic devices (flat optics) and the like. In addition to this, metallic TiNx thin films are also being widely studied and used as diffusion barrier layers, ohmic contact layers, rectifying layers in device metallization mechanisms, and gate electrodes in CMOS devices due to their low resistivity and high temperature resistance.

At present, TiNx thin films can be grown by a variety of deposition techniques, including Chemical Vapor Deposition (CVD), atomic layer deposition (A L D), and Physical Vapor Deposition (PVD) such as reactive magnetron sputtering (reactive sputtering), pulsed laser deposition (P L D), etcThe ellipsometry parameters of the TiNx film include the total amplitude and phase of the reflected light at the surface and interfaces of the film, so as to fit the optical parameters of the film, such as refractive index, extinction coefficient, etc., however, in our test, we found that when the metallic TiN film is used_xWhen the thickness of the thin film reaches several tens of nanometers, metal TiN is used_xThe specular reflection and absorption of light by the film make it difficult to accurately fit the optical parameters of the film.

Disclosure of Invention

The invention provides a metallic TiN_xThe method for measuring the absorption coefficient of the film can accurately estimate the absorption coefficient of the TiNx film and further determine the growing TiN_xThe film is metallic.

The invention provides a metallic TiN_xA method for measuring an absorption coefficient of a thin film, the method comprising:

providing a P-GaN substrate with sapphire as a base, and performing a C L test at different voltages on the same position of the P-GaN substrate by utilizing a cathode fluorescence (C L) component attached to a scanning electron microscope;

cleaning the P-GaN substrate;

TiN on P-GaN surface by Pulsed laser Deposition system (Pulsed L ase Deposition, P L D)_xGrowing a thin film;

using X-ray diffraction (XRD) and Atomic Force Microscope (AFM) to grow TiN_xThe crystal structure, orientation and surface morphology of the film are characterized;

using Scanning Electron Microscope (SEM) to treat TiN_xThe section morphology of the film is characterized to obtain the thickness of the TiNx film;

are oppositely coated with TiN_xCathodic fluorescence tests (C L) were carried out on samples of the film at the same position and at different voltages to obtain grown TiN_xThe cathode fluorescence intensity of the sample after film formation was determined according to Lambert's law, I ═ I₀e^-αdThereby obtaining TiN under different voltages_xThe absorption coefficient of the film is obtained, and then the average absorption coefficient value is obtained, and the average absorption coefficient value is compared with the range of the absorption coefficient of the metal, so as to determine the TiN_xThe metallic nature of the film;

finally, the square resistance of the film is tested by utilizing the four-probe technology to further determine the TiN_xThe metallic nature of the film.

The method has the beneficial effects that the metallic TiN is obtained by combining SEM and C L_xThe absorption coefficient of the film, thereby providing a new method for measuring the absorption coefficient of a metallic film having a thickness of several tens of nanometers on a semiconductor substrate.

Drawings

In order to make the objects, technical solutions and advantages of the present invention clearer and more clear, the present invention is further described in detail with reference to the accompanying drawings, in which:

TiN grown on P-GaN substrate of FIG. 1_xXRD pattern of the film;

figure 2 TiN grown on P-GaN substrate_xAFM topography of the film;

figure 3 TiN grown on P-GaN substrate_xA cross-sectional SEM topography of the film;

FIG. 4C L results for P-GaN at different voltages;

FIG. 5 is a TiN coated layer_xC L results for P-GaN of the film at different voltages;

FIG. 6P-GaN and TiN capping_xComparison of the results of the C L test at different voltages for P-GaN of thin films.

Detailed Description

The TiNx film grown on the Mg-doped C-plane P-GaN substrate by utilizing the pulse laser deposition (P L D) system of the laboratory presents golden yellow and has metallic luster, wherein the pulse laser deposition system is an excimer laser with the wavelength of 248nm, the pulse width is 25ns, the maximum pulse frequency is 10HZ, the P-GaN substrate is sapphire, the sample is tested and characterized, and the TiN is obtained according to the Lambert law by combining SEM and C L_xThe absorption coefficient of the film is further determined to be metallic by testing the square resistance, and the method comprises the following specific steps:

providing Mg-doped P-GaN with sapphire as a substrate, performing C L tests under different voltages at the same position of the P-GaN substrate by utilizing a cathode fluorescence (C L) component attached to a scanning electron microscope, as shown in figure 4, and then cleaning the substrate;

putting the cleaned P-GaN wafer dried by nitrogen into a deposition chamber, and vacuumizing until the background vacuum reaches 10 DEG^-6Pa above, heating to 600 deg.C, heat treating for 1h, then heating to 650 deg.C, introducing high purity N₂When the preset pressure is reached, N is generated by using a plasma device carried by a P L D system₂Plasma, the P-GaN surface is pretreated for 10 minutes, and a surface oxide layer is removed;

laser is incident at an angle of 45 degrees, enters a deposition chamber through lens focusing, a baffle plate before a substrate is put down before deposition, TiN target materials with the purity of 99.9 percent are pre-sputtered for 2-3 minutes, then the baffle plate is removed, deposition is started, the deposition temperature is 650 ℃, the air pressure is 3Pa, the deposition time is 1h, the target spacing is 8cm, the laser energy is 250mJ, the pulse repetition frequency is 2HZ, the deposition is finished, in-situ annealing is carried out for 1h, and a sample is taken out after the temperature is reduced to the room temperature, wherein the sample is golden yellow and has metallic luster as shown in figure 1;

the crystal structure and crystal orientation of the sample were characterized by X-ray diffraction (XRD), as shown in FIG. 1, for a P-GaN substrate and TiN grown_xTheta-2 theta scan curve of the film, with scan angles ranging from 20 deg. -90 deg., as can be seen from fig. 1, TiN grown on P-GaN substrate_xThe film presents (111) preferred orientation, the corresponding diffraction peak position is face-centered cubic structure TiN_xThe (111) and (222) crystal planes of (a);

using Atomic Force Microscope (AFM) to TiN_xThe surface morphology of the film was characterized as shown in FIG. 2, TiN_xThe film presents a flat and smooth surface with a surface roughness of 0.259 nm;

the cross-sectional morphology of the sample was characterized by Scanning Electron Microscopy (SEM), and as can be seen from FIG. 3, the TiN grown by us_xThe film is flat and compact, has a clear interface and the thickness of 49.6nm, thereby obtaining TiN on the P-GaN substrate_xThe average growth rate of the film is about 0.8 nm/min;

to deposition of TiN_xThe same position of the thin film sample was subjected to C L test at different voltages, as shown in FIG. 5, to deposit TiN_xAfter the film, the C L intensity was greatly reduced, indicating that the cathode fluorescence emitted by P-GaN was reflected by TiN_xThe film is greatly attenuated after absorption, and only the luminescence peak position of GaN is present and the peak position is not moved, which also indicates that the TiNx film grown by us is metallicity, and the C L intensity of the P-GaN substrate is rapidly increased along with the increase of the voltage, and TiN is grown completely_xAfter the film, the strength of C L slightly increased with increasing voltage, as shown in FIG. 6;

the peak values of the C L intensities at different voltages are shown in table 1, according to lambert's law I ═ I₀e^-αdIn which I₀C L strength of P-GaN substrate, I TiN growth_xC L Strength of the sample after film formation, d film thickness, α TiN_xAbsorption coefficient of the thin film, thereby obtaining TiN_xAbsorption coefficient of film

The specific calculation results are shown in table 1;

TABLE 1

Voltage(KV)	(P-GaN)CL I₀	CL I	Ln(I/I₀)	α(cm^-1)
					10	11337.05	2635.57	-1.45898	2.94×10⁵
12	18867.76	2781.09	-1.91461	3.86×10⁵
					14	24499.71	3140.55	-2.05426	4.14×10⁵
16	35538.33	3410.45	-2.34377	4.73×10⁵

Thus, we found that the average absorption coefficient of the film sample was 3.92 × 10^ (5) cm ^ -1 at 10⁵Magnitude, and the absorption coefficient of the metal is in the range of 10^ (4) to 10^ (5), which indicates that TiN is grown_xThe film is metallic;

finally, the square resistance of the TiNx film is tested by utilizing a four-probe technology, the test result is 14.36 omega/□, and the TiN is tested according to the SEM test_xThe film had a thickness of 49.6nm and thus had a resistivity of p ═ Rd, where R represents the sheet resistance and d represents the thickness of the film, to obtain a film having a resistivity of 7.12 × 10 < SP > -5 </SP >. omega.cm, while the resistivity of typical metals is in the range of 10 < SP > -5 </SP > -10 < SP > -6 </SP >. omega.cm, which further determined that the TiN we grown was_xThe thin film exhibits metallicity and has excellent conductivity.

The invention utilizes SEM and C L to combine to obtain metallic TiN_xThe absorption coefficient of the film, thereby providing a new method for measuring the absorption coefficient of a metallic film having a thickness of several tens of nanometers on a semiconductor substrate.

Claims

1. A method for measuring the absorption coefficient of a metallic TiNx film is characterized by comprising the following steps:

(1) providing a P-GaN substrate with sapphire as a substrate, and performing cathode fluorescence tests (C L) on the same position of the P-GaN substrate under different voltages;

(2) cleaning the P-GaN substrate;

(3) TiN on P-GaN surface by using pulsed laser deposition system_xGrowing a thin film;

(4) characterizing the crystal structure, orientation and surface morphology of the growing TiNx film by X-ray diffraction (XRD) and an Atomic Force Microscope (AFM);

(5) using Scanning Electron Microscope (SEM) to treat TiN_xThe section morphology of the film is characterized to obtain the thickness of the TiNx film;

(6) performing cathode fluorescence tests (C L) at different voltages on the same position of the sample coated with the TiNx film to obtain the growing TiN_xThe cathode fluorescence intensity of the sample after film formation was determined according to Lambert's law, I ═ I₀e^-αdThereby obtaining TiN under different voltages_xThe absorption coefficient of the film is obtained, and then the average absorption coefficient value is obtained, and the average absorption coefficient value is compared with the range of the absorption coefficient of the metal to determine the metallicity of the TiNx film;

(7) finally, the square resistance of the film is tested by utilizing the four-probe technology to further determine the TiN_xThe metallic nature of the film.

2. The TiN film as defined in claim 1 for measuring metallic properties_xThe method for measuring the absorption coefficient of the thin film is characterized in that the laser in the step (3) is a KrF excimer laser with the wavelength of 248nm, the laser pulse width is 25ns, and the maximum pulse repetition frequency is 10 HZ.

3. A measured metallic TiN as set forth in claim 1_xA method for decreasing the absorption coefficient of a thin film, characterized in that the TiN is used in the step (5)_xThe thickness of the film is about 50 nm.