Ge-Se-Te chalcogenide phase change film and preparation method thereof
The preparation of Ge-Se-Te chalcogenide phase change thin films by high-throughput magnetron co-sputtering solves the problem that existing technologies cannot simultaneously achieve high optical contrast and low loss, thus improving the efficiency of screening and R&D.
Patent Information
- Application Number
- CN202311447854.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-02
- Publication Date
- 2026-02-13
- Estimated Expiration
- 2043-11-02
AI Technical Summary
Existing technologies cannot simultaneously achieve high optical contrast and low loss in Ge-Se-Te chalcogenide phase change thin film materials.
Ge-Se-Te chalcogenide phase change thin films were prepared by high-throughput magnetron co-sputtering. A sample library with continuously varying composition was obtained by adjusting the coating parameters, and materials with high optical contrast were selected by screening using the Tauc formula and ellipsometry.
This improved the research and development efficiency of chalcogenide thin film materials, and yielded Ge-Se-Te chalcogenide phase change thin films with both high optical contrast and low loss.
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Figure CN117328028B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of semiconductor materials, in particular to a Ge-Se-Te chalcogenide phase change thin film and a preparation method thereof. BACKGROUND
[0002] Currently, people have relatively sufficient understanding of single-element materials and binary compound materials, but have limited understanding of ternary compounds, and have very little knowledge of quaternary and above compound materials. At present, most experiments still use the traditional sequential iterative method based on continuous trial and error to prepare materials, which cannot perform efficient screening. It has been proven effective and reliable to combine high-throughput material preparation with appropriate performance characterization means to quickly screen high-performance materials. This method can prepare a large number of samples in a short time, and changes the sequential iterative trial and error method used in traditional material research to parallel processing, so as to cause qualitative change in material research efficiency from quantitative change.
[0003] Co-deposition plating is a high-throughput experimental method, which can quickly form a multi-element sample with gradually varying composition by changing the relative position of different deposition sources and the substrate without the aid of any mask, and is independent of the thickness of the deposited film. The composition resolution can reach 0.1% to 1.0%, and the compound sample library with fully mixed elements can be obtained without heat treatment after deposition.
[0004] Chalcogenide glass belongs to a large category of inorganic non-oxide glass materials, which has excellent mid-to-far infrared optical properties. It has been widely studied and applied in phase change memory, infrared thermal imaging technology, infrared detectors, optical waveguides and other fields. Amorphous chalcogenide materials can also meet the material requirements of super surface lenses in the far infrared band. In theory, they have good properties such as high refractive index, high transmittance, low thermal expansion coefficient, and low refractive index temperature coefficient. The amorphous and crystalline states of current Ge2Sb2Te5(GST) and Ge2Sb2Se1Te4(GSST) materials have a large refractive index difference, but their loss is high. The Sb2S3 and Sb2Se3 materials developed on this basis have low loss, but their refractive index difference is also small. Therefore, we need to find chalcogenide thin film materials that have both large optical contrast and low loss. SUMMARY
[0005] The technical problem to be solved by the present application is to provide a preparation method of a Ge-Se-Te chalcogenide phase change thin film, to solve the problem that conventional chalcogenide thin film materials cannot simultaneously have large optical contrast and low loss.
[0006] To solve the above problems, the present application provides a preparation method of a Ge-Se-Te chalcogenide phase change thin film, comprising the following steps:
[0007] S1: take the substrate and clean, dry and save after washing, and select high purity Ge, Se, Te as sputtering target material for standby;
[0008] S2: start the vacuum system of the magnetron sputtering film system, and vacuumize the chamber;
[0009] S3: adjust the sputtering angle of the sputtering target material to 120-145°, install the Te target material on the magnetron direct current sputtering target, and install the Ge target material and Se target material on the magnetron radio frequency sputtering target for sputtering. After the vacuum degree reaches the sputtering standard, continuously introduce argon gas into the sputtering chamber until the gas pressure in the sputtering chamber reaches the required gas pressure for starting, then reduce the argon gas flux, start sputtering, and keep the power of the Te target, Ge target and Se target unchanged during sputtering. After sputtering, the deposited Ge-Se-Te chalcogenide phase change thin film is obtained.
[0010] S4: calculate the optical band gap of the material before and after phase change using Tauc formula for preliminary screening.
[0011] S5: use ellipsometer to test the refractive index of the deposited and crystallized thin film after screening to verify the accuracy of the screening process.
[0012] As a preferred scheme, in step S1, the substrate is one or more of silicon wafer, silicon oxide and calcium fluoride, and the purity of Ge, Se and Te is greater than or equal to 99.99%.
[0013] As a preferred scheme, in step S1, the taking of the substrate and cleaning, drying and saving after washing includes: cleaning the substrate in an ultrasonic cleaner with isopropyl alcohol, anhydrous ethanol and deionized water for 10 minutes, then blowing dry with a nitrogen gun, and finally washing and drying.
[0014] As a preferred scheme, in step S3, the power of the Te target material is 15W, the power of the Ge target material is 25W, and the power of the Se target material is 8W.
[0015] As a preferred scheme, in step S3, the vacuum degree of the sputtering standard is 3.0*10 -6 Pa.
[0016] As a preferred scheme, in step S3, the volume flow rate of the continuously introduced argon gas is 30sccm, and the volume flow rate of the argon gas after reducing the argon gas flux is 15sccm.
[0017] As a preferred scheme, in step S3, the sputtering time is 30min.
[0018] As a preferred scheme, in the step S3, the thickness of the as-deposited Ge-Se-Te chalcogenide phase change film is 300-650 nm.
[0019] As a preferred scheme, after the step S3, the method further comprises steps S4 and S5, comprising:
[0020] S4: calculating the optical band gap of the material before and after phase change by using Tauc formula to perform preliminary screening.
[0021] S5: testing the refractive index of the as-deposited and crystallized thin film after screening by using ellipsometer to verify the accuracy of the screening process and complete the screening.
[0022] Another technical problem to be solved by the present application is to provide a Ge-Se-Te chalcogenide phase change film to solve the problem that the conventional Ge-Se-Te chalcogenide phase change film cannot achieve large optical contrast and low loss at the same time.
[0023] In order to solve the above problems, the present application provides a Ge-Se-Te chalcogenide phase change film, which is prepared by the above preparation method.
[0024] As a preferred scheme, in the Ge-Se-Te chalcogenide phase change film, the content span of Ge is 28 at.%, the content span of Se is 10 at.%, and the content span of Te is 29 at.%.
[0025] Compared with the prior art, the present application has the advantages that: the present application provides a high-throughput preparation method for chalcogenide phase change film, a Ge-Se-Te chalcogenide film is prepared by using high-throughput magnetron co-sputtering method, a sample library with continuous composition change and obvious composition difference is obtained by adjusting the film deposition parameters, and the material with excellent optical performance is efficiently screened in the sample library. The present application designs a high-throughput combination experiment, screens the material with large optical band gap difference before and after phase change, obtains the Ge-Se-Te material with high optical contrast and verifies it by using ellipsometer. The Ge-Se-Te chalcogenide phase change film and the preparation method thereof greatly improve the research and development efficiency of high optical constant difference chalcogenide film material. BRIEF DESCRIPTION OF DRAWINGS
[0026] Figure 1 For the substrate suitable for the present embodiment, the circular substrate is divided into 52 sample points, and the Ge target, the Se target and the Te target are the target material positions.
[0027] Figure 2 The component distribution diagram of the Ge-Se-Te film sample library prepared in the present embodiment;
[0028] Figure 3Thickness distribution diagram of Ge-Se-Te thin film sample library prepared in the embodiment;
[0029] Figure 4 Temperature-resistance diagram of part of samples of Ge-Se-Te thin film sample library prepared in the embodiment;
[0030] Figure 5 Phase transition temperature distribution diagram of Ge-Se-Te thin film sample library prepared in the embodiment;
[0031] Figure 6 Resistance switching ratio distribution diagram of Ge-Se-Te thin film sample library prepared in the embodiment;
[0032] Figure 7 Spectrophotometer test transmittance spectrum diagram (250-2500nm) of part of samples of Ge-Se-Te thin film sample library prepared in the embodiment;
[0033] Figure 8 Optical band gap diagram of sample No. 11 in deposited state prepared in the embodiment;
[0034] Figure 9 Optical band gap distribution diagram of Ge-Se-Te thin film sample library prepared in the embodiment;
[0035] Figure 10 Optical band gap distribution diagram of Ge-Se-Te thin film sample library in crystallized state prepared in the embodiment;
[0036] Figure 11 Optical band gap difference distribution diagram of Ge-Se-Te thin film sample library prepared in the embodiment;
[0037] Figure 12 Deposited state refractive index extinction coefficient diagram of sample No. 37 prepared in the embodiment. DETAILED DESCRIPTION
[0038] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.
[0039] The present application provides a preparation method of Ge-Se-Te chalcogenide phase change film, comprising the following steps:
[0040] S1: take a substrate, clean, dry and save, and select high-purity Ge, Se and Te as sputtering target materials for standby;
[0041] S2: Turn on the vacuum system of the magnetron sputtering coating system, and vacuumize the chamber;
[0042] S3: Adjust the sputtering angle of the sputtering target to 120-145°, install the Te target on the magnetron direct current sputtering target, and install the Ge target and the Se target on the magnetron radio frequency sputtering target for sputtering. After the vacuum degree reaches the sputtering standard, continuously introduce argon into the sputtering chamber until the gas pressure in the sputtering chamber reaches the required gas pressure for starting glow. Then, reduce the argon flux, start sputtering, and keep the power of the Te target, the Ge target and the Se target unchanged during sputtering. After sputtering, the deposited Ge-Se-Te chalcogen phase change thin film is obtained.
[0043] Preferably, in step S1, the substrate is one or more of a silicon wafer, silicon oxide, and calcium fluoride, and the purity of Ge, Se, and Te is greater than or equal to 99.99%.
[0044] Preferably, in step S1, the taking and cleaning, drying and storing of the substrate include: sequentially cleaning the substrate in an ultrasonic cleaner with isopropanol, anhydrous ethanol and deionized water for 10 minutes, then drying with a nitrogen gun, and finally drying and storing after cleaning.
[0045] Preferably, in step S3, the power of the Te target is 15W, the power of the Ge target is 25W, and the power of the Se target is 8W.
[0046] Preferably, in step S3, the vacuum degree of the sputtering standard is 3.0*10 -6 Pa.
[0047] Preferably, in step S3, the volume flow rate of the continuously introduced argon is 30sccm, and the volume flow rate of the argon after reducing the argon flux is 15sccm.
[0048] Preferably, in step S3, the sputtering time is 30min.
[0049] Preferably, in step S3, the thickness of the deposited Ge-Se-Te chalcogen phase change thin film is 300-650nm.
[0050] As a preferred scheme, after step S3, steps S4 and S5 are further included, comprising:
[0051] S4: Calculate the optical band gap of the material before and after phase change using the Tauc formula for preliminary screening.
[0052] S5: Test the refractive index of the thin film in the deposited state and the crystalline state after screening using an ellipsometer, verify the accuracy of the screening process, and complete the screening.
[0053] The application further provides a Ge-Se-Te chalcogenide phase change film prepared by the preparation method.
[0054] Preferably, in the Ge-Se-Te chalcogenide phase change film, the content span of Ge is 28 at.%, the content span of Se is 10 at.%, and the content span of Te is 29 at.%.
[0055] The above technical solutions of the application are described below in combination with specific examples of data:
[0056] Example 1:
[0057] A preparation method of a Ge-Se-Te chalcogenide phase change film, the steps are as follows:
[0058] S1: The substrate is sequentially cleaned in an ultrasonic cleaner with isopropyl alcohol, anhydrous ethanol and deionized water for 10 minutes, then dried with a nitrogen gun, and cleaned and dried for storage;
[0059] S2: The vacuum system of the magnetron sputtering film coating system is started, and the chamber is vacuumized;
[0060] S3: In the magnetron sputtering film coating system, silicon wafer, silicon oxide and calcium fluoride are used as substrates, and a step is made on the Si substrate with adhesive tape; the Te target material is installed on the magnetron direct current sputtering target, the Ge target material and the Se target material are installed on the magnetron radio frequency sputtering target, the sputtering angles of the three target heads are adjusted, the sputtering power of the Te target material is adjusted to 15w, the sputtering power of the Ge target material is adjusted to 25w, the sputtering power of the Se target material is adjusted to 8w, and the sputtering angle of the sputtering target material is 130°;
[0061] The sputtering chamber of the magnetron sputtering film coating system is vacuumized to a vacuum degree of 3.0*10 -6 Pa, then high-purity argon gas with a volume flow rate of 30sccm is introduced into the sputtering chamber until the gas pressure in the sputtering chamber reaches the required pressure for starting, after starting, the argon volume flow rate is adjusted to 15sccm, and sputtering film coating is carried out at room temperature, after sputtering for 30 minutes, a deposited Ge-Se-Te chalcogenide phase change film is obtained, and the thickness of the film is 500nm.
[0062] S4: The optical band gap of the material before and after phase change is calculated by Tauc formula for preliminary screening.
[0063] S5: The refractive index of the deposited state and the crystalline state of the film after screening is tested by an ellipsometer to verify the accuracy of the screening process, and the screening is completed.
[0064] Example 2:
[0065] Example 2 is similar to Example 1, except that in step S3, the sputtering angle is 120°, and the thickness of the thin film is 300 nm.
[0066] Example 3:
[0067] Example 2 is similar to Example 1, except that in step S3, the sputtering angle is 145°, and the thickness of the thin film is 650 nm.
[0068] The performance of the thin film prepared in Example 1 was tested, and the results are as follows:
[0069] Figure 1 To divide the circular substrate into 52 sample points for the example, the Ge target, the Se target, and the Te target are the target material positions, and the 11th, 14th, 37th, 42nd, and 45th are the specific positions of the subsequent test samples.
[0070] 1. The thickness of each sample point in the sample library was tested using a Veeco Dektak 150 probe surface profiler. The average value was calculated after taking the average of five different positions measured in the experiment, and the sample thickness of this example is shown in Table 1. Figure 3
[0071] 2、 Figure 2 The distribution of the components of the thin film was measured by an X-ray energy spectrometer (EDS), and the maximum composition range of Ge was 28 at.%, the maximum component range of Se was 10 at.%, and the maximum component range of Te was 29 at.%, which had a wide component gradient span.
[0072] 3. The resistance test platform was composed of a digital multimeter, a vacuum heating table, a temperature controller, and PC control program software. The phase change thin film in the deposited state was tested for temperature resistance, the test temperature was 30-380℃, and the phase change temperature of each sample point was as shown in Table 2. Figure 4 The resistance switching ratio before and after phase change is shown in Table 3. Figure 5
[0073] 4. The transmittance of the thin film was measured by a spectrophotometer at 250-2500 nm, and the partial transmittance graph is shown in Figure 2. Because the film is thick, the interference is large, so the fluctuation pattern is shown in Figure 3. Figure 7 Figure 7 The Ge-Se-Te thin film sample library prepared in this example has sample numbers 11, 14, 37, 42, and 45, and the spectrophotometer test transmittance spectrum graph (250-2500 nm) is shown in Figure 4. With the decrease of Te content, the spectrum blue shifts.
[0074] 5. Using a rapid annealing furnace, the sample is annealed in batches at a temperature greater than the phase transition temperature to make the sample in a crystalline state, the annealing time is 180s, and nitrogen is introduced during the annealing process.
[0075] 6. Repeat step 4, calculate the optical band gap of the deposited state thin film before phase transition (Eg1) and the optical band gap of the crystalline state thin film after phase transition (Eg2) using the Tauc formula, and obtain the optical band gap difference (ΔEg) of the Ge-Se-Te sample library by subtracting the two figures, and perform preliminary screening to obtain samples 11 and 14 with small optical band gap difference, sample 37 with optical band gap difference at the median, and samples 42 and 45 with large optical band gap difference. Figure 9 Figure 10 Figure 11
[0076] 7. The refractive index of the deposited state and the crystalline state of the thin film after screening is tested using an ellipsometer to verify the accuracy of the screening process. The optical band gap difference, refractive index difference and extinction coefficient of the material before and after phase transition at 1550nm waveband are obtained as shown in Table 1.
[0077] Figure 6 The resistance switching ratio distribution diagram of the Ge-Se-Te thin film sample library prepared in this embodiment shows that the order of magnitude of the resistance of the phase transition thin film of the deposited state and the crystalline state differs by 3-7;
[0078] Figure 8 The deposited state optical band gap diagram of sample 11 prepared in this embodiment. The deposited state optical band gap of sample 11 is calculated by tauc method to be 0.88eV;
[0079] Figure 12 The deposited state refractive index extinction coefficient diagram of sample 37 prepared in this embodiment. The optical constant experimental value of the thin film is obtained by testing with an ellipsometer and constructing a physical model, and the refractive index of sample 37 at 1550nm waveband is 3.38.
[0080] Sample E g-沉积态 ]]> E g-结晶态 ]]> Optical band gap difference <![CDATA[N 沉积态 ]]> <![CDATA[N 结晶态 ]]> Refractive index difference k 沉积态 ]]> k 结晶态 ]]> 11 0.88 0.8 0.08 3.76 4.78 1.02 0.0066 0.5965 14 0.87 0.79 0.08 3.69 4.56 0.87 0.1119 0.3427 37 0.94 0.61 0.33 3.38 4.65 1.27 0.0704 0.3517 42 1.00 0.46 0.47 3.25 4.66 1.41 0.0204 0.3470 45 0.95 0.4 0.45 3.24 4.6 1.36 0.0059 0.3641
[0081] Through the above embodiments, it is further proved that the present application provides a Ge-Se-Te chalcogenide phase transition thin film and a preparation method thereof, which solves the problem that conventional chalcogenide thin film materials cannot simultaneously have large optical contrast and low loss.
[0082] Although the present disclosure is as disclosed above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications shall fall within the protection scope of the present application.
Claims
1. A method for preparing Ge-Se-Te chalcogenide phase change thin film, characterized in that: The method comprises the following steps: S1: take the substrate and clean it, dry it and store it, and select high-purity Ge, Se and Te as sputtering target materials for standby; S2: turn on the vacuum system of the magnetron sputtering film coating system and perform vacuum treatment on the chamber; S3: adjust the sputtering angle of the sputtering target material to 120-145°, install the Te target material on the magnetron direct-current sputtering target, and install the Ge target material and the Se target material on the magnetron radio frequency sputtering target for sputtering, after the vacuum degree reaches the sputtering standard, continuously introduce argon into the sputtering chamber until the gas pressure in the sputtering chamber reaches the required gas pressure for starting, then reduce the argon flux, start sputtering, and keep the power of the Te target material, the Ge target and the Se target unchanged during the sputtering process, after the sputtering is completed, a deposited Ge-Se-Te chalcogenide phase change thin film is obtained; in the step S3, the power of the Te target material is 15 W, the power of the Ge target material is 25 W, and the power of the Se target material is 8 W; After the step S3, steps S4 and S5 are further included, comprising: S4: calculate the optical band gap of the material before and after phase change using the Tauc formula for preliminary screening; S5: use an ellipsometer to test the refractive index of the deposited and crystalline thin film after screening, verify the accuracy of the screening process, and complete the screening.
2. The method for preparing Ge-Se-Te chalcogenide phase change thin films according to claim 1, characterized in that: In the step S1, the substrate is one or more of a silicon wafer, silicon oxide and calcium fluoride, and the purity of the Ge, Se and Te is greater than or equal to 99.99%.
3. The method for preparing Ge-Se-Te chalcogenide phase change thin films according to claim 1, characterized in that: In the step S1, the taking of the substrate, cleaning, drying and storage comprises: sequentially cleaning the substrate in an ultrasonic cleaner with isopropyl alcohol, anhydrous ethanol and deionized water for 10 minutes, then drying it with a nitrogen gun, and finally washing and drying it for storage.
4. The method of claim 1, wherein the Ge-Se-Te chalcogenide phase change thin film is prepared by the steps of: depositing a Ge-Se-Te chalcogenide phase change thin film on a substrate; and annealing the Ge-Se-Te chalcogenide phase change thin film. The vacuum degree of the sputtering standard in the step S3 is 3.0×10 -6 Pa; the sputtering time is 30 min.
5. The method of claim 1, wherein the Ge-Se-Te chalcogenide phase change thin film is prepared by the steps of: depositing a Ge-Se-Te chalcogenide phase change thin film on a substrate; and annealing the Ge-Se-Te chalcogenide phase change thin film. In the step S3, the volume flow rate of the continuously introduced argon is 30 sccm, and the volume flow rate of the argon after the reduction of the argon flux is 15 sccm.
6. The method of claim 1, wherein the Ge-Se-Te chalcogenide phase change thin film is prepared by the steps of: depositing a Ge-Se-Te chalcogenide phase change thin film on a substrate; and annealing the Ge-Se-Te chalcogenide phase change thin film. In the step S3, the thickness of the deposited Ge-Se-Te chalcogenide phase change thin film is 300-650 nm.
7. A Ge-Se-Te chalcogenide phase change thin film, characterized in that: The thin film is prepared by the method of any one of claims 1-6.
8. The Ge-Se-Te chalcogenide phase change thin film according to claim 7, characterized in that: In the Ge-Se-Te chalcogenide phase change thin film, the content span of Ge is 28 at.%, and the content span of Se is 10 at.%.