Efficient growth method for mo layer-induced aln film, and performance test method therefor

Abstract

The present invention relates to the technical field of AlN films. Disclosed are an efficient growth method for an Mo layer-induced AlN film, and a performance test method therefor. The efficient growth method comprises: using a direct current pulse magnetron sputtering method to prepare Mo films on Si; selecting an Mo film having an excellent form and performance; and preparing an AlN film having high preferred orientation on the Mo film. An AlN film is grown on an Mo electrode having fine and uniform crystal grains. The process parameters for generating the AlN film comprise: a temperature of 650°C, a target-substrate distance of 8 cm, a sputtering power of 80 W, a time of 1.5 hours, an Arn ratio of 7:3.4, and a pressure intensity of 0.5 Pa. According to the present invention, the AlN film grown on the Mo film has a sharp XRD peak and high strength. The AlN film deposited on the Mo electrode having fine and uniform crystal grains has uniform crystal grain distribution and high preferred orientation.

Description

Mo layer induced efficient growth method of AlN thin film and performance testing method Technical Field

[0001] The invention belongs to the technical field of electronic thin films, and in particular relates to a Mo layer-induced AlN thin film efficient growth method and a performance testing method thereof. Background Art

[0002] AlN thin films belong to the III-V group of insulating compounds and exhibit a wide-gap direct band structure with a bandgap width of Eg = 6.12 eV. AlN generally exists in the hexagonal wurtzite structure, with lattice constants a = 0.3114 nm and c = 0.14947 nm. AlN thin films possess many excellent physical and chemical properties, such as high breakdown field strength, high thermal conductivity, high resistivity, high chemical and thermal stability, and excellent optical and mechanical properties. High-quality AlN films also exhibit extremely high ultrasonic transmission speeds, low acoustic wave losses, a large piezoelectric coupling constant, and a thermal expansion coefficient similar to that of Si and GaAs. AlN's unique properties give it broad application prospects in mechanics, microelectronics, optics, electronic components, surface acoustic wave (SAW) device manufacturing, and high-frequency broadband communications.

[0003] In recent years, piezoelectric films have been widely used in the field of microelectromechanical systems (MEMS) technology, but researchers still need to find good piezoelectric materials that can withstand complex environments such as high temperature and high pressure and are compatible with MEMS processes. AlN piezoelectric films not only have high performance but also meet the needs of MEM devices. With the development of the packaging industry, the demand for AlN films is increasing, with requirements for denser, thinner, more uniform, smoother, and more reliable films. At the same time, it is hoped that the process adaptability and cost issues in the AlN film preparation process will be resolved. To meet the needs of this development trend, many researchers have conducted extensive research on the preparation technology and performance of AlN films.

[0004] Currently, the most common methods for preparing AlN thin films include hydride vapor phase epitaxy, molecular beam epitaxy, pulsed laser deposition, and chemical vapor deposition. Among them, molecular beam epitaxy has a slow deposition rate, high cost, and poor process compatibility, making it unsuitable for industrial production. The biggest drawback of pulsed laser deposition technology is that it cannot produce thin films with uniform surface quality. Compared with other growth methods, hydride vapor phase epitaxy has a fast growth rate and good crystallization quality, but the preparation process is complex, the chemical substances generated by the reaction are easily damaged by the equipment, the cost is high, and impurities are easily introduced. Metal organic compound chemical vapor deposition is the most commonly used thin film preparation method. The film has good crystallization quality and uniformity, but it has high requirements for the raw materials used in the preparation, and the purity of the raw materials is not very stable. Technical issues

[0005] Through the above analysis, the problems and defects of the existing technology are: complex film preparation process, high requirements for raw materials and equipment, and low quality of the produced film.

[0006] Existing technology: In the process of growing AlN thin films, the commonly used method is to grow AlN thin films directly on Si substrates. This method mainly deposits AlN directly on Si substrates through methods such as chemical vapor deposition (CVD) or physical vapor deposition (PVD).

[0007] Technical Problem Analysis: There are several key technical problems in the method of growing AlN thin films directly on Si substrates:

[0008] 1) Inconsistent crystal orientation: The crystal orientation of AlN films grown directly on Si substrates will be affected by the Si substrate, resulting in inconsistent crystal orientation. This will affect the electrical and mechanical properties of the AlN films.

[0009] 2) Slow growth rate: In the process of directly growing AlN films on Si substrates, the chemical reactivity between Si and AlN is weak, resulting in a slow growth rate of the AlN film.

[0010] 3) Unstable film quality: Due to the poor interface matching between Si and AlN, AlN films grown directly on Si substrates will experience stress, resulting in unstable film quality, cracks or peeling.

[0011] The Mo layer-induced efficient growth method of AlN thin film can effectively solve these problems by first preparing a Mo thin film on a Si substrate and then growing an AlN thin film on the Mo film. Technical Solutions

[0012] In view of the problems existing in the prior art, the present invention provides a method for efficiently growing a Mo layer-induced AlN thin film and a method for testing its performance.

[0013] The present invention provides a method for efficiently growing an AlN thin film by inducing a Mo layer, and the method comprises the following steps:

[0014] Step 1: Mo thin film is prepared on Si by using DC pulse magnetron sputtering method;

[0015] Step 2: Prepare an AlN film with high preferential orientation on the Mo film.

[0016] Furthermore, the specific method for preparing the Mo film includes:

[0017] Step 1: Hang the ultrasonically cleaned Si substrate on a sample stage and adjust the parallel distance between the Si substrate and the target;

[0018] Step 2: High-purity Ar gas is introduced into the vacuum chamber, and the pressure in the vacuum chamber is adjusted to a preset value through a flow display and a gate valve, with an accuracy of ±0.02 Pa;

[0019] Step 3: Using a DC pulse power supply, a voltage is applied between the target and the substrate to pre-sputter the target surface. When fresh metal Mo is exposed on the target surface, the pneumatic baffle is opened to sputter.

[0020] Step 4: During the film preparation process, Mo films with different properties are sputter-deposited by adjusting process parameters.

[0021] Furthermore, by comparing and selecting the sputtering power and sputtering atmosphere conditions during the Mo film deposition process, an optimal film under various process parameter constraints was obtained, and the Mo film was characterized using XRD and AFM analysis instruments.

[0022] Furthermore, the process parameters are: under Ar gas conditions, substrate temperature is room temperature, target substrate distance is 8 cm, sputtering power is 120 W, and time is 0.5 hours.

[0023] Furthermore, a DC magnetron sputtering film forming method is used to grow an AlN thin film on the Mo electrode with fine and uniform grains.

[0024] Furthermore, the process parameters for growing the AlN film are: temperature 650 °C, target-substrate distance 8 cm, sputtering power 80 W, time 1.5 hours, ArN ratio 7:3.4, and pressure 0.5 Pa.

[0025] Performance testing method of Mo layer-induced AlN film: X-ray diffracting is performed on the prepared AlN film using an X-ray diffractometer to detect and analyze the surface morphology and organizational structure of the AlN film.

[0026] Furthermore, the XRD peak of the AlN film grown on Mo is sharp and strong.

[0027] Furthermore, the deposited AlN film has uniform grain distribution and high preferred orientation. Beneficial effects

[0028] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0029] The present invention adopts direct current magnetron sputtering, which can realize low-temperature deposition. The temperature in the magnetron sputtering chamber is only tens of degrees Celsius, and the preparation process conditions are lower, which is suitable for industrial production.

[0030] The present invention guides ion and electron beams through a magnetic field, concentrating them in a very small space. At the same time, due to the interaction between the electric field generated during magnetron sputtering and particles in the air, the "uneven coating" problem that cannot be solved in traditional sputtering methods can be avoided. Therefore, large-area preparation of AlN films can be achieved, saving time and material costs.

[0031] The present invention is carried out in a vacuum environment, so it does not require the use of a large amount of chemical solvents, nor does it generate a large amount of waste and harmful substances. Therefore, its impact on environmental pollution is relatively small, and the problem of chemical substances generated during the reaction easily causing damage to equipment and easily introducing impurities is solved.

[0032] The present invention chooses to grow an AlN film on a Mo film. By controlling the morphology and structure of the Mo film in advance, the AlN film is deposited on a Mo electrode with fine and uniform grains. It is found that the XRD peak of the AlN film prepared by this method is sharp and strong, indicating that the Mo film has a significant inducing effect on the growth of the AlN film. In addition, the AlN film has uniform grain distribution and high preferential orientation, which is conducive to high-quality industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0034] FIG1 is a flow chart of a method for efficiently growing a Mo layer-induced AlN thin film according to an embodiment of the present invention;

[0035] FIG2 is a flow chart of a specific method for preparing a Mo thin film according to an embodiment of the present invention;

[0036] FIG3 is an XRD analysis diagram of an AlN film provided in an embodiment of the present invention: (a) AlN on a Mo film; (b) AlN film on Si;

[0037] FIG4 is a schematic diagram of AlN thin film growth according to an embodiment of the present invention: (a) AlN thin film growth on a Mo electrode; (b) AlN thin film growth on a Mo electrode with fine and uniform grains. Modes for Carrying Out the Invention

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the embodiments.

[0039] Example 1:

[0040] In view of the problems existing in the prior art, the present invention provides a method for efficiently growing a Mo layer-induced AlN thin film and a method for testing its performance.

[0041] As shown in FIG1 , an embodiment of the present invention provides a method for efficiently growing a Mo layer-induced AlN thin film. The method comprises the following steps:

[0042] Step 1: Mo thin film is prepared on Si by using DC pulse magnetron sputtering method;

[0043] Step 2: Select a Mo film with excellent morphology and performance;

[0044] Step three: Prepare an AlN film with high preferential orientation on the Mo film.

[0045] As shown in FIG2 , the specific method for preparing a Mo thin film provided by an embodiment of the present invention includes:

[0046] Step 1: Hang the ultrasonically cleaned Si substrate on a sample stage and adjust the parallel distance between the Si substrate and the target;

[0047] Step 2: High-purity Ar gas is introduced into the vacuum chamber, and the pressure in the vacuum chamber is adjusted to a preset value through a flow display and a gate valve, with an accuracy of ±0.02 Pa;

[0048] Step 3: Using a DC pulse power supply, a voltage is applied between the target and the substrate to pre-sputter the target surface. When fresh metal Mo is exposed on the target surface, the pneumatic baffle is opened to sputter.

[0049] Step 4: During the film preparation process, Mo films with different properties are sputter-deposited by adjusting process parameters.

[0050] Furthermore, by comparing and selecting the sputtering power and sputtering atmosphere conditions during the Mo film deposition process, an optimal film under various process parameter constraints was obtained, and the Mo film was characterized using XRD and AFM analysis instruments.

[0051] Furthermore, the process parameters are: under Ar gas conditions, substrate temperature 30 °C, target-substrate distance 8 cm, sputtering power 120 W, and time 0.5 h.

[0052] Furthermore, a DC magnetron sputtering film forming method is used to grow an AlN thin film on the Mo electrode with fine and uniform grains.

[0053] Furthermore, the process parameters for growing the AlN film are: temperature 650 °C, target-substrate distance 8 cm, sputtering power 80 W, time 1.5 hours, ArN ratio 7:3.4, and pressure 0.5 Pa.

[0054] The performance test method of Mo layer induced AlN film was used to perform X-ray diffraction on the prepared AlN film, and the surface morphology and organizational structure of the AlN film were detected and analyzed, as well as the Origin75 analysis software and SPI4000 drawing analysis were used.

[0055] Furthermore, the XRD peak of the AlN film grown on Mo is sharp and strong.

[0056] Furthermore, the deposited AlN film has uniform grain distribution and high preferred orientation.

[0057] Mo film and AlN film were prepared by DC magnetron sputtering method, and Mo film with excellent morphology and performance was selected, and AlN film was grown on it to obtain the induced growth effect of Mo film on AlN film.

[0058] As shown in Figure 3, compared with the AlN film grown on the Mo film (a) and the AlN film on the Si substrate (b), the XRD peak of the AlN film grown on the Mo film is sharper and stronger, indicating that the Mo film has a significant inducing effect on the growth of the AlN film.

[0059] As shown in Figure 4, (a) when growing an AlN film on a Mo electrode, the two (002)-oriented nuclei are far apart. In addition to growing perpendicular to the substrate surface, the grains can also grow parallel to the substrate. Consequently, the grain sizes vary and the (002) preferred orientation is low. (b) When growing an AlN film on a Mo electrode with fine, uniform grains, the distance between the two (002)-oriented nuclei is short. As the nuclei grow, they quickly encounter another (002)-preferred orientation nucleus. This limits the film's growth rate parallel to the substrate, while the growth rate is faster along the (002) direction perpendicular to the substrate. Consequently, the deposited AlN film has uniform grain distribution and a high preferred orientation.

[0060] First, a Mo film is prepared on Si using a DC pulsed magnetron sputtering method. Then, an AlN film is selectively grown on the fine, uniform Mo electrode. This AlN film has high piezoelectric properties and good heat resistance, making it an ideal piezoelectric material. The polarization direction of the AlN material is along the c-axis, that is, perpendicular to the (002) crystal plane, and the piezoelectricity of the AlN piezoelectric film is strongest along the c-axis. Therefore, during the growth of the AlN piezoelectric film, by improving the preferential growth in the (002) direction through the invented method, an AlN film material with high piezoelectricity can be obtained. Furthermore, the AlN film has high thermal conductivity and thermal expansion coefficient, which allows the AlN film to maintain a stable structure under high temperature conditions and has good heat resistance. In addition, the AlN film is inert and does not easily react chemically with oxygen, thus having good oxidation resistance. These two characteristics enable the AlN film to remain stable in high-temperature environments.

Claims

1. An efficient growth method for Mo layer-induced AlN thin films, characterized in that, it includes the following steps: Step 1, prepare a Mo thin film on Si by direct current pulsed magnetron sputtering method; Step 2, select a Mo film with excellent morphology and performance; Step 3, prepare an AlN thin film with a high preferred orientation on the Mo film.

2. The efficient growth method for Mo layer-induced AlN thin films as described in claim 1, characterized in that, the specific method for preparing the Mo thin film includes: Step 1, suspend the ultrasonically cleaned Si substrate on the sample stage and adjust the parallel distance between the Si substrate and the target; Step 2, introduce high-purity gas Ar into the vacuum chamber, and adjust the pressure in the vacuum chamber to a preset value through a flow display instrument and a gate valve, with the precision controlled within ±0.02 Pa; Step 3, apply a voltage between the target and the substrate using a direct current pulsed power supply to pre-sputter the surface of the target. When the fresh metal Mo is exposed on the target surface, open the pneumatic baffle for sputtering; Step 4, during the thin film preparation process, sputter-deposit Mo thin films with different performances by adjusting process parameters.

3. The efficient growth method for Mo layer-induced AlN thin films as described in claim 1, characterized in that, through the comparison and selection of the sputtering power and sputtering atmosphere conditions during the deposition process of the Mo thin film, an optimal thin film under various process parameter limitations is obtained, and XRD and AFM analysis instruments are used to characterize the Mo thin film.

4. The efficient growth method for Mo layer-induced AlN thin films as described in claim 3, characterized in that, the process parameters are: under Ar gas conditions, the substrate temperature is 30 °C, the target-substrate distance is 8 cm, the sputtering power is 120 W, and the time is 0.5 hours.

5. The efficient growth method for Mo layer-induced AlN thin films as described in claim 1, characterized in that, grow the AlN thin film on a Mo electrode with fine and uniform grains by direct current magnetron sputtering film preparation method.

6. The efficient growth method for Mo layer-induced AlN thin films as described in claim 1, characterized in that, the process parameters for generating the AlN film are: temperature 650 °C, target-substrate distance 8 cm, sputtering power 80 W, time 1.5 hours, Ar:N ratio 7:3.4, pressure 0.5 Pa.

7. A performance testing method for Mo layer-induced AlN thin films, characterized in that, perform X-ray diffraction on the prepared AlN film using an X-ray diffractometer to detect and analyze the surface morphology and microstructure of the AlN thin film, and use Origin75 analysis software and SPI4000 drawing analysis.

8. The performance testing method for Mo layer-induced AlN thin films as described in claim 7, characterized in that, the XRD peaks of the AlN film grown on Mo are sharp and have strong intensity.

9. The performance testing method for Mo layer-induced AlN thin films as described in claim 7, characterized in that, the deposited AlN thin film has a uniform grain distribution and a high preferred orientation degree.

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