Growth of diamond film on rod-shaped beryllium oxide
A new type of linear microwave plasma source is used to deposit diamond film on the surface of 135 mm × 1 mm × 0.5 mm rod-shaped beryllium oxide with methane and hydrogen as reaction gases. The effect of pretreatment of beryllium oxide substrate on diamond nucleation density and film continuity, as well as the influence of substrate temperature on diamond quality was studied. The surface morphology and quality of the deposited diamond film were characterized by scanning electron microscopy and Raman spectroscopy. The experimental results show that the mixed pretreatment of 600# sandpaper and diamond powder can greatly increase the nucleation density of diamond on the surface of beryllium oxide and obtain a diamond film with better continuity; at the same time, the substrate temperature not only affects the surface morphology of the diamond film, but also The quality of the diamond film. When the substrate temperature is lower, the secondary nucleation of the diamond film during the deposition process is enhanced, and the non-diamond phase content is higher; after the deposition temperature is increased, the concentration of H atoms in the plasma increases, which is beneficial to the improvement of diamond quality.
Compared with other ceramics, beryllium oxide ceramics have the advantages of high thermal conductivity, high hardness, and low dielectric constant. Therefore, it has a wide range of applications in the electronic industry. However, with the development of the microelectronics industry and breakthroughs in traveling wave tube technology, the performance of beryllium oxide ceramics has been unable to meet the requirements of the electronics industry, and has become a major obstacle to the development of microelectronics products and the further improvement of performance. Diamond has excellent optical, mechanical, acoustic and chemical stability, as well as high thermal conductivity. It is one of the materials found to have excellent properties in all aspects. The beryllium oxide ceramic has a hexagonal wurtzite structure, which provides the possibility for the deposition of diamond film on the surface of beryllium oxide. At present, hot-wire chemical vapor deposition (CVD) equipment has been used at home and abroad to perform diamond film on the surface of beryllium oxide. Deposition to improve the thermal conductivity of beryllium oxide.
The use of microwave plasma to prepare diamond films has many advantages, including relatively mature technology, stable plasma, and good quality of deposited diamond films. However, because microwave plasma is usually spherical, it is relatively long when using microwave plasma chemical vapor deposition. When a thin diamond film is deposited on the rod-shaped surface, it is limited by the shape of the plasma source and its own characteristics. The linear microwave plasma CVD equipment is a device that uses microwave energy to promote the neutral gas to produce a one-dimensional uniform and stable plasma, which solves the problem of depositing diamond films on the surface of a long rod. During the deposition process, the vacuum technology network (http://www.chvacuum.com/) believes that the substrate pretreatment, growth temperature, hydrocarbon concentration and power have an important impact on the diamond film, among which the substrate pretreatment and growth temperature not only It is related to the nucleation and plasma density, and at the same time determines the morphology and quality of the diamond film. The morphology and quality of the diamond film on the surface of beryllium oxide directly affect the performance of beryllium oxide. Therefore, the effect of matrix pretreatment on the nucleation density and temperature is studied. The influence on the surface morphology and quality of the diamond film is of great significance to the development of the preparation of high-quality beryllium oxide-based diamond films.
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In this paper, a new linear microwave plasma source is used to deposit diamond film on the surface of rod-shaped beryllium oxide ceramics with CH4 and H2 as reaction gases. The effect of substrate pretreatment on the diamond nucleation density and film continuity, and the effect of substrate temperature on the diamond film are studied. The influence of surface morphology and quality.
1. Experiment
The experiment uses a self-designed linear microwave plasma source as shown. The device is mainly composed of a microwave source, a circulator, a microwave transmission and conversion system, a vacuum system, a water cooling system and a control system. The waveguides on both sides are equipped with water-cooled hollow copper rods as the same Axial mode converter, the quartz plate and the vacuum chamber are sealed with a rubber ring. The 2.45GHz microwave generated by the magnetron passes through the circulator and three pins, and is fed into the tungsten rod and vacuum chamber from the quartz plate through the waveguide and mode converter. In the coaxial waveguide reaction chamber formed by the wall, by adjusting the power of the two magnetrons, the gas pressure and the short-circuit piston, plasma can be excited around the surface of the tungsten rod in the center of the cavity. The length of the plasma generated depends on the microwave sources on both sides Power and reaction chamber structure. The tungsten rod is not only used as the inner conductor of the coaxial reaction chamber, but also as the sample holder when the thin film is deposited on the long sample.
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In this experiment, a long strip of beryllium oxide is placed on a tungsten rod, so as to achieve a large-area uniform deposition of diamond film on the surface of the rod-shaped beryllium oxide. The rod-shaped beryllium oxide ceramics with specifications of 135 mm × 1 mm × 0.5 mm are used as the experimental substrate, and the reaction gas is a mixture of CH4 and H2. First, the rod-shaped beryllium oxide ceramics are pretreated to explore the pretreatment of diamond nucleation The influence of density and film continuity can also improve the adhesion of the diamond film and the beryllium oxide substrate, making the film not easy to fall off. The sample was polished with 600# sandpaper and diamond powder on the surface of the beryllium oxide ceramic for 10 minutes to slightly change the surface structure of the beryllium oxide to form an uneven micro-surface, and then put the beryllium oxide ceramic in alcohol for cleaning to remove surface impurities. Finally, the processed beryllium oxide is dried as a substrate for depositing the diamond film. The diamond film deposition process parameters are shown in Table 1.
Structure diagram of linear microwave plasma source device
Table 1 Diamond film deposition process parameters
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Growth of diamond film on rod-shaped beryllium oxide
2. Conclusion
A new linear microwave plasma source was used to deposit a good diamond film on the surface of 135mm × 1mm × 0.5mm beryllium oxide ceramics. The effect of pretreatment on the nucleation density and film continuity, and the influence of substrate temperature on the quality of the diamond film were studied. . Draw the following conclusions:
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(1) Mixing sandpaper and diamond powder to pre-grind the surface of beryllium oxide can greatly increase the nucleation density of diamond and obtain a diamond film with better continuity;
(2) The increase in the temperature of the beryllium oxide substrate changes the surface morphology of the diamond film, and the crystal form of the (111) plane is more obvious, the crystal plane orientation is consistent, and the diamond grains are larger;
(3) The concentration of hydrogen atoms in the plasma affects the quality of the diamond film. The increase in temperature increases the concentration of hydrogen atoms, which strengthens the etching of non-diamond phases and improves the quality of the diamond film, but the diamond surface is also etched This is not conducive to the preparation of high-quality diamond films.
Founded in 2015,Zunhua Baorui Titanium Equipment Co.,Ltd. is a manufacturer specializing in pvd vacuum ion coating equipment. The company’s products mainly include large plate coating machine, large tube collating machine, tool coating machine and LOW-E glass production line. Mr.Wang baijiang ,general manager of the company ,has been engaged in vacuum coating industry for more than 30 years. He continuously improve production technology, improve product performance and devote himself to provide customers with better product experience and higher production efficiency.