Microwave Plasma Chemical Vapor Deposition (MWPCVD) is a new method for the preparation of thin films. This paper uses this method to prepare diamond films in a self-developed water-cooled reaction chamber type MWPCVD apparatus. Equipment Container For Oil Field Container Workshop,Ice Box Container,Oil Field Container,Anti-Explosion Container Yangzhou Tonglee Reefer Container Co., Ltd. , https://www.cimctlc.com
Firstly, the working principle, structure and characteristics of the water-cooled reaction chamber type MWPCVD device are explained in detail, and the principle design of the new microwave power source for the device is emphasized. The unique way of connecting the high-voltage switching power supply with the common uncontrollable high-voltage rectifier power supply is adopted. to provide the negative high voltage magnetron cathode, and the anode current feedback control is performed so as to establish a high-precision, high power, fast response, interference voltage-controlled microwave power source, to meet the needs of the diamond film depositing gold.
The study of deposited diamond films was carried out under a stationary microwave, and the following results were obtained: 1) When the substrate was pretreated with diamond powder, the nucleation density of the diamond was different depending on the treatment method, grinding, ultrasonication, grinding and ultrasonication. It is also different. The grinding and ultrasonic treatment can obtain the maximum nucleation density, followed by the grinding treatment method, while the ultrasonic treatment method has the lowest nucleation density; the selection of fine diamond powder will help to improve the nucleation density of diamond. , reducing the size of the diamond particles in the deposited film. 2) When the microwave power is 1200W, in the pressure range of 4.0~10.66kPa, increasing the reaction pressure is beneficial to improve the deposition quality of the diamond film; when the microwave power is 1500W, in the low pressure range of 5.33~8.0kPa, Increasing the pressure is also beneficial to improve the deposition quality of the diamond film. However, in the high pressure range of 8.0~12.0 kPa, the increase of the gas pressure will degrade the deposition quality of the diamond film. 3) The lower CH4 concentration is beneficial to deposit the diamond film with lower carbon content in the non-diamond phase; 1% moderate CH4 concentration is beneficial to deposit the diamond film with the best crystal morphology. 4) Substrate H2 microwave plasma treatment is beneficial to reduce the content of non-diamond phase carbon in the deposited sample, but it is not conducive to increase the nucleation density of diamond.
The study of deposited diamond films under pulsating microwaves yielded the following results: 1) The use of suitable pulsating microwaves can significantly improve the deposition quality of diamond films and enable almost complete inhibition of microcrystalline graphite in diamond films. . 2) The too long or too short flat-bottom time or pulsation period is not conducive to the reduction of carbon content in the non-diamond phase of the diamond film. Only the moderate flat-bottom time or pulsation period has the best effect of reducing the carbon content of the non-diamond phase. 3) Pulsating microwaves will reduce the nucleation density of diamond. 4) Under pulsating microwave, even if a higher CH4 concentration is selected, a diamond film having a higher deposition quality than that of a diamond film prepared by using a lower CH4 concentration under a stationary microwave can be obtained.
The effect of O2 on the MWPCVD of diamond films was investigated under a stationary microwave. It is found that: 1) In the lower O2 concentration range, increasing the O2 concentration is beneficial to improve the deposition quality of the diamond film; but in the higher O2 concentration range, increasing the O2 concentration will reduce the deposition quality of the diamond film. 2) In the lower O2 concentration range, increasing the O2 concentration is beneficial to increase the nucleation density of diamond; but in the higher O2 concentration range, increasing the O2 concentration will reduce the nucleation density of diamond. 3) As the reaction gas pressure rises, the O2 concentration limit of the deposited diamond decreases.
The low temperature (low power low pressure) MWPCVD of diamond film was studied by a stationary microwave in CH4/H2 reaction gas. It was found that: 1) Even if the substrate temperature is as low as 355 °C, the diamond film and the better quality diamond film can be realized. Deposition; 2) When the microwave power is 900W, in the pressure range of 3.47~2.4 kPa, lowering the reaction pressure is beneficial to improve the deposition quality of the diamond film; 3) depositing at a lower substrate temperature of 484~355 °C There are compressive stresses in the diamond film.
The light transmission of the MWPCVD diamond film was studied. The following conclusions were drawn: 1) The infrared transparent diamond film and the diamond self-sustaining film can be prepared by MWPCVD; 2) The pulsating microwave is favorable for depositing the diamond film with high transmittance and transmission. A diamond self-sustaining film with a large ratio and good light transmittance; 3) A translucent diamond self-sustaining film in the visible light region can be prepared under pulsating microwave.
Microwave plasma method for producing diamond film