Processes and parameters of diamond films deposition in AC glow discharge

We report about a new PACVD reactor construction for diamond films deposition from the alternating high-current glow discharge plasma. Argon–hydrogen–methane gas mixture was used as the precursor gas. Argon percent in the gas mixture could reach 75%. The discharge was generated between two tungsten electrodes with the total area no more than 1 cm2. The electrode temperature was about 2000 °C. The discharge was in the form of plasma line and could reach 20 cm lengthwise and more. The discharge voltage was varied from 90 to 700 V depending on the argon partial pressure, the discharge current and the interelectrode spacing used. The current of discharge reached 30 A. The maximum growth rate of optical grade films was about 2 μm/h. OES spectrometry showed that hydrogen activation degree decreases from the center of plasma line to its edges. X-ray diffractometry and SEM showed the high quality of diamond films. The uniformity of the films in the transverse direction was measured.

► Diamond films were deposited in AC glow discharge plasma.
► Discharge was in the form of plasma line and could reach 20 cm lengthwise.
► OES spectroscopy was used to analyze the plasma.
► Measurement of the uniformity of films was in transverse direction.