Growing Sub-micron Diamond Films by A Novel Microwave Plasma Jet CVD System

A microwave plasma jet chemical vapor deposition (MPJCVD) method, which utilizes antenna to guide microwaves, is a technology that hasn´ t successfully applied to grow diamond films. This study overcame difficulties in system design and grew sub-micron diamond films using a self-assembled MPJCVD system. The advantageous high-density plasma of such microwave plasma jet can largely improve the uniformity of plasma density which is usually a problem in the traditional microwave plasma system. The MPJCVD of this study can provide a plasma jet with a cross-section of about 1 cm and possesses a moveable seat to grow a large area of diamond films. This study pretreated silicon substrates with ultrasonic-energized diamond powders. In an atmosphere of 0.25% methane-to-hydrogen ratio, a diamond film with its grains of nearly 0.5 um can be successfully synthesized using a high temperature plasma jet under microwave powers of 600 W, 800 W, and 1000 W. The field emission scanning electron microscopy (FESEM), Raman spectrometer, X-ray diffractometer (XRD), and X-ray photoelectron spectrometer (XPS) are used to characterize the as-grown diamond films. The results show such sub-micron diamond films possess perfect crystals and grains of averaged 0.5 mum.