LOW-TEMPERATURE LIMITS OF DIAMOND FILM GROWTH BY MICROWAVE PLASMA-ASSISTED CVD

This paper describes the low temperature deposition (270-540 degrees C ) by microwave-plasma assisted chemical vapor deposition (CVD) of diam ond thin films using various gas mixtures. The substrate temperature w as controlled without adjusting other deposition parameters. It has be en observed that limits for low temperature growth of diamond films de pend substantially on the gas system employed as well as on the carbon concentration in the particular system. Generally, a characteristic t ransition from crystalline growth to deposits containing a strongly in creased amount of non-diamond carbon occurred when the deposition temp erature was lowered. This has been defined as the low temperature limi t of diamond film growth. The conventional CH4/H-2 systems have the hi ghest transition temperatures. The addition of oxygen permits him depo sition at lower substrate temperatures; the lowest have been realized in GO-rich systems. The dependency of the growth limits on crucial dep osition parameters is discussed in terms of abundant gas phase species and surface processes, in particular, the role of oxygen in the gas p hase and surface chemistry.