PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION OF A-SIC-H FILMS FROM ORGANOSILICON PRECURSORS

A study of the growth of a-SiC:H films by plasma-enhanced chemical vap or deposition (PECVD) from two organosilicon precursors, silacyclobuta ne (H2CH2SiCH2CH2 or SCB) and methylsilane (CH3SiH3), is described. A capacitively coupled, parallel plate PECVD system was used to grow fil ms at 250 degrees C and deposition pressure of 2.0 Torr. Standard (13. 56 MHz) and low frequency (0.125 MHz) rf sources were used to generate the deposition plasma. Depositions were performed with and without ar gon dilution (neat) of the precursor. We report some of the first proc ess/property relationships for organosilicon based a-SiC:H films grown using st fixed, controlled set of de position conditions. included ar e data on film composition, structure, dielectric constant and stress. Films deposited from silacyclobutane had much higher carbon concentra tions than those deposited from methylsilane, but in both cases the ca rbon fraction in the film was lower than that in the precursor. It is found that the plasma drive frequency has a stronger influence on film composition than argon dilution of the precursor during deposition. T he low frequency plasma significantly increases the film growth rate f or the neat precursor process. Depending on the growth process, the re lative dielectric constants of the a-SiC:H films ranged from 3.6 to 8. 7. The variation of the dielectric constant over the frequency range 0 .1-1000 kHz was negligible. Ah measured film stress was compressive an d ranged from 0.1 to 1.0 GPa depending on precursor and plasma frequen cy. Films deposited from a 10% organosilicon/90% argon mixture showed higher dielectric constants, higher refractive indices and less bound hydrogen when compared to neat organosilicon precursor depositions. Th e films exhibited excellent oxidation resistance and could not be etch ed in 6:1 buffered HF solutions. The properties of the a-SiC:H films a re compared to PECVD hydrogenated silicon nitride and discussed in the context of applications requiring low temperature deposited protectiv e dielectric coatings.