Rapid transport of nano-particles in amplitude modulated rf discharges for depositing porous ultra-low-k films

We have proposed a novel one-step method for synthesizing nano-particle composite porous low-k films. For the method, nano-particles as nano-building blocks and radicals as adhesives are produced in reactive discharge plasmas; both of them are transported to a substrate; and eventually nano-particles are co-deposited there together with radicals. Size of nano-particles is controlled by the duration of pulse rf discharge; their rapid transport of a velocity more than 60 cm/s is realized by pulse rf discharges with an amplitude modulation (AM) of the discharge voltage. The deposition rate with AM is 0.65 nm/s, which is 7 times as high as that without AM, while dielectric constant k =1.1-1.4 and porosity =60-63 % of the films with AM are nearly equal to those without AM. Therefore deposition of porous low-k films using pulse rf discharges with AM is a promising method for increasing the deposition rate without varying the properties of films.