PREPARATION OF LOW DIELECTRIC-CONSTANT F-DOPED SIO2-FILMS BY PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION

Signal delays in interlayer films limit the performance of very large scale integrated (VLSI) circuits. Signal delays can be reduced by usin g interlayer films with low dielectric constants, such as fluorine-dop ed (F-doped) SiO2 films, We were able to fabricate F-doped SiO2 films with dielectric constants as low as 2.3 and with good step coverage, b y adding CF4 to SiH4/N2O plasma-enhanced chemical vapor deposition (PE CVD), The reduction of the dielectric constant apparently results from a decrease of the ionic polarization, The improvement of step coverag e is due to a decrease of the sticking probability of the film-forming species. (C) 1996 American Institute of Physics.