A New LPCVD Technique of Producing Borophosphosilicate Glass Films by Injection of Miscible Liquid Precursors

Abstract

This study introduces a new, simple, and viable LPCVD technique basedon the injection of miscible liquid precursors.The preparation ofBPSG films from liquid mixtures of TEOS, TMB, and TMP is used hereas a prime example forimplementing this concept. The relationshipbetween starting solution composition and resulting film compositionis investigatedto provide guidelines for achieving desired stoichiometries.Variations in growth rate and composition are examinedto assessthe relative effects of deposition temperature, total pressure,solution composition, and injection rate. Atthe high boron and phosphoruslevels (4 weight percent), the reaction chemistry associated withthe use of TMP is seento produce severe depletion effects. At optimumdeposition conditions, select properties of BPSG films are investigated.Theresults indicate high compositional uniformity within the film,a dielectric constant value in close agreement with thatof thermallygrown, SiO2, conformal step coverage even in the case of severeaspect ratios, and desirable flow profiles attemperatures and phosphorusconcentrations significantly lower than those being currently achievedwithphosphosilicate glass films.