Patent ID: 7132374

Claim:
A method based on plasma enhanced chemical vapor deposition techniques for depositing a porous film of a host matrix material on a substrate in a vacuum environment, comprising: (a) Using a reagent mixture stream that comprises at least one silicon-containing precursor, at least one selective silicon removal reagent, and other additional chemical reagents known to those skilled in the arts for facilitating the PECVD of the film host matrix material and the PECVD of silicon; (b) Using RE power modulation to facilitate the execution of a plurality of processing cycles to form the desired thickness of the porous film, wherein each cycle comprises codeposition of the host matrix material with silicon when the RF power level is set at a level suitable for the codeposition of the film host matrix material and silicon, and selective removal of silicon from the codeposit to form the porous structure by chemical exposure of the codeposit to the reagent mixture containing the selective silicon removal reagent when the RF power level is turned off or set below that which is required for deposition or the dissociation of the selective silicon removal reagent; wherein the selective silicon removal reagent is a vapor derived from a solution containing at least a chemical selected from the group consisting of potassium hydroxide, tetramethylammonium hydroxide (TMAH), ethylene diamine pyrocatecol (EDP), and their derivatives thereof.