Sequential gas flow oxide deposition technique

A method of depositing a silica glass insulating film over a substrate, the method comprising:

• exposing the substrate to a silicon-containing reactant introduced into a chamber in which the substrate is disposed such that one or more layers of the silicon-containing reactant are adsorbed onto the substrate;
• purging or evacuating the chamber of the silicon-containing reactant;
• converting the silicon-containing reactant into a silica glass insulating compound by exposing the substrate to oxygen radicals formed from a second reactant while introducing a fluent gas into the chamber and biasing the substrate to promote a sputtering effect, wherein an average atomic mass of all atomic constituents introduced into the chamber during the converting step is less than or equal to an average atomic mass of oxygen;
• and
• repeating the exposing, purging/evacuating and exposing sequence a plurality of times.

A method of depositing a silica glass insulating film over a substrate having a gap formed between two adjacent raised features, the gap having a bottom surface and a sidewall surface, the method comprising:

• exposing the substrate to a silicon-containing reactant introduced into a chamber in which the substrate is disposed such that one or more layers of the silicon-containing reactant are adsorbed onto the substrate;
• purging or evacuating the chamber of the silicon-containing reactant;
• converting the silicon-containing reactant into a silica glass insulating compound by exposing the substrate to a plasma formed from a second reactant comprising oxygen atoms while biasing the substrate to promote a sputtering effect, wherein an average atomic mass of all atomic constituents introduced into the chamber during the converting step is less than or equal to an average atomic mass of oxygen;
• and
• repeating the exposing, purging/evacuating and exposing sequence a plurality of times;
• wherein the substrate is maintained at a temperature between 300–800° C. during growth of the silica glass film and wherein the silica glass film grows up from the bottom surface of the gap at a rate greater than it grows inward on the sidewall surface of the gap.