Sealing porous structures

A method for controlling conformality of a deposited film on a semiconductor substrate, the method comprising:

• providing the substrate with a plurality of openings at a surface thereof;
• providing a sequence of at least two different, mutually reactive reactants in temporally separated and alternating reactant pulses;
• selecting separations of the reactant pulses and durations of the reactant pulses to control the conformality of the film deposited in the openings in the surface of the semiconductor substrate, wherein the separations and durations are selected to achieve reduced conformality compared to a corresponding atomic layer deposition (ALD) process that is optimized to achieve maximum conformality with minimum cycle length for the substrate topography;
• and
• exposing the semiconductor substrate to the sequence of the reactant pulses with the selected separations and durations to deposit the film.

A semiconductor fabrication process, comprising:

• providing a low k dielectric having an anisotropic pore structure and larger openings therein;
• preferentially sealing an upper surface of the low k dielectric layer;
• and
• conducting an atomic layer deposition process to deposit directly over the sealed upper surface.

A method for deposition of a film on a semiconductor substrate, the method comprising:

• providing the substrate, the substrate having at a surface thereof different regions with different levels of accessibility;
• providing a sequence of at least two different, mutually reactive reactants in temporally separated and alternating reactant pulses;
• selecting separations of the reactant pulses and/or durations of the reactant pulses to achieve self-saturation and self-limiting atomic layer deposition (ALD) mode deposition on the most accessible regions on the substrate surface and depletion effects in less accessible regions on the substrate surface;
• and
• exposing the semiconductor substrate to the sequence of the reactant pulses with the selected temporal separations and durations to deposit the film.