Methods for forming dense dielectric layer over porous dielectrics

A method comprising:

• forming an opening in a porous inter-layer dielectric (ILD) on a wafer, the ILD having an ultra-low dielectric constant, wherein the opening includes a sidewall surface and a bottom surface;
• and
• exposing the sidewall surface and the bottom surface to a plurality of substantially parallel ultra-violet (UV) radiation rays to form a dense dielectric layer having a substantially uniform thickness over both the sidewall surface and the bottom surface, and
• wherein the exposing comprises:
• exposing the bottom surface to the plurality of substantially parallel UV radiation rays at a first angle of incidence;
• and
• exposing the sidewall surface to the plurality of substantially parallel UV radiation rays at a second angle of incidence different than the first angle of incidence, the exposure to the bottom surface and the sidewall surface being substantially uniform, wherein exposing the sidewall surface further includes:
• positioning a UV radiation source relative to the wafer so that the plurality of substantially parallel UV radiation rays form an angle of incidence (α) with the wafer plane equal to approximately the second angle of incidence, and (ii) positioning the UV radiation source relative to the wafer so that a center of a radiation area formed by the UV radiation source corresponds to the center of the wafer, and (iii) incrementally rotating the UV radiation source about an axis that passes through the center of the wafer and is substantially perpendicular to the wafer plane.

A method comprising:

• forming an opening in a porous inter-layer dielectric (ILD) on a wafer, the ILD having an ultra-low dielectric constant, and the opening having a sidewall surface and a bottom surface;
• and
• exposing the sidewall surface and the bottom surface to a plurality of substantially parallel ultra-violet (UV) radiation rays from a UV radiation source to form a dense dielectric layer having a substantially uniform thickness over both the sidewall surface and the bottom surface, and
• wherein the exposing comprises:
• exposing the bottom surface to the plurality of substantially parallel UV radiation rays at a first angle of incidence;
• exposing the sidewall surface to the plurality of substantially parallel UV radiation rays at a second angle of incidence different than the first angle of incidence, the exposure to the bottom surface and the sidewall surface being substantially uniform;
• and
• wherein the first angle of incidence is substantially perpendicular to a plane formed by the bottom surface, and wherein the second angle of incidence is based on the dimensions of the opening and is approximately equal to an angle that provides exposure to the sidewall surface without exposing the bottom surface, and wherein exposing the sidewall surface includes positioning the wafer at an angle relative to the plurality of substantially parallel UV radiation rays equal to approximately the second angle of incidence.