Self-aligned air gap formation in microelectronics packages

A microelectronics package comprising:

• a first substrate;
• a plurality of traces attached to the first substrate and space apart from one another, each of the plurality of traces comprising:
• a first sidewall having a first portion of a photosensitive material attached thereto, and
• a second sidewall having a second portion of a photosensitive material attached thereto, the first side wall of a first of the plurality of traces facing the second sidewall of a second of the plurality of traces;
• and
• a second substrate attached to the plurality of traces, the first and second substrates and the plurality of traces forming a plurality of air gaps in between respective ones of the plurality of traces.

A method of manufacturing a microelectronics package, the method comprising:

• forming a hard mask onto a sacrificial film;
• etching the sacrificial film to form holes in the sacrificial film to reveal a portion of a first substrate, wherein each of the holes formed in the sacrificial film includes an undercut region;
• depositing a photo-imageable material onto the substrate to fill the holes, including the undercut regions, formed in the sacrificial film;
• exposing the photo-imageable material to light;
• removing exposed portions of the photo-imageable material without removing portions of the photo-imageable material within the undercut regions;
• forming traces within the holes formed by removing the exposed portions of the phot-imageable material;
• removing the sacrificial film;
• and
• attaching a second substrate to the traces, wherein attaching the second substrate forms a plurality of air gaps.