Method for selective etching using dry film photoresist

A method comprising:

• forming an opening from a first surface of a substrate and extending through said substrate to expose a stop layer at a second surface of said substrate;
• forming a material layer in said opening over an inner surface of said opening and over said stop layer;
• applying a dry film photoresist over said first surface of said substrate and over said opening by lamination to form a tent structure over said opening;
• applying a second photoresist on said dry film photoresist by spinning a liquid photoresist onto said dry film photoresist;
• forming a first hole through said second photoresist at a location of said opening;
• forming a second hole through said dry film photoresist via said first hole, such that said second hole is aligned with said first hole, wherein said first and second holes are smaller than said opening;
• and
• removing said material layer from said stop layer via said first and second holes.

A method comprising:

• creating a stop layer on a second surface of a substrate;
• creating an electrically conductive bond pad on said stop layer;
• following creation of said stop layer and said electrically conductive bond pad, forming an opening from a first surface of said substrate and extending through said substrate to expose said stop layer at said second surface of said substrate;
• forming a material layer in said opening over an inner surface of said opening and over said stop layer;
• applying a dry film photoresist over said first surface of said substrate and over said opening;
• applying a second photoresist on said dry film photoresist;
• forming a first hole through said second photoresist at a location of said opening;
• forming a second hole through said dry film photoresist via said first hole, such that said second hole is aligned with said first hole, wherein said first and second holes are smaller than said opening, wherein following said forming said first hole and said second hole, a composite structure of said dry film photoresist and said second photoresist overhangs edges of said opening;
• and
• removing said material layer from said stop layer via said first and second holes, wherein said composite structure overhanging said edges of said opening prevents removal of said material layer from said inner surface of said opening.