Conformal coating by photoresist of sharp corners of anisotropically etched through-holes in silicon

The authors describe a photoresist treatment yielding conformal coating of three-dimensional silicon structures. This even includes the sharp corners of through-holes obtained by anisotropic etching in (100)-silicon. Resist reflow from these corners is avoided by replacing the common baking procedure with a proper vacuum treatment. The investigated photoresist is Shipley's Eagle 2100 ED, a negative-working electrodeposited photoresist. Electrical frontside to backside interconnections have been made using this photoresist as an etch mask.