Patent ID: 7060624

Claim:
A process for making deep flared vias in a substrate, comprising: a.) providing a substrate having a first and a second surface in parallel, the first surface being coated with a masking layer; b.) developing with a layer of photoactive material a plurality of openings on the first surface; c.) dry etching vias through the masking layer to the depth desired in the substrate using TMDE while cooling the substrate, under bias, to a temperature between about 0° C. and about −100° C.; to form the deep vias; and d.) performing a two-stage etch process on at least one end of the deep vias, wherein the second stage of the two-stage process comprises wet etching in an HF-containing solution selected from the group consisting of: HF in a concentration between about 0.5–10 wt % : HNO 3 in a concentration between about 20–70 wt % : H 2 O; and HF in a concentration between about 0.5–10 wt %. balance H 2 O.