Patent ID: 7105097

Claim:
A method of forming an opening through a substrate, the method comprising: etching into the substrate from a first side, including forming a first portion of the opening; etching into the substrate from a second side opposite the first side, including forming a second portion of the opening; continuing etching into the substrate from at least one of the first side and the second side toward the other of the first side and the second side, including communicating the first portion and the second portion of the opening; and etching into the substrate from an interface between the first portion and the second portion of the opening, including etching from the interface toward the second side of the substrate and forming a third portion of the opening, wherein, in a first direction, the opening diverges from the second side of the substrate to the first side and, in a second direction perpendicular to the first direction, the opening converges from the second side of the substrate to the first side.