Patent ID: 8338304

Claim:
A method of forming features on a target layer, comprising: forming openings in a resist layer having a first thickness located above an intermediate layer on a target layer; forming a first set of spacers on sidewalls of the resist layer, the first set of spacers including a first material and having a second thickness at least one third the first thickness of the resist layer; removing portions of the resist layer and the intermediate layer not masked by the first set of spacers; exposing portions of the target layer except for portions masked by the first set of spacers; removing the first set of spacers; exposing remaining portions of the intermediate layer; forming second spacers on sidewalls of the remaining portions of the intermediate layer such that a first portion of the second spacers are separated from first neighboring second spacers by a distance equal to a width of the second spacers, a second portion of the second spacers are separated from second neighboring second spacers by voids and the remaining portions of the intermediate layer, and a third portion of the second spacers are separated from third neighboring second spacers by the remaining portions of the intermediate layer on both sides of the third portion of the second spacers; removing the remaining portions of the intermediate layer; and forming features in exposed portions of the target layer, the features having a critical dimension about equal to the second thickness of the first set of spacers.