Patent ID: 8557704

Claim:
A method for semiconductor processing, comprising: forming self-aligned tiered elongated mandrel structures having n tiers over a substrate, where n≧2, wherein mandrels at tier n are disposed over mandrels at tier n−1, wherein a distance between immediately adjacent mandrels at tier n is greater than a distance between adjacent mandrels at tier n−1, wherein the mandrels at tier n have exposed top surfaces, wherein mandrels at each tier are formed of a different material than mandrels at immediately adjacent tiers, wherein forming self-aligned tiered elongated mandrel structures comprises: forming a pattern in a photoresist layer, the pattern comprising photoresist features having a photoresist feature width; etching the pattern into two or more layers of the different materials corresponding to the tiers of the mandrel structure, the etched layers comprising etched features underlying the photoresist features and having a width substantially equal to the photoresist feature width; and subsequently reducing dimensions of etched features of the layer at tier n to form the mandrels at tier n; providing a layer of spacer material on the tiered mandrel structures; and subjecting the spacer material to an etch to simultaneously define spacers on sidewalls of each of the tiers.