Method of Double Patterning Lithography process Using Plurality of Mandrels for Integrated Circuit Applications

摘要

A method includes performing a double patterning process to form a first mandrel, a second mandrel, and a third mandrel, with the third mandrel being between the first mandrel and the second mandrel, and etching the third mandrel to cut the third mandrel into a fourth mandrel and a fifth mandrel, with an opening separating the fourth mandrel from the fifth mandrel. A spacer layer is formed on sidewalls of the first, the second, the fourth, and the fifth mandrels, wherein the opening is fully filled by the spacer layer. Horizontal portions of the spacer layer are removed, with vertical portions of the spacer layer remaining un-removed. A target layer is etched using the first, the second, the fourth, and the fifth mandrels and the vertical portions of the spacer layer as an etching mask, with trenches formed in the target layer. The trenches are filled with a filling material.

主权项

1. A method comprising:
forming a mandrel encircling a first opening and a second opening, wherein the first opening and the second opening are separated from each other by a first mandrel strip; etching a middle portion of the first mandrel strip to form a third opening connecting the first opening to the second opening, wherein the first mandrel strip comprises a first portion and a second portion remaining on opposite sides of the third opening; forming a blanket spacer layer over the mandrel; etching horizontal portions of the blanket spacer layer to form spacers, wherein the third opening is fully filled by the spacers, and the first opening and the second opening are narrowed by the spacers; etching the first portion and the second portion of the first mandrel strip to form a fifth opening and a sixth opening encircled by the mandrel and the spacers; using the mandrel and the spacers as an etching mask to etch a target layer, with trenches formed in the target layer; and filling the trenches with a filling material.