Trench Formation using Horn Shaped Spacer

摘要

A method includes forming a mandrel layer over a target layer, and etching the mandrel layer to form mandrels. The mandrels have top widths greater than respective bottom widths, and the mandrels define a first opening in the mandrel layer. The first opening has an I-shape and includes two parallel portions and a connecting portion interconnecting the two parallel portions. Spacers are formed on sidewalls of the first opening. The spacers fill the connecting portion, wherein a center portion of each of the two parallel portions is unfilled by the spacers. Portions of the first opening that are unfilled by the spacers are extended into the target layer.

主权项

1. A method comprising:
forming a mandrel layer over a target layer; etching the mandrel layer to form mandrels, wherein the mandrels have top widths greater than respective bottom widths, and wherein the mandrels define a first opening in the mandrel layer, wherein the first opening has an I-shape and comprises:
two parallel portions; anda connecting portion interconnecting the two parallel portions; forming spacers on sidewalls of the first opening, wherein the spacers fill the connecting portion, and wherein a center portion of each of the two parallel portions is unfilled by the spacers; and extending portions of the first opening unfilled by the spacers into the target layer.