Design of a fine alignment system featuring active orientation adjustment for nano imprint lithography

Abstract

The fine alignment between a template with nano patterns and a wafer substrate, especially the parallelism between the two surfaces, is critical to Nano Imprint Lithography. A fine alignment system featuring active orientation adjustment which is composed of an imprint unit and a 6-DOF micromanipulator is proposed in this work. Deformations of a compact flexure layer caused by imprint loads are measured by four identical force sensors embedded in the imprint unit. The tilt of the flexure layer can thus be eliminated by adjusting the orientation of the 6-DOF micromanipulator. Kinematics and stiffness analysis are then developed, followed by dynamic performance evaluations. Based on the proposed system, an imprint tool is further developed and corresponding experiments are conducted. A saw shape grating pattern with 1.6 μm linewidth and a lattice pattern with 0.9 μm period are both imprinted with a minimum feature of 30 nm well reserved on the substrate. A maximum parallelism error of 14 nm across the template surface is also demonstrated by further section analyses on the imprinted patterns, hence the feasibility and superiority of the proposed method is verified.