Study on nano thickness inspection for residual layer of nanoimprint lithography using near-field optical enhancement of metal tip

We propose a novel nano thickness inspection method of residual layer film of nanoimprint lithography, allowing nondestructive evaluation of residual layer thickness independent of the diffraction limit. In the proposed method, we applied near-field optical enhancement of a fine metal tip as a high spatial resolution measurement probe, with which we can get near-field optical response generated by dynamic interaction of the tip, thin residual layer film and a Si substrate. By performing theoretical analyses based on finite-difference time-domain (FDTD) method and fundamental experiments using a newly developed near-field optical response detection system, we verified the feasibility of the proposed method.