Daniel A. Babbs

Step and Repeat UV nanoimprint lithography tools and processes

Step and FlashTM Imprint Lithography (S-FILTM) process is a step and repeat nano-replication technique based on UV curable low viscosity liquids. Molecular Imprints, Inc. (MII) develops commercial tools that practice the S-FIL process. The current status of the S-FIL tool and process technology is presented in this paper. The specific topics that are covered include: • Residual layer control • Etch process development • Patterning of lines, contacts and posts • CD control • Defect and process life • Alignment and magnification control

Development of imprint materials for the Step and Flash Imprint Lithography process

The Step and Flash Imprint Lithography (S-FILTM) process is a step and repeat nano-replication technique based on UV curable low viscosity liquids. Molecular Imprints, Inc. (MII) develops commercial tools that practice the S-FIL process. This talk will present the imprint materials that have been developed to specifically address the issue of process life and defects. The S-FIL process involves field-to-field dispensing of low viscosity (<5 cps) UV cross-linkable monomer mixtures. The low viscosity liquid leads to important advantages that include: • Insensitivity to pattern density variations • Improved template life due to a lubricated template-wafer interface avoids “hard contact” between template and wafer • Possibility for lubricated (in-situ) high-resolution alignment corrections prior to UV exposure The materials that are optimal for use in the S-FIL process need to possess optimal wetting characteristics, low evaporation, no phase separation, excellent polymer mechanical properties to avoid cohesive failure in the cured material, low adhesion to the template, and high adhesion to the underlying substrate. Over 300 formulations of acrylate based monomer mixtures were developed and studied. The imprint materials were deemed satisfactory based on the process of surviving imprinting more than 1500 imprints without the imprints developing systematic or repeating defects. For the purpose of these process studies, printing of sub-100 nm pillars and contacts is used since they represent the two extreme cases of patterning challenge: pillars are most likely to lead to cohesive failure in the material; and contacts are most likely to lead to mechanical failure of the template structures.

Design and performance of a step and repeat imprinting machine

Molecular Imprints, Inc. (MII) has developed the ImprioTM 100, which is the first commercial step and repeat imprint lithography system with field-to-field alignment. This system is designed to implement the UV curable nano-replication capability of the Step and FlashTM Imprint Lithography (S-FILTM) process. To-date, the Imprio 100 system has demonstrated: 1) Full 200 mm wafer coverage with lithographically useful patterning; 2) Full wafer residual thickness control to enable practical etching (thickness variation < 50 nm, 3 sigma); 3) Field edge control compatible with 50 um kerf regions. 4) Multi-day CD uniformity measured on an analytical SEM < 2 nm, 3 sigma with no process adjustments; 5) Etch pattern transfer including break-through etch of residual material, followed by a bi-layer etch through thick planarization layers; 6) Initial level-to-level alignment target acquisition with accuracy of better than 100 nm. 7) Low air borne particle counts in tool microenvironment consistent with Class 0.1 while imprinting.

The impact of step and flash imprint lithography for nano-manufacturing applications

Summary form only given, as follows. Step and Flash Imprint Lithography (S-FILTM) process is a step and repeat nano-replication technique based on UV curable low viscosity liquids. Investigation by this group and others has shown that the resolution of replication by imprint lithography is limited only be the size of the structures that can be created on the template (mold). S-FIL uses field-to-field drop dispensing of the W curable liquids for the step and repeat patterning. This approach allows for nanomanufacturing of devices with widely varying pattern densities and complicated structures. There are numerous bio applications for imprint lithography. One of the more interesting is to imprint small posts to manage cell =-growth. Images will be shown of distortion free 100 to 60 nm posts that are replicated by SFIL processing. Process data for repeatability, process control, effects and etch pattern transfer of sub 100 nm posts and other features will also be shown.

Status of Step and Flash Imprint Lithography tools and processes

The Step and Flash/sup TM/ Imprint Lithography (S-FIL/sup TM/) process is a step and repeat nanoreplication technique based on UV curable low viscosity liquids. This article discusses various process capability of S-FIL including imprint resolution and line edge roughness; field-to-field CD control; imprinted film thickness uniformity; process life and defect data; and overlay alignment accuracy.