SmartNIL® high-pattern-fidelity replication using TOK TPIR™-2000S NL
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SmartNIL® high-pattern-fidelity replication using TOK TPIR™-2000S NL By Martin Eibelhuber1 (M.Eibelhuber@EVGroup.com), Thanner Christine1 (C.Thanner@EVGroup.com), Mr. Yohei Aoyama2 (y-aoyama@tok.co.jp), Mr. Katsuhito Iijima2 (k-iijima@tok.co.jp) 1EV Group,2 Tokyo Ohka Kogyo Co., Ltd Nanostructured layers and surfaces are fundamental for development of many novel devices and applications in semiconductor, photonic and biomedical industries. Such nanostructure-based devices are already well established for silicon, compound semiconductors and glasses as well as for polymer structures. Nanoimprint lithography is now a well-established method for patterning nanostructures and also a proven fabrication method for various devices [1]. Leading manufacturers of augmented reality devices, optical sensors and biomedical chips are already utilizing NIL and realizing the benefits of this technology, including the ability to mass manufacture micro- and nano-scale structures down to less than 30 nm without restrictions to device dimensions. Additionally, complex structures, which typically need direct writing technologies, can be replicated easily and for many devices the replicated layer can be directly used as a functional layer in the product. In particular, permanent optical layers have proven to benefit a broad variety of photonic products. Next to the nanoimprint technology and equipment, a key ingredient for successful implementation of this technique is given by the imprint resin. One example is TPIRT"-2000S NL, designed by Tokyo Ohka Kogyo Co., Ltd (TOK), which is the world's top supplier of photoresists for semiconductor markets. It is a Si-containing UV imprintable material, which shows extremely high reliability (e.g., high temperature, humidity, and thermal shock), and has high transparency. The material can be applicable for various types of optical devices requiring high reliability. Further information and other material portfolios are available from https://www.tok.co.jp/eng/products/newfield/list/structure-materials/nanoimprint-materials To unlock the potential of nanostructured optical resists it is important that they have good replication behavior. In particular, the complete filling of nanostructures, excellent pattern fidelity and defect-free demolding are crucial for high-quality devices. This has been investigated in more detail using a 200-mm master with 249 dies, which have a 500-nm / 300-nm line and space (L/S) pattern with 400-nm height. Images of the SmartNIL replication of these patterns are shown in Figure 1. As can be easily observed in these pictures, the TOK TPIRT"-2000S NL resist shows a nice and defect free filling of all dies and the wafer scale nanoimprint could be performed in high quality. January/2021 - SmartNIL® high-pattern-fidelity replication using TOK TPIR™-2000S NL EV Group - DI Erich Thallner Strasse 1 - 4782 St. Florian am Inn - Austria - Contact@EVGroup.com

For more detailed analysis of the resist properties, a full wafer lot of 25 wafers has been imprinted and investigated. To resolve the patterns, scanning electron microscope (SEM) cross section imaging has been done. In Figure 2, such cross sections are depicted from imprint 1, 15 and 25 as representative examples. As can be seen, the whole wafer lot showed excellent pattern fidelity and uniform layer control. All structures are completely filled and nicely show the L/S pattern with high pattern fidelity. Layer thickness and uniformity are also controlled very well. Figure 2 SEM cross...