is normally made of transparent material like fused silica or PDMS. After the mold and the substrate are pressed together, the resist is cured in UV light and becomes solid. After mold separation, a similar pattern transfer process can be used to transfer the pattern in resist onto the underneath material. The use of a UV-transparent mold is difficult in a vacuum, because a vacuum chuck to hold the mold would not be possible. Resist-free direct thermal nanoimprint lithography Different from the above mentioned nanoimprint methods, resist-free direct thermal nanoimprint does not require an extra etching step to transfer patterns from imprint resists to the device layer. In a typical process, photoresist patterns are first defined using photolithography. A polydimethylsiloxane (PDMS) elastomer stamp is subsequently replica molded from the resist patterns. Further, a single-step nanoimprint directly molds thin film materials into desired device geometries under pressure at elevated temperatures. The imprinted materials should have suitable softening characteristics in order to fill up the pattern. Amorphous semiconductors (for example chalcogenide glass) demonstrating high refractive index and wide transparent window are ideal materials for the imprint of optical/photonic device. This direct imprint patterning approach offers a monolithic integration alternative with potentially improved throughput and yield, and may also enable roll-to-roll processing of devices over large substrate areas inaccessible using conventional lithographic patterning methods. In thermal nanoimprint methods the trade off between full pattern transfer and deforming the substrate creates limitations in quality of fabrication. Few approached have created other solvent assisted methods for direct resistless nanoimprinting processes. Schemes Full wafer nanoimprint In a full wafer nanoimprint scheme, all the patterns are contained in a single nanoimprint field and will be transferred in a single imprint step. This allows a high throughput and uniformity. An at least diameter full-wafer nanoimprint with high fidelity is possible. To ensure the pressure and pattern uniformities of full wafer nanoimprint processes and prolong the mold lifetime, a pressing method utilizing isotropic fluid pressure, named Air Cushion Press (ACP) by its inventors, is developed and being used by commercial nanoimprint systems. Alternatively, roll on technologies (e.g. roll to plate) in combination with flexible stampers (e.g. PDMS) have been demonstrated for full wafer imprint. Step and repeat nanoimprint Nanoimprint can be performed in a way similar to the step and repeat optical lithography. The imprint field (die) is typically much smaller than the full wafer nanoimprint field. The die