Laser direct write system for fabricating seamless roll-to-roll lithography tools

Abstract

Implementations of roll to roll contact lithography require new approaches towards manufacturing tooling, including stamps for roll to roll nanoimprint lithography (NIL) and soft lithography. Suitable roll based tools must have seamless micro-or nano-scale patterns and must be scalable to roll widths of one meter. The authors have developed a new centrifugal stamp casting process that can produce uniform cylindrical polymer stamps in a scalable manner. The pattern on the resulting polymer tool is replicated against a corresponding master pattern on the inner diameter of a centrifuge drum. This master pattern is created in photoresist using a UV laser direct write system. This paper discusses the design and implementation of a laser direct write system targeting the internal diameter of a rotating drum. The design uses flying optics to focus a laser beam along the axis of the centrifuge drum and to redirect the beam towards the drum surface. Experimental patterning results show uniform coatings of negative photoresist in the centrifuge drum that are effectively patterned with a 405 nm laser diode. Seamless patterns are shown to be replicated in a 50 mm diameter, 60 mm long cylindrical stamp made from polydimethylsiloxane (PDMS). Direct write results show gratings with line widths of 10 microns in negative photoresist. Using an FPGA, the laser can be accurately timed against the centrifuge encoder to create complex patterns.

Direct-Write Photolithography for Cylindrical Tooling Fabrication in Roll-to-Roll Microcontact Printing

“…The parameters included the thickness of the photoresist layer and the exposure dose per unit of surface area (modulated via the centrifuge rotation speed). The apparatus that formed the base for these experiments, as developed by Petrzelka and Hardt [8], is shown in Fig. 7.…”

“…To address these problems, Petrzelka and Hardt [8] developed a method for the fabrication of seamless cylindrical stamps for lCP using a centrifugal casting method. In this method, a cylindrical master pattern is created by a laser direct-write process on a positive photoresist spun to even thickness within the centrifuge.…”

Step and scanning lithography for patterning seamless microstructures on the inner surface of a hollow roller

“…As imprinting areas increase, the loss caused by discontinuities rises too. As a result, some efforts have been focusing on directly patterning microstructures on cylindrical surfaces so that seamless molds can be obtained, for example precision machining [9,10], laser ablation [11,12], curved surface lithography [13][14][15] and maskless curved surface lithography [16][17][18][19]. In curved surface lithography, a photoresist (PR) layer is first uniformly coated on the roller surface and then exposed by ultraviolet (UV) light energy through a photomask.…”

Roll-to-Roll Microcontact Printing of Flexible Aluminum Substrates Using Octadecylphosphonic Acid (ODPA)

“…The need for continuous cylindrical tools with appropriate micro-scale features and substrate uniformity to produce consistent, large area printing has been addressed by Petrzelka and Hardt [11] and Nietner and Hardt [12]. Using a novel centrifugal casting and cylindrical mask-less patterning method, seamless cylindrical PDMS tools, such that shown in Fig.…”