title:  The Transfer of Laser-Machined Micro-Structured Patterns from Silicon to Polymethyl Methacrylate
Creators: name: Withrow, Warren E.
Publisher: name: Old Dominion University
publisherIdentifier: https://ror.org/04zjtrb98
publisherIdentifierScheme: ROR
Year: 2011

description: This research project's purpose was transferring a micro-scaled pattern from a silicon wafer to a polymethyl methacrylate (PMMA), or acrylic, substrate through light absorption generated heat. The secondary objective was to determine if the pattern on the silicon wafer could then be transferred to silica (i.e. a microscope glass slide) through light absorption generated heat. Once this pattern-transfer technique is developed for the micro scale, it could be instituted on the nano scale. The experiment was designed to find an alternate method to that currently being used to mass-produce compact discs (CDs). The most popular method employs a stamping process by which an expensive glass master copy, or stamper, presses out the CDs. A master stamper produces about 20,000 presses before the microstructure pattern wears down. Theoretically, an inexpensive silicon master could be used to produce these glass master stampers at a lower cost.

This research employed a laboratory experiment rather than a numerical approach. Chapter One reviews current CD manufacturing production processes. Chapter Two discusses the problem statement and lays the foundation for executing the laboratory experiment. The procedures include laboratory set-up procedures, specimen preparations, micro-machining of the silicon wafer, and transferring the pattern from the wafer to the substrates. These laboratory set-up procedures included a programmable stage capable of moving in three-dimensional planes at a specified velocity and a neodymium (Nd3+) yttrium aluminium garnet (YAG) laser. Chapter Three introduces the analysis and testing of both the experimental data and theory behind heat transference from the laser to the specified substrate. Chapter Four describes the research results in detail, including the different substrate surface preparations and optimal laser settings that were used, describes the problems that arose during the experiment, and theorizes briefly any foreseeable future experimentation. Chapter Five relays the conclusions from this research.

The micro-structured pattern could be transferred to the PMMA but only by using a lubricant as a medium between the machined silicon wafer and the PMMA. In this case, the lubricant medium was Tap Magic® Pro-Tap Cutting Fluid as it offered a greater degree of controlled heat dissipation during the heat transfer process. In other words, it acted like the heat sink used during soldering electronic components. Initially, both air and water mediums were considered instead of the cutting fluid; however, both options had similar results. Air did not provide even heat dissipation flow. As a result, the PMMA either permanently adhered to the wafer or was burnt. Water boiled off in a matter of seconds providing similar results. Replacing the PMMA with silica and using the Tap Magic® Pro-Tap Cutting Fluid as the medium had mixed results. The glass alternately cracked or broke despite all laser setting variations. It was theorized that an oven could heat the glass to its softening point temperature just prior to laser heating; but limited funding prevented testing this theory.