Compatibility of 3-D printed devices in cleanroom environments for semiconductor processing
Materials Science in Semiconductor Processing
URL with Digital Object Identifier
3-D printing has potential to revolutionize manufacturing of customized low-cost scientific equipment, and numerous self-designed applications have already been realized and demonstrated. However, the applicability of 3-D printed devices to cleanrooms used for semiconductor processing is not as straightforward, as the controlled environment sets strict requirements for the allowed materials and items. This work investigates the opportunity to utilize 3-D printing in cleanrooms by analyzing three potentially suitable polymers (polylactic acid (PLA), acrylonitrile butadiene styrene (ABS) and polypropylene (PP)) for two applications that do not require particular chemical compatibility: a custom single wafer storage box and a wafer positioner for a metrology system. The designed equipment supplements commercial selection by introducing support for samples with non-standard shape or size and simultaneously reduces the price of often extensively expensive cleanroom equipment. The results show that the single wafer boxes 3-D printed from PLA and ABS generate as little particles as a commercial equivalent, whereas slightly more particles are found from a wafer stored in the self-printed PP box. Nevertheless, the number of particles on all wafers is in the same order of magnitude, indicating that 3-D printed boxes are not significant particle sources. The 3-D wafer positioner seems to cause a negligible particle increase on the manipulated wafer, while abrasion of the mechanical parts generate larger numbers of particles that may disperse in the environment. Regular cleaning of those parts is thus recommended, and applicability in a cleanroom environment will depend on the cleanliness constraints. Elemental analysis reveals that 3-D printed objects contain no other harmful metal impurities than those originating from colorants. Thus, 3-D printing filaments with natural color should be preferred for purposes, where metal contamination could be an issue, including semiconductor processing. Finally, 3-D printing filaments considered in this study are shown to be resistant to isopropanol and deionized water, which is critical for efficient cleaning for use of 3-D printed objects in cleanrooms. The results demonstrate that simple 3-D printed objects, such as wafer boxes or tweezers, are not notable contamination sources, and hence, are equally suitable for use in cleanrooms as the commercial equivalents.