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	FABRICATION GROUP RECOMMENDATIONS It is the consensus opinion of this group that MEMS fabrication technologies, in certain selected areas, have matured beyond the research and development stage and have enabled several high-volume products. Currently, the largest market segments for the MEMS industry include silicon-based pressure sensors, air-bag crash sensors, print heads for ink-jet printers, and digital light processors (DLP) for video projectors. The fabrication technologies that enable these high-volume products fall under two broad categories: bulk micromachining (e.g., pressure sensors and ink-jet print heads) and surface micromachining (e.g., air-bag accelerometers and DLP). Challenges It is the consensus of this group that there remain significant challenges in MEMS fabrications that are worth investigating. There is little dispute that MEMS fabrication research requires a multi-disciplined approach. In contrast to the IC industry, there are virtually no standardized MEMS fabrication techniques equivalent to the CMOS technology that will satisfy a majority of MEMS device fabrication needs. The materials used in MEMS fabrication are also far more varied than in electronics. Furthermore, compared with the IC industry, the volumes in MEMS are inherently lower due to the specialized nature of the specific devices. Finally, it is also obvious to this group that MEMS fabrication is coupled with the specific application as well as packaging and reliability, which are the subject matters of the other two groups. Due to the vast diversity in MEMS fabrication methods and the intended applications, the task to establish prioritized lists for research investment and technology roadmaps are more complicated than those for the microelectronics industries. This group engaged in in-depth discussions on this issue. Several findings are outlined in this report. Research Topics There are several proposed research topics in MEMS fabrication: LIGA and Ultra-Deep LIGA The goals are to establish a LIGA process that is manufacturable and to enable precision microstructures as thick as several mm. Research issues include Wet developing process Thermal stress control Numerical simulation of wet processes Materials issues Micro-embossing technologies Science of plating high-strength alloys Extending and including LIGA to larger-dimension objects. The potential benefits include Low-cost manufacturing of molding microstructures with wide choices of structural materials Excellent heat transfer characteristics in the final metal or alloy devices Molds for polymer and plastic parts Further Miniaturization and Nanofabrication The goal is to establish processes to create sub-micron-scale devices. Research issues include Internal dissipation and materials characteristics Surface science of nanostructures Transduction mechanisms Integration techniques with micromechanical devices and electronics, Ever-higher aspect ratios Dimensional uniformity and repeatability Combining both small (microns and sub-microns) and large (> cm) dimensions in the same process flow Speed and throughput of nanofabrication processes Sciences of ultra thin-film coatings Laser/FIB/FEB maskless fabrication CAE/CAD/CAM tools for process flows and atomistic designs The potential benefits include Higher operating frequencies Potentially greater durability Ultra-sensitive force and/or mass detection Enabling novel toolbox for nanostructural studies of materials, etc. Polymers and Other New Materials The goal is to establish processes that incorporate new materials beyond silicon, such as "active" materials, optical coatings, polymers, plastic, biodegradable materials, etc. Research issues include Process compatibility with existing MEMS fabrication techniques Diversity in processing techniques and properties of polymers Scaling polymer processes to MEMS level Multi-functions and multi-materials systems Processing of quartz and glass Optical properties of transparent and translucent materials Integration with electronics and mechanics The potential benefits include Better performance and better suitability for specific applications such as biomedical, RF MEMS, harsh-environment applications Polymers are suitable for low-to-medium-precision device applications New functionality Low-cost production at all production volumes Disposable products Biocompatible devices Self-packaged polymer devices True 3-D shapes Leveraging the existing vast infrastructure of the polymer industry Manufacturing Sciences and manufacturing infrastructures The goals are to establish the technology to ensure manufacturability and to establish a resource for flexible manufacturing to support different process sequences while maintaining high quality, reproducibility, and relative low cost. The specific research topics include The science and physics of surface properties of materials used in MEMS fabrication The study of bulk properties of materials used in MEMS fabrication Effective and coordinated uses of standard process control monitors Process and quality controls methodologies The physics of contamination causes and effects Low-temperature fabrication processes Non-silicon fabrication technologies The use of computer modeling for prediction of process outcomes The development of software technology for manufacturing databases Process modularization Undergraduate trainings in generic Statistical Process Control (SPC) and Design of Experiments (DE) The benefits include Understanding and/or lowering the substantial entry barriers into MEMS Efficient and cost-effective prototyping of research designs Stable manufacturing process for small to large volume productions Short product development cycles Increased accessibility to fabrication infrastructures Enhance MEMS fabrication predictability, repeatability, and producibility Analyses of Research Topics The group analyzed the proposed research topics in relative terms of technology push vs. application pull as well as near term (a few years) vs. long term (10 years and beyond). The results are summarized in Table I. It should be noted that the listed research topics all require variable degrees of design tools and CAD abstraction technologies.

Table 1. Comparison of the four research topics in MEMS fabrication in relative terms*

Technology Push (T/t) vs. Application Pull (A/a)	Near Term (N/n) vs. Long Term (L/l)	Research Topics
t A	N l	MEMS manufacturing sciences and infrastructure
T A	n l	Polymer and other MEMS materials
T a	L n	Nano fabrication Thin-film coating
T a	L N L	LIGA / LIGA-like processes Molding plastics Molding of other materials

* "T" represents strong technology push and "t" weak technology push, while "A" represents strong application pull and "a", weak application pull. Similarly for "N", "n", "L", and "l" for near term vs. long term.

One clear observation that stands out from the analyses is that the topic of MEMS manufacturing sciences and infrastructure should be at the top of research priorities because there exists a critical near-term need that is based on strong application pull. This research topic has the potential of maximum impact on the advancement of the MEMS field and the highest payoff on research investment. However, due to some inevitable issues in sensitivity and competitiveness in the commercial arena, the government needs to play a crucial role in facilitating pre-competitive collaboration in the pursuit of this topic to eliminate wasteful duplication of research efforts and to lower the entry barriers for general MEMS developers.