Microelectromechanical Systems Advanced Materials and Fabrication Methods (1997) / Chapter Skim
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2 Integrated Circuit-Based Fabrication Technologies and Materials
2 Integrated Circuit-Based Fabrication Technologies and Materials
Pages 14-22
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From page 14... ...
These desirable characteristics of batch fabrication are key to the low costs, manufacturability, and reliability associated with ICs. In current IC production, a common set of materials and repeated process steps can be used to manufacture numerous circuits that may, in turn, be used by many diverse designers.
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From page 15... ...
Compatible processing with ICs has been demonstrated using either technique, but the complexity of the process, the sizes and possible shapes of the mechanical elements, the sizes of the chips, the minimum sizes of the features, the costs, and the yields are all strongly influenced by the chosen process and the level of system integration in the MEMS. 15 Bulk Micromachining Processes Bulk micromachining was first demonstrated decades ago.
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From page 16... ...
The bottom wafer can either be patterned by traditional wet etching methods (a) or can have an oxide defined region that will later be removed by sacrificial etching.
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From page 17... ...
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From page 18... ...
the etch rate above 3,um/min and/or increasing the production throughput using multiple-wafer DRIE tools; developing conformal deposition processes that deposit uniform layers of ceramics and metals on the sidewalls of the high-aspect-ration processes; developing low-temperature deposition processes compatible with deposition on completed ICs; and developing multiple level bulk micromachining processes. Surface Micromachining Processes Surface micromachining makes use of traditional microelectronics fabrication techniques to create mechanical systems with micron-sized features.
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From page 19... ...
The fabrication sequence is completed with the immersion of the wafer in hydrofluoric acid, the etch rate of whichis very different for polycrystalline silicon then for silicon dioxide. This highly selective release-etch removes the silicon dioxide and leaves the polycrystalline silicon structures suspended above the wafer surface everywhere except where the anchor cuts were made.
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From page 20... ...
A broad variety of researchers have made use of this service to create both simple and complex structured MEMS. Surface-micromachining technologies can also be used on material systems other than structural polysilicon and sacrificial layers of silicon dioxide.
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From page 21... ...
This technology has applications in all areas of traditional bulk micromachining, such as pressure sensors, fluidic microstructures, and accelerometers. An example of uninventive use of DRIEis fortheprocess called HEXSIL (combining HEXagonal honeycomb geometries for making rigid structures with thin films and SILicon)
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From page 22... ...
The expertise and advanced state of the current microelectronics industry provides an enormous advantage for the development of MEMS. Leveraging and extending existing IC tools, materials, processes, and fabrication techniques are excellent strategies for producing MEMS with comparable levels of manufacturability, performance, cost, and reliability to those of modern VLSI circuits.
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