Class26 - Microsystems Laboratory UC-Berkeley ME Dept...

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Microsystems Laboratory UC-Berkeley, ME Dept. 1 Liwei Lin, University of California at Berkeley Introduction to MEMS – Class#26 Liwei Lin Professor, Dept. of Mechanical Engineering Co-Director, Berkeley Sensor and Actuator Center The University of California, Berkeley, CA94720 e-mail: [email protected] http://www.me.berkeley.edu/~lwlin
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Microsystems Laboratory UC-Berkeley, ME Dept. 2 Liwei Lin, University of California at Berkeley Outline The Rest of the Semester 11/26 (today) – Paper #9 & LIGA 12/3 – Review & Wafer Bonding Process 12/5 – Quiz II 12/12 (Thursday) & 12/13 (Friday) – final project presentations Review for Class 25 Paper #9
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Single Crystal Silicon Brittle Misconception: Silicon is weak Young’s Modulus approaches that of Steel, Nickel Knoop Hardness is close to Quartz Tensile strength is 3x that of stainless steel wire Main Difference: Silicon yields by fracture rather than plastic deformation Still encounters problems Breaks and fractures Mainly due to edge defects Figure Credit: (Top) A. Danilewsky, J. Wittge, K. Kiefl, D. Allen, P. McNally, J. Garagorri, M.R. Elizalde, T. Baumbach, B.K. Tanner, Crack propagation and fracture in silicon wafers under thermal stress, Journal of Applied Crystallography, Vol. 46, Part 4, August 2013, Pages 849-855 (Bottom) Kurt E. Peterson, Silicon as a Mechanical Material, Proceedings of the IEEE, Vol. 70, No.5 May 1982, Page 421
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Results of Different Etchant Systems
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Etch Stops Doped layers buried in epitaxial layers Anisotropic etching stops at doped layer. Depth of hole determined by thickness of epi-layer.
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Thermomigration is the movement of alumina on silicon towards the hotter side of a wafer with a temperature gradient. At sufficiently high temperatures, alumina on silicon forms a molten alloy. The silicon on the wafer begins to dissolve on the hot side and the Al/Si alloy migrates to take its place. start DEFINITION
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PROCESS Glass slide placed over wafer (bare or oxidized) Assembly is heated to 400 ° C High voltage applied between silicon and metal contact on glass (~1200 V)
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Optical Benches and Integrated Optics Long V grooves in wafers are crucial for alignment of small optical fibers Fibers can be attached together or precisely aligned to surface features V Groove
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Miniature Circuit Board Packaging Density of silicon chips can be increased by using silicon as miniature pluggable circuit boards Silicon Wafers with Anisotropically etched holes are bonded together and their cavities are filled with mercury Mini socket plugs are inserted to make a circuit board
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ME119. Fall 2013. Joanna Wu GAS CHROMATOGRAPH ON A WAFER SILICON AS A MECHANICAL MATERIAL KURT E. PETERSEN
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GAS CHROMATOGRAPH 1. Sample input 1. Purge input 2. Valve region 3. Exhaust of unused sample 4. Sensor region 5. Separation column Fabricated on a 2” silicon wafer with 3 main components: Capillary column Gas control valve Detector element 1.
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Class26 - Microsystems Laboratory UC-Berkeley ME Dept...

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