Lec5p.ProcessModulesI - EE 245: Introduction to MEMS...

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EE 245: Introduction to MEMS Lecture 5: Process Modules I CTN 9/10/09 Copyright © 2009 Regents of the University of California EE C245 : Introduction to MEMS Design LecM 3 C. Nguyen 8/20/09 1 EE C245 – ME C218 Introduction to MEMS Design Fall 2009 Prof. Clark T.-C. Nguyen University of California at Berkeley Berkeley, CA 94720 Lecture Module 3 EE C245 : Introduction to MEMS Design LecM 3 C. Nguyen 8/20/09 2 Lecture Outline Reading: Senturia, Chpt. 3; Jaeger, Chpt. 2, 3, 6 ª Example MEMS fabrication processes ª Oxidation ª Film Deposition ( Evaporation ( Sputter deposition ( Chemical vapor deposition (CVD) ( Plasma enhanced chemical vapor deposition (PECVD) ( Epitaxy ( Atomic layer deposition (ALD) ( Electroplating EE C245 : Introduction to MEMS Design LecM 3 C. Nguyen 8/20/09 3 MEMS Fabrication EE C245 : Introduction to MEMS Design LecM 3 C. Nguyen 8/20/09 4 Making Mechanical Devices How best does one make a mechanical product? Assembly line production? ª Pick and place parts ª Used for many macroscopic mechanical products ª Robotic automation greatly reduces cost Problem : difficult to do this with MEMS-scale parts (but not impossible, as we’ll soon see …) Solution : borrow from integrated circuit (IC) transistor technology ª Use monolithic wafer-level fabrication methods ª Harness IC’s batch methods, where multiple devices are achieved all at once Automobile Assembly Line CMOS Integrated Circuit Wafer
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EE 245: Introduction to MEMS Lecture 5: Process Modules I CTN 9/10/09 Copyright © 2009 Regents of the University of California EE C245 : Introduction to MEMS Design LecM 3 C. Nguyen 8/20/09 5 Silicon Substrate Polysilicon Surface-Micromachining Uses IC fabrication instrumentation exclusively Variations : sacrificial layer thickness, fine- vs. large- grained polysilicon, in situ vs. POCL 3 -doping Silicon Substrate Free- Standing Polysilicon Beam Hydrofluoric Acid Release Etchant Wafer 300 kHz Folded-Beam Micromechanical Resonator Nitride Interconnect Polysilicon Sacrificial Oxide Structural Polysilcon Isolation Oxide EE C245 : Introduction to MEMS Design LecM 3 C. Nguyen 8/20/09 6 Aluminum Electroplating: Metal MEMS Use electroplating to obtain metal μ structures When thick: call it “LIGA” Pros : fast low temp deposition, very conductive Cons : drift, low mech. Q ª but may be solvable? Nickel Silicon Substrate Suspended Nickel Microstructure Electrode Silicon Substrate Ti/Au Isolation Si 3 N 4 Wafer Aluminum Release Etchant Photoresist EE C245 : Introduction to MEMS Design LecM 3 C. Nguyen 8/20/09 7 Silicon Substrate Glass Substrate Bulk Micromachining and Bonding Use the wafer itself as the structural material Adv : very large aspect ratios, thick structures Example : deep etching and wafer bonding Silicon Substrate Metal Interconnect Anchor
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This note was uploaded on 10/30/2010 for the course C 218 taught by Professor Clarknguyen during the Fall '09 term at University of California, Berkeley.

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Lec5p.ProcessModulesI - EE 245: Introduction to MEMS...

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