Coursera Specialization on Embedding Sensors and Motors ESM_C4M4V2 What is MEMS Technology? • MEMS stands for Micro-electromechanical systems. • A system of micro sensors, actuators, and electronics made on a common substrate • Typically consist of a dedicated sensor and the microelectronics to process the voltage and output a digital signal • MEMS chips range from .02 to 2 milllimeters in length or width [1] [1] [2] Deposition Processes Common to MEMS and IC’s [3] Chemical Vapor Deposition (CVD) (wafer) Sputtering [4] Spin Coating of Photoresist [5] Optical Processes Common to MEMS and IC’s [7] [6] Photolithography Photomask Etching Processes Common to MEMS and IC’s [8] Isotropic Wet Etching [10] Wafer Before Dry (RIE) Etching RIE Chamber [11] [9] Anisotropic Wet Etching Dry Etching Process [12] Wafer After Dry Etching [13] Process Steps to make a cantilever beam [14] (a) (b) (f) Bulk Micromachining • Selective removal of wafer via chemical etching to produce mechanical structures, such as beams and diaphragms Doped Silicon (e) Silicon wafer (a) (c) (d) (b) Silicon wafer Doped Silicon Photoresist Doped Silicon (c) [15] Completed cantilever beam Silicon wafer [16] Process Steps to make a diaphragm Surface Micromachining (silicon oxide) (a) • Layers deposited on the surface of the wafer become mechanical structures (silicon) (b) (c) (silicon oxide) (d) (polycrystalline silicon) (e) (polycrystalline silicon) (f) (silicon oxide) [18] (g) [17] (silicon) Cantilever beam: summary process Cantilever beam: detail process Polysilicon Resonator Made using Surface Micromachining [19] [1] Comb structure produced with surface micromachining • The proof mass of the capacitive accelerometer is separated into four sections, each supported by springs and connected to its own set of the capacitive sensing fingers Wafer Bonding • The joining of two wafers via fusion bonding, anodic bonding, or bending using an intermediate layer. • All methods require wafers that are flat, smooth, and clean [20] Fusion Bonding + Eutectic Bonding [21] Anodic Bonding [22] Citations [1] www.mems-exchange.org [2] www.memsjournal.com/2006/07/nanochips_mems_.html [3] www.semitracks.com [4] www.elveflow.com [5] www.semicore.com [6] www.sciencedirect.com [7] www.wikipedia.com [8] www.ucdavis.edu [9] www.slideplayer.net [10][13] www.nptel.ac.in ESM_C4M4V2 Citations [11] www.memsnet.org [12] www.sciencedirect.com [14] www.researchgate.net [15] www.iopscience.iop.org [16] http://81.161.252.57/ipci/courses/technology/inde_376.htm [17] www/slideplayer.net [18] https://www.photonics.com/images/Web/Articles/ 2008/11/1/thumbnail_35519.jpg [19] www.oakland.edu [20] www.slideplayer.com [21] www.mdpi.com [22] www.seas.upen.edu ESM_C4M4V2 ESM_C4M4V2 ESM_C4M4V2
