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Figure 29.1 A gyroscope sensor used for automotive applications that combinedmechanical and electronic systems. Perhaps the most widespread use of MEMSdevices is in sensors of all kinds. Source: Courtesy of Motorola Corporation.
Figure 29.3 Schematic illustration of the steps in surface micromachining: (a)deposition of a phosphosilicate glass (PSG) spacer layer; (b) etching of spacerlayer; (c) deposition of polysilicon; (d) etching of polysilicon; (e) selective wetetching of PSG, leaving the silicon and deposited polyilicon unaffected.
Figure 29.4 A microlamp produced from a combination of bulk and surfacemicromachining technologies. Source: Courtesy of K.R. Williams, AgilentTechnologies.
Figure 29.5 Stiction after wet etching: (1) unreleased beam; (2) unreleased beambefore drying; (3) released beam pulled to the surface by capillary forces duringdrying. Source: After B. Bhushan.
Figure 29.7 Schematic illustration of the steps required to manufacture a hinge. (a)Deposition of a phosphosilicate glass (PSG) layer and polysilicon layer. (b)Deposition of a second spacer layer. (c) Selective etching of the PSG. (d)Deposition of polysilicon to form a staple for the hinge. (e) After selective wetetching of the PSG, the hinge can rotate.
Figure 29.8 The Texas Instrumentsdigital pixel technology device. (a)Exploded view of a single digitalmicromirror device. (b) View of twoadjacent pixels. (c) Images of DMDarrays with some mirrors removed forclarity; each micromirror measuresapproximately 17 µm (670 µin.) on aside. (d) A typical digital pixeltechnology device used for digitalprojection systems, high definitiontelevisions, and other image displaysystems. The device shown contains1,310,720 micromirrors and measuresless than 50 mm (2 in.) per side.Source: Courtesy of TexasInstruments Corporation.
Figure 29.13 (a) Schematicillustration of silicon-diffusionbonding combined with deepreactive-ion etching to producelarge, suspended cantilevers.(b) A microfluid-flow devicemanufactured by DRIE etchingtwo separate wafers, thenaligning and silicon-diffusionbonding them together.Afterward, a Pyrex layer (notshown) is anodically bondedover the top to provide a windowto observe fluid flow. Source:(a) After N. Maluf. (b) Courtesyof K.R. Williams, AgilentTechnologies.
Figure 29.14 Sequence of operation of a thermal inkjet printer. (a) Resistive heating element isturned on, rapidly vaporizing ink and forming a bubble. (b) Within five microseconds, the bubblehas expanded and displaced liquid ink from the nozzle. (c) Surface tension breaks the inkstream into a bubble, which is discharged at high velocity. The heating element is turned off atthis time, so that the bubble collapses as heat is transferred to the surrounding ink. (d) Within24 microseconds, an ink droplet (and undesirable satellite droplets) are ejected, and surfacetension of the ink draws more liquid from the reservoir. Source: From Tseng, F-G, "MicrodropletGenerators," in The MEMS Handbook, M. Gad-el-hak, (ed.), CRC Press, 2002.
Figure 29.16 The LIGA(lithography, electrodeposition andmolding) technique. (a) Primaryproduction of a metal final productor mold insert. (b) Use of theprimary part for secondaryoperations, or replication. Source:IMM Institute für Mikrotechnik.
Figure 29.19 SEM images of Nd2Fe14B permanent magnets. Powder particle size rangesfrom 1 to 5 µm, and the binder is a methylene-chloride resistant epoxy. Mild distortion ispresent in the image due to magnetic perturbation of the imaging electrons. Maximumenergy products of 9 MGOe have been obtained with this process. Source: T. Christenson,Sandia National Laboratories.
Figure 29.20 (a) Multilevel MEMS fabrication through wafer-scale diffusionbonding. (b) A suspended ring structure for measurement of tensile strain, formedby two-layer wafer-scale diffusion bonding. Source: After T. Christenson, SandiaNational Laboratories.
Figure 29.22 (a) SEM image of micro-scale tweezers used in microassembly andmicrosurgery applications. (b) Detailed view of gripper. Source: Courtesy ofMEMS Precision Instruments (memspi.com).
Figure 29.23 The instant masking process: (a) bare substrate; (b) duringdeposition, with the substrate and instant mask in contact; (c) the resulting patterndeposit. Source: After A. Cohen, MEMGen Corporation.
Figure 29.24 Schematic illustration ofa micro-acceleration sensor. Source:After N. Maluf.
Figure 29.24 Photograph of AnalogDevices’ ADXL-50 accelerometer witha surface micromachined capacitivesensor (center), on-chip excitation,self-test and signal conditioningcircuitry. The entire chip measures0.500 by 0.625 mm. Source: FromR.A. Core, et al., Solid State Technol.,pp. 39-47, October 1993
Figure 29.26 Preparation of IC chipfor polysilicon. (a) Sensor areapost-BPSG planarization and moatmask. (b) Blanket deposition of thinoxide and thin nitride layer. (c)Bumps and anchors made in LTOspacer layer. Source: From Core,R.A., et al., Solid State Technol.,pp. 39-47, October 1993.
Figure 29.27 Polysilicon depositionand IC metallization. (a) Cross-sectional view after polysilicondeposition, implant, anneal andpatterning. (b) Sensor area afterremoval of dielectrics from circuitarea, contact mask, and PlatinumSilicide. (c) Metallization scheme andplasma oxide passivation andpatterning. Source: From R.A. Core,et al., Solid State Technol., pp. 39-47,October 1993.