1. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Chapter 29 Fabrication of Microelectromechanical Devices and Systems (MEMS)

2. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Parts Made by Chapter 29 Processes Figure 29.1 A gyroscope sensor used for automotive applications that combined mechanical and electronic systems. Perhaps the most widespread use of MEMS devices is in sensors of all kinds. Source: Courtesy of Motorola Corporation.

3. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Bulk Micromachining Figure 29.2 Schematic illustration of bulk micromachining. (1) Diffuse dopant in desired pattern. (2) Deposit and pattern masking film. (3) Orientation-dependent etching (ODE) leaves behind a freestanding structure. Source: Courtesy of K.R. Williams, Agilent Laboratories.

4. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Surface Micromachining Figure 29.3 Schematic illustration of the steps in surface micromachining: (a) deposition of a phosphosilicate glass (PSG) spacer layer; (b) etching of spacer layer; (c) deposition of polysilicon; (d) etching of polysilicon; (e) selective wet etching of PSG, leaving the silicon and deposited polyilicon unaffected.

5. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Microlamp Figure 29.4 A microlamp produced from a combination of bulk and surface micromachining technologies. Source: Courtesy of K.R. Williams, Agilent Technologies.

6. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Stiction After Wet Etching Figure 29.5 Stiction after wet etching: (1) unreleased beam; (2) unreleased beam before drying; (3) released beam pulled to the surface by capillary forces during drying. Source: After B. Bhushan.

7. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Example: Surface Micromachining of a Hinge Figure 29.6 (a) SEM image of a deployed micromirror. (b) Detail of the micromirror hinge. Source: Courtesy of Sandia National Laboratories. (a) (b)

8. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Example: Hinge Manufacture 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 wet etching of the PSG, the hinge can rotate.

9. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Digital Pixel Technology Figure 29.8 The Texas Instruments digital pixel technology device. (a) Exploded view of a single digital micromirror device. (b) View of two adjacent pixels. (c) Images of DMD arrays with some mirrors removed for clarity; each micromirror measures approximately 17 µm (670 µin.) on a side. (d) A typical digital pixel technology device used for digital projection systems, high definition televisions, and other image display systems. The device shown contains 1,310,720 micromirrors and measures less than 50 mm (2 in.) per side. Source: Courtesy of Texas Instruments Corporation.

10. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Digital Pixel Technology Device Manufacture Figure 29.9 Manufacturing sequence for the Texas Instruments DMD device. Figure 29.10 Ceramic flat- package construction used for the DMD device.

11. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. SCREAM Figure 29.11 The SCREAM process. Source: After N. Maluf.

12. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. SIMPLE Figure 29.12 Schematic illustration of silicon micromachining by single-step plasma etching (SIMPLE) process.

13. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Diffusion Bonding and DRIE Figure 29.13 (a) Schematic illustration of silicon-diffusion bonding combined with deep reactive-ion etching to produce large, suspended cantilevers. (b) A microfluid-flow device manufactured by DRIE etching two separate wafers, then aligning and silicon-diffusion bonding them together. Afterward, a Pyrex layer (not shown) is anodically bonded over the top to provide a window to observe fluid flow. Source: (a) After N. Maluf. (b) Courtesy of K.R. Williams, Agilent Technologies.

14. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Thermal Inkjet Printer Figure 29.14 Sequence of operation of a thermal inkjet printer. (a) Resistive heating element is turned on, rapidly vaporizing ink and forming a bubble. (b) Within five microseconds, the bubble has expanded and displaced liquid ink from the nozzle. (c) Surface tension breaks the ink stream into a bubble, which is discharged at high velocity. The heating element is turned off at this time, so that the bubble collapses as heat is transferred to the surrounding ink. (d) Within 24 microseconds, an ink droplet (and undesirable satellite droplets) are ejected, and surface tension of the ink draws more liquid from the reservoir. Source: From Tseng, F-G, "Microdroplet Generators," in The MEMS Handbook, M. Gad-el-hak, (ed.), CRC Press, 2002.

15. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Manufacture of Thermal Inkjet Printer Heads Figure 29.15 The manufacturing sequence for producing thermal inkjet printer heads. Source: From Tseng, F-G, "Microdroplet Generators," in The MEMS Handbook, M. Gad-el-hak, (ed.), CRC Press, 2002.

16. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. LIGA Figure 29.16 The LIGA (lithography, electrodeposition and molding) technique. (a) Primary production of a metal final product or mold insert. (b) Use of the primary part for secondary operations, or replication. Source: IMM Institute für Mikrotechnik.

17. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Electroformed Structures Figure 29.17 (a) Electroformed, 200 µm tall nickel structures; (b) Detail of 5 µm wide nickel lines and spaces. Source: After Todd Christenson, MEMS Handbook, CRC Press, 2002. (a)(b)

18. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Micromold Manufacturing

19. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Example: Rare Earth Magnets Figure 29.18 Fabrication process used to produce rare-earth magnets for microsensors. Source: T. Christenson, Sandia National Laboratories.

20. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Example: Rare Earth Magnets (cont.) Figure 29.19 SEM images of Nd 2 Fe 14 B permanent magnets. Powder particle size ranges from 1 to 5 µm, and the binder is a methylene-chloride resistant epoxy. Mild distortion is present in the image due to magnetic perturbation of the imaging electrons. Maximum energy products of 9 MGOe have been obtained with this process. Source: T. Christenson, Sandia National Laboratories.

21. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Wafer-Scale Diffusion Bonding Figure 29.20 (a) Multilevel MEMS fabrication through wafer-scale diffusion bonding. (b) A suspended ring structure for measurement of tensile strain, formed by two-layer wafer-scale diffusion bonding. Source: After T. Christenson, Sandia National Laboratories.

22. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. HEXSIL Figure 29.21 Illustration of the HEXagonal honeycomb structure, SILicon micromachining and thin-film deposition, or HEXSIL process.

23. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. HEXSIL Example: Microtweezers Figure 29.22 (a) SEM image of micro-scale tweezers used in microassembly and microsurgery applications. (b) Detailed view of gripper. Source: Courtesy of MEMS Precision Instruments (memspi.com). (a) (b)

24. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Instant-Masking Figure 29.23 The instant masking process: (a) bare substrate; (b) during deposition, with the substrate and instant mask in contact; (c) the resulting pattern deposit. Source: After A. Cohen, MEMGen Corporation.

25. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Case Study: Airbag Accelerometer Figure 29.24 Schematic illustration of a micro-acceleration sensor. Source: After N. Maluf. Figure 29.24 Photograph of Analog Devices’ ADXL-50 accelerometer with a surface micromachined capacitive sensor (center), on-chip excitation, self-test and signal conditioning circuitry. The entire chip measures 0.500 by 0.625 mm. Source: From R.A. Core, et al., Solid State Technol., pp. 39-47, October 1993

26. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Accelerometer Manufacture Figure 29.26 Preparation of IC chip for polysilicon. (a) Sensor area post-BPSG planarization and moat mask. (b) Blanket deposition of thin oxide and thin nitride layer. (c) Bumps and anchors made in LTO spacer layer. Source: From Core, R.A., et al., Solid State Technol., pp. 39-47, October 1993.

27. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Accelerometer Manufacture (cont.) Figure 29.27 Polysilicon deposition and IC metallization. (a) Cross- sectional view after polysilicon deposition, implant, anneal and patterning. (b) Sensor area after removal of dielectrics from circuit area, contact mask, and Platinum Silicide. (c) Metallization scheme and plasma oxide passivation and patterning. Source: From R.A. Core, et al., Solid State Technol., pp. 39-47, October 1993.

28. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Figure 29.28 Pre-release preparation and release. (a) Post- plasma nitride passivation and patterning. (b) Photo-resist protection of the IC. (c) Freestanding, released, polysilicon beam. Source: From Core, R.A., et al., Solid State Technol., pp. 39-47, October 1993. Accelerometer Manufacture (conc.)