Preface

There have been numerous advances and inventions directly related to microelectromechanical systems (MEMS) and devices. The researchers have used the modified IC fabrication techniques at the beginning of MEMS era. Since then, MEMS researchers have continually advanced and augmented the capabilities of wafer-based fabrication technologies. These advances have been instrumental in the demonstration of new devices and applications, and even in the creation of new fields of research and development: bioMEMS, micro total analysis and system (µTAS), microfluidic devices, optical MEMS and RF MEMS. Experience indicates a need for a MEMS book covering biomedical materials as well as the most important process steps in bulk micromachining and modeling. A special emphasis is put on silicon, the most important substrate in MEMS devices, and its material properties and measurement techniques as well as analytical methods used in the silicon material characterization. The primary aim of this book is to give a broader overview tailored for the needs of the MEMS industry rather than go too details in the scientific details. The other aims of this book are to disseminate practical knowledge about selective MEMS technology and its applications, to create a clear consciousness about the effectiveness of MEMS technologies, to stimulate the theoretical and applied research in these very important areas, and promote the practical using of these techniques in the industry.

As a particularly diverse and multidisciplinary area of research, the field of MEMS offers a vastly different set of challenges relative to typical IC fabrication and design. A wealth of knowledge exists in the MEMS community, but much of this expertise is most readily accessed by informal, nonmethodological means such as discussions with colleagues at conferences. We intend this book to provide the reader with the MEMS materials and processes, but beyond this goal, we intend for it to give practical insight into the workings and standard procedures carried out in research labs and production facilities on a daily basis. The chapters are meant to be a springboard of sorts, providing basic information about each topic, with a large number of classic and contemporary literature references to provide in-depth knowledge. We hope this book consolidates important information for readers and thereby spurs the creation of many new devices and processes. The authors of this book view the devices and processes as the fundamental building blocks for making complex systems. Keeping this in mind, the book is divided into four main sections: Chapters 1, 2, 3, and 4 covering materials

#### X Preface

related to bioMEMS devices; Chapters 5, 6, 7 and 8 covering materials on MEMS characterization and micromachining; Chapters 9, 10, 11, 12, and 13 covering RF and optical MEMS; Chapters 14, 15, 16, 17 and 18 covering MEMS based actuators.

Preface XI

requires careful consideration of not only the individual thermal, optical, and mechanical parameters, but also the coupling that exists between them. All these are

Section IV emphasizes on MEMS based actuators. In Chapter 14 an exhaustive review on the preparation of PZT thick films have been carried out, taking specific focus in the effect of the infiltration in the preparation of high-quality films. Flexible MEMS Color Display on Polymer Materials is covered in Chapter 15. In order to design a flexible MEMS, special substrates and multilayer with high flexibility such as polymeric materials, ultra thin glass, thin metal foil, or even fabric should be considered and the authors have used the Printing Techniques to fabricated flexible MEMS. Chapter 16 discusses the design, fabrication, characterization, modeling, and reliability of thermal microactuators. Thermal, electrical, and mechanical measurements for bent-beam polycrystalline silicon thermal microactuators are also reported in this chapter. In Chapter 17, the major research activities that use a tensile testing method to study the mechanical behavior of thin film materials are reviewed. The final chapter of the book discusses mainly the characterization technique of diamond, Diamond-like carbon (DLC) and Diamond-like Nanocomposite (DLN) thin

Finally the editor would like to express his great appreciation to all the contributors for this unique window of opportunity to work with them, resulting in a comprehensive MEMS book, which illustrates a global cutting edge knowledge and expertise within the most vigorously growing industry today. The valuable contributions of the renowned researchers from different parts of the globe working on various aspects of MEMS devices deserve great appreciations. The entire credit goes to the InTech publishing group members for their tireless efforts to work on this project to publish the book in time. The editorial assistance of the process manager,

Mr. Vedran Greblo needs special mention for the success of this book project.

**Dr. Nazmul Islam** 

USA

Director, NEMS/MEMS Lab

The University of Texas at Brownsville

covered in Chapter 13.

films and their application in MEMS devices.

Section I starts with the emerging field of bioMEMS, including MEMS coil for retinal prostheses, DNA extraction by micro/bio-fluidics devices, microcantilever integration with ACEO for lab-on-a-chip devices, and acoustic wave biosensors. Chapter 1 in the first section starts with the development of MEMS coils for retinal prostheses and those coils are fully micromachined in a way compatible with multielectrode arrays and the Parylene-based embedded chip packages. Chapter 2 presents overview of an integrated micro/bio-fluidic device capable of performing online cell lysis and DNA extraction. This device is a powerful tool for biological sample pre-treatment. More of the MEMS microfluidics devices are covered in Chapter 3. This chapter focuses on the MEMS microcantilever integration with ACEO and integrated micropump characterization with lab-on-a-chip applications. The entirety of Chapter 4 is devoted to the MEMS based acoustic wave biosensors characterization that has applications in emerging field of bioMEMS.

MEMS characterization, measurement, micromachining, macromodels are discussed in Section II. Chapter 5 of this section uses computer micro-vision and microscopic interferometry to carry out MEMS measurements, including dimensional (static) and moving (dynamic) properties analysis. Chapter 6 focuses on the description of issues and techniques in the interfacial adhesion for the MEMS devices. In chapter 7 the etch rate anisotropy in surfactant-modified etch solution is investigated. The surfactant in etching enables manufacturing of advanced and exciting structures for MEMS. Chapter 8 discusses the MEMS elements of different embedding systems and their macromodels for system-level simulation. Having System-level models of all MEMS components allow a fast and sufficiently exact simulation of entire MEMS. Analytical and numerical modeling is also covered in this chapter.

Section III focuses on the RF and Optical MEMS switches, microfabrication techniques and the new developments. RF MEMS switch has been demonstrated in Chapter 9 of this section. In addition, the experimental results and surface forces, charging contributions is also presented. RF MEMS switches are extended to Chapter 10. Two configurations of RF MEMS switches using electrostatic actuation, and several MIMs devices simulating the RF MEMS actuation pads, with various dielectric materials and electrodes, have been measured in this chapter. Chapter 11 provides a brief study of capillary forces based on a RF MEMS series switch. A six mask all metal fabrication process and fabrication of different novel switches is also presented. Chapter 12 presents the theory, basic physical design, and fabrication of various optical MEMS devices for display, and medical imaging. The optical MEMS technology promises to revolutionize broad categories by bringing together silicon-based microelectronics with micromachining technology, and optical components. That is the reason, understanding the thermal and optical response of laser-irradiated microsystems requires careful consideration of not only the individual thermal, optical, and mechanical parameters, but also the coupling that exists between them. All these are covered in Chapter 13.

X Preface

emerging field of bioMEMS.

and numerical modeling is also covered in this chapter.

related to bioMEMS devices; Chapters 5, 6, 7 and 8 covering materials on MEMS characterization and micromachining; Chapters 9, 10, 11, 12, and 13 covering RF and

Section I starts with the emerging field of bioMEMS, including MEMS coil for retinal prostheses, DNA extraction by micro/bio-fluidics devices, microcantilever integration with ACEO for lab-on-a-chip devices, and acoustic wave biosensors. Chapter 1 in the first section starts with the development of MEMS coils for retinal prostheses and those coils are fully micromachined in a way compatible with multielectrode arrays and the Parylene-based embedded chip packages. Chapter 2 presents overview of an integrated micro/bio-fluidic device capable of performing online cell lysis and DNA extraction. This device is a powerful tool for biological sample pre-treatment. More of the MEMS microfluidics devices are covered in Chapter 3. This chapter focuses on the MEMS microcantilever integration with ACEO and integrated micropump characterization with lab-on-a-chip applications. The entirety of Chapter 4 is devoted to the MEMS based acoustic wave biosensors characterization that has applications in

MEMS characterization, measurement, micromachining, macromodels are discussed in Section II. Chapter 5 of this section uses computer micro-vision and microscopic interferometry to carry out MEMS measurements, including dimensional (static) and moving (dynamic) properties analysis. Chapter 6 focuses on the description of issues and techniques in the interfacial adhesion for the MEMS devices. In chapter 7 the etch rate anisotropy in surfactant-modified etch solution is investigated. The surfactant in etching enables manufacturing of advanced and exciting structures for MEMS. Chapter 8 discusses the MEMS elements of different embedding systems and their macromodels for system-level simulation. Having System-level models of all MEMS components allow a fast and sufficiently exact simulation of entire MEMS. Analytical

Section III focuses on the RF and Optical MEMS switches, microfabrication techniques and the new developments. RF MEMS switch has been demonstrated in Chapter 9 of this section. In addition, the experimental results and surface forces, charging contributions is also presented. RF MEMS switches are extended to Chapter 10. Two configurations of RF MEMS switches using electrostatic actuation, and several MIMs devices simulating the RF MEMS actuation pads, with various dielectric materials and electrodes, have been measured in this chapter. Chapter 11 provides a brief study of capillary forces based on a RF MEMS series switch. A six mask all metal fabrication process and fabrication of different novel switches is also presented. Chapter 12 presents the theory, basic physical design, and fabrication of various optical MEMS devices for display, and medical imaging. The optical MEMS technology promises to revolutionize broad categories by bringing together silicon-based microelectronics with micromachining technology, and optical components. That is the reason, understanding the thermal and optical response of laser-irradiated microsystems

optical MEMS; Chapters 14, 15, 16, 17 and 18 covering MEMS based actuators.

Section IV emphasizes on MEMS based actuators. In Chapter 14 an exhaustive review on the preparation of PZT thick films have been carried out, taking specific focus in the effect of the infiltration in the preparation of high-quality films. Flexible MEMS Color Display on Polymer Materials is covered in Chapter 15. In order to design a flexible MEMS, special substrates and multilayer with high flexibility such as polymeric materials, ultra thin glass, thin metal foil, or even fabric should be considered and the authors have used the Printing Techniques to fabricated flexible MEMS. Chapter 16 discusses the design, fabrication, characterization, modeling, and reliability of thermal microactuators. Thermal, electrical, and mechanical measurements for bent-beam polycrystalline silicon thermal microactuators are also reported in this chapter. In Chapter 17, the major research activities that use a tensile testing method to study the mechanical behavior of thin film materials are reviewed. The final chapter of the book discusses mainly the characterization technique of diamond, Diamond-like carbon (DLC) and Diamond-like Nanocomposite (DLN) thin films and their application in MEMS devices.

Finally the editor would like to express his great appreciation to all the contributors for this unique window of opportunity to work with them, resulting in a comprehensive MEMS book, which illustrates a global cutting edge knowledge and expertise within the most vigorously growing industry today. The valuable contributions of the renowned researchers from different parts of the globe working on various aspects of MEMS devices deserve great appreciations. The entire credit goes to the InTech publishing group members for their tireless efforts to work on this project to publish the book in time. The editorial assistance of the process manager, Mr. Vedran Greblo needs special mention for the success of this book project.

> **Dr. Nazmul Islam**  Director, NEMS/MEMS Lab The University of Texas at Brownsville USA

**Part 1** 

**BioMEMS Devices** 

**Part 1** 

**BioMEMS Devices** 

**1** 

*USA* 

**Implantable Parylene MEMS RF** 

Wen Li1, Damien C. Rodger2, James D. Weiland2, Mark S. Humayun2, Wentai Liu4 and Yu-Chong Tai3

Age related macular degeneration (AMD) and retinitis pigmentosa (RP) are two of the most common outer retinal degenerative diseases that have resulted in vision impairment and blindness of millions of people. Specifically, AMD has become the third leading cause of blindness on global scale, and is the primary cause of visual deficiency in industrialized countries (World Health Organization [WHO], 2011). In the United States, more than 500,000 people are suffering from RP and around 20,000 of them are legally blind (Artificial Retina Project, 2007). Whereas many treatment methods, including gene replacement therapy (Bennett et al., 1996), pharmaceutical therapy, nutritional therapy (Norton et al., 1993), photoreceptor and stem cell transplantations (MacLaren et al., 2006 & Tropepe et al., 2000), and dietary, have been explored to slow down the development of AMD and RP diseases in their early stages, vision impairment and blindness due to outer retinal

In the 1990's, researchers discovered that although the retinal photoreceptors are defective in RP patients, their optic nerves, bipolar and ganglion cells to which the photoreceptors synapse still function at a large rate (Humayun et al., 1999). Further studies showed similar results in AMD patients (Kim et al., 2002). These findings have created profound impact on the ophthalmology field, by providing the possibility of using artificial retinal prostheses to partially restore the lost vision function in AMD and RP patients. Two main retinal implant approaches are currently in development according to the layer of retina receiving the implanted device: subretinal (Chow et al., 2006; Rizzo, 2011; Zrenner et al., 1999) and epiretinal prostheses (Humayun et al., 1994; Weiland & Humayun 2008; Wong et al., 2009). Particularly, epiretinal implantation has received widespread attention over the last few years, for not only successful clinical trials demonstrating its efficacy in patients, but also its many advantages compared to others (Horch K.W. & Dhillon, G.S., 2004). First, the device implantation and follow-up examination only require standard ophthalmologic technologies, which can effectively reduce the risk of trauma during the surgery and also allow for the implant to be replaced easily. In addition, most of the implanted electronics are kept in the vitreous cavity so

**1. Introduction** 

degeneration currently remain incurable.

**Coil for Epiretinal Prostheses** 

*1Michigan State University, 2University of Southern California, 3California Institute of Technology 4University of California, Santa Cruz* 
