Final 2003

MEMS (MICRO ELECTRO-MECHANICAL SYSTEMS)

THE FUTURE TECHNOLOGY BY: -

Shrikant Harish Raut MCM-II

Contents

Introduction Mems Pictures What Actually Mems are? Making Mems MEMS AND IC INTEGRATION Integrating MEMS and Electronics Integration through Effective Co-Design Integration through Effective Co-Design MEMS IN ACTION Automotive: the first high volume application MEMS in Wireless More functionality but more components Towards a single-chip RF circuit Higher performance, reliability, lower cost per unit MEMS in Optical Networks World's Fastest Switch Provides Key to Next-Generation Optical Networks Life Sciences Wireless Sensor Networks INDIAN INITIATIVES Conclusion

Introduction

Imagine a machine so small that it is imperceptible to the human eye. Imagine working machines with gears no bigger than a grain of pollen. Imagine these machines being batch fabricated tens of thousands at a time, at a cost of only a few pennies each. Imagine a realm where the world of design is turned upside down, and the seemingly impossible suddenly becomes easy. A place where gravity and inertia are no longer important, but the effects of atomic forces and surface science dominate. Welcome to the micro domain, a world now occupied by an explosive new technology known as MEMS (Micro-Electro Mechanical Systems) or, more simply, micro machines.

MEMS PICTURES

WHAT ACTUALLY MEMS ARE? • Micro-Electro-Mechanical Systems (MEMS) is the integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate through micro fabrication technology. While the electronics are fabricated using integrated circuit (IC) process sequences (e.g., CMOS, Bipolar, or BICMOS processes), the micromechanical components are fabricated using compatible "micromachining" processes that selectively etch away parts of the silicon wafer or add new structural layers to form the mechanical and electromechanical devices.

MAKING MEMS • MEMS microstructures are manufactured in batch processes similar to computer microchips. The lithographic techniques that mass-produce millions of complex microchips can also be used simultaneously to develop and produce mechanical sensors and actuators integrated with electronic circuitry. The processes are based on depositing thin films of metal or crystalline material on a substrate, which are then etched away selectively, leaving multi-layered

MEMS AND IC INTEGRATION: A SYSTEM-LEVEL APPROACH • Although MEMS are often referred as a single technology, they are actually an ensemble of design, materials and process knowledge. Unlike IC design, where the aim is usually to densely pack submicron transistors into a single piece of silicon using the same set of basic rules, there is no one set of design and manufacturing rules for the development of MEMS. Every device requires separate techniques based on the intended application, the level of optimization, the materials and processes used, and even the effects of MEMS on the electronics. For this reason it is critical that design teams undertaking MEMS-based product development be well acquainted with the trade-offs involved in the design of MEMS with the associated electronics and packaging.

Integrating MEMS and Electronics: Configurations • From a physical configuration perspective, a design team has a number of choices. The designer may elect to deploy a two-chip system – one with the MEMS, one being the IC -- on a multi-chip module. This approach, usually referred to as hybrid integration. • The second option, commonly referred to as monolithic integration, is to integrate the MEMS device and the electronics on the same wafer. In this approach, in effect a combined MEMS-IC process, post-processing (in order to release the structure) is typically executed at the same foundry. However, monolithic integration can be very expensive, as it requires top-notch process engineers, a greater focus on effective integration as well as the use of both Icoriented and MEMS-

Integration through Effective CoDesign • Once a design team has decided on the specs and physical configuration of their product, they must evaluate how to go about that integration from a CAD perspective. Typically a MEMS product development group will consist of an interdisciplinary team working at the device level, IC level and system level. • Besides being able to pass modified design and analysis data back and forth seamlessly, the team must have available a means to simulate MEMS and electronics together in the same simulator to determine how the design functions at a system level.

MEMS IN ACTION • Imagine dust, floating in the air, gathering information on the weather, winds, humidity and pollution – all in a tiny cubic millimeter package. Thousands or millions of these dust motes will sense the environment and communicate simultaneously using MEMS devices. Other applications under development range from such medical uses as hospital rooms that track patients and their medications and treatments, to the use of tiny surgical “scrapers” injected into arteries to clean out plaque, to military reconnaissance, to the detection of biological and chemical weapons.

Automotive: the first high volume application •

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After spending about 25 years in the lab, however, it was the automotive industry which first commercially embraced MEMS devices in the '90's as airbag accelerometers, recognizing the benefits of MEMS devices' small size, relative low cost and high degree of sensitivity. Early airbags required the installation of several bulky accelerometers made of discrete components mounted in the front of the car, with separate electronics near the airbag. Today, because of MEMS, the accelerometer and electronics are integrated on a single chip at a very low cost. The small size (about the dimensions of a sugar cube) provides a quicker response to rapid deceleration. And because of the very low cost, manufacturers are adding side impact airbags as well. The sensitivity of MEMS devices is also leading to improvements where size and weight of passengers will be calculated so the airbag response will be appropriate for each passenger.

MEMS in Wireless • The wireless industry is growing and changing rapidly. With the advent of new technology combined with the demand for more bandwidth and increased mobility, wireless applications are spreading to new markets – from radar-equipped passenger vehicles to biomedical devices that, when injected or inserted, send data to a receiver outside the body. As the wireless device market grows, so will the semiconductor products that support it.

More functionality but more components • Wireless system manufacturers compete to add more functionality to equipment. A 3G “smart” phone, PDA, or base station, for example, will require the functionality of as many as five radios – for TDMA, CDMA, 3G, Bluetooth and GSM operation. A huge increase in component count is required to accomplish this demand. And other wireless verticals are facing the same challenge. Yet while the market demands the new functions, it also expects smaller form factors, lower costs and reduced power consumption.

Towards a single-chip RF circuit • A solution with tighter and cost-effective integration is clearly needed. Integrating MEMS devices directly on the RF chip itself or within a module, can enable the replacement of numerous discrete components while offering such competitive benefits as higher performance and reliability, smaller form factors, and lower cost as a result of high-volume, high-yield IC-compatible processes. Discrete passives such as RF-switches, varicaps, high-Q resonators and filters have been identified as components that can be replaced by RF-MEMS counterparts. For radio frequency, or RF, applications there is the innovative “aboveIC” (AIC) technology that enables the placement of RF MEMS devices directly on top of the IC by using a thick copper technology compatible with CMOS, BiCMOS and gallium arsenide processes.

Higher performance, reliability, lower cost per unit • Higher speed and reliability are other likely improvements. Having components on-chip means they are more tightly integrated and can communicate faster with the IC. And because lighter MEMS components are really part of the chip and not attached to the board, they are less likely to be damaged if a phone is dropped.

MEMS in Optical Networks • An important new application for MEMS devices is in fiber optic networks. At the micron level, MEMSbased switches route light from one fiber to another. Such an approach enables a truly photonic (completely light-based) network of voice and data traffic, since switching no longer requires conversion of light signals into digital electronic signals and then back to optical.

World's Fastest Switch Provides Key to Next-Generation Optical Networks • The development of an 80-channel optical communications switch that adopts MEMS (micro electromechanical system) mirrors. The new device achieves a switching speed of one millisecond, the fastest of any multi-channel optical switch to date.The new switch is expected to enable the development of the optical cross-connect systems essential for next-generation optical transmission

Life Sciences • MEMS used in various disciplines of life sciences are referred to as BioMEMS. After the computer & information technology, life science is the next biggest market for MEMS. BioMEMS find applications in medical sciences, forensics, pharmaceuticals, food & drink industry, & environment sensing. In future, new application control, agriculture, & Anti-bioweapons may also be developed. • BioMEMS can be broadly classified into four groups, namely, Bio sensing, Bioanalysis, Bio-instruments, & Bio-function.

Wireless Sensor Networks • Smart, wireless networked sensors will soon be everywhere around us, collecting and processing vast amounts data – from air quality and traffic conditions, to weather conditions and tidal flows. And this means not just monitoring a few isolated sensors, but literally tens of thousands of intelligent sensor nodes which provide not merely local me Within the next few years, this significant new technology will help run factories, optimize widely spread processes, monitor the weather, detect the spread of toxic gases in chemical spills, and even provide precious extra time in advance of tornados and earthquakes. asurements, but overall patterns of change.

INDIAN INITIATIVES • With its Outstanding manpower, a few semiconductor foundries, many research labs, and low production cost, India is uniquely positioned to excel in the field of MEMS. After information technology (IT), MEMS may be the next technological forte of the country. We are a late starter, but still not out of the race. A base technology (semiconductor processing) and starting level R&D awareness already exist in the country.

CONCLUSION • TODAY LARGE EXPENSIVE & DUMB • TOMMOROW TINY CHEAP & SMART

REFRENCES • • • • • •

Electronics For You Electronics Today www.memx.com www.memscape.com www.allaboutmems.com www.sandia.gov.in