Microelectromechanical systems (MEMS) are micron-size devices that can sense or manipulate the physical world. MEMS are created using so-called micro machining processes, essentially operations like those used to produce integrated circuit (IC) devices. This allows a two or three-dimensional mechanical system to be created in the same small area typical of an IC device. Because the manufacturing process is similar to that of producing ICs, MEMS are most typically created on silicon wafers but can employ other substrate types as well. Due to their size, tens of thousands of these devices can be fabricated on a single wafer.

MEMS technology has actually been demonstrated in research and development facilities for about 25 years. In some forms it has been in production for almost 20 years, specifically in the area of pressure sensors. For example, the auto pressure sensor and disposable blood pressure sensor became a commercial reality in the 1980's. Today, the widespread use of MEMS as accelerometers and gyroscopes in the automotive sector is commonplace. Presently, new techniques have enabled the formation of many more types of surface structures, and true micro-machines have been enabled by recently developed thin film and etching techniques. MEMS now span a wide range of applications including sensors, telecommunications, micro-switches, and medical devices. Everyday industry is realizing new applications for MEMS in different technology areas.

Benefits of MEMS

Customers today are demanding smaller, lighter products with more features. Manufacturers are therefore being forced to develop technology that satisfies this demand. Precisely because MEMS are a combination of mechanical and electrical features on a very small scale, they can be used where traditional mechanical structures would be too bulky. MEMS are extremely small and can therefore be capable of faster, more precise and more reliable operation than their larger mechanical counterparts.

For example, RF MEMS components are mostly tunable, and offer low loss switching and high quality factors not possible with conventional components. Similarly, in optical switching applications where bandwidth and data volume trafficking must be maximized, the use of advanced optical modulation technologies is finding application in the form of Micro Optical Electronic Machines (MOEMs). The areas where performance / size / cost benefits can be realized using MEMS are almost unlimited.

Typical Device Applications

Amkor Technology is the world's leader in micro electronic packaging technologies and the world's largest outsource provider of Micro Electronic Mechanical Systems (MEMS) and Micro Optical Electronic Mechanical Systems (MOEMS).

• Inertial Measurements - Accelerometers, gyroscopes, rate sensors, vibration sensors.
• Pressure Measurements - TPMS (Tire Pressure Monitoring System) , disposable blood pressure sensors and various industrial applications.
• Display Technology - Optical MEMS in projectors, plasma displays.
• RF Technology - Tunable filters, RF switches, antennas, phase shifters, passive components (capacitors, inductors).
• Chemical Measurements - Microfluidics: Lab-On-Chip devices, DNA test structures, micro-dispensing pumps, hazardous chemical and biological agent dectectors

MEMS Packaging Technology

MEMS devices typically require an extra fabrication process where the device wafer is bonded to a second wafer which effectively encapsulates the MEMS structure. This method leaves the device free to move within a vacuum or an inert gas atmosphere. These bonds are typically hermetic and therefore prevent moisture contamination and subsequent failure of the microstructure. Once protected in this way, devices are considered robust. They can then be assembled into a wide variety of package options including SOIC, PLCC, System-in-Package (SiP) or MicroLeadFrame^® (MLF^®) which can all be adapted to meet the height requirement of the capped device.

Even though either embedded or capped, MEMS devices can exhibit sensitivities that must be accounted for in the packaging solution. Device performance can be affected by stresses imparted to the body of the die by the packaging materials. Options developed to address this type of issue include cavity packages (premolded) and specially designed die coat and transfer molding processes. Existing packages in this arena include CERDIP, Ceramic LCC, SOIC, and MLF^® derivatives. These applications also typically include the packaging of more than one die per package, and all of the aforementioned package solutions offer multi-die capability.

Protection is a key element in packaging MEMS and MOEMS because corrosion, moisture, and debris can prevent the devices from working. Each device must be hermetically sealed in order to prevent the devices from becoming contaminated. Amkor presently builds MEMS in a variety of hermetic packages for air bag and rollover detection sensors for automotive applications. Amkor has also developed System in Package (SiP) solutions that combine multiple chips and passives into one package. These SiP solutions are aimed at reducing the cost of MEMS packaging, and increasing functionality through greater levels of integration.

Packaging Options for MEMS

Amkor Technology is the world's leader in micro electronic packaging technologies and the world's largest outsource provider of Micro Electronic Mechanical Systems (MEMS) and Micro Optical Electronic Mechanical Systems (MOEMS).

• Philippines (ATP) - Sensors, Accelerometers - Ceramic Cavity Packages, Accelerometers - Plastic Molded Packages, Hermetic Packages (HVM), Gel Domed Molded Packages
• Taiwan (ATT) - Optical MEMS - Ceramic Cavity Packages
• Korea (ATK) - Sensors, Si capped MEMS devices, Plastic Cavity Packages

Molded & Over-Molded

SOIC, MLF^®, PLCC Packages (Molded Plastic MEMs with Gel Dome)

• Target market: MEMS sensor application, automotive industry, consumer products
• Capped MEMS devices (silicon, metal lid, etc.)
• Smaller form factor leadframe packages with generous mold cap (eg. SOIC, MLF^®, PLCC)
• SiP motion sensing modules especially for emerging handheld applications (eg. SiP module)

MEMS SOIC

• Body size is typically 300 mils, (body size ranging from 150-525 mils)
• 8, 16, 24 lead count, (8-64 leads is offered)
• High conductivity copper leadframes, solder plate lead finish

MEMS MLF^®

• Body sizes are typically 3-7 mm (MLF^® body size ranging from 1.5-12 mm)
• Extendibility multi-die, or stacked die

MEMS PLCC

• Body sizes 0.325” - 1.152”
• 20-84 lead counts
• High density leadframe

Premolded Cavity

SOIC, MLF^® Packages

• Cost reduction, capped MEMS devices that do not require hermeticity, stress sensitive
• Low modulus die coating gel
• Lower cost than ceramic
• Liquid crystal polymer based material
• High electrical and thermal conductivities
• Near hermetic, MSL level 1 reliability
• Low RF losses

Ceramics Cavity

BGA, LCC, LGA, CerDIP Packages

• Target market: Accelerometer and gyroscopes
• Hermetic package construction
• High volume mass production
• Uncapped MEMS devices

Amkor's Value Proposition

MEMS packaging is a highly integrated technology that requires both a range of process capabilities and a sound command of materials and their characterization. Amkor is the world's leading service provider in MEMS packaging technology and offers a variety of modeling and characterization expertise to complement a proven high volume manufacturing (HVM) capability. This combination uniquely positions Amkor to assist customers quickly through the development phase and into HVM with new applications.

Material Characterization:
DMA, DSC, TGA, TMA, thermo moiré, Universal mechanical testing, FTIR, interferometer, hardness, ARES, diffusivity, solubility, and more.

Modeling and Simulation:
Complete electrical and thermo-mechanical capabilities (resistance, inductance, capacitance, impedance, S-parameters, delay, Spice decks, thermal resistance, warpage, moisture absorption, interface delamination, Cu interconnect behavior, solder joint fatigue analysis, low-K interface modeling).

Tools include:

• RF / Microwave - Agilent ADS, linear & harmonic balance, envelope simulator
• Electromagnetic - Ansoft HFSS, Agilent Momentum
• Digital Signal Integrity - Synopsys HSPICE, Ansoft Q3D Extractor, Sigrity, Optimal PakSi-E
• Mechanical - ProE, Solid Works, ANSYS, Flotherm
• Layout - Cadence APD, Synopsys Encore IC Package Designer, Autodesk AutoCAD

Package and Board Level Reliability:
Amkor boasts a full repertoire of reliability test capabilities in multiple locations.

Amkor Technology Certifications Status:

• Assembly and Test - ISO-9002, ISO-9001, QS-9000 , ISO-9001:2000, TS-16949, OHSAS 18001
• Design - ISO-9001, ISO-9001:2000, TS-16949, OHSAS 18001

Additional Information:

Description	File Type	File Size
MEMS Micro-Machine Technology  Solution Sheet		277 kb

For more information on MEMS or MOEMs Technology, please contact an Amkor Regional Sales Office near you, your Account Manager or fill out the Request for Additional Information Form.