田中秀治研究室 ~Student Page~

Stay in Germany 2 : ENAS

Guten Morgen.
Good evening.

I’m Kaneko, M2 student.
From this time, I’d like to introduce Fraunhofer Institute for Electronic NANO Systems (ENAS) where I am staying now.
Before the main topic, I mention Fraunhofer briefly. Fraunhofer is founded in 1949. At present, it maintains 66 institutes and research units, with nearly 24,000 staffs. They undertake applied research that drives economic development and serve the wider benefit of society. ENAS is one of the institutes of Fraunhofer, founded in 2008 by Prof. Dr. Thomas Gessner.

Some of you know the name of “ENAS” because Esashi/Tanaka lab has been collaborating long time, but I believe few members, especially students, know what they are researching well. So, I will share what I learn here as much as possible.

Today’s topic is departments in ENAS.
Here is ENAS building in TU-Chemnitz. After sunset, these building light-up. I heard this design shows printed circuit board.

There are six departments belonging to ENAS; Multi Device Integration, Micro Material Center, Printed Functionalities, Back-End of Line, System Packaging and Advanced System Engineering. The common strength of all departments is the development of smart integrated systems for different applications. These systems combine nano-micro devices like MEMS with electro components, high technologies and smart products. ENAS covers vast field related to integrated technologies; for example, high-precision sensors for industrial applications, sensor and actuator systems with control units and evaluation electronics, printed functionalities like antennas as well as material reliability research for microelectronics and micro system technology. Their application areas are semiconductor industry, medical engineering, mechanical engineering, security sector, automotive industry as well as aeronauts.

Then, I will explain technologies of each department. Of course, I cannot introduce everything, so I will write some characteristic topics and notes. Please search if you find interesting topics. I attach homepage address of each department.

1. Multi Device Integration
(Head of department: Prof. Dr. Thomas Otto)
HP: http://www.enas.fraunhofer.de/en/departments/MDI.html

This department focuses on the integration of MEMS/NEMS into functional modules and development of MEMS/NEMS using silicon based and non-silicon materials like polymer. In detail, this department combines following technologies;

MEMS/NEMS design
They combine modeling and multi simulations for analysis and optimization of MEMS/NEMS.
Design: Electronic (Analog, digital, mixed signal, PCB layout, Software programming), RF-MEMS, optical designs, photomask design, so on.
Simulations: Structural analysis, electromechanical coupling, fluid-structure coupling, micro fluidics and acoustics, thermo mechanical stress, electromagnetic simulation for RF-MEMS and antennas.
(Fig.1: Design and Simulation in the Fraunhofer ENAS MEMS/NEMS lab.)

Infrared MEMS spectrometer, Temperature Scanner, chemical sensors for Food studies, environmental, condition and process monitoring, medical diagnostics, so on.

Fluidic integration and system technologies
Microfluidic systems enable faster analysis, lower sample volumes, new methods of detection, advanced cooling mechanisms and chemical reaction control for many applications like medical diagnostics, health care, food and environment monitoring and chemical processing.
(Fig.2: Microfluidic cartridge with integrated, gel based low-cost pumps for in-vitro diagnostics.)

Nanocomposites is hybrid materials which combine polymeric matrices with nanoscale inclusions such as particles, fibers or tubes. They realize different functions from original materials. In this department, humidity sensors and piezoresistive composite sensors for the detection of forces are developed.

Measurement, test and characterization
・A method for the extremely fast determination of dimensional and material parameters based on a combination of Finite Element Method (FEM)
・Measurement of Eigenfrequencies
・Test equipment for MEMS motion, dymanic deformation, RF-MEMS

System integration
Condition monitoring system of sealing rings: This system can prevent unnecessary downtime and personnel cost for maintenance measures, plant failures due to sudden failure of components, unnecessary expenses for preventive component change.
Laser Micromaching: They also realize highly precise structures in almost all kinds of materials by ultra short pulse laser. They customize the laser for bulk structuring, drilling, cutting, selective layer structuring and laser welding.
(Fig.3 : Condition monitoring system of a sealing ring.)
(Fig.4 : Silicon parts, fabricated by ultra short pulse laser micro machining.)


2. Micro Materials Center (MMC)
(Head of department: Prof. Dr. Sven Rzepka)
HP: http://www.enas.fraunhofer.de/en/departments/MMC.html

This department has long research history about material reliability. Therefore, they have strength in many fields regarding material evaluation. Regarding reliability,

Microreliability and nanoreliability of components, systems and complete applications
(Fig.5 Nondestructive analysis and fully parametric modeling of real micro and nano structures.)

Thermo-electro-mechanical reliability analysis

・Reliability for avionics and space applications

・Microreliability for electronics and smart sensor systems in fully electrical but also in hybrid and ICE vehicles.

・Solder reliability for micro nano interconnects

・Reliability for packaging in the micro/nano integration field

3D integration technology
More than Moore technology
(Fig.6 Fracture mechanics at nanometer scale.)

And they also analyze material properties like;
・Physics of failure analysis, fatigue and creep analysis

・Design for manufacturability and reliability based on numerical methods fully calibrated and validated

・Local deformation analysis

microDAC/nanoDAC: Thermo-mechanical failure, movements, deformations in structure and materials of micro/nano size.
fibDAC: Stresses on micro and nanotechnology devices
Micro/Nano Raman
EBSD(Electron Back Scatter Diffraction Patterns): Maximum spatial resplution in crystalline materials
(Fig.7 microDAC- Deformation analysis at crack tip.)

・Analysis of internal stress with highest special resolution
Thin film stacks
Back end of line structures


3. Printed Functionalities
(Head of department: Prof. Dr. Reinhard Baumann)
HP: http://www.enas.fraunhofer.de/en/departments/PF.html

Some people should know printing technology; gravure, offset, flexo and screen printing as traditional processes, and ink-jet, xerography as digital processes. These technologies can transfer ink dots onto even fiber based substrates, plastic foil and sheet metals. Their products will be equipped with functionalities not only color but electrical conductivity, semi conductivity, optimized porosity, and electric power. With these functionalities, they will be able to perceive their surroundings, save these data and communicate them via computer network with other members of the Internet of Things (ITO). In this department, they develop following technologies;

Printed thin film battery
This is one of the applications of printing technology for Microsystems and consumer electronics.
(Fig.8: +/- 15 V printed battery)

Radio Frequency Identification Technology (RFID)
RFID is used in vehicle tracking system like the access and exit controlling of cars in car parks and industrial sites, for example. About this RFID Antennas technology, they published interesting journals. Their work is also applied in car access system of ENAS. Now, RFID is also recognized as key technology in industry 4.0 in Germany.
(Fig.9: Vehicle tracking system in ENAS.)

Hybrid Roll-to-Roll Manufacturing System
They developed hybrid printing machine which consists of unwinding, web guide roll, optical mark detection, rotary screen printing, ink-jet printing, LED UV curing, IR heating, photonic sintering and rewinding. Its web speed is up to 20 m/min.
(Fig.10: microFLEXTM machinery (3D Micromac).)



4. Back-End of Line
(Head of department: Prof. Dr. Stefan E. Schulz)
HP: http://www.enas.fraunhofer.de/en/departments/BEOL.html

The researches of this department are helpful to our laboratory. Back-End-of-Line technologies comprise all processing step from contact level up to the completely processed wafer prior to electrical testing. With downscaling of the transistor, the resistance-capacitance product (RC-product) of the interconnect system increases, resulting in strongly increasing signal delay. Therefore, they research suitable materials, advanced processing methods and analytical tools as well as novel modeling and simulation approaches. Their technologies are following;

CVD : barrier, metal, dielectrics
ALD : metal, metal oxides, nitrides, Carbon nanotubes 
Electrochemical deposition : Cu, Ni, Au, Sn
Electroless deposition : Ni, Au
Dry etching : metals, dielectrics
CMP : Si, SiO2, barrier/copper film system, Al, various glasses
Grinding : Si, glass, lithium niobate, lithium tantalate, ceramics
(Fig. 11: Selective grown CNTs coated by ALD.)

Interconnects for Micro and Nano Electronics
Low-k and Ultralow-k dielectrics: Shrinking pattern size is getting serious effect on RC delay (signal delay). Low-k materials which have lower dielectric constant enable to decrease RC delay as well as power consumption and crosstalk.
Air gap technology: The k-value of air gap is lower than other materials. That's why it is called ultra low-k material. They developed some approaches of air gap formation and evaluated them. They published many journals about low-k dielectrics.
Copper Damascene Metallization 
Carbon nanotubes(CNTs): CNTs are a well known material in nanotechnology for their unique mechanical, electrical and thermal properties. They can withstand extreme current densities and thermal load. Also, they have high electron mobility and high current carrying capacity, as well as high sensitivity to external strain, thermal load, illumination and chemical environment. 
(Fig. 12: Air gap formation between copper interconnects.)

Materials and Metallization for NEMS

Technologies for 3D integration in MEMS Applications

Through Silicon Via (TSV)
Wafer thinning
Alignment and bonding
(Fig. 13: TSV filled with copper by electrochemical deposition.)
(Fig. 14: Optimized etching profile for TSVs with an aspect ratio of 20.)

Simulation of devices, CVD/PVD processes
(Fig. 15: Simulation stress field within a MOSFET transistor caused by deposition of a nitride stressor film.)

By the way, I’m now taking one lecture given by Prof. Dr. Shulz, “Advanced Integrated Circuit Technology”. It covers every specific processing, simulation, modeling, integrated circuit technologies as well as 3D technology, including above technologies. It is really informative because it also covers state-of-the-art technologies which are applied industry or are developing. I’d like to study a lot from this class.


5. System Packaging
(Head of department: Dr. Maik Wiemer)
HP: http://www.enas.fraunhofer.de/en/departments/SP.html

This is just the department which I am now belonging. This department focuses on versatile packaging technologies from zero-level packaging up to multi-level packaging. MEMS Packaging is important technology because it accounts for from 20 up to over 90 percent of manufacturing cost. They also focus on micro and nano patterning of surface areas in micro system technology.
There technologies are following;

MEMS packaging and 3D integration
Wafer level packaging
TSV(Through Silicon Via)
Wafer, chip, and wire bonding
Die separation
Electrical, mechanical, and thermal connecting
Characterization (hermiticity, strength, ultrasonic and IR microscopy.)
(Fig.16 : Wafer level bonding of pressure-sensor.)

Wafer bonding
Standard bonding: silicon direct bonding, anodic bonding, eutectic bonding, adhesive bonding, glass frit bonding.
Low-temperature bonding: reactive bonding, laser assisted bonding.
Other bonding: Polymer bonding, thermo-compression bonding.

The importance of the wafer bonding technology for both semiconductor industry and micro systems technology has been steadily increasing for a number of years. Add to standard bonding methods, many bonding methods have been developing so far. We need to select proper bonding method with the bonding device property. For example, low temperature bonding is often necessary for heterogeneous devices. Intermediate layer, hermiticity, homogeneity and bonding strength are also important factor.
(Fig.17 : MHz ultra sonic cleaning for wafer bonding, and Mr. Froemel.)

Nano scale effects
They analyze nano scale intermediate layers and layer systems that are deposited with PLD, PVD and Aerosol jet technology. Moreover, surface and material effects are investigated and characterized based on metallic nano structures for new bonding techniques.

Imprint technologies
Nano imprint technology has the advantage of high resolution, high throughput, little dimension error and low cost. First, embossing or imprinting micro and nanostructures are molded (Master). Then, the patterns are transferred to photo resist and exposed. Finally, micro and nano patterns are formed by removing master tool. They research not only include the development of embossing process but also the design and production of some kinds of tools like silicon master tools, tools with patterned photo resist or soft tools, so on.
(Fig.18: Sub-micron patterned resist via nano imprint lithography.)

Surface modification

Plasma activation treatment

Aerosol jet and Screen printing
Aerosol jet allows the maskless and non-contact deposition of a wide range of functional liquids in flexible patterns. Additional to the printing of organic materials, adhesives and biological relevant materials, it allows the printing of conductive structures and other functional materials.
Screen printing is used for selective patternings of interlayers for wafer bonding by coating paste like materials on a flexible screen.
(Fig.19: Screen printed glass paste structures)

Chip bonding
Flip-Chip (FC)
Chip-to-Chip (C2C)
Chip-to-Wafer (C2W)
Multi-Chip-Module (MCM)
Chip-on-Board (COB)
Surface Mounted Devices (SMD)


6. Advanced System Engineering
(Head of department: Dr. Christian Hedayat)
HP: http://www.enas.fraunhofer.de/en/departments/ASE.html

This department is located in University of Paderborn. The main efforts of this department are the design, the simulation and the characterization of micro and nano complex electronic systems. (Electromagnetic compatibility, electromagnetic reliability, signal integrity, radio frequency, so on.)
Their technologies are following;

Advanced 3D near-field scanning
(Fig.20: Near-field measuring system. )

Wire-less energy transmission
(Fig.21: Demonstrator of parallel communications and wireless energy transmission.)

Mobile wireless and RFID smart sensor systems for harsh environment

Advanced modeling and analysis of EMC and SI-effects

System modeling and simulation

(Fig.22: Modeling of a wireless energy transmission; current distribution within the activated transmitting antennas.)

Model-based development methods for custom specific heterogeneous systems

RF and EMC measurement on wafer-level

Multiphysics modeling and simulation

(Fig.23: 3D-Packaging: numerical simulation of electronic properties.)


As I mention above, each department has own research field in smart integrated systems and own business partners. At present, ENAS collaborates with over 150 partners from industry worldwide. Not only industry field but some universities and research institutes collaborates ENAS. Tohoku University has been one of the main partners of basic research for long years.
Their annual report (2014) shows their growth on business, finance as well as human resources on every year. Their investment is also enlarging. For example, in 2014, ENAS invested 2.8 million EUR in equipment investment as well as building activities. Moreover, 4.05 million EUR were invested for purchasing a nanolithography system which enable the usage for both direct write and mask making for a large variety of applications in industry and applied research.
So, their business scale is expected to enlarge steadily in the future.

This is the end of this report.
Thank you for reading such a long report.
What I’d like to say in this report is ENAS covers so many and so interesting technologies for smart integrated systems that it is really informative for me, and you.
I will study much more during my stay.
I’m glad if you are interested in some technologies from this report.

Next topic will be about experimental environment in ENAS.
I’ve already entered their cleanrooms and labs, and found some differences from our laboratory. I will report experimental systems in ENAS with the differences from Tohoku University.


・Fraunhofer ENAS homepage
・ Brochures of the departments(All pictures are reproduced from here.)
・Fraunhofer ENAS Annual Report 2014