STMicroelectronics Presents Latest Advances in Thermal, Mechanical and Multiphysics Simulation at EuroSimE 2006

Geneva, April 21,2006 - STMicroelectronics (NYSE: STM), one of the world’s most innovative semiconductor companies, will participate as presenter of nine contributions, including two keynotes, at this year’s IEEE European conference on thermal, mechanical and multiphysics Simulation and Experiments in Micro-Electronics and micro-systems (EuroSimE), which takes place in Como, Italy, on April 23-25, 2006. ST’s contributions to the conference highlight the importance of simulation to assess the reliability of electronic devices, which represents a critical issue for advanced electronic products, and especially for mobile terminals.

Keynote Speeches
In the opening keynote, Carlo Cognetti, ST’s Director for Corporate Package Development, will give an overview on the evolution of semiconductor packaging, a key issue for new generations of semiconductor products. Mobile terminals, with mobile phones at the forefront, demand higher integration of components in a limited space, while keeping costs very low. This need has driven the trend to integrate more devices in one single package, which has totally changed the concept of packaging and has had a strong impact on design and manufacturing of integrated circuits.

The second keynote, by Benedetto Vigna, General Manager of ST’s MEMS Business Unit, will present the company’s point of view on the future of MEMS. Micromachined physical sensors such as pressure and motion sensors have already pervaded the medical and automotive markets, while inkjets printheads and micromirrors for display projectors are widely spreading in consumer products. The availability of tiny and inexpensive micromachined products will consolidate this trend towards ‘MEMS consumerization,’ and will result in the widest diffusion of microphones, motion and pressure sensors and advanced applications, such as wireless sensor networks and diagnostic devices, like smart pills.

Drop-Impact Modeling
ST packaging expert, Tong Yan Tee, CAE Team Leader in ST’s Corporate Packaging and Automation organization, will conduct a professional course on board-level drop-impact modeling and testing for handheld electronic products, which will introduce innovative methodologies to predict the life or reliability of components in final products by using a drop-impact life-prediction model rather than actual testing. This innovative approach allows for achieving considerable savings in testing costs and development time.

Modeling of Innovative RF Microswitches
Power consumption of RF microswitches is a key factor for the duration of batteries in mobile terminals and for the capability to run power-intensive applications. Therefore, ST is investigating possible alternatives to the current electrostatic, electrothermal or piezoelectric microswitches. At this conference, ST researchers will detail the promising results obtained from simulations on the usage of Aluminum Nitride as the piezoelectric actuator.

High-Speed Test Methodologies for Packaging
The robustness of the package is also becoming a key feature. On one hand, this is due to the increasing diffusion of mobile terminals, where devices are subject to big mechanical shocks. On the other hand, environmental protection issues have imposed the adoption of lead-free solder and component metallization. Therefore, the introduction of new effective testing methodologies is becoming increasingly important. ST researchers will propose an innovative methodology to test the robustness of semiconductor packaging, aiming at reducing time and costs of this task, while ensuring the same reliability levels as traditional package testing.

Stacked Memory Solutions
The new generation of handheld terminals needs high-capacity fast-access Flash memory to store data; however, the small terminal size requires the usage of small packages. Stacked packages represent a key solution to this problem. At the conference, ST researchers will present the implementation and performance of a 1-Gbit Flash memory obtained by stacking four 256-Mbit Flash memories in a single package.

Prediction of Thermo-Mechanical Failures
The move to 65nm CMOS technology and beyond manufacturing processes and the introduction of new materials will have a major impact on the thermo-mechanical performance of total IC stacks to be integrated in single packages, and this becomes a critical issue in Systems-in-Packages (SiPs). The prediction of thermo-mechanically induced failures in electronic packages in early stages, and the understanding of the precise failure mechanisms, will be extremely important to estimate the reliability of these devices. Within the CAA (Crolles2 Alliance Assembly) modeling cooperation setup, within the framework of the Crolles2 Alliance of ST, Freescale and Philips, researchers have developed a set of virtual prototyping techniques to support the development and qualification of next technology nodes. Using combined DOE/RSM techniques, the critical variables for each package, in terms of sizes, thickness, and/or material combinations can be explored.

On-Chip Fatigue Characterization
Robustness of MEMS components, such as accelerometers, gyroscopes and sensors, represents a key enabling factor to allow for their wide usage in commercial products. The study of failure mechanisms of thin silicon films used in their manufacturing is very important to determine their actual reliability. To this aim, researchers from ST, in cooperation with the Institute of Industrial Technology and Automation of the Italian National Research Council, have developed a new promising method to test the on-chip fatigue characterization.

MEMS Mechanical Reliability
The issue of mechanical reliability of MEMS is becoming increasingly important. To assess the actual robustness of micro-machined devices, it is very important to assess the impact rupture of their structural material. To this aim ST, in cooperation with the Politecnico of Milan, has developed an innovative simulation approach, showing promising experimental results. Researchers used an explicit dynamic FE code to simulate the mechanical response of polysilicon specimens, produced with ST’s Thelma process, to the impact loading typically caused by an accidental drop of handheld terminals containing MEMS devices.

Mechanical Reliability Issues in Miniaturization
The increasing miniaturization of semiconductor devices implies a continuous down-scaling of interconnect dimensions, which has led to the introduction of copper and brittle low-k dielectric materials. Their usage poses a great integration challenge. Indeed, mechanically induced reliability issues, such as stress voiding in copper interconnects and cracking of low-k dielectrics are now key factors for device integrity. Up to now, these two failure modes were considered separately; however, recent experimental observations demonstrate the possible interaction of these two failure modes. ST and Philips researchers working in the Crolles2 Alliance present the results of a thermo mechanical analysis using energy-based failure criteria, where the risk of void nucleation and growth was compared with crack related failure.

Further information about EuroSimE is available at: http://www.eurosime.org/index.htm


About STMicroelectronics
STMicroelectronics is a global leader in developing and delivering semiconductor solutions across the spectrum of microelectronics applications. An unrivalled combination of silicon and system expertise, manufacturing strength, Intellectual Property (IP) portfolio and strategic partners positions the Company at the forefront of System-on-Chip (SoC) technology and its products play a key role in enabling today’s convergence markets. The Company’s shares are traded on the New York Stock Exchange, on Euronext Paris and on the Milan Stock Exchange. In 2005, the Company’s net revenues were $8.88 billion and net earnings were $266 million. Further information on ST can be found at www.st.com.
Information last updated Jan 2006.

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