Single-Mask Fabrication of Temperature Triggered MEMS Switch for - PowerPoint PPT Presentation

Single-Mask Fabrication of Temperature Triggered MEMS Switch for Cooling Control in SSL System J. Wei, H. Ye , H.W. van Zeijl, P.M Sarro, G.Q. Zhang Delft University of Technology, Dimes Materials innovation institute, M2i

What is SSL? Solid State Light || Light Emit Diode Serve Light 2 H.Ye ( 叶怀宇 )

Outline • Introduction • Thermal switch • Conclusions • Acknowledgements Page 3 H.Ye ( 叶怀宇 )

Incandescent bulb to LED • More efficiency (6 times) • Long life time (5 years or more) • Energy saving 4 H.Ye ( 叶怀宇 )

Heat in LED • LED package suffers high temperature • For other higher power SSL, even worse 5 H.Ye ( 叶怀宇 )

Why thermal management? • For 5K difference, lumen output of blue light LEDs will decrease 4% and lifetime drops from 60,000 down to 50,000 hours • Required temperature of LED(Lower than 150 ˚ C) • Required temperature of Driver(Lower than 100 ˚ C) Reference: Che Cheung, Brandon Noska and Kim van der heide, “Thermal management: Comparison of passive and active cooling effectiveness.” LED Professional Review, (2009) pp. 42. 6 H.Ye ( 叶怀宇 )

Thermal management • Active cooling has been applied to LEDs • Intelligent temperature control system needed AVR based intelligent temperature monitoring and control system 7 H.Ye ( 叶怀宇 )

Concept • Smart -> switch on/off the cooling system based on Temperature • Small -> can be put it very close to the LED • Suitable -> easy to be integrated -> fabricated by Si micromachining technology Page 8 H.Ye ( 叶怀宇 )

Technology V-shape thermal actuator • Local heating by electrical current • Temperature difference • Local expansion Displacement is a function of ∆ T Not suitable for uniform heating Temperature Triggered Switch Uniform temperature distribution • A larger CTE is required on the actuation beam than the substrate (anchor) • Aluminium/Silicon combined beam is used. Displacement is a function of absolute T Page 9 H.Ye ( 叶怀宇 )

Thermal switch • Design with parameter analysis – Initial distance between plate and electrodes – Length of the beam – Ratio of the Al/Si • Simulation and results H.Ye ( 叶怀宇 )

Thermal switch • Process – single-mask • deep reactive-ion etching (DRIE) • thermal oxidation – Thin silicon-1.5 μ m • aluminum deposited on the side wall • thin titanium nitride (TiN) H.Ye ( 叶怀宇 )

Thermal switch • SEM (Dimension: 1.0x0.4 mm 2 ) • Size • \height 30um H.Ye ( 叶怀宇 )

Thermal switch • Testing with increasing temperature • The physical contact around 130ºC H.Ye ( 叶怀宇 )

Thermal switch • Validation of concept H.Ye ( 叶怀宇 )

Thermal switch • Video • Thermal switch on/off at designed temperature threshold H.Ye ( 叶怀宇 )

Conclusion – 1.Concept of simple and smart control for SSL • A cost-effective temperature trigger for cooling control – 2. Design and process • A single-mask 3D micro-machining process – 3. Concept validation – 4. Further work • A functional LED package The concept and process could be developed for other applications • Further development of the temperature trigged switch concept and fabrication process for other applications 16 H.Ye ( 叶怀宇 )

Acknowledgement The authors would like to acknowledge the technical staff of DIMES-ICP group for their precious help. This research is supported by the Enlight project (http://www.enlight-project.eu/), funded by ENIAC. 17 H.Ye ( 叶怀宇 )

Thank you!!! 18 H.Ye ( 叶怀宇 )

Cross-section SEM Page 19 H.Ye ( 叶怀宇 )

Cross-section SEM Page 20 H.Ye ( 叶怀宇 )

Cross-section SEM Page 21 H.Ye ( 叶怀宇 )