1. Temperature Sensitive Micro-electro-mechanical Systems Amy Kumpel Richard Lathrop John Slanina Haruna Tada Tufts University TAMPL REU 1999

2. Overview Background information of T-MEMS –current project goals Experimental Setup –recent modifications –how it works Experimental Results –imaging –numerical model Conclusion and future work

3. An Introduction to T-MEMS Measurement and characterization –mechanical properties of micro-scale devices –thermal properties of device materials under high temperatures Application to rapid thermal processing (RTP)

4. Composition of T-MEMS Tri-layered cantilever beams 1.03  m SiO 2, 0.54  m poly-Si 0.19  m SiO 2 (thin, protective coat) 0.19  m SiO 2 1.03  m SiO 2 0.54  m poly-Si Si substrate

5. Composition of T-MEMS Tri-layered cantilever beams 1.03  m SiO 2, 0.54  m poly-Si 0.19  m SiO 2 (thin, protective coat) 25  m well etched into Silicon substrate

6. Beams are processed at 840°C –initial experimental condition is room temperature Upward room temperature curvature –due to differences in  th of poly-Si and SiO 2 (beams bend downward when heated) Initial curvatures vary with material and/or deposition rate – typical curvatures range from 5 to10  m for a 100  m poly-Si beam Fabrication Process SiO 2 Poly-Si

7. Our Goals Modify the experimental setup to decrease system error Collect curvature data from poly-Si beams Determine Young’s Modulus, E(T), and the coefficient of thermal expansion,  (T), of thin films (poly-Si, SiN x ) at high temperatures Improve method for curve fitting and resolution analysis

8. CCD camera collimated light source beam splitter Al reflector quartz plate W-halogen lamp and housing sample thermocouple Si wafer quartz rod Experimental Setup

9. Modifications Fixed Mounting –CCD camera, beam splitter, collimated light source Leveling –all surfaces with mounting plates or rods –the system is leveled to the Silicon wafer (sample) Alignment –collimated light source to beam splitter –CCD camera to beam splitter light source centered in the IMAQ image when aligned

10. Experimental Setup with Modifications

11. Experimental Procedure Center sample to CCD camera Heat T-MEMS (slowly) to ~800°C using W- halogen lamp then gradually cool to room temperature Save the beam image every ~20-30 seconds during the run Set LabVIEW SCXI program to record temperature vs. time data

12. Imaging Results

14. Determining E(T) and  (T) Two material properties approximate beam curvature for both Poly-Si and SiO2 –Young’s Modulus (E) –Coefficient of Thermal Expansion (  ) Estimate E(T) from previous publications Find a best fit  (T) using a numerical model of the thin film poly-Si layer

15. Preliminary Results for  (T) of Poly-Si 0.E+00 2.E-06 4.E-06 6.E-06 8.E-06 1.E-05 0200400600800 Temperature (°C) Coefficient of Thermal Expansion

16. Conclusion Modified setup for increased accuracy Acquisition of data with new setup Used numerical method for determining the thermal properties

17. Future Work Create x-y-z stage for easy movement of sample Take more data with new setup Modify numerical method for thermal properties Get more values for E(T) and  (T) Modify LabVIEW programs Help Haruna with her thesis MACIS or MANTIS?

18. Any Questions For Us?