1. Silicon Carbide Temperature Sensor for Harsh Environments

2. Chris RiceJason Wallace Michael JacksonJovan Bjelobrk ADVISOR Dr. Stephen Saddow “a hot project…a cool advisor” Team Members

3. Team Responsibilities Jovan Bjelobrk Jason Wallace Michael Jackson Chris Rice Project Planning/Coordination Sensor Design Fabrication Sensor Design Documentation Software/Web Design Documentation Device Controller Design

4. Group Motivation Research of New System Research of New Materials in Semiconductor Technology Within our Realm of Capability

5. Overview No reliable way to detect temperature changes in extreme environments using typical semiconductor material (Si) Space travel involves extreme temperatures SiC has the ability to operate in and withstand extreme temperatures (>500 °C) Problem detection = Problem prevention! Spacecraft problems have proven fatal

6. Key Specifications Increased Sensing Range 25 ° C to 500 ° C Operating Voltage 5 volts to 24 volts Tolerance Temperature reading is accurate to  0.5 °C at 25 °C

7. System Components Temp. Sensing Voltage Output A/D Conversion Serial Interface Temp. Display Advanced Functions

8. Prototype Layout p+p+ n-n- Metal Contacts n + Doping Levels 5x10 18  1x10 16 

9. Design Equations R =  *(L/A) A = W*t  = 1/(n*q*  n) Ni = sqrt(nc*nd)*e (-Eg/2*k*T)  n = (2.5*10 7 )*T -2

10. Si & SiC Plot of Resistance vs. Temperature Test Spec of 25 to 500 degrees C Silicon CarbideSilicon

11. Controller Board Development

12. Tolerance The tolerance goal of 0.5 ° C of accuracy was met

13. Operating Voltage Voltage Regulator output varies from 4.8 to 5.2 volts The desired accuracy is still obtained with this variation

14. Cost Analysis Approximately $2000 per substrate (2 inch diameter wafer) Approximately $600 for whole-wafer EPI Growth Approximately $400 for Fabrication Run Producing 25 devices per wafer, and assuming overall yield of process of 72%, produces 18 usable devices at approximately $167 each Control board components: $26.61 Total cost for working unit: $193.61

15. Determined the limits of Pspice with respect to SiC modeling Utilization of MATLAB for simulations of SiC device and controller board circuitry Design will be later incorporated into a single MEMS device for determining temperature, pressure, and vibration from a single point on a space vehicle Conclusions/Future Work

16. Silicon Carbide Temperature Sensor for Harsh Environments

17. References [1]Herbert B. Sachse, Semiconducting Temperature Sensors and their Applications, John Wiley & Sons INC., New York, New York, USA, 1975. [2]Jeffrey B. Casady, William C. Dillard, R.Wayne Johnson, and U. Rao, "A Hybrid 6H – SiC Temperature Sensor Operational from 25 ° C to 500° C," IEEE Transactions on Components, Packaging, and Manufacturing Technology - Part A, vol. 19, no. 3, pp., September 1996. [3]Dr. Stephen E. Saddow, "Emerging Solid – State Switch Technologies," A Short Course given by Dr. Stephen E. Saddow at the 24 th International Modulator Symposium June 26-29, 2000, Norfolk, VA. [4]Mark Holdaway, "Factors Affecting Accuracy in Silicon Digital Temperature Sensors,"Electronic Engineering, vol. 72 Issue 876, pp 26, January 2000. [5]Frank Goodenough, "Monolithic Silicon Temperature Sensors Challenge Thermistors, RTDS, and Thermocouples," Electronic Design, vol. 45 Issue 22, pp 54, October 1997. [6]Charles H. Small, "Diodes and Rectifiers Gain improved performance, packaging," Computer Designs : Electronic Systems Technology & Design, vol. 37, Issue. 4, pp. 69, April 1998. [7]Don Lancaster, "Understanding Crest Factors, temperature – sensing circuits, and more," Electronics Now, vol. 69, Issue 3, pp. 53, July 1998. [8]Mehran Mehregany, Christian A. Zorman, Narayanan Rajan, Chien Hung Wu,"Silicon Carbide MEMS for Harsh Environments," Proceedings of the IEEE, Volume: 86 No: 8, August 1998 Page(s): 1594 –1610 [9]F. Nallet, D. Planson, K. Isoird, M. Locatelli, J.P. Chante, "Comparison of Static, Switching and Thermal Behavior Between a 1500 V Silicon and Silicon Carbide Bipolar Diodes," Semiconductor Conference, 1999. CAS '99 Proceedings. 1999 International, Volume: 1, 1999 Page(s): 195 -198 vol. [10]A.A. Yasseen, Chien-Hung Wu; C.A. Zorman, M. Mehregany, "Fabrication and Testing of Surface Micromachined Silicon Carbide Micromotors," IEEE Electron Device Letters, Volume: 21 Issue: 4, April 2000 Page(s): 164 -166