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Measurements of Piezoresistive Coefficients in Lightly Doped (111) Silicon. Chun Hyung Cho & John Sunwoo Electrical & Computer Engineering Auburn University. OUTLINE. Introduction Piezoresistive Theory Results of Measurements Discussion Conclusion. INTRODUCTION.
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Measurements of Piezoresistive Coefficients in Lightly Doped (111) Silicon Chun Hyung Cho & John Sunwoo Electrical & Computer Engineering Auburn University
OUTLINE • Introduction • Piezoresistive Theory • Results of Measurements • Discussion • Conclusion
INTRODUCTION • Stress due to mechanical loadings • Degradation of performance • Stress analyses of electronic packages and their components have been performed
INTRODUCTION(continued) • The basic application concepts • Semiconductor chips are incorporated into electronic packages • The sensors have most often been resistors
Basic BMW2 Test Chip (200 x 200 mils) • The doped active region is typically designed using a serpentine pattern • Electrical isolation between the doped surface resistor and the bulk of the chip
Result: p-type resistance changeTypical vaule: B1p =507/TPa, B2p = -145/TPa
Result: n-type resistance changeTypical vaule: B1n =-230/TPa, B2n = 207/TPa
Discussion: Typical piezo-resistive coefficient values for BMW2
DISCUSSION • IntelliSuite software is used • Under-estimated result • Measured resistance changes was assumed to be independent of T • Beam rotation error • Loading symmetry error • Weight and length measurement error
CONCLUSION • Measurements of piezoresistive coefficients in lightly doped (111) silicon • Applications of piezoresistive sensors in electronic packaging. • The sensors are not mounted on the chips. • Integral part of the structure to be analyzed by the way of the fabrication process.
CONCLUSION (Continued) • The sensor are capable of providing non-intrusive measurements of surface on chip even within encapsulated packages. • Piezoresistive stress sensors have much higher sensitivity than metallic stress sensors.