Renata Melamud Thesis Defense - 9am Friday 06/13/08

Renata Melamud rmelamud at stanford.edu
Mon Jun 9 15:54:21 PDT 2008


Renata Melamud
Ph.D. Thesis Oral Examination
"Temperature Insensitive Microelecromechanical Resonators"
Advisor: Prof. Thomas Kenny

Date: Friday, June 13th
Time: 9:00 am (Refreshments beforehand)
Place: CISX-101 (Auditorium)
http://campus-map.stanford.edu/index.cfm?ID=04-055

Abstract:

Silicon resonators for frequency reference applications capitalize on 
the size and cost advantages of silicon processing. Start-ups developing 
silicon resonators, such as SiTime, Discera, and Silicon Clocks, seek to 
displace the $2.5 billion quartz crystal frequency reference market that 
is at the core of modern electronic devices. However, unacceptable 
frequency deviations caused by the temperature dependence of silicon’s 
material properties prevent these resonators from competing with quartz 
resonators in high precision applications.

This work describes the design, fabrication, and testing of silicon - 
silicon dioxide composite resonators whose temperature sensitivity is 
comparable to quartz crystal resonators. The optimization of the 
composite resonator demonstrates a thirty-fold reduction in 
frequency-temperature sensitivity compared to uncompensated silicon 
resonators. These temperature insensitive devices are single anchored 
flexural mode resonators, are isolated from packaging stresses, and are 
hermetically sealed in a CMOS compatible wafer-level encapsulation 
technology. In conjunction with active temperature compensation schemes, 
such as those employed in the quartz industry, this passive technology 
enables silicon-based frequency references to surpass the size and power 
limitations of quartz crystals in high precision applications.




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