Title:
In situ monitoring of reactive ion etching using a surface micromachined integrated resonant sensor

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dc.contributor.advisor May, Gary S.
dc.contributor.author Morris, Bryan George Oneal en_US
dc.contributor.committeeMember Brand,Oliver
dc.contributor.committeeMember Hasler,Paul
dc.contributor.committeeMember Kohl,Paul
dc.contributor.committeeMember Shamma,Jeff
dc.contributor.department Electrical and Computer Engineering en_US
dc.date.accessioned 2010-01-29T19:41:57Z
dc.date.available 2010-01-29T19:41:57Z
dc.date.issued 2009-08-18 en_US
dc.description.abstract This research explores a novel in-situ technique for monitoring film thickness in the reactive etching process that incorporates a micromachined sensor. The sensor correlates film thickness with changes in resonant frequency that occurs in the micromachined platform during etching. The sensor consists of a platform that is suspended over drive and sense electrodes on the surface of the substrate. As material is etched from the platform, its resonant vibrational frequency shifts by an amount that is proportional to the amount of material etched, allowing etch rate to be inferred. This RIE monitoring methodology exploits the accuracy of resonant micromechanical structures, whereby shifts in the fundamental resonant frequency measure a physical parameter. A majority of these systems require free-standing mechanical movement and utilize a sacrificial layer process as the key technique to develop and release the structure on a substrate. A sacrificial layer technique that incorporates a low temperature sacrificial polymer was utilized to develop and release the suspended RIE sensor with excellent performance and is capable of fabricating other low cost, high performance and reliable suspended MEMS devices. The integration of sensors and electronic circuitry is a dominant trend in the semiconductor industry, and much work and research has been devoted to this effort. The RIE sensor relies on capacitive transduction to detect small capacitance changes and the resulting change in resonant frequency during the RIE process. The RIE sensor's overall performance is limited by the interface circuit, and integration with the proper circuit allows the RIE sensor to function as a highly sensitive measure of etch rate during the RIE process. A capacitive feedback charge amplifier interface circuit, when configured with the RIE senor at the input achieves very low noise sensing of capacitance changes and offers the potential for wide dynamic range and high sensitivity. As an application vehicle, process control was demonstrated in the PlasmaTherm SLR series RIE system located in the Georgia Tech Microelectronics Research Center. en_US
dc.description.degree Ph.D. en_US
dc.identifier.uri http://hdl.handle.net/1853/31688
dc.publisher Georgia Institute of Technology en_US
dc.subject Capacitive interface circuit en_US
dc.subject Sacrificial layer technique en_US
dc.subject Integrated MEMS sensor en_US
dc.subject RIE process control en_US
dc.subject Etch rate monitoring en_US
dc.subject Resonant MEMS sensor en_US
dc.subject RIE en_US
dc.subject Reactive ion etching en_US
dc.subject.lcsh Plasma etching
dc.subject.lcsh Semiconductor industry
dc.title In situ monitoring of reactive ion etching using a surface micromachined integrated resonant sensor en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.corporatename School of Electrical and Computer Engineering
local.contributor.corporatename College of Engineering
relation.isOrgUnitOfPublication 5b7adef2-447c-4270-b9fc-846bd76f80f2
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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