DocumentCode :
394109
Title :
On-chip monitoring of MEMS gear motion
Author :
Tanner, Danelle M. ; Swanson, Scot E. ; Walraven, Jeremy A. ; Dohner, JefFrey L.
Author_Institution :
Sandia Nat. Labs., Albuquerque, NM, USA
fYear :
2003
fDate :
30 March-4 April 2003
Firstpage :
484
Lastpage :
490
Abstract :
We have designed and fabricated a polysilicon sidewall-contact motion monitor that fits in between the teeth of a MEMS gear. The monitor has a center grounded member that is moved into contact with a pad held at voltage. When observing motion, however, the monitor fails after only a few actuations. A thorough investigation of the contacting interfaces revealed that for voltages > 5 V with a current limit of 100 pA, the main conduction process is Fowler-Nordheim tunneling. After a few switch cycles, the polysilicon interfaces became insulating. This is shown to be a permanent change and the suspected mechanism is field-induced oxidation of the asperity contacts. To reduce the effects of field-induced oxidation, tests were performed at 0.5 V and no permanent insulation was observed. However, the position of the two contacting surfaces produced three types of conduction processes: Fowler-Nordheim tunneling, ohmic, and insulator, which were observed in a random order during switch cycling. The alignment of contact asperities produced this positional effect.
Keywords :
condition monitoring; failure analysis; microactuators; motion measurement; oxidation; scanning electron microscopy; semiconductor device reliability; 0.5 V; 100 pA; 5 V; Fowler-Nordheim tunneling; MEMS gear motion; MEMS gear teeth; SEM; Si; Si-SiO2; asperity contacts; cantilever design; center grounded member; conduction process; contacting interfaces; field-induced oxidation; insulator conduction; ohmic conduction; on-chip monitoring; permanent insulation; polysilicon sidewall-contact motion monitor; positional effect; switch cycles; torsional spring design; Condition monitoring; Contacts; Gears; Insulation; Micromechanical devices; Oxidation; Switches; Teeth; Tunneling; Voltage;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Reliability Physics Symposium Proceedings, 2003. 41st Annual. 2003 IEEE International
Print_ISBN :
0-7803-7649-8
Type :
conf
DOI :
10.1109/RELPHY.2003.1197796
Filename :
1197796
Link To Document :
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