Stress Monitoring of Post-processed MEMS Silicon Microbridge Structures Using Raman Spectroscopy

Authors

Lavern A. Starman, Air Force Institute of TechnologyFollow
Ronald A. Coutu Jr., Marquette UniversityFollow

Document Type

Article

Language

eng

Publication Date

11-2012

Publisher

Springer

Source Publication

Experimental Mechanics

Source ISSN

0014-4851

Abstract

Inherent residual stresses during material deposition can have profound effects on the functionality and reliability of fabricated Micro-Electro-Mechanical Systems (MEMS) devices. Residual stress often causes device failure due to curling, buckling, or fracture. Typically, the material properties of thin films used in surface micromachining are not well controlled during deposition. The residual stress; for example, tends to vary significantly for different deposition methods. Currently, few nondestructive techniques are available to measure residual stress in MEMS devices prior to the final release etch. In this research, micro-Raman spectroscopy is used to measure the residual stresses in polysilicon MEMS microbridge devices. This measurement technique was selected since it is nondestructive, fast, and provides the potential for in-situ stress monitoring. Raman spectroscopy residual stress profiles on unreleased and released MEMS microbridge beams are compared to analytical and FEM models to assess the viability of micro-Raman spectroscopy as an in-situ stress measurement technique. Raman spectroscopy was used during post-processing phosphorus ion implants on unreleased MEMS devices to investigate and monitor residual stress levels at key points during the post-processing sequences. As observed through Raman stress profiles and verified using on-chip test structures, the post-processing implants and accompanying anneals resulted in residual stress relaxation of over 90%.

Comments

Accepted version. Experimental Mechanics, Vol. 52, No. 9 (November 2012): 1341-1353. DOI. © 2018 Springer Nature Switzerland AG. Part of Springer Nature. Used with permission.

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Ronald A. Coutu, Jr. was affiliated with the Air Force Institute of Technology at the time of publication.

Recommended Citation

Starman, Lavern A. and Coutu, Ronald A. Jr., "Stress Monitoring of Post-processed MEMS Silicon Microbridge Structures Using Raman Spectroscopy" (2012). Electrical and Computer Engineering Faculty Research and Publications. 361.
https://epublications.marquette.edu/electric_fac/361