Residual stress compensated silicon nitride microcantilever array with integrated poly-Si piezoresistor for gas sensing applications
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This work reports a novel method of microfabrication for silicon nitride based piezoresistive microcantilever device, to minimize the residual stress induced bending. The microcantilever of dimension L × W ~ 250 × 100 µm2 with stack (Si3N4/Poly-Si/Si3N4/SiO2) thickness ~ 1 µm was realized, by using standard six masks and bulk silicon micromachining fabrication process. In order to compensate the residual inbuilt stress, asymmetric structure layers for microcantilever was proposed and the presence of thin oxide layer underneath the released microcantilever stack was used to control the bending. The surface profiler measurement results showed the curvature bending in the range of ~ 4 ± 3 µm. The microcantilever was characterized further to evaluate its physical parameters such as mechanical deflection sensitivity and spring constant. The deflection sensitivity and spring constant values were ~ 0.161 ppm/nm and ~ 0.2 N/m, respectively. Finally, the practical application of fabricated piezoresistive microcantilevers was demonstrated by using it for explosive vapors sensing.
The authors acknowledge all the support and encouragement received from principle of scientific advisor (PSA) office, Government of India and Indian Institute of Technology, Bombay for providing their electrical testing setup for characterization of devices. We would like to thank Mr. Sajal Mathur for optimization of poly silicon thin films, Mr. Ramesh Banoth and Mr. M. M. Zafar for useful technical discussions. We also acknowledge Indian Institute of Science, Bangalore for Atomic force microscopy and Central scientific instruments organization (CSIO), Chandigarh for providing vapor generator facility. We wish to acknowledge all the support received from MFD, AMNSD and VPD team members and Group Head-VMFG, Shri Manoj Wadhwa for this work at SCL.
Compliance with ethical standards
Conflict of interest
The authors declare no competing financial interest.
- Bharadwaj R, Mukherji S, Mukherji S (2012) U-bend fiber optic sensor using 6-mercaptonicotinic acid (6-MNA) functionalized gold nanoparticles for detection of explosives RDX and TNT. In: International conference on fiber optics and photonics. ISBN: 978-1-4673-4718-1Google Scholar
- Gilda NA, Patil S, Seena V, Joshi S, Thaker V, Thakur S, Anvesha A, Baghini MS (2011) Piezoresistive 6-MNA coated microcantilevers with signal conditioning circuits for electronic nose. In: IEEE asian solid-state circuits conference, November, 2011, ISBN: 978-1-4577-1785-7Google Scholar
- Kandpal M, Bandela AK, Hinge VK, Rao VR, Rao CP (2013) Fluorescence and piezoresistive cantilever sensing of trinitrotoluene by an upper-rim tetrabenzimidazole conjugate of calixarene and delineation of the features of the complex by molecular dynamics. ACS Appl Mater Interfaces 5:13448–13456CrossRefGoogle Scholar
- Kandpal M, Adami A, Giacomozzi F, Zen M, Rao VR, Lorenzelli L (2017) Theoretical and experimental analysis of residual stress mitigation in piezoresistive silicon nitride cantilever. In: AISEM 2017, sensors and microsystems, pp 229–235Google Scholar
- Lang HP, Berger R, Battiston F, Ramseyer JP, Meyer E, Andreoli C, Brugger J, Vettiger P, Despont M, Mezzacasa T, Scandella L, Güntherodt HJ, Gerber C, Gimzewski JK (1998) A chemical sensor based on a micromechanical cantilever array for the identification of gases and vapors. Appl Phys A 66:61–64CrossRefGoogle Scholar
- Lutzenberger BJ, Dickensheets DL (2001) Vertical stiffening members for flatness control of surface micromachined structures. In: Proceedings of MOEMS and Miniaturized Systems II, p 4561Google Scholar
- Pierson HO (1999) Handbook of chemical vapor deposition: principles, technology and applications. William Andrew Publishing, New YorkGoogle Scholar