Fabrication and Characterization of PECVD Si3N4 Diaphragm-Based Capacitive-type Acoustic Sensor for IoT Application. (2016)

• Record Type: Journal Article
• Authors: Lee, Jaewoo; Yang, W.S.; Moon, S.E.; Lee, S.-G.
• Is Part Of: Procedia engineering. Volume 168(2016)
• Page Start: 749
• Page End: 752
• Publication Date: 2016
• Subjects: Capacitive-type acoustic sensor -- PECVD Si3N4 diaphgram -- ALEM; Engineering -- Congresses; Engineering -- Periodicals; Engineering; Conference proceedings; Periodicals; 620.005
• DOI: 10.1016/j.proeng.2016.11.269
• Languages: English
• ISSNs: 1877-7058

Abstract

Abstract: A bottom-inlet capacitive acoustic sensor with PECVD-Si3 N4 diaphragm is presented for Internet of things (IoT) application which is simple and compatible with the CMOS process. The polyimide sacrificial layer enables the photo-mask to be used at least for 5 photo-masks, resulting a simple fabrication process. For a bottom-inlet-type package, the diaphragm composed of a PECVD-Si3 N4 structure layer and a TiN electrode layer was designed to be placed over the back-plate. The sensor has a total chip area of 1 mm 2 and a chip thickness of 0.4 mm, and a 355 μm-radius diaphragm, respectively. To characterize the open-circuit sensitivity in a static state, an analytical approximately linearized electric-field method (ALEM) capacitor model was applied. The effective radius of the diaphragm was determined to be 316 μm, and the effective residual stress was modelled to be +61 MPa. From the model, the open-circuit sensitivity was characterized as 3.65 mV/Pa under an 8 V bias condition.