New diaphragm structure based on SiNx/SOG for flow sensor

Yuichi Sakai; Akira Yamashita; Tsukasa Matsuura; Kazuhiko Tsutsumi

doi:10.1117/12.324058

1 September 1998 New diaphragm structure based on SiNx/SOG for flow sensor

Yuichi Sakai, Akira Yamashita, Tsukasa Matsuura, Kazuhiko Tsutsumi

Proceedings Volume 3512, Materials and Device Characterization in Micromachining; (1998) https://doi.org/10.1117/12.324058
Event: Micromachining and Microfabrication, 1998, Santa Clara, CA, United States

Abstract

This paper describes the new diaphragm structure using SiNx/SOG for a micro flow sensor. Its purpose is the measurement of a correct flow rate of various gases or liquids. The proposed sensor consists of sputtered SiNx/Pt/SiNx thin film diaphragm structure, which reduces thermal capacitance. The platinum film resistors detect a change of the temperature distribution on the membrane caused by forced convection. In sensors having these film structures, sputtering methods make it much easier than other film fabrication methods, such as CVD (Chemical Vapor Deposition) to control the internal stress of SiNx film in order to stretch the diaphragm tight. However, the reliability is often spoiled by the column structue of the sputtered SiNx protective film which grows on the platinum film resistors. In order to prevent the growth of the column structure, Spin-On Glass (SOG) film is introduced between platinum film resistors and sputtered SiNx protective film. Because the SOG film is an amorphous structure. SiNx films on SOG films are dense. Additionally, SOG films reduce the step height of platinum film resistors, so the step-coverage of sputtered SiNx protective film is improved.

Citation Download Citation

Yuichi Sakai, Akira Yamashita, Tsukasa Matsuura, and Kazuhiko Tsutsumi "New diaphragm structure based on SiNx/SOG for flow sensor", Proc. SPIE 3512, Materials and Device Characterization in Micromachining, (1 September 1998); https://doi.org/10.1117/12.324058

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