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33 results on '"Kuwabara, Kei"'

28. Integrated RF-MEMS Technology with Wafer-Level Encapsulation

Author

Kuwabara, Kei, primary, Urano, Masami, additional, Kodate, Junichi, additional, Sato, Norio, additional, Sakata, Tomomi, additional, Ishii, Hiromu, additional, Kamei, Toshikazu, additional, Kudou, Kazuhisa, additional, Yano, Masaki, additional, and Machida, Katsuyuki, additional

Published
2005
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30. Elimination of Curvature in Microelectromechanical-System Membrane

Author

Sakata, Tomomi, Yamaguchi, Keita, Nemoto, Naru, Usui, Mitsuo, Sassa, Fumihiro, Ono, Kazuyoshi, Takagahara, Kazuhiko, Kuwabara, Kei, Kodate, Junichi, and Jin, Yoshito

Abstract

This paper describes the correlation between microelectromechanical-system (MEMS) membrane curvature and implanted argon in a microelectromechanical-system membrane. When a free-standing silicon membrane, fabricated through ashing of an organic film, is cleaned by exposure to argon plasma to remove the oxidized surface, the membrane is curved uniformly. The curvature is released by annealing. Total-reflection X-ray fluorescence analysis before/after annealing reveals that argon, which is implanted into the crystal lattice of silicon by argon plasma exposure, is desorbed by annealing. This analysis also indicates that there is a linear correlation between the curvature change and implanted argon.

Published
2013

31. Residue-Free Dry Etching of Polymer Sacrificial Layer for Microelectromechanical-System Device Fabrication

Author

Takagahara, Kazuhiko, Ono, Kazuyoshi, Kuwabara, Kei, Sakata, Tomomi, Ishii, Hiromu, Sato, Yasuhiro, and Jin, Yoshito

Abstract

Residue-free dry etching of a photosensitive-polymer sacrificial layer using O2/CF4/CO-plasma exposure is described for the fabrication of microelectromechanical-system (MEMS) devices. Energy dispersive X-ray spectroscopy reveals that O2/CF4/CO-plasma exposure removes polymer sacrificial layers without leaving residue and severely damaging Au structures. Since the O2/CF4/CO-plasma exposure hardly damages Au structures, this process is applicable for the removal of sacrificial layers for MEMS with Au structures.

Published
2013

32. Cleaning of Gold Interconnection Surface by Low-temperature Hydrogen Annealing for MEMS Device Fabrication

Author

Sakata, Tomomi, Kuwabara, Kei, Ono, Kazuyoshi, Sato, Norio, Machida, Katsuyuki, and Ishii, Hiromu

Abstract

A technique for cleaning a gold surface using a dry process is described for the fabrication of microelectromechanical system (MEMS) devices. X-ray photoelectron spectroscopy (XPS) shows that gold is oxidized after exposure to oxygen plasma used for ashing of organic contaminants or etching of a sacrificial-layer film. On such oxidized gold surface, there are different incubations at the different places, which give rise to non-uniform thickness in film growth by electrochemical techniques, such as electrodeposition and electroplating. A surface analysis by thermal desorption spectroscopy (TDS) revealed that annealing causes oxygen to desorb from the gold oxide. The surfaces were annealed in a vacuum or nitrogen or hydrogen ambient to examine the effectiveness of dry-process surface cleaning. For the annealing in a vacuum and nitrogen ambient, a temperature of over 260deg is necessary for the oxide removal. Annealing in hydrogen ambient drastically lowers the cleaning temperature from 260 to 110deg.

Published
2008

33. Lightweight heartbeat detection algorithm for consumer grade wearable ECG measurement devices and its implementation.

Author

Matsuura N, Kuwabara K, and Ogasawara T

Subjects
Algorithms, Heart, Heart Rate, Electrocardiography, Wearable Electronic Devices
Abstract

We have developed a lightweight heartbeat detection algorithm for electrocardiogram (ECG) measurement in consumer-grade wearable devices. Based on a principle of calculating the clearance height in the inverted time differential of an ECG, the algorithm has a sensitivity specific to the QRS complex in an ECG. Because this algorithm is simple and lightweight, an efficient implementation form has been established for porting the algorithm to consumer-grade devices. We experimentally confirmed that the algorithm runs in an actual commercialized wearable device and provides improvement of heart rate measurement with noise caused by body motion.

Published
2022
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