New structure and fabrication process for thermal-type microsensors

Han Ji-song; Tadashi Kadowaki; Kazuo Sato; Mitsuhiro Shikida

doi:10.1117/12.442969

28 September 2001 New structure and fabrication process for thermal-type microsensors

Han Ji-song, Tadashi Kadowaki, Kazuo Sato, Mitsuhiro Shikida

Proceedings Volume 4557, Micromachining and Microfabrication Process Technology VII; (2001) https://doi.org/10.1117/12.442969
Event: Micromachining and Microfabrication, 2001, San Francisco, CA, United States

Abstract

We describe the structure and fabrication of a one- dimensionally arrayed high density thermal-type micro fingerprint sensor. To provide thermal isolation, we designed and fabricated two sets of insulation cavities for each heater element, one for reducing the heat-transfer from the heater to the substrate, and the other one for that of heat to the wiring. The first set of cavities were etched under each heater bridge, leaving an SiO₂ diaphragm with the heater bridge on it, and laterally penetrating with the cavities of neighboring heater bridges. The second ones were etched at the both ends of each heater element, leaving a set of SiO₂- wiring bridges. This SiO₂-wiring bridge structure was used as a thermal isolator when performing a metal-film wiring. The wiring (an electrical feed-through) was formed by a lift-off method, and runs on the SiO₂ insulation surface from the heater element to the bonding pad through the SiO₂-wiring bridges. The fabricated sensor device was made on a (100) SOI (silicon-on-insulator) wafer. Each heater element was 5 X 17 X 50 (micrometer³) with a pitch of 80 micrometer. Because of its small thermal capacity and effective thermal isolation, the sensor element was very sensitive. When a 0.4- V/20-microsecond pulse-voltage was applied to the heater elements, their resistance reached a steady maximum value in about 4 to approximately 5 microseconds. This level of sensitivity will be useful in variety of thermal sensors, such as micro temperature sensors and micro flow sensors, in addition to the thermal-type fingerprint sensors.

Citation Download Citation

Han Ji-song, Tadashi Kadowaki, Kazuo Sato, and Mitsuhiro Shikida "New structure and fabrication process for thermal-type microsensors", Proc. SPIE 4557, Micromachining and Microfabrication Process Technology VII, (28 September 2001); https://doi.org/10.1117/12.442969

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
9 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Sensors

Bridges

Chemical elements

Etching

Silicon

Semiconducting wafers

Thermal effects

Show All Keywords

Keywords/Phrases

Search In:

Publication Years