The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 19, 2017
Filed:
Nov. 28, 2011
Norio Ishitsuka, Tokyo, JP;
Keiji Hanzawa, Hitachinaka, JP;
Yasuo Onose, Hitachinaka, JP;
Noriyuki Sakuma, Tokyo, JP;
Norio Ishitsuka, Tokyo, JP;
Keiji Hanzawa, Hitachinaka, JP;
Yasuo Onose, Hitachinaka, JP;
Noriyuki Sakuma, Tokyo, JP;
Hitachi Automotive Systems, Ltd., Hitachinaka-shi, JP;
Abstract
A thermal air flow sensor that produces less measurement error is provided. The thermal air flow sensor includes: a semiconductor substrate; a heating resistor, resistance temperature detectors, and an electrical insulator that includes a silicon oxide film, wherein the heating resistor, the resistance temperature detectors, and the electrical insulator are formed on the semiconductor substrate; and a diaphragm portion formed by removing a portion of the semiconductor substrate. The heating resistor and the resistance temperature detectors are formed on the diaphragm portion. The thermal air flow sensor further includes a silicon nitride film formed as the electrical insulator above the heating resistor and the resistance temperature detectors. The silicon nitride film has steps conforming to the patterns of the heating resistor and the resistance temperature detectors. The silicon nitride film has a multilayer structure.