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:
Feb. 10, 2009
Filed:
Jan. 26, 2007
Atsushi Isobe, Kodaira, JP;
Kengo Asai, Hachioji, JP;
Hisanori Matsumoto, Kokubunji, JP;
Nobuhiko Shibagaki, Kokubunji, JP;
Atsushi Isobe, Kodaira, JP;
Kengo Asai, Hachioji, JP;
Hisanori Matsumoto, Kokubunji, JP;
Nobuhiko Shibagaki, Kokubunji, JP;
Hitachi Media Electronics Co., Ltd., Iwate, JP;
Abstract
An object of the present invention is to provide an inexpensive thin film piezoelectric bulk acoustic wave resonator that allows fine-tuning of a resonant frequency. Another object is to provide an inexpensive filter with dramatically improved frequency characteristics, using thin film piezoelectric bulk acoustic wave resonators that can be formed on one substrate. A thin film piezoelectric bulk acoustic wave resonator of the present invention has a laminated structure including a piezoelectric thin film, and a first metal electrode film and a second metal electrode film between which part of the piezoelectric thin film is sandwiched; the first metal electrode film has a plurality of holes formed on an electrode plane opposite to the second metal electrode film and having a depth equivalent to at least the thickness of the first metal electrode film; and if a combined thickness of top and bottom electrode layers and the piezoelectric thin film is ht, the covering ratio σ of the electrode plane of the first metal electrode film satisfies a condition 0<σ<1 for every 1.28 ht pitch.