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:
Jun. 11, 2002
Filed:
Jul. 27, 2000
Yasushi Maeda, Naka-gun, JP;
Masaharu Horiguchi, Naka-gun, JP;
Shinji Makikawa, Annaka, JP;
Seiki Ejima, Annaka, JP;
Other;
Abstract
A silicon substrate is prepared by furnishing a silicon substrate ( ) having a step ( ) of at least 5 &mgr;m high on one surface, forming by high pressure heat oxidation an oxide film ( ) which is thinner than the step, and removing the oxide film on the higher surface region until the silicon surface is exposed in the higher surface region while leaving the oxide film on the lower surface region. Because of excellent electrical properties, minimized warpage, a substantially constant oxygen concentration, and a definitely ascertainable oxide-silicon boundary, the silicon substrate is suitable for use in optical waveguide devices.