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:
Oct. 26, 1999
Filed:
Jul. 27, 1995
Chiaki Kudo, Kyoto, JP;
Akihiro Yamamoto, Kyoto, JP;
Matsushita Electronics Corporation, Osaka, JP;
Abstract
A MOS capacitor has a p-type silicon substrate, an n-type impurity diffusion area formed by implanting an impurity into a region of the silicon substrate, a silicon oxide layer formed on the diffusion area, and a polysilicon electrode formed on the silicon oxide layer. An impurity profile is formed in the region such that the concentration of the impurity increases from a surface common to the diffusion area and the silicon oxide layer towards the inside of the silicon substrate. The concentration of the impurity at the interface is less than or equal to 1.times.10.sup.20 cm.sup.-3, and a peak concentration lies at a depth of more than 0.05 .mu.m under the interface. This controls accelerated oxidization during the thermal oxidization and also controls the dependence of the capacitance on the voltage.