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:
Mar. 09, 1999
Filed:
Oct. 23, 1997
Hans R Camenzind, Los Altos, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
An epitaxial pinched resistor includes a semiconductor substrate of a first conductivity type having a surface on which an epitaxial layer of a second conductivity type grown. An up isolation region of the first conductivity type is diffused from the surface of the semiconductor substrate up into the epitaxial layer. A first down isolation region of the first conductivity type is diffused down into the epitaxial layer and overlapping with the up isolation region. The first down isolation region and the up isolation region isolate a portion of the epitaxial layer to be used to conduct a current. A second down isolation region of the first conductivity type is diffused down into the epitaxial layer between first and second contact surface areas of the epitaxial layer and into the portion of the epitaxial layer used to conduct the current. The second down isolation region is diffused a depth approximately equal to the first down isolation region so as to reduce a conductive cross-sectional area of the epitaxial layer. First and second ohmic contacts of the second conductivity type are diffused into the first and second contact surface areas of the epitaxial layer. The present invention also provides a method of forming an epitaxial pinched resistor.