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:
Apr. 11, 1989
Filed:
Feb. 12, 1988
William G Easter, Reading, PA (US);
Daniel D Leffel, Earl Township, Berks County, PA (US);
American Telephone and Telegraph Company, Berkeley Heights, NJ (US);
AT&T Technologies, Inc., Berkeley Heights, NJ (US);
Abstract
A method has been developed for providing tub regions with various resistivities in a dielectrically isolated (DI) structure. The starting substrate material is etched to expose the locations designated for a resistivity modification, and epitaxial material of the modified resistivity value is used to fill the exposed tubs. The remainder of the fabrication process follows conventional DI fabrication techniques. The procedure may simply be used to create a DI structure containing both n-type and p-type tube regions. The idea may also be extended, however, to providing separate tubs with, for example, n+ resistivity, n- resistivity, p- resistivity and p+ resistivity, all within the same DI structure.