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. 23, 1999
Filed:
Mar. 31, 1997
Applicant:
Inventor:
Seiko Yoshida, Tokyo, JP;
Assignee:
Kabushiki Kaisha Toshiba, , JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01L / ;
U.S. Cl.
CPC ...
438239 ; 438242 ; 438243 ; 438246 ; 438249 ; 438386 ; 438389 ; 438392 ;
Abstract
A method for forming a contact is disclosed. A buried impurity region of a second conductivity type is formed in a semiconductor substrate of a first conductivity type. First and second well regions of a first and second conductivity types, respectively, are also formed in the semiconductor substrate. The second well region overlaps the first well region and contacts and surrounds the buried impurity region. A surface impurity concentration of the first well region is greater than a surface impurity concentration of the second well region. A contact to the second well region is formed.