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. 17, 2009
Filed:
Mar. 03, 2006
Masato Kijima, Kakogawa, JP;
Atsushi Harikai, Ono, JP;
Masato Kijima, Kakogawa, JP;
Atsushi Harikai, Ono, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
A method is provided for forming plural kinds of wells on a single semiconductor substrate with an improved alignment accuracy and obviating the generation of step height between the wells. The method includes forming a selective etching film on the semiconductor substrate, forming openings on the selective etching film overlying a first well forming region and an alignment mark forming region using a first resist film as a mask for defining the first well forming region and the alignment mark forming region, implanting the first well forming region with a dopant of a first conductivity type and removing the first resist film, forming a second resist film to mask at least the first well forming region, having an opening overlying the alignment mark forming region larger than the opening of the selective etching film overlying the same region, and forming the alignment mark by performing an etching process using the second resist film and selective etching film as a mask.