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:
Dec. 23, 2003
Filed:
Aug. 06, 2002
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A technique for preventing a decrease in alignment accuracy during a photolithography process is provided. A substrate ( ) is prepared, in the surface ( ) of which trenches ( ) for use as alignment marks and trenches ( ) each forming an element isolation structure are formed and on the surface ( ) of which a polysilicon film ( ) is formed, avoiding the trenches ( ). The trenches ( ) are filled with an insulation film ( ). The insulation film ( ) is then selectively etched to partially remove the insulation film ( ) in the trenches ( ) and to leave the insulation film ( ) on side and bottom surfaces ( ) of the trenches ( ). Using the insulation film ( ) in the trenches ( ) as a protective film, the polysilicon film ( ) is selectively etched. The use of the insulation film ( ) in the trenches ( ) as a protective film prevents the substrate ( ) from being etched and thereby prevents the shape of the trenches ( ) from being changed. This results in prevention of a decrease in alignment accuracy during a photolithography process.