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. 30, 1997
Filed:
Jun. 01, 1995
Tadashi Mitsui, Wappingers Falls, NY (US);
Katsuhiko Hieda, Wappingers Falls, NY (US);
Kabushiki Kaisha Toshiba, , JP;
Abstract
Photolithographic alignment marks (e.g., mask and measurement overlay marks) are formed of a pattern of very small marks using the design configuration and rule of a circuit pattern feature. A relatively large mark comprising a pattern of small marks modeled after the circuit pattern feature results in an etch rate within the mark area that is substantially the same as the etch rate in the circuit pattern (e.g., cell or peripheral circuit) area. This allows for simultaneous formation of circuit pattern features, and the alignment marks, in a common etching step, while avoiding underetching (shallow etch depth) due to a microloading effect. In this manner, proper formation of readily detectible marks is ensured.