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:
Oct. 25, 2011
Filed:
Jul. 30, 2009
Hideto Ohnuma, Kanagawa, JP;
Shigeharu Monoe, Tochigi, JP;
Shunpei Yamazaki, Tokyo, JP;
Semiconductor Energy Laboratory Co., Ltd., Kanagawa-ken, JP;
Abstract
The present invention provides a TFT including at least one LDD region in a self-alignment manner without forming a sidewall spacer and increasing the number of manufacturing steps. A photomask or a reticle provided with an assist pattern that is formed of a diffraction grating pattern or a semi-transmitting film and has a function of reducing light intensity is employed in a photolithography step of forming a gate electrode, an asymmetrical resist pattern having a region with a thick thickness and a region with a thickness thinner than that of the above region on one side is formed, a gate electrode having a stepped portion is formed, and an LDD region is formed in a self-alignment manner by injecting an impurity element to the semiconductor layer through the region with a thin thickness of the gate electrode.