Method of manufacturing semiconductor device having oxide films with different thickness

Abstract

After a first gate oxide film is formed on a substrate, a nitride layer is formed by a first oxynitriding process. The first gate oxide film is selectively removed from a thinner film part area of the substrate. A second gate oxide film forming process forms a second gate oxide film in the thinner film part area and a third gate oxide film in a thicker film part area. By executing second oxynitriding process, nitride layers are formed at the thinner and the thicker part areas.

Description

[0001] This application is a Continuation in Part of U.S. patent application Ser. No. 10 / 843,694, filed on May 12, 2004. This application claims priority to prior Japanese Application JP 2003-134265, the disclosure of which is incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] This invention relates to a method of manufacturing a semiconductor device, in particular, to a manufacturing method of a semiconductor device including transistors having gate insulating films with different thickness. [0003] There is a known semiconductor device, in which plural kinds of transistors having gate insulating films with different thickness are formed on a common substrate as a combination of a semiconductor memory and peripheral circuits thereof. [0004] A conventional method of manufacturing the semiconductor device of the above type uses an oxynitriding process for a thinner gate insulating film for one of the transistors. That is, nitrogen elements are mainly introduced into t...

AI Technical Summary

Benefits of technology

"The present invention provides a method of manufacturing a semiconductor device that can introduce nitrogen elements into both thinner and thicker gate insulating films on a substrate. This is achieved through a multi-oxidation process for forming oxide films with different thickness on the substrate, followed by an oxynitriding process for forming nitride layers in each oxide film. The resulting semiconductor device has a substrate with a plurality of regions, where oxide films with different thickness are formed, and nitride layers are formed at interfaces between the oxide films and the substrate."

Problems solved by technology

Moreover, the oxynitriding process is undesirable when the thickness of the gate oxide film is 5 nm or more because it deteriorates reliability of the gate oxide film.

However, the gate oxide film of the transistor tends to become thin according to demands of miniaturizing, implementing thin design, and saving power consumption of the semiconductor device recently.

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