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:
Jul. 18, 2000
Filed:
Sep. 30, 1998
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
There are provided a method for fabricating semiconductor nanocrystals which are highly controllable and less variable in density and size, as well as a semiconductor memory device which, with the use of the semiconductor nanocrystals, allows thickness of a insulating film between nanocrystals and channel region to be easily controlled and involves less variations in characteristics such as threshold and programming performance, and which is fast reprogrammable and has nonvolatility. Under a low pressure below atmospheric pressure, an amorphous silicon thin film 3 is deposited on a tunnel insulating film 2 formed on a silicon substrate 1. After the deposition of the amorphous silicon thin film 3, the amorphous silicon thin film 3 is heat treated at a temperature not lower than the deposition temperature of the amorphous silicon thin film 3 in an atmosphere of helium gas having no oxidizability, by which a plurality of spherical nanocrystals 4 with a diameter of 18 nm or less are formed on the tunnel insulating film 2 so as to be spaced from one another. The plurality of nanocrystals 4 are used as the floating gate of a semiconductor memory device.