Method for fabricating semiconductor nanocrystal and semiconductor memory device using the semiconductor nanocrystal
Patent 6090666 Issued on July 18, 2000. Estimated Expiration Date: 
September 30, 2018. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
September 30, 2018. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesLow voltage memory Method for photolytic liquid phase synthesis of silicon and germanium nanocrystalline materials Flash memory with nanocrystalline silicon film floating gate Multi-state flash memory cell and method for programming single electron differences Patent #: 5959896 InventorsApplicationNo. 163552 filed on 09/30/1998US Classes:438/257, Having additional gate electrode surrounded by dielectric (i.e., floating gate)117/87, Forming a platelet shape or a small diameter, elongate, generally cylindrical shape (e.g., whisker, fiber, needle, filament)117/935, Silicon from vapor or gaseous state {C30B 29/06}117/936, Germanium {C30B 29/08}257/E21.102, Epitaxial deposition of Group IV elements, e.g., Si, Ge, C (EPO)257/E21.132, Preparation of substrate for selective epitaxy (EPO)257/E29.301, Programmable by two single electrons (EPO)438/263, Tunneling insulator438/264Tunneling insulatorExaminersPrimary: Elms, RichardAssistant: Smith, Bradley K. Attorney, Agent or FirmInternational ClassH01L 021/336Foreign Application Priority Data1997-09-30 JPAbstractThere 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.Other References
Field of SearchHaving additional gate electrode surrounded by dielectric (i.e., floating gate)Tunneling insulator Tunneling insulator Silicon from vapor or gaseous state {C30B 29/06} Germanium {C30B 29/08} Forming a platelet shape or a small diameter, elongate, generally cylindrical shape (e.g., whisker, fiber, needle, filament) | |
