Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
2006-02-21
2006-02-21
Thomas, Tom (Department: 2815)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S257000, C438S261000, C438S589000
Reexamination Certificate
active
07001809
ABSTRACT:
A split-gate flash memory cell having a three-dimensional source capable of three-dimensional coupling with the floating gate of the cell, as well as a method of forming the same are provided. This is accomplished by first forming an isolation trench, lining it with a conformal oxide, then filling with an isolation oxide and then etching the latter to form a three-dimensional coupling region in the upper portion of the trench. A floating gate is next formed by first filling the three-dimensional region of the trench with polysilicon and etching it. The control gate is formed over the floating gate with an intervening inter-poly oxide. The floating gate forms legs extending into the three-dimensional coupling region of the trench thereby providing a three-dimensional coupling with the source which also assumes a three-dimensional region. The leg or the side-wall of the floating gate forming the third dimension provides the extra area through which coupling between the source and the floating gate is increased. In this manner, a higher coupling ratio is achieved without an increase in the cell size while at the same time alleviating the punchthrough and junction break-down of source region by sharing gate voltage along the side-wall.
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Hsieh Chia-Ta
Kuo Di-Son
Lin Yai-Fen
Sung Hung-Cheng
Yeh Jack
Richards N. Drew
Taiwan Semiconductor Manufacturing Co. Ltd.
Thomas Tom
Thomas Kayden Horstemeyer & Risley
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