Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
2006-03-21
2008-09-30
Wilczewski, M. (Department: 2822)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S262000, C438S423000, C438S449000, C438S530000, C438S593000, C438S766000, C438S773000, C438S981000
Reexamination Certificate
active
07429514
ABSTRACT:
A sidewall oxidation process for use during the formation of a transistor such as a flash memory cell allows for improved control of a gate oxide profile. The method comprises doping transistor source and drain regions to different doping levels, then performing a transistor sidewall oxidation using a particular process to modify the gate oxide thickness. The oxide forms at a faster rate along the source sidewall than along the drain sidewall. By using ranges within the oxidation environment described, a source side gate oxide having a variable and selectable thickness may be formed, while forming a drain-side oxide which has a single thickness where a thinner layer is desirable. This leads to improved optimization of key competing requirements of a flash memory cell, such as program and erase performance, while maintaining sufficient long-term data retention. The process may allow improved cell scalability, shortened design time, and decreased manufacturing costs.
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Powell Don C.
Rudeck Paul J.
Thomas Toniae M.
Wilczewski M.
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