| Summary: | 碩士 === 國立交通大學 === 電子工程系 === 90 === Overestimation of capacitance coupling coefficients in flash memory cells is encountered in the case of body effect while operating both flash memory cells and dummy transistors in subthreshold region. Existing subthreshold slope method also faces the same problem. The origin of these intolerable error can be pointed to process variations induced current mismatch between flash memory cells and dummy transistors, as explained in terms of current factor and slope factor n in a two-parameters subthreshold current model: . To minimize the effect of process variations, a new method incorporating body effect is built, in which dummy transistors are biased above-threshold while still operating flash memory cells in subthreshold. Once the slope factor n is gotten from threshold voltage versus source-to-substrate bias measurement, strikingly the resultant capacitance coupling coefficients are found to be fairly close to design value. This method is also fast and thus is able to serve as in-line monitor of capacitance coupling coefficients.
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