| Summary: | 碩士 === 國立中山大學 === 電機工程學系 === 87 === In this thesis, we discuss the characteristics of a new SOI device with triple-gates structure proposed in [32], and hereinafter we call it - 3W SOI1. In order to compare the current driving ability, we change the 3W SOI1 structure with non-recessed side gates, and hereinafter we call it 3W SOI2.
First at all, we use the TMA two-dimensional process simulation tool- TSUPREM-4 to check some process parameters in[32]. After that, we use device simulation tools-MEDICI and DAVINCI to compare the characteristics of 3W SOI with those of conventional SOI.
According to the simulation results of MEDICI and DAVINCI, 3W SOI shows five unique characteristics which are superior to conventional SOI with same device parameters. First, 3W SOI device has a lower threshold voltage. Second, 3W SOI has a novel excess current gain. Third, 3W SOI has excellent short channel effect immunity than that of conventional SOI. Fourth, the breakdown voltage of 3W SOI device is higher than that of conventional SOI. Fifth, although 3W SOI has excess current gain, the self-heating effect of 3W SOI is not more serious than conventional SOI. These five advantages show more or less relations with its triple-gates structure. The coupling effect between these three gates will promote the potential inner the silicon film.
In order to understand the potential distribution in 3W SOI device, we solve two-dimensional poisson equation by two different aspects-direct coupling and indirect coupling. Furthermore, we use these formulas to calculate the threshold voltage of 3W SOI device. In comparison with TMA simulation results, the direct coupling method shows more approximation than indirect coupling. Last of all, we derive the current model of 3W SOI device with an approximate analysis.
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