| Summary: | 碩士 === 國立中山大學 === 電機工程研究所 === 83 === SOI金氧半有很多優點, 如低次臨閥斜率,所以近年來受大家注意。它之所
以有很多比傳統金氧半的優點是在於多一個絕緣體。但此會使SOI 金氧半
的模型比較複雜, 因為有耦合和遮敝效應。所以當必需模擬大電路時高效
率是很重要的。故本論文提供一高效率的SOI 金氧半模型。縮小元件尺寸
可降低成本, 因此縮小化理論也被研究。為了得到高效率的模型, 我們用
固定表面電位模形, 然而在表面空乏時, 耦合和遮敝效應被考慮。表面電
位可用通道電荷密度來記算。為算電荷, 一維波以松方程式和高斯定律被
應用。從導出的公式發現電位是偏壓,前表面和後表面電位的函數, 可以
用來模擬耦合和遮敝效應。從模擬的結果可看在空乏區有不同的斜率, 表
示兩表面有不同互相影響。在直流分析中,我們有新的解析式移動率模型
。在暫態分析中,節點電量被用來計算本質電容。在縮小化理論方面,我們
用一維波以松方程式來計算表面電位。其中可得到特徵質λ和其它參數λ
f,λb,λB,λBf,λBb來決定元件參數。本論文提出在空乏區時表面電位
的算法,解析式移動率模型, 簡單的本質電容算法。另一方面也提供如何
決定元件尺寸的簡單基本原則。
The SOIMOSFETs provides many advantages such as low
subthreshold slope over the bulk MOSFETs because the additional
insulator. However, it makes the simulation model more complex
than the bulk MOSFETs that beacause of coupling and shielding
effect. Thus, a high efficient model is important when we
simulate a larger circuit. So, this thesis develops a simple
high efficient model of SOI MOSFETs. Scaling down the device
will reduce the cost. Thus, the scale down theory is also
disscussed. To get high efficient model, the fixed surface
potential approach is used. However, in depletion region, the
effects of coupling and shielding are consider. The channel
charge density is used to calculate surface potential. To
calculate it, the 1-D Poisson''''s equation and the Gauss''''s law
are used. From the results , the charge density is the function
of gate bias, front and back surface potential. Thus, the
effects of back surface(coupling and shielding) can be
considered in this model. The surface potential -gate bias
curve has diffenet slopes in depletion region. In DC analsis,
the new analytic mobility model has been used. In transient
analysis,the intranic capacitances are calculated by nodes
charge. In scale down theory, the 2-D Poisson''''s equation is
used to to calculate the surface potential. We obtain a
eigenvalue λ and other important parameters: λf,λb,λB,λBf,
λBb. By using this, we can model the threshold voltage
shifting and subthreshold slope. When we draw the S-Leff/λ
curve, we obtain a smooth curve. This curve can help us to
decide the device parameters to avoid the short channel effect.
In this thesis, the surfce potential in the depltion region has
been calculated. And, a basis to decide the device parameter
has aslo been provided.
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