奈米尺寸金氧半場效電晶體通道逆向散射實驗與理論

Abstract

本篇論文介紹一個簡易的金氧半場效電晶體的通道逆向散射理論.這個創新的理論是利用散射係數來代替原本我們用遷移律代表的電流-電壓關係.對於長通道的電晶體,這麼模型可以簡化成我們所認知傳統的飄移-擴散理論,但是這個模型同樣也可以適用於跟平均自由路經相比擬的通道長度,甚至比平均自由路徑還短的通道一樣都可以適用. 基於這個理論,我們對於通道長度短到75nm的金氧半場效電晶體進行低溫(-40 oC to 25 oC)與高溫(25 oC to 75 oC)的實驗,也建立了一個通道逆向理論的溫度版本模型.我們可以藉此去粹取逆向散射的參數,這些參數是能夠被表達成包括通道長度與汲極電壓的相關方程式,同樣的也被發現此參數是與閘極電壓是幾乎無關的.這個結果找到了通道逆向散射理論架構的真正起源,而且對於要預測奈米尺寸級的金氧半場效電晶體的性能極限是相當有幫助的.同樣的,我們也跟之前已發表過的逆向散射係數做了比較.

A simple channel backscattering theory of the silicon MOSFET is introduced. Current–voltage (I-V) characteristics are expressed in terms of scattering parameters rather than mobility. For long-channel transistors, the results reduce to conventional drift-diffusion theory, but they do apply to devices in which the channel length is comparable to or even shorter than the mean-free-path. We perform temperature experiment (-40 oC to 25 oC and 25 oC to 75 oC) on MOSFETs down to 75-nm mask gate length and also build a temperature version of channel backscattering theory. In such way, we are able to extract backscattering parameter, which is expressed as a function of both gate length and drain voltage and is found to be independent of gate voltage. The resulting relation does find the origin in the framework of backscattering theory, and is very helpful in projecting performance limit of nanoscale MOSFETs. Comparisons with published values of backscattering coefficients are carried out as well.