探討奈米級場效電晶體之遠距庫倫效應

Abstract

由近年研究可得知，元件尺寸縮減時電子遷移率會伴隨遞減，這也指出了有額外的碰撞機制存在，並且此機制會對下一世代的元件造成很大的影響。日前我們透過實驗探討遠距庫倫效應是由於在長通道場效電晶體內多晶矽閘極裡的電漿電子造成。而在本篇論文，我們進一步探討在高濃度的源極與汲極的電漿電子所造成的遠距庫倫散射機制所造成的影響。我們使用的量測的元件為在同一製程下做出的不同尺寸元件，其中並包含了短通道長度為33奈米的元件。研究方法主要藉由一系列有系統的實驗與二維模擬器的搭配，並根據馬西森定則去萃取造成短通道電子遷移率下降的額外散射機制。由溫度效應去探討Ｎ型超短通道場效電晶體下的散射機制。最後根據其溫度效應我們認為源極與汲極的電漿電子造成的影響，會隨著通道長度的減短而增加。此外我們也提供了另一項證據，我們在大的汲極電壓下量測到的轉導值與文獻中考慮遠距庫倫效應下的模擬值相符。

Electron mobility degradation is currently frequently encountered in highly scaled devices. This means that additional scattering mechanisms exist and will become profoundly important in the next-generation of devices. We have recently experimentally probed long-range Coulomb interactions due to plasmons in polysilicon gate of long-channel (1 m) MOSFETs. In this paper, we further probe those due to plasmons in the highly-doped source and drain. Test vehicles include four more samples from the same manufacturing process but with small channel lengths (down to 33 nm). I-V’s of devices are measured at two drain voltages of 0.05 and 1 V, in a temperature range of 292 to 380 K. Inverse modeling technique is applied to furnish calibrated doping profiles. The inversion-layer electron effective mobility is thereby extracted, showing a decreasing trend with decreasing channel length. Such differences reflect more additional scatterers in the shorter devices. Mobility components limited by these additional scatterers are assessed using Matthiessen’s rule. Extracted temperature dependencies reveal that the strength of source/drain plasmons increases with decreasing channel length. Corroborative evidence is given as well.