标题: 金氧半场效应电晶体在次临界区的不匹配效应
Mismatch of MOSFETs in Subthreshold Region
作者: 蔡浚泽
陈明哲
电子研究所
关键字: 不匹配;次临界;随机掺杂;Mismatch;Subthreshold;Random dopant
公开日期: 2010
摘要: 本论文研究随机掺杂物以及电路的不匹配效应对于临界电压扰动的影响与其物理模型。首先,我们量测各种不同尺寸的电晶体,并观察到在次临界区存在比过临界区更大的电特性误差。接着我们萃取出许不同的制程参数,并且建立一个有关通道掺杂浓度变异的新模型来解释临界电压随着闸极长度的缩短而上升。同时我们发现到萃取出的临界电压变动值会与元件面积平方根的倒数成正比,这与前人所提出的理论符合。我们也发现背闸顺向偏压可以减少制程参数变动值并可用来补偿小尺寸电晶体较大的参数变动值。
接着我们特别着重在进一步探讨临界电压的扰动特性。过程中我们观察到在不同的汲极电压下,所造成的临界电压的差异,此时因电子的能阶产生变化,而会导致元件的控制力有所升降。再来我们利用Takeuchi的模型做比对,并考虑到随机掺杂以及硼簇合族对于临界电压扰动的影响。从我们分析的结果看来,随机掺杂对于临界电压扰动的影响会因为硼簇合族的原子个数上升而更加明显。在最后,我们推导出一个在次临界区中,与汲极电流误差相关的新的临界电压扰动模型,并且此模型能经由电流误差成功的估计临界电压的扰动值。
The physical model of the threshold voltage fluctuation from random dopant, as well as current mismatch, is investigated in the thesis. At first we have extensively characterize MOSFETs with different gate widths and lengths, especially in subthreshold region of operation. We observe that the mismatch exhibits a larger mismatch while operating in subthreshold region than in above-threshold region. We extract various process parameters and hence construct a new model due to varying of channel doping to explain the threshold voltage increase with gate length decrease. The threshold voltage variations are shown to follow the inverse square rule. Simultaneously, the back-gate forward bias is found to be able to reduce the mismatch and compensate for larger variations for smaller devices.
Further, we pay more attention to the threshold voltage fluctuation, and observe that the drain voltage might cause the DIBL. Then we discuss the threshold voltage fluctuation by a Takeuchi plot, and the effect of random dopant and the boron clusters are taken into account. From our analysis, the random dopant induced threshold voltage fluctuation has more significant effect on threshold variation while the number of boron atoms per cluster increases. Finally, we also statistically derive a new model that can estimate the threshold voltage fluctuation from drain current mismatch in subthreshold region. The validity of the model is verified.
URI: http://140.113.39.130/cdrfb3/record/nctu/#GT079711573
http://hdl.handle.net/11536/44275
显示于类别:Thesis


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