Effect of Channel Dopant Profile on Difference in Threshold Voltage Variability Between NFETs and PFETs
Effect of Channel Dopant Profile on Difference in Threshold Voltage Variability Between NFETs and PFETs
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沟道掺杂剂分布对 NFET 和 PFET 之间阈值电压变化差异的影响
DOI：
10.1109/ted.2010.2091452
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发表时间：
2011
影响因子：
3.1
通讯作者：
T. Hiramoto
中科院分区：
文献类型：
--
作者：
T. Tsunomura;A. Nishida;T. Hiramoto
从沟道掺杂剂分布的角度研究了n型和p型场效应晶体管（NFET和PFFET）之间阈值电压VT变化差异背后的机制。首先，通过比较具有不同深度沟道剖面的FET之间的VT变化来研究深度剖面的影响。澄清了NFET的VT变化性大于具有类似深度剖面的PFFET。横向通道轮廓的效果也检查。作为横向沟道轮廓调制的原因之一，晕注入的效果进行了评估。证实了晕圈注入增强了VT变异性。然而，即使没有晕注入，NFET的VT变异性仍然大于PFFET。在没有晕注的情况下，NFET出现了反向短沟道效应，而PFFET没有。从这个结果中，我们发现，横向沟道轮廓的不均匀性出现在NFET，即使没有晕注入，因为瞬态增强扩散（TED）的沟道掺杂剂的硼在NFET。由于在PFFET中使用不显示TED特性的砷或磷作为沟道掺杂剂，所以在没有晕注入的PFFET中不会出现横向沟道轮廓不均匀性。沟道轮廓的不均匀性，这是由硼TED，被认为是NFET和PFFET之间的VT可变性差异的起源。
The mechanism behind the threshold voltage VT variability difference between n- and p-type field-effect transistors (NFETs and PFETs, respectively) is investigated from the viewpoint of the channel dopant profile. First, the effect of the depth profile is investigated by comparing the VT variability among FETs with various depth channel profiles. It is clarified that the VT variability of NFETs is larger than that of PFETs with similar depth profiles. The effect of the lateral channel profile is also examined. As one of the causes of the modulation of the lateral channel profile, the effect of halo implantation is evaluated. It is confirmed that VT variability is enhanced with halo implantation. However, the VT variability of NFETs is still larger than that of PFETs even without halo implantation. Without halo implantation, the reverse short-channel effect appears in NFETs but not in PFETs. From this result, we find that lateral channel profile nonuniformity appears in NFETs even without halo implantation because of the transient-enhanced diffusion (TED) of the channel dopant of boron in NFETs. Since arsenic or phosphorus, which shows no TED characteristic, is used as the channel dopant in PFETs, lateral channel profile nonuniformity does not appear in PFETs without halo implantation. Channel profile nonuniformity, which is caused by boron TED, is thought to be the origin of the VT variability difference between NFETs and PFETs.