镧系元素掺杂二氧化铪和超薄二氧化铪的总剂量效应研究

Ultrathin HfO2 dielectrics (2 - 4nm) have been used for gate insulators and dynamic random access memory (DRAM) in 45nm node. And, its higher dielectric constant (k> 32) can be reached by lanthanide doping (such as La or Ce doping) for next generation CMOS and DRAM technologies. Previous work has focused on irradiated HfO2 thin films at least 4nm thick, but little was known about the radiation response and long-term reliability of lanthanide doped HfO2 and ultrathin HfO2 gate dielectrics. The objectives of this project are to investigate their radiation response and radiation damage mechanisms under and post X-ray or gamma ray irradiation, including (1) characterizing the buildup and annealing of radiation-induced traps and charges by using pulsed C-V, pulsed I-V, and pulsed on-the-fly measurements under and post X-ray or gamma ray irradiation; (2) investigating the effect of growth conditions and annealing conditions of lanthanide doped HfO2 thin films on their radiation hardness; (3) investigating the effect of crystal grain size of the monoclinic, tetragonal or cubic phases of lanthanide doped HfO2 thin films on gate leakage current, hole trapping and detrapping, hydrogen release and transport during and post irradiation; (4) investigating the mechanisms of radiation-induced leakage current and breakdown of ultrathin HfO2 dielectrics; (5) investigating the relationship between the as-grown electron traps/oxygen vacancies and radiation-induced traps/charges.

超薄二氧化铪(2 至4 纳米)已用于45 纳米工艺中。镧系元素掺杂的二氧化铪具有更高的介电常数(k>32)，因此可用于下一代的CMOS 和DRAM 工艺中。过去的工作主要集中在辐射过后的较厚的二氧化铪薄膜(>4 纳米)上，少有超薄二氧化铪和镧系元素掺杂二氧化铪栅介质的辐射响应和长期可靠性的报道。本研究的目标是要调查在X-射线或伽玛射线辐射期间和辐射过后，这些介质的辐射响应和损伤机理，包括：1、利用脉冲电容-电压、脉冲电流-电压和脉冲on-the-fly 技术，来分析辐射诱生的陷阱/电荷的产生和恢复；2、通过优化这些介质的生长条件和退火条件，来研究它们的抗辐射加固工艺；3、研究镧系元素掺杂氧化铪中单斜、立方体和四面体晶相的晶粒尺寸，对栅漏电流、空穴的陷落和去陷落、氢的释放和传输等的影响；4、研究超薄氧化铪中辐射诱发的漏电流和击穿；5、研究原生电子陷阱和氧空位与辐射诱生的陷阱和电荷的关系。

本项目研究了在伽玛射线辐射期间和辐射过后，高介电常数介质（如HfO2、ZrO2、HfZrOx、LaAlO3、NdAlO3、LaZrOx、HfTiO2等）的辐射响应和损伤机理，包括：.1、报道了辐射条件下的脉冲电容-电压、脉冲电流-电压和脉冲on-the-fly 技术，并用该技术表征了辐射期间和辐射过后这些高介电常数介质（简称高k介质）中缺陷的产生和退火；.2、通过优化这些介质的生长条件和退火条件，研究了这些高k 介绍的抗辐射加固工艺；.3、辐射条件下随着Zr组分的增加，HfxZr1−xOy氧化物中辐射诱发的漏电流增加；.4、实验数据显示原生电子陷阱和氧空位对辐射响应的影响取决于辐射期间所施加的偏置条件；.5、研究了高k介质结构，对界面态产生、空穴的陷落和去陷落、平带电压漂移等的影响。