Dynamics of Point Defect/Impurity Interactions and Clustering Due to Ion Implantation and Thermal Annealing

离子注入和热退火引起的点缺陷/杂质相互作用和团簇的动力学

• 批准号: 0075723
• 负责人: George Rozgonyi
• 金额: $ 44.88万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-05-01 至 2004-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0075723&HistoricalAwards=false
• 关键词: Dynamics; Point; Defect; Impurity; Interactions

The aim of this project is to achieve greater understanding of damage in crystalline silicon caused by energetic low and medium mass ion implantation, and to conduct a survey study of similar effects in GaN and SiC. Prior research established that most of the point defects remaining after implantation are trapped in defect cluster/disorder regions. The clusters subsequently re-emit point defects during an-nealing, producing a spectrum of stable defect complexes. It was also shown that the defect cluster dis-tribution after both 80 K and room temperature implantation produces, in addition to the expected in-terstitial dislocation layer near the projective range, Rp, and a vacancy-rich defect band between the surface and Rp (called the Rp/2 layer), another defect layer of unknown origin at depths of 2 to 3 times Rp. An understanding of the physics responsible for this behavior impacts the performance achievable from ultra-shallow pn junctions, and the correct modeling of post-implantation annealing defect dy-namics which are operative in impurity gettering and transient enhanced diffusion phenomena. In addi-tion to providing new fundamental data on processes in crystals with point defect supersaturations, this project seeks options for control/suppression of these phenomena, particularly during the implantation itself. The general approach is to study defect accumulation and evolution within individual collision cascades using very low fluence MeV ions over a wide temperature range starting from ~ 80 K. The negligible cascade overlap for such implants isolates intrinsic intra-cascade point defect processes. The use of sensitive in-situ electrical measurements, together with a broad and complementary set of diag-nostic techniques allows characterization of a spectrum of defect types. Rutherford Backscattering Spectroscopy (RBS) and bevel-polish/etching will provide total damage data, while two-detector coin-cidence Positron Annihilation Spectroscopy (PAS) will provide vacancy/impurity identification. Deep level transient spectroscopy (DLTS) and electron beam induced current (EBIC) techniques will be used to identify centers with "native" electrical activity, as well as those with the electrical activity "in-duced" by trapping of hydrogen or diffusing metal impurities. Underlying these point defect/impurity phenomena are fundamental issues related to the release, diffusion, and capture stages of gettering and near-surface dopant diffusion. Specific objectives of the research are to: understand structural, chemi-cal, and electrical properties of the defect clusters formed in Si crystals due to implantation with low and medium mass ions; specifically examine the physical properties of cluster thermal stability, its ability to emit mobile point defects, which enable the formation of stable complexes during annealing; understand the nature of defects formed above(RP/2) and below(2RP) the projected range region and determine their impact on dopant/impurity redistribution and gettering; explore photon/electric field procedures which enable control of implant defect cluster properties and distribution in order to create defect engineering options.%%%The project addresses basic research issues in a topical area of materials science with high technologi-cal relevance. Advanced implantation and characterization techniques allow greater understanding and control of elementary processes which will allow advances in fundamental materials science and tech-nology. The basic knowledge and understanding gained from the research is expected to contribute to improving the ability to achieve doping with high residual crystal quality for electronic and photonic applications. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area.***

该项目的目的是为了更好地了解高能中、低质量离子注入对晶体硅的损伤，并对GaN和SiC中的类似效应进行调查研究。先前的研究表明，植入后残留的大多数点缺陷都被困在缺陷簇/无序区。这些团簇随后在退火过程中重新发射点缺陷，产生稳定缺陷复合物的光谱。80k和室温注入后的缺陷团簇分布，除了在投影范围Rp附近形成预期的腔内位错层外，在表面和Rp之间形成一个富含空位的缺陷带（称为Rp/2层），在深度为2 ~ 3倍Rp处形成另一个未知来源的缺陷层。对这种行为的物理理解影响了超浅pn结的性能，以及对杂质捕集和瞬态增强扩散现象的植入后退火缺陷动力学的正确建模。除了提供点缺陷过饱和晶体过程的新基础数据外，该项目还寻求控制/抑制这些现象的选择，特别是在植入过程中。一般的方法是在~ 80k的宽温度范围内，使用极低通量的MeV离子研究单个碰撞级联中的缺陷积累和演化。这种植入物的可忽略的级联重叠分离了固有的级联内点缺陷过程。使用敏感的原位电测量，加上广泛和互补的诊断技术，可以对缺陷类型的光谱进行表征。卢瑟福后向散射光谱（RBS）和斜面抛光/蚀刻将提供总损伤数据，而双探测器巧合正电子湮灭光谱（PAS）将提供空位/杂质识别。深层瞬态光谱（DLTS）和电子束感应电流（EBIC）技术将用于识别具有“原生”电活动的中心，以及由氢捕获或扩散金属杂质“诱导”的电活动的中心。这些点缺陷/杂质现象背后的基本问题与捕集和近表面掺杂扩散的释放、扩散和捕获阶段有关。该研究的具体目标是：了解由于注入低质量和中等质量离子而在Si晶体中形成的缺陷团簇的结构、化学和电学性质；具体考察了团簇热稳定性的物理性质，其发射移动点缺陷的能力，使其能够在退火过程中形成稳定的配合物；了解在投影范围区域（RP/2）以上和（2RP）以下形成的缺陷的性质，并确定它们对掺杂/杂质再分布和捕集的影响；探索光子/电场程序，以控制植入体缺陷簇的性质和分布，从而创建缺陷工程选项。该项目涉及与高技术相关的材料科学主题领域的基础研究问题。先进的植入和表征技术允许更好地理解和控制基本过程，这将允许基础材料科学和技术的进步。从研究中获得的基本知识和理解有望有助于提高在电子和光子应用中实现高残留晶体质量掺杂的能力。该计划的一个重要特点是通过在基础和技术重要领域培养学生，将研究和教育相结合