An XAS study of P clustering in Si

Generating p- or n- type semiconductors through the introduction of either phosphorus (P) or boron (B) has underpinned the semiconductor industry for decades. As device scaling moves towards 3D structures, it is necessary to increase doping levels by 2 -3 orders of magnitude to several at.%. This comes with new material challenges as the spatial distribution of the dopants is unknown and can form clusters which influences their functional properties. Here we will use X-ray absorption spectroscopy recorded at the P K edge to probe the local atomic arrangement, clustering, and bonding around the P atoms in samples with 4 at. % doping. Data will be correlated with density function theory (which suggests clusters may form around vacancies) as well as resistivity measurements. The X-ray data will be compared with real space images determined from 3D atom probe and be used to benchmark that new metrology and its analysis protocols.

数十年来，通过掺入磷（P）或硼（B）制备p型与n型半导体，始终是半导体产业的核心支撑基础。随着器件微缩迈向三维结构，需将掺杂浓度提升2至3个数量级，直至数个原子百分比（at.%）。这一工艺升级带来了全新的材料挑战：掺杂剂的空间分布尚不明确，且可能形成团簇，进而影响其功能特性。本研究将采用磷K边（P K edge）的X射线吸收光谱（X-ray absorption spectroscopy），对掺杂浓度为4 at.%的样品中磷原子周围的局域原子排布、团簇状态与成键情况进行表征。上述光谱数据将与密度泛函理论（density function theory，该理论预测空位周围可形成团簇）的计算结果以及电阻率测量数据开展关联分析。该X射线光谱数据还将与三维原子探针（3D atom probe）获取的实空间图像进行对比，并用于对该新型计量技术及其分析流程进行性能基准测试。