• 硅中硼注入深度剖面浓度标准样片的研制

    Development of standard reference wafers for boron-implanted depth profiles in silicon

    • 针对半导体掺杂浓度及深度分布测量设备二次离子质谱(Secondary Ion Mass Spectrometry,SIMS) 比对或校准用硅中硼注入深度剖面浓度标准样片的准确定值及纵向、横向均匀性需求,本文在倾斜注入的基础上,提出了基于Ar+预非晶化的双离子注入和基于非晶硅(α-Si)注入的两种制备方法,以抑制离子注入过程中的沟道效应,改善注入深度、均匀性及重复性难以控制的问题。采用SIMS对两种方法制备的标准样片中注入目标元素的纵向分布及11B/10B元素含量比例进行分析,并进一步利用中子深度剖面法(Neutron Depth Profiling, NDP)对目标元素含量进行定值及片内均匀性评估。结果表明,相较于基于Ar+预非晶化的双离子注入法,基于非晶硅注入法制备的标准样片在注入目标元素的纵向分布和横向均匀性方面均表现更优。同时,该法制备的样片定值结果与预设值吻合良好,其纵向分布曲线与美国国家标准与技术研究院(National Institute of Standards and Technology,NIST)的SRM2137标准物质基本重合,整体性能达到SRM2137的技术水平。

       

      Abstract: To fulfill the requirements for accurate quantification and both longitudinal and lateral uniformity of boron-implanted depth-profile concentration reference materials in silicon, intended for the comparison and calibration of secondary ion mass spectrometry (SIMS) instruments, this paper proposes, on the basis of tilted implantation, two fabrication approaches: dual-ion implantation with Ar+ pre-amorphization and implantation into amorphous silicon (α-Si). These methods are devised to suppress channeling effects during ion implantation, thereby overcoming the difficulties in controlling implantation depth, uniformity, and reproducibility. The longitudinal distributions of the implanted target elements and the 11B/10B isotopic ratios in the reference materials prepared by the two methods are characterized using SIMS. Furthermore, neutron depth profiling (NDP) is employed for the quantitative assignment of target element concentrations and the assessment of intra-wafer uniformity. The results indicate that the reference materials fabricated by the α-Si implantation method exhibit superior longitudinal distribution and better lateral uniformity compared to those prepared by the Ar+ pre-amorphization dual-ion implantation approach. Moreover, the assigned concentration values of the α-Si-implanted samples are in excellent agreement with the preset values, and their longitudinal distribution curves substantially overlap with those of the National Institute of Standards and Technology (NIST) SRM 2137 reference material, demonstrating that the overall performance reaches the technical level of SRM 2137.

       

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