电子束套刻精度量测中TIS的影响研究

Investigation of TIS Effect in the E-beam Overlay Measurement

  • 摘要: 随着半导体集成电路制造工艺的不断进步,图形尺寸逐渐缩小,器件结构日益复杂,这对光刻工艺中的套刻精度(overlay, OV)控制提出了更高要求。由于光学OV量测结果容易受到底层膜厚、薄膜特性及OV光栅对称性等因素的影响,先进制程逐渐引入电子束(electron beam, E-beam)OV量测作为补充手段。在光学OV量测中,机台误差(tool induced shift, TIS)作为一项关键指标,反映了光学系统对OV结果的影响,必须加以消除以确保量测结果的准确性。然而,针对E-beam OV量测中TIS影响的研究仍较为匮乏。本文针对E-beam OV量测,通过改变成像方式验证了TIS在E-beam OV量测中的存在,并进一步探讨了TIS与电子束扫描方式之间的关系。此外,还对不同层(layer)的TIS进行了验证。结合实际量测结果,本文提出了一种在E-beam OV量测中验证及消除TIS的操作方法,旨在提高量测结果的准确性。

     

    Abstract: With the ongoing progression of semiconductor integrated circuit manufacturing processes, the reduction in pattern dimensions and the growing complexity of device structures have imposed higher demands on OV control within lithography processes. Optical OV measurement results are vulnerable to influences from factors such as underlying film thickness, film characteristics, and OV grating symmetry. As a result, advanced manufacturing processes have increasingly adopted electron beam (E-beam) measurement as a complementary technique. In optical OV measurement, TIS serves as a crucial indicator that reflects the influence of the optical system on OV outcomes, necessitating correction to ensure measurement precision. Nevertheless, research on the impact of TIS in E-beam OV measurement remains scarce. This paper focuses on E-beam OV measurement and utilizes imaging mode variations to verify the presence of TIS effects in E-beam OV measurements. Additionally, the study explores the relationship between TIS effects and electron beam scanning techniques. Moreover, TIS is validated across different layers, and operational approaches are proposed to verify and mitigate TIS during E-beam OV measurement, with the objective of enhancing measurement accuracy.

     

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