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量测结果易受底层膜厚、薄膜特性以及OV光栅对称性等因素的影响,因此在先进制程中,电子束(E-beam)OV量测逐渐被引入作为补充手段。在光学OV量测中,机台诱发偏移(tool induced shift, TIS)是衡量光学系统对OV结果影响的关键指标,必须加以消除以确保量测结果的准确性。然而,目前针对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,通过改变成像方式来验证TIS在E-beam OV量测中的存在,并进一步探究TIS与E-beam扫描方式之间的关系。此外,我们还对不同层的TIS进行了验证。结合实际量测结果,提出一种在E-beam OV量测中验证并消除TIS的操作方法,以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 overlay (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 E-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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