在高数值孔径、低工艺因子的光刻技术中,投影物镜彗差对光刻质量的影响变得越来越突出,因而需要一种快速、高精度的彗差原位测量技术。为此提出了一种新的基于双线空间像线宽不对称度的彗差测量技术,利用国际上公认的半导体行业光刻仿真软件PROLITH对该方法的测量精度进行了仿真分析。结果表明,与基于硅片曝光的彗差测量方法相比,基于空间像的彗差测量技术速度上的优势十分明显。其测量精度优于1.4 nm,较国际前沿的多照明设置空间像测量技术(TAMIS)提高30％以上,测量速度提高1/3左右。在ASML公司的PAS5500型步进扫描投影光刻机上,多次测量了投影物镜彗差,结果表明,该技术测量重复精度优于1.2 nm,能实现高精度的彗差原位测量。

In high numerical aperture and low technic factor lithography process, degradation of the image quality because of the coma aberration in the projection lens has become a serious problem. Fast and accurate on-site measurement of coma aberration is required. A novel on-site coma measurement technique based on linewidth asymmetry of the aerial image is proposed. Compared with the resist-based coma measurement techniques, the technique based on the aerial image possess the advantage of time-saving. The simulation results of PROLITH show that the measurement accuracy of the technique is better than 1.4 nm. The accuracy increases approximately 30 percent and 1/3 measuring time is saved compared with the TAMIS technique. Using the technique, the coma of the projection lens on PAS5500 scanner of ASML is measured. The experiment shows that the reproducibility of the coma measurement is better than 1.2 nm, and this technique can meet the requirement of the high-accuracy coma measurement.