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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 lithography with high numerical aperture and low process factor, the influence of projection lens coma aberration on lithography quality becomes more and more prominent, so a fast and accurate coma aberration measurement technique is needed. Therefore, a new coma aberration measurement technique based on two-line space image linewidth asymmetry is proposed. The accuracy of this method is simulated and analyzed by the internationally recognized lithography simulation software PROLITH of the semiconductor industry. The results show that compared with the coma aberration measurement method based on wafer exposure, the speed advantage of space-based coma measurement technology is obvious. The measurement accuracy is better than 1.4 nm, which is more than 30% higher than that of the international advanced multi-illumination space imaging technology (TAMIS) and the measurement speed is increased by about 1/3. The coma aberration of the projection objective was measured many times on ASML PAS5500 step scanning projection lithography machine. The result shows that the measurement repeatability is better than 1.2 nm, and the in-situ measurement of coma aberration can be realized with high accuracy.