Messinis Christos, van Schaijk Theodorus T M, Pandey Nitesh, Tenner Vasco T, Witte Stefan, de Boer Johannes F, den Boef Arie
Opt Express. 2020 Dec 7;28(25):37419-37435. doi: 10.1364/OE.413020.
In semiconductor device manufacturing, optical overlay metrology measures pattern placement between two layers in a chip with sub-nm precision. Continuous improvements in overlay metrology are needed to keep up with shrinking device dimensions in modern chips. We present first overlay metrology results using a novel off-axis dark-field digital holographic microscopy concept that acquires multiple holograms in parallel by angular multiplexing. We show that this concept reduces the impact of source intensity fluctuations on the noise in the measured overlay. With our setup we achieved an overlay reproducibility of 0.13 nm and measurements on overlay targets with known programmed overlay values showed good linearity of R= 0.9993. Our data show potential for significant improvement and that digital holographic microscopy is a promising technique for future overlay metrology tools.
在半导体器件制造中，光学对准计量可精确到亚纳米级别来测量芯片中两层之间的图案对准情况。随着现代芯片器件尺寸不断缩小，需要持续改进对准计量技术。我们展示了首次使用一种新型离轴暗场数字全息显微镜概念得到的对准计量结果，该概念通过角度复用并行采集多个全息图。我们表明，这一概念降低了光源强度波动对测量对准中噪声的影响。利用我们的装置，实现了0.13纳米的对准重复性，对具有已知编程对准值的对准目标进行测量显示出良好的线性，R = 0.9993。我们的数据表明有显著改进的潜力，并且数字全息显微镜是未来对准计量工具的一种很有前景的技术。
