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arXiv 2310.14815cs.CVeess.IV

深度学习降噪器辅助从低信噪比(SNR)SEM图像中提取薄光刻胶粗糙度测量:基于SMILE的分析

Deep learning denoiser assisted roughness measurements extraction from thin resists with low Signal-to-Noise Ratio(SNR) SEM images: analysis with SMILE

imec(比利时微电子研究中心);University of Bologna(博洛尼亚大学);Paul Scherrer Institut(保罗·谢尔研究所)

Sara Sacchi, Bappaditya Dey, Iacopo Mochi, Sandip Halder, Philippe Leray

AI总结:

本研究提出利用深度学习降噪器提升薄光刻胶低信噪比SEM图像质量,结合SMILE软件分析表明,该方法能在低帧数下保持关键尺寸并准确测量粗糙度,有效提高量测吞吐量。

摘要:

高数值孔径极紫外光刻(High NA EUVL)的技术进步开启了对更薄光刻胶(低于30nm)的广泛研究,这是实现High NA EUVL工业化应用的必要条件。因此,扫描电子显微镜(SEM)图像面临成像对比度降低和低信噪比(SNR)的问题,影响了无偏线边缘粗糙度(uLER)和线宽粗糙度(uLWR)的测量。本工作旨在利用深度学习降噪器提升SEM图像的SNR,实现薄光刻胶的稳健粗糙度提取。本研究采集了线-空间(L/S)图案的SEM图像,采用不同厚度(15nm、20nm、25nm、30nm)、底层(旋涂玻璃-SOG、有机底层-OUL)和平均帧数(4、8、16、32和64 Fr)的化学放大型光刻胶(CAR)。降噪后,使用开源量测软件SMILE 2.3.2对含噪和降噪图像进行系统分析,研究平均CD、SNR改善因子、有偏和无偏LWR/LER功率谱密度(PSD)。帧数较少的降噪图像保持了未改变的关键尺寸(CD),提升了SNR(尤其在低积分帧数时),并能精确测量uLER和uLWR,其精度与具有持续更高帧数的含噪图像相同。因此,积分帧数少且SNR < 2的图像可被成功降噪,在保持薄光刻胶可靠粗糙度测量的同时,有利于提高量测吞吐量。

英文摘要:

The technological advance of High Numerical Aperture Extreme Ultraviolet Lithography (High NA EUVL) has opened the gates to extensive researches on thinner photoresists (below 30nm), necessary for the industrial implementation of High NA EUVL. Consequently, images from Scanning Electron Microscopy (SEM) suffer from reduced imaging contrast and low Signal-to-Noise Ratio (SNR), impacting the measurement of unbiased Line Edge Roughness (uLER) and Line Width Roughness (uLWR). Thus, the aim of this work is to enhance the SNR of SEM images by using a Deep Learning denoiser and enable robust roughness extraction of the thin resist. For this study, we acquired SEM images of Line-Space (L/S) patterns with a Chemically Amplified Resist (CAR) with different thicknesses (15nm, 20nm, 25nm, 30nm), underlayers (Spin-On-Glass-SOG, Organic Underlayer-OUL) and frames of averaging (4, 8, 16, 32, and 64 Fr). After denoising, a systematic analysis has been carried out on both noisy and denoised images using an open-source metrology software, SMILE 2.3.2, for investigating mean CD, SNR improvement factor, biased and unbiased LWR/LER Power Spectral Density (PSD). Denoised images with lower number of frames present unaltered Critical Dimensions (CDs), enhanced SNR (especially for low number of integration frames), and accurate measurements of uLER and uLWR, with the same accuracy as for noisy images with a consistent higher number of frames. Therefore, images with a small number of integration frames and with SNR < 2 can be successfully denoised, and advantageously used in improving metrology throughput while maintaining reliable roughness measurements for the thin resist.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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