Spectroscopic EUV metrology for nanoscale gratings

纳米级光栅的光谱 EUV 计量

• 批准号: 415848294
• 负责人: Professor Dr. Carlo Holly, since 7/2021
• 金额: --
• 依托单位: Lehrstuhl für Technologie optischer Systeme (TOS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/415848294?language=en
• 关键词: Spectroscopic; EUV; metrology; nanoscale; gratings

Constantly decreasing feature sizes in semiconductor manufacturing lead to increasing demands on the metrology used in the production process. The metrology of nanoscale grating structures for the determination of the critical dimension is one of the core tasks.Since currently used spectroscopic metrology methods using infrared, visible and ultraviolet light are reaching their limits with respect to the sensitivity to very small feature sizes, alternative metrology methods are being explored. Especially metrology methods using X-rays have been extensively tested over the last years. However, these do not provide sufficiently small measuring spots and demonstrate only limited throughput. Metrology methods in the EUV spectral range, on the other hand, have the potential to overcome the mentioned disadvantages. The applicability of EUV metrology as a metrology method for nanoscale gratings should therefore be theoretically and experimentally investigated within the planned project.Spectroscopic EUV reflectometry at grazing angles of incidence will be used to identify contrasts in EUV reflectance of nanoscale gratings of different geometries (line width, trapezoidal angle). For this purpose, theoretical investigations will be carried out by means of rigorous electromagnetic diffraction simulations. After that, the simulation results will be used to extract spectral ranges and illumination settings for which particularly high contrasts between gratings of different geometries are expected. Based on these results, a set of samples with relevant geometry variations will be fabricated. Subsequently, the EUV reflectance of the fabricated samples will be determined experimentally in the applicant’s existing experimental setup for spectroscopic EUV reflectometry. In a further step, the grating geometry parameters will be reconstructed from the experimentally acquired EUV reflectance values by an iterative fit of simulated reflectance values to the experimentally measured ones. Conclusively, the theoretical limits of EUV metrology for nanoscale gratings will be evaluated, taking into account real measurement uncertainties, and including spectral ranges and illumination settings that are not directly accessible in the experiment. Finally, a comparison to the already existing metrology methods will be made with respect to the applicability to future feature sizes in semiconductor manufacturing.A successful outcome of the project will show that EUV metrology has the necessary sensitivity even for the smallest semiconductor feature sizes. EUV metrology can thus become an integral part of quality assurance and process control in future semiconductor manufacturing.

半导体制造中特征尺寸的不断减小导致对生产过程中使用的计量的要求不断增加，用于确定关键尺寸的纳米级光栅结构的计量是核心任务之一。由于目前使用红外、可见光的光谱计量方法。和紫外光对于非常小的特征尺寸的敏感性已达到极限，人们正在探索替代的计量方法，特别是在过去几年中已经测试了使用 X 射线的计量方法，但是这些方法并不能提供足够小的测量点。和另一方面，EUV 光谱范围内的计量方法具有克服上述缺点的潜力，因此应在计划的项目中对 EUV 计量作为纳米级光栅计量方法的适用性进行研究。掠射角的光谱 EUV 反射率将用于识别不同几何形状（线宽、梯形角）的纳米级光栅的 EUV 反射率对比。为此，将通过严格的电磁衍射模拟进行理论研究，然后，根据这些结果，将使用模拟结果来提取不同几何形状的光栅之间预期特别高的对比度的光谱范围和照明设置。随后，将制造一组具有相关几何形状变化的样品，然后，将在申请人现有的光谱EUV反射测量装置中通过实验确定所制造的样品的EUV反射率。下一步，将通过模拟反射率值与实验测量值的迭代拟合，从实验获得的 EUV 反射率值重建光栅几何参数，最后，将评估纳米级光栅的 EUV 计量的理论极限。考虑到实际测量的不确定性，并包括实验中无法直接访问的光谱范围和照明设置，将与现有的计量方法对未来特征尺寸的适用性进行比较。该项目的成功结果将表明，即使对于最小的半导体特征尺寸，EUV 计量也具有必要的灵敏度，因此 EUV 计量可以成为未来半导体制造中质量保证和流程控制的一个组成部分。