Kim Sungtae, Jeong Min-Woo, Kim Kuntae, Kim Ung-Gi, Kim Miyoung, Lee So-Yeon, Joo Young-Chang
Department of Materials Science & Engineering, Seoul National University 1, Gwanak-ro Gwanak-gu Seoul 08826 Republic of Korea
Memory Thin Film Technology Team Giheung Hwaseong Complex, Samsung Electronics, 1, Samsungjeonja-ro Hwaseong-si Gyeonggi-do 18448 Republic of Korea.
RSC Adv. 2023 Jan 12;13(3):2131-2139. doi: 10.1039/d2ra06808g. eCollection 2023 Jan 6.
The importance of developing a hardmask with excellent performance, and physical and chemical properties to utilize in long-term etching is spotlighted due to the acceleration of development in high-density semiconductors. To develop such a hardmask, amorphous carbon hardmasks doped with various concentrations of N were fabricated with a DC magnetron sputtering system using varying inert gas (Ar to N) ratios. In contrast to the expectation that doped nitrogen would block the permeation of fluorine and improve the etch resistance, as the nitrogen concentration increased, the selectivity of the doped amorphous carbon films decreased. To understand this degradation with increasing nitrogen concentration, systematic X-ray photoelectron spectroscopy (XPS), radial distribution function (RDF), and X-ray reflectometry (XRR) analyses were conducted. In this study, we found that as the amount of nitrogen increased, the density of the film decreased, and the amount of pyridinic and pyrrolic nitrogen bonds with low formation energy increased. In contrast, based on time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis of etched nitrogen-doped amorphous carbon films, the penetration depth of fluorine ions from the etchant decreased as the amount of nitrogen increased. Therefore, in order to develop an excellent hardmask using amorphous carbon, it is important to increase the density of the film and the nitrogen concentration in the film while lowering the ratio of pyrrolic N to pyridinic N, , increasing the ratio of graphitic N.
随着高密度半导体开发的加速，开发一种具有优异性能以及物理和化学性质、可用于长期蚀刻的硬掩膜的重要性受到关注。为了开发这样一种硬掩膜，使用直流磁控溅射系统，通过改变惰性气体（氩气与氮气）的比例，制备了掺杂不同浓度氮的非晶碳硬掩膜。与掺杂氮会阻止氟渗透并提高抗蚀刻性的预期相反，随着氮浓度的增加，掺杂非晶碳膜的选择性降低。为了理解随着氮浓度增加而出现的这种降解现象，进行了系统的X射线光电子能谱（XPS）、径向分布函数（RDF）和X射线反射率（XRR）分析。在本研究中，我们发现随着氮含量的增加，薄膜的密度降低，具有低形成能的吡啶型和吡咯型氮键的数量增加。相反，基于对蚀刻后的氮掺杂非晶碳膜的飞行时间二次离子质谱（TOF-SIMS）分析，随着氮含量的增加，蚀刻剂中氟离子的渗透深度降低。因此，为了使用非晶碳开发出优异的硬掩膜，提高薄膜的密度和薄膜中的氮浓度，同时降低吡咯型氮与吡啶型氮的比例，增加石墨型氮的比例是很重要的。
