Kim Doo San, Kim Ju Eun, Gill You Jung, Park Jin Woo, Jang Yun Jong, Kim Ye Eun, Choi Hyejin, Kwon Oik, Yeom Geun Young
School of Advanced Materials Science and Engineering, Sungkyunkwan University Suwon 16419 Republic of Korea
Process Development Team, Semiconductor R&D Center Samsung Electrics Co. Ltd Republic of Korea.
RSC Adv. 2020 Oct 1;10(59):36141-36146. doi: 10.1039/d0ra05321j. eCollection 2020 Sep 28.
Etch characteristics of ovonic threshold switch (OTS) materials composed of Ge-As-Te for a phase-change random access memory (PCRAM) has been investigated using reactive ion etching hydrogen-based gases such as H, CH, NH, CH + H, and CH + NH. Among the investigated hydrogen-based gases, NH showed the highest etching rate of about 0.52 nm s, but the formation of nitride compounds and the increased roughness were observed on the OTS surface by nitrogen. The use of other hydrogen-based gases such as CH and CH + H showed the deposition and low OTS etch rate, respectively, due to the presence of carbon in CH. Even though H showed the better etch characteristics due to the no surface residues or compounds on the OTS surface related to carbon or nitrogen in the etch gases, the best OTS etch characteristics such as the second highest etch rate of 0.45 nm s, the lowest surface roughness of 0.21 nm, and no surface residues or compounds were observed with CH + NH due to the removal of carbon and nitrogen on the surface by the formation of volatile CN compounds while maintaining a high hydrogen atomic concentration in the plasma.
利用反应离子蚀刻技术，研究了由锗-砷-碲组成的用于相变随机存取存储器（PCRAM）的硫系阈值开关（OTS）材料在诸如H、CH、NH、CH + H和CH + NH等基于氢的气体中的蚀刻特性。在所研究的基于氢的气体中，NH显示出最高的蚀刻速率，约为0.52 nm/s，但在OTS表面观察到氮化物化合物的形成以及粗糙度增加。由于CH中存在碳，使用其他基于氢的气体（如CH和CH + H）分别显示出沉积现象和较低的OTS蚀刻速率。尽管H由于蚀刻气体中与碳或氮相关的OTS表面无表面残留物或化合物而显示出较好的蚀刻特性，但由于通过形成挥发性CN化合物去除了表面的碳和氮，同时在等离子体中保持了高氢原子浓度，CH + NH显示出最佳的OTS蚀刻特性，如第二高的蚀刻速率0.45 nm/s、最低的表面粗糙度0.21 nm以及无表面残留物或化合物。
