Kim Kwang Pyo, Song Wan Soo, Park Min Kyu, Hong Sang Jeen
Department of Electronics Engineering, Myong-ji University, Yongin, 17058, South Korea.
J Nanosci Nanotechnol. 2021 Mar 1;21(3):2032-2038. doi: 10.1166/jnn.2021.18919.
When the aspect ratio of a high aspect ratio (HAR) etching process is greatly increased, an amorphous carbon layer (ACL) hard mask is required for dynamic random-access memory (DRAM). To improve the durability of an etch hard mask, an understanding of the plasma deposition mechanisms and the deposited film properties associated with the plasma conditions and atomic structure, respectively, is required. We performed a series of plasma depositions, material characterizations and dry-etching to investigate the effect of the deposition process condition on the surface characteristics of an ACL film to be used as a dry etch hard mask in an HAR etch process. We found that a lower chamber pressure at a higher temperature for the plasma deposition process yielded higher film hardness, and this infers that higher plasma ion energy in lower pressure regions helps to remove hydrogen atoms from the surface by increased ion bombardment. It was postulated that a higher substrate temperature gears the bake-out of hydrogen or hydroxide contaminants. From the results of inductively coupled plasma-reactive ion etching of the deposited ACL film, we observed that the etch selectivity over the silicon dioxide film was improved as C═C ₂ and C-C ₃ bonds increased.
当高深宽比（HAR）蚀刻工艺的宽高比大幅增加时，动态随机存取存储器（DRAM）需要非晶碳层（ACL）硬掩膜。为提高蚀刻硬掩膜的耐久性，分别需要了解与等离子体条件和原子结构相关的等离子体沉积机制及沉积膜特性。我们进行了一系列等离子体沉积、材料表征和干法蚀刻，以研究沉积工艺条件对用作HAR蚀刻工艺中干法蚀刻硬掩膜的ACL膜表面特性的影响。我们发现，等离子体沉积过程中在较高温度下采用较低的腔室压力可产生更高的膜硬度，这意味着在较低压力区域较高的等离子体离子能量有助于通过增加离子轰击从表面去除氢原子。据推测，较高的衬底温度有助于氢或氢氧化物污染物的烘烤去除。从对沉积的ACL膜进行电感耦合等离子体反应离子蚀刻的结果来看，我们观察到随着C═C₂和C-C₃键增加，对二氧化硅膜的蚀刻选择性得到改善。
