Ohmi Hiromasa, Sato Jumpei, Shirasu Yoshiki, Hirano Tatsuya, Kakiuchi Hiroaki, Yasutake Kiyoshi
Department of Precision Science and Technology, Graduate School of Engineering and Research Center for Ultra-Precision Science and Technology, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
ACS Omega. 2019 Feb 27;4(2):4360-4366. doi: 10.1021/acsomega.8b03163. eCollection 2019 Feb 28.
The characteristics of copper (Cu) isotropic dry etching using a hydrogen-based plasma generated at 13.3 kPa (100 Torr) were improved dramatically by simply introducing a moderate amount of N gas into the process atmosphere. A maximum Cu etch rate of 2.4 μm/min was obtained by nitrogen addition at a H mixture ratio ( ) of 0.9 and an input power of 70 W. The etch rate for the optimally N-added plasma was 8 times higher than that for the pure H plasma. The Cu etch rate increased with increasing input power. The maximum etch rate reached 3.1 μm/min at an input power of 100 W and a of 0.9. The surface roughness of the etched copper decreased as a result of optimum N addition. Furthermore, N addition also improved the etch selectivity between Cu and SiO such that the selectivity ratio reached 190. Finally, selective etching of a trench-patterned Si wafer with an electroplated Cu layer was demonstrated.
通过在工艺气氛中简单引入适量的氮气，使用在13.3 kPa（100托）下产生的氢基等离子体进行铜（Cu）各向同性干法蚀刻的特性得到了显著改善。在氢气混合比（ ）为0.9且输入功率为70 W的条件下添加氮气，获得了2.4μm/min的最大铜蚀刻速率。最佳添加氮气的等离子体的蚀刻速率比纯氢等离子体的蚀刻速率高8倍。铜蚀刻速率随输入功率的增加而增加。在输入功率为100 W且 为0.9时，最大蚀刻速率达到3.1μm/min。由于最佳的氮气添加，蚀刻后的铜表面粗糙度降低。此外，添加氮气还提高了铜与二氧化硅之间的蚀刻选择性，使得选择性比达到190。最后，展示了对具有电镀铜层的沟槽图案化硅晶片的选择性蚀刻。
