Nano-scale gap filling and mechanism of deposit-etch-deposit process for phase-change material

• Published in: Chinese physics B 2012-11, Vol.21 (11), p.335-339
• Main Author: 任万春 刘波 宋志棠 向阳辉 王宗涛 张北超 封松林
• Format: Article
• Language: English
• Subjects: Argon; Deposition; Devices; Etching; Gain; Ge2Sb2Te5; Nanostructure; Physical vapor deposition; Random access memory; 填充; 存款; 物理气相沉积; 相变材料; 纳米级; 蚀刻; 间隙
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/21/11/115203

Ge2Sb2Te5 gap filling is one of the key processes for phase-change random access memory manufacture. Physical vapor deposition is the mainstream method of Ge2Sb2Te5 film deposition due to its advantages of film quality, purity, and accurate composition control. However,the conventional physical vapor deposition process cannot meet the gap- filling requirement with the critical device dimension scaling down to 90 nm or below. In this study, we find that the deposit-etch-deposit process shows better gap-filling capability and scalability than the single-step deposition process, especially at the nano-scale critical dimension. The gap-filling mechanism of the deposit-etch-deposit process was briefly discussed. We also find that re-deposition of phase-change material from via the sidewall to via the bottom by argon ion bombardment during the etch step was a key ingredient for the final good gap filling. We achieve void-free gap filling of phase-change material on the 45-nm via the two-cycle deposit-etch-deposit process. We gain a rather comprehensive insight into the mechanism of deposit-etch-deposit process and propose a potential gap-filling solution for over 45-nm technology nodes for phase-change random access memory.