Park Yoonsoo, Lim Hyuna, Kwon Sungyool, Kim Younghyun, Ban Wonjin, Jung Donggeun
Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Dielectric Deposition Product Division, Applied Materials Korea, Icheon 17379, Republic of Korea.
J Nanosci Nanotechnol. 2020 Nov 1;20(11):6706-6712. doi: 10.1166/jnn.2020.18785.
Low-dielectric-constant SiCOH films fabricated using plasma enhanced chemical vapor deposition (PECVD) are widely used as inter-metallic dielectric (IMD) layers in interconnects of semiconductor chips. In this work, SiCOH films were deposited with 1,1,1,3,5,7,7,7-octamethyl-3,5-bis(trimethylsiloxy)tetrasiloxane (OMBTSTS), and plasma treatment was performed by an inductively coupled plasma (ICP) system with mixture of He and H₂. The values of relative dielectric constant () of the as-deposited SiCOH films ranged from 2.64 to 4.19. The He/H₂ plasma treatment led to a reduction of the values of the SiCOH films from 2.64-4.19 to 2.07-3.94. To investigate the impacts of the He/H₂ plasma treatment on the SiCOH films, the chemical compositions and structures of the as-deposited and treated the SiCOH films were compared by Fourier transform infrared spectroscopy. The experimental results indicate that the value of the SiCOH films was decreased, there was a proportional increase in pore-related Si-O-Si structure, which is commonly called the cage structure with lager angle than 144°, after He/H₂ plasma treatment. The He/H₂ plasma treatment was considered to have reduced the value by forming pores that could be represented by the cage structure. On the other hand, the leakage current density of the SiCOH films was slightly degraded by He/H₂ plasma treatment, however, this was tolerable for IMD application. Concludingly the He/H₂ plasma treated SiCOH film has the lowest relative dielectric constant (~2.08) when the most highly hydrocarbon removal and cage structure formation increased.
采用等离子体增强化学气相沉积（PECVD）制备的低介电常数SiCOH薄膜被广泛用作半导体芯片互连中的金属间电介质（IMD）层。在这项工作中，使用1,1,1,3,5,7,7,7-八甲基-3,5-双（三甲基硅氧基）四硅氧烷（OMBTSTS）沉积SiCOH薄膜，并通过电感耦合等离子体（ICP）系统在He和H₂的混合气体中进行等离子体处理。沉积态SiCOH薄膜的相对介电常数（）值范围为2.64至4.19。He/H₂等离子体处理使SiCOH薄膜的 值从2.64 - 4.19降低至2.07 - 3.94。为了研究He/H₂等离子体处理对SiCOH薄膜的影响，通过傅里叶变换红外光谱比较了沉积态和处理后的SiCOH薄膜的化学成分和结构。实验结果表明，He/H₂等离子体处理后，SiCOH薄膜的 值降低，与孔隙相关的Si - O - Si结构（通常称为笼状结构，其角度大于144°）成比例增加。He/H₂等离子体处理被认为是通过形成可由笼状结构表示的孔隙来降低 值。另一方面，He/H₂等离子体处理使SiCOH薄膜的漏电流密度略有下降，然而，这对于IMD应用来说是可以接受的。结论是，当最高程度的碳氢化合物去除和笼状结构形成增加时，He/H₂等离子体处理的SiCOH薄膜具有最低的相对介电常数（约2.08）。
