Effects of UV-Curing Time on the Thin-Film and Mechanical Properties of Porous Dielectrics

• Main Authors: Kuo-En Yen, 顏國恩
• Other Authors: Tian-Shiang Yang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/52135454333447071959

碩士 === 國立成功大學 === 機械工程學系碩博士班 === 96 === Two materials are used to solve the RC delay issue in the multi-layer conducting line of integrated circuit (IC) devices. One is low-k dielectric material (for its low capacity), and the other is copper contact line (for its low resistitivity). However, as there will be residue stress due to the thermal expansion coefficient difference between the low-k dielectric and its adjacent material. Furthermore, as the low-k dielectric material generally has a loose structure, and hence a low mechanical yield strength, the IC device would be easily destroyed during subsequent processing or packaging. To alleviate the aforementioned problems, the brand new idea of ultraviolet (UV) curing process can be used for the processing of porous low-k dielectric materials. In this thesis, we discuss the effects of the UV curing time on the thin-film and mechanical properties of the low-k dielectric material SiOCH, which is typically used in nano-IC manufacturing. One of the major goals of this work is to systematically investigate the UV curing process applied on the SiOCH film, and to deduce optimized process parameters of the thin film processing. Specifically, the porous SiOCH thin film is deposited on a silicon substrate by a plasma enhanced chemical vapor deposition (PECVD) system. The bonding structure of the SiOCH film then is characterized by Fourier transform infrared spectropy (FTIR). The dielectric constant and current leakage are examined by the metal-insulator-semiconductor (MIS) structure. The residual stress is calculated by the Stoney’s equation. The FTIR results show that the peak ratios of CHx/Si-O and Si-CH3/Si-O decrease with increasing UV curing time. Also, the size of the porous structure increases with the time of the UV curing process. The residual stress and hardness of the film increase with the the UV curing time as well. It is also found that the dielectric constant decreases drastically with the the UV curing time at first, but then increases for longer curing time. The findings of this work can be used to determine the optimal UV curing time that produces the best compromise between thin film hardness and residual stress.