Fluorinated nanoporous SiO2 films with ultra-low dielectric constant

Properties of Liquid‐Phase Deposited Silica Films for Low‐k Dielectric Applications

“…The remarkably low k and fairly high modulus LPD silica films achieved by this lowtemperature process make it into a very promising candidate for low-k dielectric materials for semiconductor devices and flexible electronics. Elastic Modulus (GPa) 24 12 2.0 Sol-gel processing NA He et al 9 1.65 Sol-gel method with catalyst HF NA Shen et al 10 B2.5 Dip-coating process NA Farrell et al 22 2.3 Evaporation-induced self-assembly (EISA) NA Zhen et al 11 1.67 Sol-gel method and spin coating technique NA Maruo et al 21 1.5-1.7 Sputtering NA Shen et al 23 3.09 PECVD 13.98 GPa/nanoindentation Wang et al 7 B2.4 PECVD B4 GPa/nanoindentation Jung et al 24 2.55 Evaporation-induced self assembly (EISA) 13-14.4 GPa/nanoindentation This paper 1.7-2.7 LPD with different ''F'' content and microstructure 18.9-24.5 GPa/nanoindentation…”

“…13 In the sol-gel method, the F ions were introduced by using hydrofluoric acid (HF) as a catalyst. 9,11 The resultant F-doped silica films showed an obvious decrease in the k from both processing methods.…”

“…Basically, the k can be reduced through a reduction in electronic polarization or through the introduction of porosity 7 . The introduction of porosity is widely studied due to the controllability of pore size and distribution in some deposition process, like sol–gel 8–12 . However, the high‐porosity silica‐based film is at the cost of mechanical strength, which makes the integration process more difficult and device performance less reliable.…”

“…Plasma‐enhanced chemical vapor deposition introduced F into the silica film using a fluorine gas source, such as CF 4 and SiF 4 13 . In the sol–gel method, the F ions were introduced by using hydrofluoric acid (HF) as a catalyst 9,11 . The resultant F‐doped silica films showed an obvious decrease in the k from both processing methods.…”

“…7 The introduction of porosity is widely studied due to the controllability of pore size and distribution in some deposition process, like sol-gel. [8][9][10][11][12] However, the high-porosity silica-based film is at the cost of mechanical strength, which makes the integration process more difficult and device performance less reliable. Therefore, introducing the fluorine ion (F), which has the least polarizability, into the silica film becomes a very promising means of achieving low-k silica.…”