The effect of oxygen content on bonding configuration and properties of low-k organosilicate glass dielectric film

Low-k organosilicate glass (SiOC:H) film as inter-metal dielectric (IMD) layer in advanced ultra-large-scale integrated circuits (ULSI) was deposited by plasma-enhanced chemical vapor deposition (PECVD) with trimethylsilane (TMS) and oxygen. The effects of oxygen on the bonding configuration, optical and electrical properties were investigated by adjusting TMS/O2 gas ratios. The absorbance spectra of Fourier transform infrared (FT-IR) spectroscopy shows that the frequency of the Si-O stretching vibration mode shifted to a lower wave number (red shift) with an increase in the ratio of TMS/O2. The related elements contented in SiOC:H films calculated from FT-IR spectra coincided with the analysis of Rutherford backscattering spectroscopy. Results of optical and electrical properties indicated that a lower refractive index (RI), a higher strength of breakdown voltage, a lower dielectric constant, and a lower leakage current density were achieved at lower TMS/O2 gas ratios.