Spectroscopic ellipsometry and ellipsometric porosimetry studies of CVD low‐k dielectric films

Aurora ELK, a porous low-k SiCOH film deposited by CVD, was used to study the effect of UV curing. Samples were cured for various curing times and the purpose of this work is to observe the effects of UV curing on optical, mechanical and structural properties of the low-k film. We have used 1) ellipsometric porosimetry to determine the porosity and the pore-size distribution and 2) nitrogen purged UV ellipsometry in a range from 2 to 9 eV to observe the changes of the di-electric function of the cured material. Additional FTIR and laser-induced surface acoustic wave measurements were performed. The porogen removal and the increase of porosity were observed, and a k-value of 2.3 was reached for the optimum curing time. However for longer curing times, densification and reduction of the porosity occurs. The growth of the hydrogen incorporation has been observed.