The effects of C on the low-temperature formation and the properties of the spin-on dielectric films used for sub-50 nm technology and beyond

摘要

Precursor films based on polysilazane and polymethylsilazane were deposited on Si-substrates or on stacked TiN/Ti/tetraethyl orthosilicate/Si-substrates by spin-coating, subsequently annealed at 150-850 ℃ or at 150-400 ℃, and physicochemically characterized or integrated further to form a top electrode and pad. They were then electrically characterized. Compared to perhydro-polysilazane, annealing the precursor films of hydro polymethylsilazane led to a more difficult formation of good-quality spin-on dielectric films by evaporating smaller amounts of N, H, and C and gaining a smaller amount of 0 at 400 ℃, whereas evaporating and gaining larger amounts at 850 ℃, results in a shrink ratio of 14.5% less than the 15.6% ratio of perhydro-polysilazane at 400 ℃ but 37.4% more than that of 19.4% at 850 ℃ Fourier-transform infrared spectroscopy indicated that C induced fewer Si-O bonds, a non-uniform property, and lower resistance to chemical etching. Electrical measurements indicated that a larger capacitance of 2.776×10~(-11) F compared to 9.457×10~(-12)F and a lower leakage current of 0.4 pA from the polysilazane-based dielectric films compared to the value of 2.4 pA from a polymethylsilazane based film were obtained at less than 0.6 MV/cm, giving therefore higher dielectric constant of 5.48 compared to 3.96. Better electrical properties are directly correlated with larger numbers of Si - O bonds and better bonding structures of spin-on dielectric films as derived from a precursor without C.