This paper introduces a low-k dielectric material, a novel epoxy siloxane
polymer, made by Polyset Co. Inc, which has promising properties. The
polymer was spin-deposited, and thickness and optical properties were
measured using variable-angle spectroscopic ellipsometry (VASE). Fourier
transform infrared (FTIR) spectra of as deposited and cured polymers showed
that the polymer is fully cured at 165 °C. The low curing temperature of the
polymer lowers stress in back-end-of-line (BEOL) stack and thus improves the
reliability. The polymer is thermally stable up to 400 °C. The polymer has
Young's modulus of ∼5 GPa and hardness of greater than 0.4 GPa. After
multiple stress cycles up to 300 °C, the residual stress in the polymer at
room temperature is less than 60 Mpa. The polymer has good adhesion with
semiconductor and dielectrics such as Si, SiC, and SiO2, metals
such as Al, Cu, Co, and W, and barrier materials such as TaN. The bulk
dielectric constant of the polymer is 2.4 - 2.7. The leakage current density
in the polymer at the applied electrical field of 1 MV/cm is in
10−9 A/cm2 range and the breakdown field of the
polymer is ranging from 5 to 7 MV/cm. The polymer when subjected to
bias-temperature stress (BTS) conditions of 150 °C and 0.5 MV/cm shows no
C-V shift for up to 100 min indicating that the polymer resists Copper
diffusion. The current density under stress conditions of 150 °C and 0.5
MV/cm was less than 10−9 A/cm2 for up to 7 hrs.