ECR Principle
Electrons rotating within the confines of lines of magnetic force of a field strength of 87.5 mT (Tesla) are excited by an alternating electric field at 2.45 GHz (electronic cyclotron resonance), and absorb energy to rotate at high speed. This ensures that gas molecules collide, even at low pressures where discharge is difficult, to generate a plasma efficiently.
High refractive index control
- No electrical power, low gas pressure (0.01-0.2 Pa), large-current ion bombardment effect at low energies (10-30 eV) to a high-density (5-10 mA/cm²) substrate surface
- Formation of precise, smooth, high-quality thin films, with low heating and low damage
Physical properties of ECR thin films
Flatness
Tiny irregularities at the single-atom level
(Rmax of Al2O3 film = 0.48 nm at a film thickness of 100 nm)
Hardness
SiN films and carbon films have hardnesses similar to those of diamond
Strictness
Waterproofing characteristics of SiN film (reliable blocking with SiN film coating)
Hydrogen barrier characteristics of AI2O3 film (barrier ability similar to bulk)
Superior optical characteristics
Highly precise refractive index control, high optical permeability (SiO2, SiN, AI2O3, AIN, Ta2O5, ZrO2, etc.)
Impurity-free
High-purity target and gas used as ingredients to achieve high levels of purity with no reaction products (H, F, CI, etc.)
High compoundability
Orientation of AIN films, MgO films, etc. Low-resistivity TiN films and α-Ta films.
Coatability
Coatability of bumps is much higher than with general sputtering, by formation of inclined rotation film at low gas pressure and high ionization rate.
High voltages
High-voltage insulation film similar to bulk. 10 MV/cm for SiO2 and Al2O3 films (similar to 1000°C thermal oxidation film).
Low damage
C-V characteristics of MOS capacitor using ECR-SiO2 film (implementation of superior boundary characteristics by unheated ECR oxide)
Low boundary levels and boundary charges of MOS capacitor
High permittivity
Formation of boundary oxide films inhibited by metal-mode deposition
