Plasma-deposited passivation layers for moisture and water protection

The barrier properties of electron cyclotron resonance plasma deposited silicon oxide (SiO), silicon oxynitride (SiON) and silicon nitride (SIN) films against moisture and water penetration were studied as a function of the deposition parameters gas flux ratios, microwave power and reactor pressure. Three methods were used to quantify these barrier properties: measurement of film etch rate in water at different temperatures and pH values, determination of moisture permeation coefficient and electrical characterization of samples during humidity exposure. Although the dissolution rate of SiN in water is slightly higher compared with SiO the lower moisture permeation coefficient and the higher electrical stability during exposure to humidity of silicon nitride make it an attractive passivation material for different applications.