Investigation of instability in multi-layer dielectric structures

Stability of secondary passivation layers as RF plasma sputtered SiO/sub 2/ (Sp-SiO/sub 2/), P-SiO/sub 2/, and P-SiN in high-voltage integrated circuits under bias-temperature (BT) stress aging was investigated by using an MIS diode and a lateral pnpn thyristor. It was shown that the initial electrical properties were almost the same for each passivation layer system. However, variations in net number of charges by +or-BT stress aging were observed owing to different charge storage mechanisms, such as residual charges, interface trapped charges, and polarized charges. These instabilities are discussed in conjunction with variations in the device blocking characteristics.<>