A double interlayer of high-density plasma fluorinated silica glass (FSG) and SiO 2 has been developed to control fluorine instability for sub-0.18-m devices. However, the interlayer conditions need further study for robust integration. The authors investigate the optimum conditions to prevent Al wiring delamination. The correlation between the incidence of delamination and F concentration at Ti-SiO 2 was demonstrated by the three-dimensional mapping of interfacial F concentrations with various thicknesses of SiO 2 and F contents in FSG. Detailed analysis of the Ti-SiO 2 interface reveals that the anomalous growth of the interface layer by absorbing F atoms into the Ti layer causes delamination. The properties of SiO 2 , such as the compressive stress and the density of oxygen deficiency, were adjusted to reduce F diffusion. In addition, the thickness was controlled to above 4500 Å to suppress F accumulation at Ti-SiO 2 to within the permissible level. In contrast, the F content in the FSG film was used at 4.4 at.% since the interfacial F concentration was independent of the F content in the range of 2-5 at.%. These conditions resulted in preventing delamination and obtaining integration reliability without increasing the capacitance between adjacent metal lines.Index Terms-Fluorinated silica glass, high-density plasma, intermetal dielectric, metal delamination.

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The correlation of the current-voltage curve for the gate (Ig-Vg) with fatal events (abrupt fall-off of threshold voltage (VT) and subsequent gate-oxide destruction) under hot carrier stress in a lateral diffused PMOS transistor with shallow trench isolation (STI) is experimentally investigated. Time to failure caused by these events becomes shortest long before Ig reaches its first peak. In this region of small Vg stress, electrons trapped in a gate oxide above a drain-side channel cause an abrupt fall-off of VT due to the hot-electron-induced punchthrough effect. A stronger electric field combined with the more numerous hot electrons it produces makes the substrate hot electron effect more influential, resulting in earlier destruction near the top edge of the STI. In contrast, in the region of large stress Vg where a substantial Ig due to Kirk effect is seen, these fatal events are not detected since much of Ig flows through the STI rather than the gate oxide.I.