Multilevel interconnections, insulating layer

The most effective use of PIQ in semiconductors is as an insulating layer for multilevel interconnections. After the first metallization is formed, a PIQ prepolymer solution is spin coated on the wafer and then thermally cured. 

The increasing importance of multilevel interconnection systems and surface passivation in integrated circuit fabrication has stimulated interest in polyimide films for application in silicon device processing both as multilevel insulators and overcoat layers. The ability of polyimide films to planarize stepped device geometries, as well as their thermal and chemical inertness have been previously reported, as have various physical and electrical parameters related to circuit stability and reliability in use (1, 3). This paper focuses on three aspects of the electrical conductivity of polyimide (PI) films prepared from Hitachi and DuPont resins, indicating implications of each conductivity component for device reliability. The three forms of polyimide conductivity considered here are bulk electronic ionic, associated with intentional sodium contamination and surface or interface conductance. 

The ILD CMP process has been used to polish plasma-enhanced tetraethylortho-silicate (PETEOS) or high-density plasma chemical vapor deposition (HDPCVD) film on deposited silicon wafer. Figure 15.2 shows the ILD CMP process. The stacking of additional layers on top of one another produces a more and more rugged topography. Between each layer, the dielectric is deposited as an insulating material. To obtain a multilevel interconnection, the surface of the wafer must be... 

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