Selective Aluminum CVD for Sub-Micron VIA Plug Filling

Abstract

ABSTRACTWe present a novel technique to metallize high-aspect-ratio, small-dimension contact holes and via plugs for application to integrated circuits and packaging. The technique uses a laser-assisted process to deposit a thin film of aluminum from DMA1H, which forms a seed layer for subsequent selective CVD. The resistivity of the deposited aluminum is nearly that of the bulk metal, the contact resistivity is good (∼0.03 μΩ-cm2), and the morphology of the deposited film is comparable to that obtained with physical vapor deposition. This process has been used to fill via holes in a SiO2 substrate, and small-diameter (0.7 μm), high-aspect-ratio (3:1), aluminum plugs have been repeatedly formed without the incorporation of voids. A custom-made via chain structure was used to determine the via resistance (plug and contact), which was found to be 0.1 -0.3 Ω. Our technique opens a new process window for void-free high-aspect-ratio via and contact hole filling, and is particularly interesting in that it offers the potential to use aluminum or aluminum-copper in plug metallization.