0.8 micron double level metal technology with SOG filled tungsten plug

The authors describe a 0.8 mu m double level metal technology developed for high density memory applications. A SOG (spin-on-glass) filled tungsten contact plug with barrier metal underneath and aluminum film on the top is proposed. Low contact-1 resistance to n+, p+ and polycide has been achieved. Because of the structure of this contact, a composite film of barrier metal, tungsten and aluminum is formed for the first metal; therefore, this type of contact process requires no tungsten etchback as does the typical tungsten plug. The composite film of metal-1 shows sheet resistance below 0.2 ohm/square. Due to the relatively flat nature of the topography a simple non-etchback SOG intermetal planarization process with sloped contact-2 was adopted for this technology, and the electrical results of metal-2 continuity and bridging tests meet expectations.<
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