W-CMP FOR SUBMICRON INVERSE METALLIZATION

Chemical Mechanical Polishing (CMP) of tungsten for an inverse metalli sation scheme is investigated. The influence of CMP parameters on remo val rate and uniformity is studied. The main effects on the removal ra te are the applied pressure and the rotation rate of the polishing pad . To the first order Preston's equation is obeyed. The uniformity is b est with equal rpm of pad and wafer and with perforated pads. Also, pa ttern density effects of CMP of W/PETEOS are investigated. Dishing inc reased at larger W-linewidth. Oxide erosion increased at larger patter n density and smaller W-linewidth. Electrical measurements on submicro n (0.4 and 0.5 mu m) test structures yielded good CMP results.