| 摘要 |
A two-step chemical mechanical polishing (CMP) process is provided for low dishing of metal lines in trenches in an insulation (oxide) layer, e.g., of silicon dioxide of a thickness of about 100-2000 nm, of a semiconductor wafer, e.g., of silicon, during its fabrication. The first step involves chemically mechanically polishing a metal layer, e.g., of copper of a thickness of about 200-2000 nm, disposed on the oxide layer and having a lower portion located in the trenches for forming metal lines and an upper portion overlying the lower portion. The first step polishing is effected at a high downforce, e.g., 3-8 psi, to remove at a high rate the upper portion of the metal layer substantially without removing the lower portion thereof and substantially without dishing of the lower portion located in the trenches. The second step involves continuing the CMP at a lower downforce, e.g., 1-5 psi, to remove at a lower rate the lower portion of the metal layer with attendant minimized dishing to an extent for providing the metal lines as individual metal lines correspondingly disposed in the trenches. The total polishing time is about 120-48 seconds (2-8 minutes).
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