Tungsten Film Chemical Mechanical Polishing Using MnO2 Slurry

It has been demonstrated that MnO 2 abrasive can polish tungsten films without using an oxidizer solution. The polishing rate of MnO 2 slurry is 1.5 times higher than that of commercially available Al 2 O 3 slurry. A W plug is formed without etching holes (keyholes) during chemical mechanical polishing with MnO 2 abrasive slurry. With MnO 2 slurry, no key holes were formed even after overpolishing by an additional 0.6 μm. On the other hand, with conventional Al 2 O 3 slurry, keyholes were formed after overlpolishing by an additional 0.4 μm. The residual MnO 2 abrasive on the surface after chemical mechanical polishing was completely removed by the cleaning process because MnO 2 abrasive easily dissolves in a cleaning solution of HCl, H 2 O 2 , and H 2 O. These results indicate that, since MnO 2 is in itself a solid oxidizer, MnO 2 abrasive can polish W films without using an oxidizer solution and does not etch the seam.