Investigation of Tungsten Rich Residue Defects Induced by Electron Beam Inspection post Contact Tungsten Chemical and Mechanical Polish

Tungsten (W) rich residue defects are observed post the layer of contact (CT) tungsten chemical and mechanical polish (CMP). The failure model of the defects was presented. And the mechanism involving micro electrochemical reaction in the chemical bond with metastable structure on the wafer was discussed. Then a series experiments were carried out, and the failure model of the defects was demonstrated. Solutions to avoid or remove the W rich residue defects with ion-chemical clean pre or post DI water clean was discussed as well.