The surface structure and the crystalline features in the near surface region have been investigated for CZ(Czochralski) grown Si wafers. Si wafers were annealed by RTA (Rapid Thermal Annealing) method in H$_2$ambient after mirror polished process. The densities of COPs (Crystal Originated Particles) after RTA process were remarkably decreased at the surface and in the region of 5um depth from the surface as well. terrace type surface structure which was formed by etching and re-arrangement of Si atoms during $H_2$annealing process also has been observed.