CONTROL OF OXYGEN CONTENT WITH OXYGEN GAS INTRODUCTION IN Cr(N,O) THIN FILMS PREPARED BY PULSED LASER DEPOSITION

摘要

Hard coatings, such as CrN, are used in cutting tools. By partial replacement of the N in CrN with O, Cr(N,O) thin films with a Bl (NaCl type) structure can be produced. Furthermore, the hardness of these thin films can be increased by increasing the oxygen content. In our previous work, thin films were prepared by depositing Cr vapor in N_2 or NH_3 ambient gas with residual oxygen, but controlling the oxygen content precisely was difficult. In this work, O_2 gas was introduced with precise control of oxygen content in Cr(N,O) thin films prepared by pulsed laser deposition. After the chamber was evacuated to a pressure of 2.5×10~(-5) Pa, O_2 gas was introduced and nitrogen plasma from a RF radical source was applied. They were then characterized by X-ray diffraction, infrared spectroscopy and electron energy loss spectroscopy. It was found that the oxygen content of the thin films changed from 0 to 62 mol % with increasing oxygen partial pressure (P_(O2)- The thin films with only the Bl-Cr(N,O) phase were prepared under P_(O2)< 7.5×10~(-5) Pa. The oxygen content of the Cr(N,O) thin films was successfully controlled by P_(O2).