Colorimetric properties of TiN thin films prepared by the Facing Targets Sputtering system

The purpose of the present work is to confirm the condition for obtaining gold-yellow TiN films with the reactive sputtering method without bias and to quantitatively evaluate the colorimetric properties of these films. Therefore, TiN films were prepared by D.C. reactive sputtering under a no-bias condition in the Facing Targets Sputtering (FTS) apparatus, in which a discharge is maintained at a low gas pressure of less than 0.3 Pa. The color of the films was evaluated by means of the chromaticity coordinates, x and y, and the stimulus value, Y, which is an index of the brightness or luminance factor based on a CIE standard colorimetric system. Gold-yellow TiN films were obtained, and a study of their colorimetric properties has provided the following conclusions; (i) Even without bias application, a gold-colored TiN film with higher brightness, Y, has been obtained by deposition at an appropriate mixing ratio of N²/Ar and also under lower total gas pressure. (Y = 49-53 for the films deposited at 0.14-0.15 Pa) (ii) The colorimetry of the films is affected by both the mixing ratio and total gas pressure. Particularly, the brightness, Y, varied greatly with a change in total gas pressure. (iii) As the total gas pressure was increased, the column size and oxygen content showed a clear increase. Thus, the films deposited under an atmosphere higher than 0.15 Pa had lower brightness.