The effect of density and microstructure on the performance of TiN barrier films in Cu metallization

The properties of 100-nm-thick reactively sputter-deposited TiN films with different deposition conditions and one chemical-vapor-deposited film have been studied as diffusion barriers between Cu and Si by using sheet resistance measurements, x-ray diffractometry, etch-pit test, and Auger electron spectroscopy (AES). Based on Rutherford backscattering spectrometry (RBS), AES, and transmission electron microscopy (TEM) analyses, the relationship between the density, oxygen content, and microstructure of the as-deposited TiN film has been established. As the density of the TiN film decreases, the microstructure of the film becomes porous and the oxygen content in the film increases. The result of the etch-pit test has shown that the failure temperature of the TiN diffusion barrier varies from 500 to 750 °C, depending upon the microstructure of the film. It is concluded that high density of the TiN film is of primary importance in achieving a good diffusion barrier performance between Cu and Si.