Diffusion Barrier Properties of the Tin Films Prepared by Ecr Pecvd Method

Abstract

TiN film is used as a diffusion barrier layer in contact and via holes in the metallization process of the microelectronics. In most cases, TiN film has been prepared by sputtering which has limited conformality. With the shrinkage of the dimension of the device structure there has been an urgent request for new deposition methods which offer better conformality. Recently, modified PVD systems like highly ionized sputtering system and CVD systems like MOCVD and PECVD systems have been developed.

We prepared TiN films with TIC₄, N₂, and H₂ in an ECR PECVD system. TiN films prepared at the temperature of 450°C had resistiveity lower than 50 μm Ω cm and better step coverage than those prepared by PVD system. Barrier properties of the TiN films against Cu were investigated and related with the film properties like composition and microstructure.

The Cu/TiN/Si structure were annealed in an H₂/Ar atmosphere for 30 min at the temperature range from 500 to 600°C.

Plasma treatment and thermal treatment during and/or after the deposition in various atmosphere were adopted to change the composition and the microstructure of the TiN films.

The composition of the film was analyzed with AES, the microstructure of the film was observed with SEM and the crystallinity was analyzed with XRD. The electrical resistivity was measured with four-point probe method. Barrier properties of the films were studied again Cu metallization. The change in the resistivity and the structure of the Cu/TiN/Si were investigated after the heat-treatment.