Additive vapour effect on the conformal coverage of a high aspect ratio trench using MOCVD copper metallization from (hfac)Cu(DMB) precursor

Abstract

A low pressure chemical vapour deposition technique was used to deposit MOCVD copper films on submicron-level trenches. Conformal coverage of the trenches with the MOCVD copper films has been investigated. MOCVD TiN (1000 Å) was initially deposited on a Si wafer with trenches employing tetrakis-ethylmethyl-amido titanium precursor. The Cu film was then deposited on the TiN film employing (hfac)Cu(DMB) precursor. A high aspect ratio (7:1) trench was used to investigate conformal coverage of the Cu films. C2H5I vapour was added to the Ar carrier gas stream to alter the deposition characteristics and enhance the conformal coverage of the Cu films. The additive vapour affected the film growth rate, activation energy, preferred orientation, surface morphology/roughness and conformal coverage of the deposited Cu films. The conformal coverage of the Cu films on the trenches was enhanced with the addition of C2H5I and by decreasing the substrate temperature. Optimum conformal coverage was obtained at 140 °C with C2H5I as an additive.