Void formation in the Cu layer during thermal treatment of SiN_x/Cu/Ta₇₃Si₂₇/SiO₂/Si systems

Abstract

The thermal stability of a SiN x passivation layer and its influence on the annealing behavior of an amorphous Ta 73 Si 27 diffusion barrier deposited between copper and SiO 2 were analyzed by X-ray diffraction, glow discharge optical emission spectroscopy, Auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy. During heat treatment at a temperature T an = 500 °C, diffusion of Cu atoms out of the Cu metallization into the SiN x passivation occurs. The Cu diffusion intensifies with increasing annealing temperature and annealing time and seems to be a necessary precondition for a defect formation process observed within the Cu metallization. Depending on the chemical composition of the SiN x /Cu interface, voids in the µm-range can be formed within the Cu film. Compared to an unpassivated sample, heat treatment leads to a reduced diffusion of Ta atoms from the barrier through the copper into the SiN x /Cu interface. The barrier crystallization process into Ta 5 Si 3 occurring during annealing at T an = 600 °C is principally not affected by the presence of a SiN x passivation.

Application of Al–Nb alloy film to metal capping layer on Cu

“…Traditionally, dielectric films of SiN, SiC, and SiCN have been used on the Cu surface as a capping layer. [1][2][3][4] Hu et al reported the good performance of a CoWP alloy or Pd against Cu electromigration at the cap=Cu interface. 5) Thereafter, the failure at the interface between the dielectric cap and Cu due to poor adhesion is drastically improved.…”

Diffusion Barriers

“…Systematic studies to characterize the failure mechanisms and, in particular, their dependency on the chemical composition of the Ta-Si-N diffusion barrier were carried out by Hübner et al [16,81,[148][149][150]. For this purpose, 10 nm thick Ta 73 Si 27 , Ta 56 Si 19 N 25 and Ta 30 Si 18 N 52 films were prepared onto pure and thermally oxidized Si substrates and partially covered with a 50 nm Cu layer.…”

Oxidation Characteristics of Thin Al–Mo Alloy Films with Various Compositions as Metal Capping Layer on Cu

“…The Cu surface is generally passivated with dielectric films such as SiN, SiC, and SiCN. [1][2][3][4] However, a higher dielectric constant (k) of the dielectric capping layer than of the low-k insulating material around the Cu line causes an increase in line-to-line capacitance, resulting in signal delay through interconnecting lines. This problem with dielectric capping layers can be solved, in principle, using a metal capping layer, in addition to or instead of a dielectric cap.…”