Titanium nitride (TiN) films are used as anti-reflection coatings (ARC) on aluminum (Al) films to facilitate lithography processes during multilevel metallization for the manufacture of integrated circuits on silicon-based (Si) semiconductor devices. It is generally accepted in the literature that the microstructure of multilevel metal stacks is influenced by the texture of the substrate. For the case of interconnect materials used in the semiconductor industry, a typical metal stack is as follows: Titanium/Titanium Nitride/Al-alloy/ARC-Titanium Nitride. The Ti/TiN layer underneath the Al-alloy film is used as a barrier stack to prevent junction spiking. The Ti/TiN underlayer also determines the growth conditions (crystallography and orientation relationships) of the subsequent Al-alloy film.This study focuses on the microstructural characterization of the ARC-TiN layer on Si-oxide and Ti/TiN/Al-alloy substrates that are fabricated under similar conditions using conventional physical vapor deposition (PVD - sputtering) techniques. The ARC-TiN microstructure was investigated by transmission electron microscopy (TEM) using a Philips EM430 operating at 300 kV.
ABSTRACTCu-Al alloys have been recommended for application as the diffusion barriers/adhesion promoters for advanced copper based metallization schemes. This approach to barrier formation is to generate an ultra-thin interfacial layer through Cu alloying without significantly affecting the resistivity of Cu. In this paper the microstructure of the bilayers of Cu/Cu-5 at%Al and Cu-5 at%Al/Cu sputter deposited on SiO2 before and after thermal annealing is investigated by transmission electron microscopy (TEM). Interfacial layer is observed in both cases. The variation of the resistance of the Cu-Al alloy film is consistent with its microstructure. The x-ray diffraction (XRD) spectra of Cu-5 at%Al on SiO2 shows that the addition of Al into Cu intends to favor the Cu (111) texture. These results will be presented and discussed showing that films of Cu doped with Al appear to act as a suitable barrier and adhesion promoter between SiO2 and Cu.
ABSTRACTThe effect of the addition of Si to an Al alloy on the reaction morphology of Al12W in Al-Cu-Si/Ti-W bilayers was studied with plan-view and cross-section transmission electron microscopy (TEM). The addition of 0.5 wt.% Si to an Al-0.5Cu alloy film increases multiple spiked growths of the Al12W compound by the reaction of the Al-0.5Cu-0.5Si film with the Ti-W sublayer after heat treatment at 450°C for 30 min. Increasing the Cu and Si content from 0.5 to 1.5% significantly reduced the spiked growth of Al12W into the Al-1.5Cu-1.5Si film. However the spike number density remained high compared to the reaction of a binary Al-1.5Cu film with the Ti-W layers. The result indicates that the addition of Si to form a ternary Al-Cu-Si film results in a more irregular, less planar Al12W morphology. This morphology can have a detrimental effect on thermal stability and electromigration resistance.
A Study on Sealing Process of Anodized Al Alloy Film