Atomic layer deposition process of ruthenium, iridium and rhodium thin films

Abstract

The thin film industry has shown growth in the recent years, as devices become smaller and more powerful. Thin film desposition technique such as Atomic Layer Deposition (ALD) has shown increasing attractiveness in the modern industry. The ability to deposit films with high conformality and uniformity is well sought after.

In this study of the Thermal ALD process via ozone reaction, deposition of noble metal thin films for Ruthenium, Iridium and Rhodium will be reviewed. The focus would be on the following precursors, Ir(acac)3 (acac = 2,4-pentanedione) for Iridium thin film deposition, Rh(acac)3 for Rhodium thin film and RuCp2 (Cp = cyclopentadienyl) for Ruthenium thin film. Reaction mechanisms and process parameters of each thin film will be reviewed.

Ru thin films were fabricated from RuCp2 and ozone on silicon (111) substrate at 240-260oC. This is the first time ozone has been used as reactant with RuCp2. Films obtained were amorphous with good uniformity, with evidence of RuO2 formation.

For Rh thin film, metallic Rh thin film was achieved on sapphire (α-Al2O3, (0001)), with Rh(acac)3 and ozone at 200-220oC without the aid of reducing reactants (H2). Films grown were uniform and crystalline with traces of oxidation belonging to RhO2.

Thermal ALD of Ir was successful and metallic Ir thin films were fabricated at 190oC on sapphire with Ir(acac)3 and ozone. Ir thin films deposited were highly crystalline and uniform.

Future recommendation for this project would be the deposition of mixed-noble metal alloys by ALD process through the homemade ALD reactor.