Substrate-independent palladium atomic layer deposition

A novel method is presented for the atomic layer deposition (ALD) of palladium on a tetrasulfide self-assembled monolayer functionalized SiO2 surface. Additionally, a novel reducing agent (glyoxylic acid) was used to remove the organic ligands from the chemisorbed palladium(II) hexafluoroacetylacetonate metallorganic. Glyoxylic acid is an effective reducing agent above 200 degreesC, which is not optimal for palladium but it is effective enough to show proof-of-concept and deposit a Pd "seed" layer. Palladium was also deposited on iridium at 80 degreesC and 130 degreesC via a hydrogen process or on the Pd seed layer at 80 degreesC. The 60 Angstrom Pd film grown on the tetrasulfide self-assembled monolayer (SAM) showed nearly random texture and higher carbon and fluorine contamination levels compared to the one grown on In The 55 Angstrom film grown on Ir at 80 degreesC is highly (111) textured with a grain size of similar to60 Angstrom, as shown by reflection high energy electron diffraction (RHEED). The higher contamination levels of the Pd film deposited on the tetrasulfide SAM, as measured by X-ray photoelectron spectroscopy (XPS), is attributed to the high temperatures needed to deposit the Pd seed layer. The higher deposition temperatures cause more dissociation of the hfac ligand and a higher metallorganic desorption rate. These equate to less Pd being deposited and with higher contamination levels.