Study on self-organized Ru dots using ALD and low temperature rapid thermal annealing process

Self-organized ruthenium (Ru) dots were fabricated by 400°C RTA (rapid thermal anneahng) and ALD (atomic layer deposition). The dots were produced under the 400°C RTA conditions for 10, 30 and 60 seconds on all Si(100)/200 nm-Si02, glass, and glass/fluorine-doped tin oxide (FTO) substrates. Electrical sheet resistance, and surface microstructure were examined using a 4-point probe and FE-SEM (field emission scanning electron microscopy). Ru dots were observed when a 30 nm-Ru layer on a Si(100)/200 nm-Si02 substrate was annealed for 10, 30 and 60 seconds, whereas the dots were only observed on a glass substrate when a 50 nm-Ru layer was annealed on glass. For a glass/FTO substrate, RTA <30 seconds was needed for 30 nm Ru thick films. Those dots can increase the effective surface area for silicon and glass substrates by up to 5-44%, and by 300% for the FTO substrate with a < 20° wetting angle.