A new RuO4 solvent solution for pure ruthenium film depositions

Ruthenium films were deposited using an inorganic precursor, RuO4. Ruthenium tetroxide was dissolved in a solvent chosen for its complementary properties with the precursor. The resulting solution is called ToRuS. The use of hydrogen as the only reducing co-reactant enabled us to form low impurity content ruthenium films. Tests were successfully carried out at low pressure by Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD) methods, in which ruthenium films were deposited at temperatures as low as 200 °C. ToRuS can also be used as a single source precursor for depositing ruthenium dioxide films at temperatures of 400 °C and above. This new process, using the volatile RuO4 precursor, is characterized by high deposition rates, pure films with good uniformity, good adherence to many types of substrates and negligible incubation time. Inhalation tests of the solution were performed on rats and its low-toxicity was proven.