Sol−Gel Synthesis of High-Quality SrRuO3 Thin-Film Electrodes Suppressing the Formation of Detrimental RuO2 and the Dielectric Properties of Integrated Lead Lanthanum Zirconate Titanate Films

A facile solution chemistry is demonstrated to fabricate high-quality polycrystalline strontium ruthenium oxide (SrRuO 3 ) thin film electrodes on silicon substrates suppressing the formation of undesired ruthenium oxide (RuO 2 ) for the deposition of dielectric and ferroelectric materials like lead lanthanum zirconate titanate (PLZT). The robust, highly crystalline SrRuO 3 film fabrication process does not favor the formation of RuO 2 because of molecular level modification of the precursors possessing analogous melting points, yielding homogeneous films. This chemistry is further understood and complemented by kinetic and thermodynamic analysis of the DTA data under nonisothermal conditions, with which the activation energies to form RuO 2 and SrRuO 3 were calculated to be 156 ± 17 and 96 ± 10 kJ/mol, respectively. The room-temperature resistivity of the SrRuO 3 film was measured to be ∼850 ± 50 μΩ cm on silicon (100) substrates. The dielectric properties of sol−gel-derived PLZT thin film capacitors on polycrystalline SrRuO 3 electrodes were also measured to illustrate the high quality of the formed SrRuO 3 bottom electrode. These results have broad implications for the expanded use of these conductive oxide electrodes in many applications that require low thermal budgets. The PLZT (8/52/48) films exhibited well-defined hysteresis loops with remanent polarization of ∼10.5 μC/cm 2, dielectric constant of >1450, dielectric loss of <0.06, and leakage current density of ∼3.8 × 10 −8 A/cm 2 . These dielectric properties are similar to those of PLZT on platinized silicon, indicating the high quality of the bottom conductive oxide layer. In addition, the PLZT capacitors were essentially fatigue free for >1 × 10 9 cycles when deposited over an oxide electrode.