(BA, SR)TIO3 FILMS PREPARED BY LIQUID SOURCE CHEMICAL-VAPOR-DEPOSITION ON RU ELECTRODES

Electrical properties of (Ba,Sr)TiO3 [BST] films have been investigate d on RuO2/Ru and Ru electrodes instead of Pt, because they are easy to be etched, BST films were deposited at a substrate temperature of T-s = 420 degrees C and a reactor pressure of P = 1.5 Torr by employing a two-step liquid source chemical vapor deposition (CVD) process. BST f ilms on RuO2/Ru were electrically shorted, which was considered to be caused by surface roughening during BST film deposition and/or post-an nealing. In the case of Ru electrodes. an equivalent SiO2 thickness of t(eq) = 0.50nm (a dielectric constant of epsilon(r) = 190), a leakage current of J(L) = 4.6 x 10(-8) A/cm(2) at +1.1V, and a dielectric los s of tan delta = 0.018 were achieved at a total film thickness of 250 Angstrom, by restricting Ru surface oxidation and its surface rougheni ng. Moreover, BST film deposition on Ru storage nodes, 0.24 mu m wide, 0.6 mu m deep, 0.15 mu m high, and each spaced by 0.3-0.14 mu m, veri fied that the storage capacitance can be successfully increased by usi ng sidewalls of the storage node, without a significant increase in th e leakage current.