Improvement in the leakage current characteristic of metal-insulator-metal capacitor by adopting RuO2 film as bottom electrode

Abstract

The dielectric constant, equivalent oxide thickness (tox), and leakage current properties of Pt/(Al-doped)TiO2/RuO2 capacitors were examined in comparison with Pt/(Al-doped)TiO2/Ru capacitors. The Al-doped TiO2 and undoped TiO2 films grown on RuO2 showed high dielectric constants of 60 and 102, respectively. The minimum tox of these films were 0.46 nm and 0.56 nm, respectively, while still satisfying the dynamic random access memory leakage current density specification (< 1 × 10−7 Acm−2 at capacitor voltage of 0.8 V). These excellent electrical properties of (Al-doped) TiO2 on RuO2 were attributed to the high work function and the reduced interfacial effect on RuO2.

Evaluating the Top Electrode Material for Achieving an Equivalent Oxide Thickness Smaller than 0.4 nm from an Al-Doped TiO2 Film

“…19 Hence, it can be said that the leakage current due to the slightly smaller work function (∼5.1 eV) of RuO 2 compared with Pt (∼5.6 eV) may induce a leakage current problem for RuO 2 TE. Nevertheless, the EOT decrease effect from the adoption of RuO 2 overcompensates for such loss in J and largely improves the J-EOT performance, which is the most critical parameter for the MIM capacitor for DRAM, as shown in Figure 2a.…”

(Invited) ALD and Pulsed-CVD of Ru, RuO2, and SrRuO3

“…Much improved leakage current density was achieved by adopting p-CVD RuO 2 bottom electrode due to its high work function (~5.1 eV) and very smooth surface property. [22] Growth of SrRuO 3 film by combined CVD/ALD In spite of several attempts to grow SrRuO 3 film by ALD, there have been only reports available on the PVD and CVD SrRuO 3 process. Authors also attempted to deposit ALD SrRuO 3 film by the alternating growth of SrO ALD using Sr(iPr 3 Cp) 2 /O 2 and RuO x ALD using DER/O 2 .…”

“…5 (b). [14] [22] In order to achieve t ox of < 0.4 nm from high-k dielectrics in MIM configuration, the development of dielectric materials with k value as high as 80 -150 is necessary. In this aspect, TiO 2 based films have been spotlighted as promising high-k material due to its high dielectric constants (rutile TiO 2 : ~80 -120, anatase TiO 2 : ~40).…”

Controlling Work Function and Damaging Effects of Sputtered RuO2 Gate Electrodes by Changing Oxygen Gas Ratio during Sputtering

“…5−7 Such a positive effect has been well demonstrated in metal-insulator (high-k)-metal (MIM) systems, 8 as well as metal-insulator (high-k)-semiconductor (MIS) systems, 9 where the adoption of an RuO 2 electrode results in the EOT decreasing by ∼0.5 nm in the EOT range ≲2 nm. In addition, EWF of RuO 2 is quite large (>5.0 eV), making it suitable in p-type MOSFETs, which can also decrease the electron injection from the gate metal to dielectrics.…”