Chemistry of ruthenium as an electrode for metal–insulator–metal capacitor application

Abstract

Notwithstanding its excellent properties such as high work function and low resistance, Ru has not been widely applied in the preparation of electrodes for various electronic devices. This is because of the occurrence of severe morphological degradation in the actual devices employing Ru. Herein, we investigated Ru chemistry for electrode application and the degradation mechanism of Ru during subsequent processes such as thin film deposition or thermal annealing. We revealed that subsurface oxygen induces Ru degradation owing to the alteration of Ru chemistry by the pretreatment under various gas ambient conditions and due to the growth behavior of TiO2 deposited via atomic layer deposition (ALD). The degradation of Ru is successfully ameliorated by conducting an appropriate pretreatment prior to ALD. The TiO2 thin film deposited on the pretreated Ru electrode exhibited a rutile-phased crystal structure and smooth surface morphology, thereby resulting in excellent electrical properties. This paper presents an important development in the application of Ru as the electrode that can facilitate the development of various next-generation electronic devices.

Enhanced Electrical Properties of an Al-Doped TiO2 Dielectric Film on a TiN Electrode by Adopting an Atomic Layer Deposited Ru Interlayer

“…Figure b shows the variations in the work function and sheet resistance of the bottom electrode as a function of the Ru interlayer thickness. In the case of the bare TiN electrode without a Ru interlayer, a work function of ∼4.4 eV was obtained, consistent with the TiN electrode value in previous studies . With Ru interlayer thicknesses of over 18 nm, the work functions were ∼4.7 eV, which is consistent with the value of the Ru electrode in previous studies .…”

Reliable high work-function molybdenum dioxide synthesis via template-effect-utilizing atomic layer deposition for next-generation electrode applications

“…1,2 However, because these two requirements are trade-offs, no high-k material has been developed yet that can satisfy the requirements for application to next-generation DRAM devices. In contrast, although the electrode properties also strongly influence those of the MIM capacitor, 1,[3][4][5] research on electrode deposition to develop MIM capacitor materials has been limited.…”

Suppressing Interfacial Layer Formation in ZrO2-Based Capacitors with TiN Electrodes via a MgO Thin-Film Oxygen Diffusion Barrier

“…Therefore, the use of high-dielectric-constant materials is essential to overcoming the limitations of DRAM capacitor technology, and additional device downscaling must be accomplished. , TiO 2 and SrTiO 3 (STO) have been extensively studied as novel high-dielectric-constant materials. With surprisingly high dielectric constants (90–300), both materials are promising next-generation film materials for DRAM capacitor dielectrics. − However, novel metal electrodes, such as ruthenium-based electrodes whose atomic layer deposition (ALD) process has not matured, must be used, and leakage current control is difficult in dielectric films with a physical thickness of 5 nm or less, limiting mass production. − ZrO 2 grown using ALD is a typical high-dielectric-constant material applied to DRAM capacitors. Although ZrO 2 -based materials have a relatively lower dielectric constant (<40) than TiO 2 or STO, they have long been used in mass-production processes because of their appropriate bandgap and compatibility with TiN electrodes. ,, However, when ZrO 2 is grown on a TiN electrode via ALD using O 3 as a reactant, it forms an unwanted TiO x N y interfacial layer because of the high reactivity of the TiN bottom electrode (BE).…”