ZrO₂Thin Film Deposition on TiN by Plasma Enhanced Atomic Layer Deposition Using Cyclopentadienyltris(dimetylamino)zirconium

Abstract

In this paper, we report the growth of ZrO 2 thin films on TiN substrates using Plasma Enhanced Atomic Layer Deposition (PEALD) process starting from cyclopentadienyltris(dimetylamino)zirconium and oxygen plasma as precursor and reactant, respectively. The material properties -structure, morphology and composition -are investigated as a function of process parameters such as number of cycles, deposition temperature and plasma conditions. Electrical performances -in terms of breakdown field and leakage currents -are investigated as a function of deposition temperature on Au/ZrO 2 /TiN capacitors, giving an evidence for an impact of the crystallinity and impurities.With the continuous downscaling of integrated circuits (ICs), the replacement of SiO 2 or Si 3 N 4 standard dielectrics by a high κ material, i.e. a material with a higher dielectric constant, has emerged recently. This solution allows for instance keeping large capacitance density with oxide thickness reduction. Among these high κ materials, transition metal oxides such as HfO 2 , ZrO 2 , Ta 2 O 5 and others have been widely proposed and recently reviewed 1 for integration in complementary metal oxide semiconductor (CMOS) devices as well as metal insulator metal (MIM) capacitors, and resistive random access memory (RRAM) applications. 2 For MIM devices, ZrO 2 is preferred for its capacitance density and leakage current, 3 strongly influenced by intrinsic properties such as crystallinity and interface quality. 4 The permittivity of such dielectric depends on its crystalline structure, reaching the value of 47 in the tetragonal phase. 5 In addition, ZrO 2 presents a large bandgap (around 5.5 eV). 6 As a consequence, the main criteria for MIM capacitances, such as low leakage currents, voltage linearity and high breakdown voltage can be achieved. The physical and chemical properties of high κ oxides are also important in oxide based RRAM devices, where the material structure and composition are influent parameters for the switching. 7 In these above ICs applications (RF capacitors, RRAM), from a process integration point of view, the high κ thin films (usually less than 50 nm thick, even less than 10 nm) should be deposited at low temperature (in most cases less than 400 • C) in order to avoid the degradation of the CMOS and metallic lines.Among the various possibilities existing for the growth of high κ thin layers, Atomic Layer Deposition (ALD) is considered as the more appropriated technique because it can produce high quality materials with an excellent control of the thickness, especially for thin films. 8 Various Zr precursors, such as halides, 8 alkyls and alkylamides, 9 β-diketonates 10 and cyclopentadienyl 10,11 have already been investigated for the ALD ZrO 2 growth. The ZrCl 4 / H 2 O combination has been first used in the 180 • -600 • C temperature range 12 and different crystallographic states (with crystalline cubic, monoclinic or tetragonal phases) could be obtained by varying the deposition conditions. 13 However, the presence of chlorine c...

Controlled Synthesis of ZrO2 Nanoparticles with Tailored Size, Morphology and Crystal Phases via Organic/Inorganic Hybrid Films

“…Binding energy values (182.0 and 184.4 eV) and separation (2.4 eV) determined in the Zr3d spectrum (Fig. 5a ) are due, respectively, to Zr3d 5/2 and Zr3d 3/2 emissions of Zr 4+ sites 48 . Whereas, binding energy values (530.0 and 531.5 eV) determined in the O1s spectrum (Fig.…”

“…5b ) are assignable, respectively, to lattice oxide (O 2− ) sites and the oxygen of OH/H 2 O/CO x surface species 48 . Table 1 shows that irrespective of the hybrid film used and the calcination temperature applied, binding energies determined for Zr3d (182.0–181.7 eV for Zr3d 5/2 and 184.4–184.3 eV for Zr3d 3/2 ) and O1s (530.0–529.7 eV for O 2− and 531.5–531.3 eV for OH/H 2 O/CO x ) occur in narrow ranges assignable to surfaces exposed on ZrO 2 lattice with minority oxygen-containing surface groups (OH/CO x ) 41 , 48 , 49 . Accordingly, surfaces of the entire set of ZrO 2 NPs recovered are composed dominantly of Zr 4+ and O 2− sites, as well as minority surface groups of OH and CO x species, and water molecules.…”

Atomic layer deposition of zirconium dioxide from zirconium tetrachloride and ozone

“…As a dielectric metal oxide, ZrO 2 has been of interest at first as a potential candidate for gate dielectrics in transistors [1][2][3][4][5]. ZrO 2 has found, in nanoelectronics, an application as a memory capacitor dielectric [6][7][8][9][10], and is investigated also as a potential dielectric for resistive random-access memories [11]. In addition, ZrO 2 has been considered as a host ion conductor material for solid oxide fuel cells [12,13] or encapsulation material layer for organic electronic devices [14].…”

“…Often, both precursors contain hydrogen and thus the residual hydrogen content could be diminished after substituting either one or both precursors by hydrogen-free ones. ZrO 2 films have been grown by several water-free ALD processes [21], such as in those based on (C 5 H 5 )Zr(N(CH 3 ) 2 ) 3 and oxygen plasma [7,22], Zr[N(CH 3 ) 2 ] 4 and O 3 [14], Zr[N(CH 3 )(C 2 H 5 )] 4 and O 3 [6,9,11,23], Cp 2 ZrCl 2 and O 3 [13,24], or Zr(NEtMe) 3 (guanNEtMe) and O 3 [25]. Regarding metal halide based and hydrogen-free ALD processes, depositions of Al 2 O 3 from AlCl 3 and O 3 [26], TiO 2 from TiCl 4 and O 3 [27], Ta 2 O 5 from TaCl 5 and O 3 [28], HfO 2 from HfCl 4 and O 3 [29], and HfO 2 from HfI 4 and O 2 [30] have been reported.…”

“…There is also an implication about the possibility to atomic layer deposition of [29], although the details of the process have remained beyond the scope of that study. ZrO 2 films have been grown on electrodes assumptionally most relevant to the particular applications, such as on silicon under potential gate dielectrics [20,22] or titanium nitride for memory capacitors [7][8][9]23]. Certain issues related to the increment of leakage currents due to the roughness of TiN electrodes have been pointed out [31].…”