Sub-0.5 nm Equivalent Oxide Thickness Scaling for Si-Doped Zr_1–xHf_xO₂ Thin Film without Using Noble Metal Electrode

Abstract

The dielectric properties of the Si-doped Zr1-xHfxO2 thin films were investigated over a broad compositional range with the goal of improving their properties for use as DRAM capacitor materials. The Si-doped Zr1-xHfxO2 thin films were deposited on TiN bottom electrodes by atomic layer deposition using a TEMA-Zr/TEMA-Hf mixture precursor for deposition of Zr1-xHfxO2 film and Tris-EMASiH as a Si precursor. The Si stabilizer increased the tetragonality and the dielectric constant; however, at high fractions of Si, the crystal structure degraded to amorphous and the dielectric constant decreased. Doping with Si exhibited a larger influence on the dielectric constant at higher Hf content. A Si-doped Hf-rich Zr1-xHfxO2 thin film, with tetragonal structure, exhibited a dielectric constant of about 50. This is the highest value among all reported results for Zr and Hf oxide systems, and equivalent oxide thickness (EOT) value of under 0.5 nm could be obtained with a leakage current of under 10(-7) A·cm(-2), which is the lowest EOT value ever reported for a DRAM storage capacitor system without using a noble-metal-based electrode.

Role of Ge and Si substrates in higher-k tetragonal phase formation and interfacial properties in cyclical atomic layer deposition-anneal Hf1−xZrxO2/Al2O3 thin film stacks

“…The M-atoms (M ¼ Hf, Zr) in the tetragonal structure of MO 2 is surrounded by 8 oxygen atoms, 4 of which are at a shorter distance. 35 Thus, replacement of some of the M-atoms by Ge-atoms of smaller ionic radius 28 can proceed with minimal lattice distortion, eventually forming a Ge-stabilized tetragonal structure at the IL which could act as a template 34 for subsequent bottom-up crystallization 17 of the 100 ALD cycle Hf 1Àx Zr x O 2 films, thus explaining the requirement for a smaller amount of ZrO 2 for films grown on Ge by the DADA ALD process. XPS measured binding energy differences of the Zr 4þ 3 d core electrons support the maximum entropy ARXPS compositional depth profiling which indicates that the IL mostly consists of a network of M-O-Ge type bonds compared to the M-O-M type bonding arrangement in the bulk of the dielectric film.…”

“…14,15,27 The composition dependent m-t phase transition is consistent with Gibbs free energy calculations which show that the contribution of the surface energy term becomes dominant over the bulk energy term for ZrO 2 based films smaller than $7 nm. 28 We fitted Voigt line-shapes to the XRD plots in Fig. 1(a) and calculated the normalized integrated peak area (IPA) ratio…”

On the electrostatic control achieved in transistors based on multilayered MoS2: A first-principles study

“…Note that the values lower than 0.5 nm have been reported recently. 29 So we considered a hypothetic value of 0.1 nm to investigate the best achievable behavior in our…”

Low Power Switching Characteristics of CNT Field Effect Transistor Device with Al-Doped ZrHfO2 Gate Dielectric

“…Meanwhile, the abrupt size reduction of dynamic random-access memory (DRAM) cell keeps pushing on the development of new high-k dielectric materials. Zr-and Hfbased oxides have been applied as a representative dielectric component of complementary metal oxide semiconductor circuit [11]. Furthermore, a ZrO 2 film with an ultrathin Al 2 O 3 layer, deposited by atomic layer deposition (ALD), has been also used in current DRAM capacitor [11].…”

“…Zr-and Hfbased oxides have been applied as a representative dielectric component of complementary metal oxide semiconductor circuit [11]. Furthermore, a ZrO 2 film with an ultrathin Al 2 O 3 layer, deposited by atomic layer deposition (ALD), has been also used in current DRAM capacitor [11]. Diverse crystal structures (monoclinic, cubic, tetragonal, or orthorhombic) of the high-k oxides exist depending on film preparation method, which indicates that the corresponding ALD deposition methods require precise control of precursors, temperature, phase, stoichiometry, and so on.…”