Cubic-Structured With Optimized Doping of Lanthanum for Higher Dielectric Constant

Silicon Nano Device Lab., Nat. Univ. of Singapore, Singapore
IEEE Electron Device Letters (Impact Factor: 2.79). 07/2009; DOI: 10.1109/LED.2009.2020613
Source: IEEE Xplore

ABSTRACT It is demonstrated that HfO2 films can have much higher dielectric-constant values than the usual reported value of 20-24 by optimized incorporation of lanthanum element and crystallization to cubic structure. When HfO2 with 8% La is crystallized into cubic structure, the film exhibits the kappa value of ~38 which is the highest among ever reported HfO2 -based high-kappa dielectrics. The increased kappa value of HfO2 with 8% La enables the leakage current to be reduced more than one order of magnitude lower, compared to amorphous-phase HfO2 under the same electric field. The dependence of film thickness and annealing temperature on the cubic crystallization is also reported.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Low-voltage and high-performance pentacene thin-film transistors with a hybrid gate dielectric consisting of ultrathin PVP (8 nm) and a high-κ HfLaO (20 nm) have been demonstrated. The hybrid gate dielectric exploits the advantages of both dielectrics, i.e., a good interface between the organic dielectric and channel material as well as the insulating properties of the inorganic metal-oxide, resulting in very low leakage current, hysteresis-free behavior, superior drain-current drivability, and successful operation at -2 V. The superior device performance is attributed to good intermolecular ordering and the large grain size of the pentacene channel layer formed on the hybrid dielectric.
    IEEE Electron Device Letters 12/2010; · 2.79 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Grain boundaries (GBs) in polycrystalline high-κ (HK) dielectric materials affect the electrical performance and reliability of advanced HK-based metal-oxide-semiconductor (MOS) devices. In this work, we present a localized study comparing the electrical conduction through grains and GBs for CeO2 and HfO2-based HK dielectrics using scanning tunneling microscopy (STM) and transmission electron microscopy (TEM) at the nanometer scale, in conjunction with macroscopic MOS capacitor device level analysis. Nanoscale STM conduction analysis clearly reveals faster degradation at GB sites and their vulnerability to early percolation. Multi-layer HK dielectric stacks (capping of La2O3 on CeO2 and dual-layer ZrO2/HfO2) are proposed as an effective technique to significantly enhance the time-dependent dielectric breakdown (TDDB) robustness of advanced HK metal gate (MG) stacks.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Metal-insulator-metal (MIM) capacitors fabricated with (8%) La-doped HfO<sub>2</sub> single layer as well as HfLaO/ LaAlO<sub>3</sub>/HfLaO multilayer dielectric stack are demonstrated. While the La-doped HfO<sub>2</sub> single layer is crystallized at 420<sup>??</sup>C annealing, HfLaO/LaAlO<sub>3</sub>/HfLaO multilayer dielectric stack remains amorphous. A high dielectric-constant value of 38 can be obtained when 8% La-doped HfO<sub>2</sub> is crystallized into cubiclike structure. However, it is observed that the linearity of MIM capacitor is degraded upon crystallization. The multilayer film has lower average dielectric constant but shows low quadratic voltage linearity of less than 1000 ppm/V<sup>2</sup> up to a capacitance density of 9 fF/??m<sup>2</sup> . It is observed that the HfLaO single-layer MIM is suitable for the applications with requirements of high capacitance density and robust reliability, while the multilayer MIM is suitable for a precision circuit.
    IEEE Electron Device Letters 02/2010; · 2.79 Impact Factor