Hf-Based High-κ Dielectrics: A Review

Abstract

In the last decades, the number of transistors per chip with integrated circuits has increased leading to reduction in the thickness of silicon dioxide used as gate dielectrics. However, at small dielectric thicknesses leakage current formation has begun due to the quantum tunneling effect. Thus, it became essential to replace SiO2 with alternative dielectrics with high dielectric constant to maintain the same capacitance at higher gate dielectric thicknesses. This review analyzes alternative high-κ dielectric materials substituting for SiO2. For this reason, the properties of materials with high dielectric constant are compared to SiO2 with a special emphasis on HfO2, since it is the most promising high-κ dielectric to replace SiO2. The fundamental points concerning HfO2 gate dielectrics are their high dielectric constant and their thermodynamic stability when in contact with Si. In this article, properties of HfO2 fabricated with different coating methods and doped with different elements such as N, Si, Al, Ti and Ta have been compared and discussed. In the conclusion part, we have summarized the results of characterization obtained by X-ray diffraction, scanning electron microscopy, leakage current density-voltage (J-V ), capacitance-voltage (C-V ) and UV-vis spectroscopy of HfO2 thin films.

Inorganic ferroelectric thin films and their composites for flexible electronic and energy device applications: current progress and perspectives

“…107 Moreover, nanoscale ferroelectric HfO 2 , Hf x Zr 1Àx O 2 (HZO) (with x ranging from 0 to 1), and ZrO 2 are suitable candidates for large-area, cost-effective energy storage. [108][109][110][111][112][113][114] Given the possibility of achieving robust ferroelectric polarization in sub-10 nm thick HZO films, flexible HZO thin films deposited on PET substrates did not show obvious deterioration in ferroelectric properties during spalling and transfer. 115 However, flexible HZO films have not being investigated for energy harvesting, while FE HfO 2 thin films deposited on an Si substrate demonstrated excellent current responsivity with an ultrafast response time (in the ms range) utilizing the ferro-pyro-phototronic effect will be useful for applications such as security alert systems, memory storage, and vision sensors.…”

Hafnium Oxide (HfO2) – A Multifunctional Oxide: A Review on the Prospect and Challenges of Hafnium Oxide in Resistive Switching and Ferroelectric Memories

“…However, over the years, this technology has adopted several high-k oxide materials because of superior scalability of equivalent oxide thickness (EOT) and other advantages as compared to SiO 2 . [1][2][3][4][5][6][7][8][9] Among several adopted high-k materials, sub-stoichiometric hafnium oxide (HfO x ) or switching properties and predicted similar behavior. [217][218][219][220][221][222][223][224][225][226] Both theoretical and experimental findings equip this technology for emerging applications.…”

“…However, over the years, this technology has adopted several high‐k oxide materials because of superior scalability of equivalent oxide thickness (EOT) and other advantages as compared to SiO 2 . [ 1–9 ] Among several adopted high‐k materials, sub‐stoichiometric hafnium oxide (HfO x ) or stoichiometric hafnium oxide (HfO 2 ) is an attractive material with a high dielectric constant of 20–25 and bandgap of 5.3–5.7 eV. [ 3 ] In the flash memory domain, HfO x has been used in several forms such as gate oxide, charge trapping layer, doped oxide, formation of a nano‐laminate layer with other high‐k material, and so on.…”

Design and Performance Optimization of Junctionless Bottom Spacer FinFET for Digital/Analog/RF Applications at Sub-5nm Technology Node

“…Hafnium dioxide (HfO 2 ) having dielectric constant of k = 22 is utilized as high-k gate dielectric in GS formation. 39 The contact resistivity (silicide resistivity) of 7 Ω.μm 2 (7.5 Ω/sq) is used in gate parasitics computation. Silicon dioxide (SiO 2 ) (k = 3.9) is used as sidewall spacer material.…”