Characterization of Al Incorporation into HfO2 Dielectric by Atomic Layer Deposition

Abstract

This study presents the characteristics of HfAlO films for a series of Al incorporation ratios into a HfO2 dielectric by atomic layer deposition on a Si substrate. A small amount of Al doping into the HfO2 film can stabilize the tetragonal phase of the HfO2, which helps to achieve a higher dielectric constant (k) and lower leakage current density, as well as a higher breakdown voltage than HfO2 film on its own. Moreover, assimilation of Al2O3 into HfO2 can reduce the hysteresis width and frequency dispersion. These are indications of border trap reduction, which was also verified by the border trap extraction mechanism. X-ray photoelectron spectroscopy (XPS) analysis also verified the HfAlO microstructural properties for various Al compositions. In addition, higher amounts of Al2O3 in HfAlO resulted in better interface and dielectric behavior through trap minimization, although the equivalent-oxide-thickness (EOT) values show the opposite trend.

Characterization of Electrical Traps Formed in Al2O3 under Various ALD Conditions

“…The aggressive scaling of the equivalent oxide thickness (EOT) of metal–oxide–semiconductor field-effect transistors (MOSFETs) for achieving sophisticated device speeds and minimal power consumption has made SiO 2 obsolete as an insulating material [ 1 , 2 , 3 ]. As a result, oxide materials, which have a high dielectric constant ( k ), have emerged as the most suitable alternatives from the viewpoint of the realization of faster devices and overcoming the high leakage current problem [ 2 , 4 , 5 ].…”

“…The aggressive scaling of the equivalent oxide thickness (EOT) of metal–oxide–semiconductor field-effect transistors (MOSFETs) for achieving sophisticated device speeds and minimal power consumption has made SiO 2 obsolete as an insulating material [ 1 , 2 , 3 ]. As a result, oxide materials, which have a high dielectric constant ( k ), have emerged as the most suitable alternatives from the viewpoint of the realization of faster devices and overcoming the high leakage current problem [ 2 , 4 , 5 ]. Although many studies have reported several candidate high- k dielectric materials, Al 2 O 3 has attracted attention as the most desirable of such materials, predominantly because of its comparatively larger band gap (which provides a better band alignment with the channel material), better thermal solidity, lower oxygen and ionic transportation, and more effective inactivation of interface traps in the channel material [ 5 , 6 , 7 , 8 ].…”

Border Trap Characterizations of Al2O3/ZrO2 and Al2O3/HfO2 Bilayer Films Based on Ambient Post Metal Annealing and Constant Voltage Stress

“…As potential gate insulator candidates in III-V channel material-based nano-metric metal oxide semiconductor field-effect transistors (MOSFETs), which are considered as a future device for logic applications with a higher speed and bottled-up power consumption, the most studied Hf and Zr-based high-k oxides suffer from a lower barrier elevation as well as a destitute interface with the semiconductor material compared to the SiO 2 /Si-based system. These shortcomings are hindrances to achieving the leakage current challenge [1][2][3][4][5]. To solve these issues, an interfacial layer of Al 2 O 3 is added between the above-mentioned dielectric materials and semiconductor.…”

“…The conventional interface trap model is unable to explain the border trap behavior due to a time constant mismatch between both types of traps, as well as the border trap estimation from capacitance-voltage (C-V) hysteresis, which suffers from complete re-emission of captured charge at the C-V reverse sweep. Consequently, it is appropriate to characterize these traps by regarding accumulation frequency dispersion [3,17]. Furthermore, there are already several reports regarding border trap reduction by following some annealing process, although a clear understanding of the annealing ambient is lacking [16][17][18].…”

Gamma‐Ray Irradiation Effect on Ferroelectric Devices with Hafnium Aluminum Oxides

“…We also find that the small variation on hysteresis windows of 9%‐ and 12%‐Al‐doped devices are associated with reduced oxygen vacancies or defects in gate stack due to high‐content Al doping . Although the Al doping into HfO 2 can effectively reduce the defects traps and improve leakage current, it also brings the issue of strong antiferroelectric property affecting the magnitude of 2 P r . Based on our experimental results shown in Figure b, we can observe that 9%‐Al‐doped devices exhibit a correspondingly large and stable hysteresis window under various irradiation doses, which confirms that the higher Al‐doping concentration is beneficial for enhancing the resistant to radiation exposure.…”