I made a capacitor device: 150nm Au/ 50nm Cr/ 50nm HfO2/ 45nm Au/ 5nm Cr/SiO2, where the 150nm Au/ 50nm Cr are top electrodes and 45nm Au itself is the bottom electrode, to test how good the HfO2 is as a gate dielectric The HfO2 was grew by ALD at 100C. However, it is giving a very high electrical leakage (more than 1e-6A at 0.1V) which it is not supposed to be according to literatures. Any help on how I can improve the HfO2 insulating properties will be appreciated (even better if you can provide a reference). Thank you very much!
https://www.researchgate.net/publication/305729376_Effects_of_Ultrasonication_and_Conventional_Mechanical_Homogenization_Processes_on_the_Structures_and_Dielectric_Properties_of_BaTiO3_Ceramics
https://www.researchgate.net/publication/312230608_Dielectric_Properties_of_Nb_doped_BaTiO_3_Ceramics_by_Mechanical_and_Ultrasonic_Deagglomeration?ev=prf_pub
https://www.researchgate.net/publication/312229924_A_Comparison_on_the_Structural_Properties_of_Nb-BaTiO3_Ceramics_Homogenized_Conventional_and_Ultrasonic_Methods
Article Effects of Ultrasonication and Conventional Mechanical Homog...
Presentation Dielectric Properties of Nb doped BaTiO 3 Ceramics by Mechan...
Presentation A Comparison on the Structural Properties of Nb-BaTiO3 Ceram...
Since the current density (A/cm2) is measure of leakage and dielectric quality. So please estimate the top electrode area and estimate the leakage current density. It will give you the exact quality.
Look like your HfO2 film is leaky and conduction, and may be having very fine pinholes.
You can try do post annealing treatment of HfO2 film in air or oxygen after doing your ALD at a certain high temperature (upto 400 deg C). Too high a temperature is not good as it may destroy your underlying Cr/Au electrodes. Anneal your film, and then deposit your top electrode.
Probably a short annealing treatment by rapid thermal annealing methods also can improve the insulating quality of your film, and reduce the leakage currents.
K. Sreenivas
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