Results
Results
In Stage 2 - Deposition and Characterization of Thin Ferroelectric Films, all proposed objectives were achieved:
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Deposits of ferroelectric films (NiO:N, HfO2, HfO2:Zr, and HfO2:Y) and oxide films (NiO) were successfully made;
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To assess the properties of the ferroelectric materials used, as well as their relationships and influence, two types of devices were created: ferroelectric storage capacitive structures (MIMIM) and field-effect ferroelectric structures (FeFET);
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A meticulous analysis of the influence of process parameters was conducted, establishing optimal parameters for obtaining materials with the desired properties;
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Specifications for DM1 and DM2 were defined during the progress of obtaining ferroelectric materials with the desired properties;
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For Zr:HfO2/NiO:N/Ni/NiO:N/Zr:HfO2 heterostructures with a thickness of 7 nm for HfZrO2 layers, a sharp current jump was observed in the I-V curves, suggesting a strong reversible phase transition from an insulating to a conducting state. The device, once modeled according to requirements, can be used as a switch in future logic circuits or as a short-term capacitive storage device;
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High memory window values were obtained for the NiO:N/Al2O3 device (MW=6.7V) and NiO/HfO:Y/Al2O3 device (MW=3.4V), enabling the storage of a broader spectrum of information or clearer distinction between different memory states;
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Very good subthreshold values SS = ∂VG/(logID) of 43 mV/decade in the abrupt region of ID–VG characteristics were achieved for NiO:N/Al2O3 devices and 61 mV for NiO/HfO/Al2O3 devices;
During Stage 1 - Realization of the technological design, characterization of the thin ferroelectric films deposited and creation of the project web page, all the proposed objectives were achieved:
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The technological design of the demonstrator 1 (DM1) and the demonstrator 2 (DM2) were realized (Fig. 1)
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Fig. 1. Design for a) demonstrator 1 and b) demonstrator 2 |
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The technological workflow of the test structures based on ferroelectric films (NiO:N and HfO2:ZrO) has been designed, taking into account the optimal parameters of the materials resulting from Activity A1.1. Within this activity, the corresponding photolithographic mask set was also designed and implemented, and a sheet regarding the evaluation of technological risks based on the NPR risk index using the Failure Mode and Effects Analysis (FMEA) method was created.
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The NiO:N and Hf2:ZrO films were deposited on titanium nitride (TiN) through radiofrequency reactive sputtering and atomic layer deposition (ALD) techniques.
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The ferroelectric films obtained so far in Activity I.3 have been characterized morphologically (Surface Topography - AFM), structurally (X-ray Diffraction - XRD, X-ray Reflectometry - XRR), and their dielectric and ferroelectric properties have been evaluated (polarization measurements).
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