Research On The Structure Of Nitride RRAM Based On Quantum Dots

With the sharp increase in the integration of integrated circuits,the existing memory performance can no longer meet the storage requirements.Currently,the most widely used Flash memory is about to reach its physical limit.There is an urgent need for new non-volatile memory with advantages such as high performance and reliability,low power consumption and cost.Among the many new types of memory,RRAM stands out for its low cost,low power consumption,high speed and good reliability.Al ON-based RRAM has low operating voltage,fast switching speed,excellent reliability,and is compatible with traditional CMOS technology,thus has high research value.However,there is still room for improvement in the electrical parameters of Al ON-based RRAM.In this paper,the performance optimization of Al ON-based RRAM is studied.The performance parameters and conduction mechanism before and after optimization are deeply analyzed and compared.A resistive model is constructed based on experimental phenomena and related theories.The specific research results are as follows:1.The performance improvement of single-layer Al ON-based resistive memory with different insertion positions of PbS QDs films was studied.In this paper,the electrical parameters of the three structural devices were compared and analyzed.The optimized structure was obtained,with explored conduction mechanism and constructed resistance-switching model.In the study of device parameters of three structures,it is found that the PbS QDs/Al ON structure can optimize the operating voltage and current fluctuation of the device to the greatest extent with self-establishment characteristics,which greatly reduces the power consumption of the device and enhances the reliability.The Al ON/PbS QDs structure has an operating voltage opposite to that of the single-layer Al ON device.Secondary SET occurs at a slightly larger V_reset,resulting in an increase of nearly an order of magnitude in the low-resistance state current.In the analysis of the conduction mechanism,it is found that the Al ON/PbS QDs structure has the lowest Schottky barrier height,which provides a reasonable explanation for the above-mentioned secondary SET phenomenon.Finally,according to the material properties and experimental phenomena of PbS QDs,resistive switching models of Al ON-PbS QDs stacked devices are established.The model suggests that the improvement of device performance is mainly due to the local electric field enhancement properties of quantum dots and a large number of suspensions inside the quantum dot film.The conductive channels formed by the bonds affect the voltage and current parameters,respectively.2.In order to further improve the device performance,the parameter optimization ability of different PbS QDs film thickness and device size was investigated based on the PbS QDs/Al ON structure.In the study of film thickness,it is found that the optimization degree of device parameters increases with the film thickness.A trend from increasing to saturation and finally decreasing is observed,and the film thickness threshold corresponding to the saturation point is about 7.5 nm.The optimal film thickness for parameter optimization is about 4.5 nm.At this thickness,the device performance is greatly improved with the highest improved efficiency and the best reliability.Next,a set of optimal parameters for improving the device is studied by combining device size and quantum dot film thickness.The study found that the 500μm size device is compatible with the four film thicknesses involved in this paper.In the 300μm size device,devices has the largest resistive window,while the parameter improvement is not obvious.Although has the best performance,the 100μm size device can only match the film thickness between 1.5～4.5 nm.Due to the narrow matching range of device film thickness,the comprehensive optimization capability is not good as that of 500μm size devices.Finally,a set of optimal parameters including device structure,quantum dot film thickness and device size for optimizing single-layer Al ON devices are compared and analyzed.