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Abstract

This work deals with the modeling and the simulation of ferroelectric non-volatile memory cells. Their design strategy utilizes the hysteresis in the $D/E$ characteristics that occurs in some of the perovskite type crystals. These devices are the most promising alternative to standard non-volatile memories like EPROM, EEPROM and Flash, primarily because of their drastically lower energy consumption and the easier write access.

The basic purpose of this work was to find models for a rigorous analysis of this new type of storage devices and their implementation into the device simulator MINIMOS-NT. Starting from an analysis of existing models, suitable approaches that match the constraints of two-dimensional device simulation were developed. These include algorithms for single crystals as well as for structures built by a large number of arbitrarily oriented grains.

In addition to the development and implementation of these two-dimensional algorithms, also transient properties are thoroughly investigated, and a new model based on differential equations was introduced. This model offers an excellent fit to the measured data for a frequency range from zero up to 1MHz.

Special care was taken regarding the implementation of the new models into the device simulator MINIMOS-NT. Following the generic approach of MINIMOS-NT a modular concept was found that will also be easily extendable to future simulation tasks, which is absolutely necessary as the knowledge about ferroelectric materials and the possible applications is still increasing.

In order to demonstrate possible applications of the new tools a series of concrete examples is provided. One of these examples builds a bridge from two-dimensional device geometry to circuit simulation, another one allows deep insight into the field properties inside an anisotropic crystal. The last example serves as the first profound analysis of a new, very promising nonvolatile memory cell, the ferroelectric field effect transistor (FEMFET), and several critical issues concerning device performance and reliability are pointed out.


next up previous contents
Next: Acknowledgment Up: diss Previous: Kurzfassung   Contents
Klaus Dragosits
2001-02-27