Key Technologies Based On Organic Ferroelectric Medium Capacity-change Memory

In these years, the developing of information technology requires more and more high performance electrical devices. The inorganic ferroelectric thin-film memory has been in commercial volume production. But a high temperature annealing is required in the integration of inorganic material and silicon device; which can cause inter-diffusion between the ferroelectric material and the silicon. Also the depolarization field was generated as a result of the large difference of the dielectric constant between inorganic material and silicon oxide. While, the dielectric constant of organic material is much lower than that of the inorganic material, then it will not introduce a considerable depolarization field into the device. Comparing with inorganic case, the organic ferroelectric memory has many advantages such as easier integratation, simpler fabrication process and much higher storage density. In this paper for 100nm thickness scale level P(VDF-TrFE) copolymer ferroelectric thin-film, the process and parameters of fabrication and test were determined; the surface topography, XRD and C-V characteristics was measured for quality evaluation; the retention and fatigue characterization for reliability were studied1. The method and process of fabrication and test. The spin-coating was determined as the fabrication method. The electrode was evaporated after annealing. C-V was selected to be the electrical performance charaterization method since SiO2 was introduced as a barrier layer to improve electrical performance.2. The impact of C-V test parameters and the fabrication parameters on the result. It is revealed that there is no impact of OSC amplitude on the result. The sweep time (0s to 10s) has significant impact but the impact disappears while the sweep time is longer than 10s. It is also revealed that the rev of spin-coating has direct proportion with the on-off ratio, but no influence on the window width which is an important parameter to represent the ferroelectricity. Annealing time has direct proportion with both of on-off ratio and the window width. Solution viscosity has inverse proportion with on-off ratio but has direct proportion with window width.3. Quality and reliability analysis. AFM as well as the XRD results both demonstrate the good crystallinity of the thin-film after annealing. After annealing at 140℃, XRD shows the formation ofβphase which has most ferroelecticity. The C-V measurements show the window width has the direct proportion to the DC bias before breakdown, and has the inverse proportion to the DC bias after breakdown. A wide range of working voltage was observed. It is revealed that retention characteristics has the direct proportion to the duration time of written voltage. The fatigue speed has the inverse proportion to the frequency of fatigue voltage, and it is also related to the wave form of fatigue voltage.