Effects of scaling the film thickness on the ferroelectric properties of SrBi2Ta2O9 ultra thin films

We have investigated the effect of reducing the thickness of strontium bismuth tantalate film to as low as 25 nm on its ferroelectric characteristics. A degradation of ferroelectric properties such as significant reduction in remanent polarization is generally observed with reduction in film thickness, in particular below 100 nm. This has been overcome by using a modified deposition process sequence and a crystallization technique based completely on the rapid thermal annealing process. The resulting ultrathin films show good remanent polarization, low-voltage saturation, low leakage current, high breakdown strength, and good endurance. These films demonstrate the potential for scaling and are excellent candidates for several generations of ferroelectric random access memory applications.