Direct integration of ferroelectric La-Sr-Co-O/Pb-Nb-Zr-Ti-O/La-Sr-Co-O capacitors on silicon with conducting barrier layers

The growth of a polycrystalline La-Sr-Co-O/Pb-Nb-Zr-Ti-O/La-Sr-Co-O ferroelectric capacitor heterostructure is demonstrated on platinized conducting barrier layers of TiN/poly-Si/Si substrate for integration into high density nonvolatile memory (HDNVM). The concept of conducting bottom layers allows the realization of three-dimensional stacked capacitor-transistor geometry with a direct contact to the memory capacitor, occupying significantly less area on the chip required for HDNVM application. The growth of the ferroelectric heterostructure is achieved at a low temperature of 500-550°C, compatible with existing Si based technology, without losing the structural and phase integrity of the ferroelectric stack and conducting bottom layers. The fatigue-free characteristics up to 1011 cycles at room temperature and 100°C, imprint test and good retaining capability evaluated on these capacitors prove their suitability for HDNVM devices. © 1996 American Institute of Physics.