Asymmetrically structured memory cells and a fabrication method are
provided. The method comprises: forming a bottom electrode; forming an
electrical pulse various resistance (EPVR) first layer having a
polycrystalline structure over the bottom electrode; forming an EPVR
second layer adjacent the first layer, with a nano-crystalline or
amorphous structure; and, forming a top electrode overlying the first and
second EPVR layers. EPVR materials include CMR, high temperature super
conductor (HTSC), or perovskite metal oxide materials. In one aspect, the
EPVR first layer is deposited with a metalorganic spin coat (MOD) process
at a temperature in the range between 550 and 700 degrees C. The EPVR
second layer is formed at a temperature less than, or equal to the
deposition temperature of the first layer. After a step of removing
solvents, the MOD deposited EPVR second layer is formed at a temperature
less than, or equal to the 550 degrees C.