ANALYSIS OF THE DEGRADATION OF PZT AND SRBI2TA2O9 THIN-FILMS WITH A REDUCTIVE PROCESS

Electrical properties, crystal structure and composition were analyzed about ferroelectric PZT and SET thin films with a reductive heat trea tment. PZT films annealed in the atmosphere containing H-2 turned into paraelectric, while SET films were shorted. Ferroelectricity of these degraded films recovered by a subsequent anneal in oxygen. Oxygen con tent in PZT and SET films decreased by the reductive heat treatment an d was compensated by the subsequent anneal in oxygen. Residual hydroge n was also detected in reduced SBT films. The loss of ferroelectricity or short of capacitor would be due to the oxygen defects and the resi dual hydrogen in ferroelectric thin films. A TiN layer covering ferroe lectric capacitors acted as an Hz barrier. Pt top electrode also playe d a role in preventing the reduction. This effect was enhanced by usin g a Pt electrode thicker than 300 nm and by anneal it at 600 degrees C .