Electrical characteristics and thermal stability of n+ polycrystalline-Si/ZrO2/SiO2/Si metal-oxide-semiconductor capacitors

We have investigated the thermal stability of n(+) polycrystalline-Si(poly-Si)/ZrO2(50-140 Angstrom)/SiO2(7 Angstrom)/p-Si metal-oxide-semiconductor (MOS) capacitors via electrical and material characterization. The ZrO2 gate dielectric was prepared by atomic layer chemical vapor deposition using ZrCl4 and H2O vapor. Capacitance-voltage hysteresis as small as similar to 12 mV with the flatband voltage of -0.5 V and the interface trap density of similar to 5x10(10) cm(-2) eV(-1) were attained with activation anneal at 750 degreesC. A high level of gate leakage current was observed at the activation temperatures over 750 degreesC and attributed to the interfacial reaction of poly-Si and ZrO2 during the poly-Si deposition and the following high temperature anneal. Because of this, the ZrO2 gate dielectric is incompatible with the conventional poly-Si gate process. In the MOS capacitors having a smaller active area (<50x50 <mu>m(2)), fortunately, the electrical degradation by further severe silicidation does not occur up to an 800 degreesC anneal in N-2 for 30 min. (C) 2002 American Institute of Physics.