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

Abstract

We have investigated the thermal stability of n+ polycrystalline-Si(poly-Si)/ZrO2(50–140 Å)/SiO2(7 Å)/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 ∼12 mV with the flatband voltage of −0.5 V and the interface trap density of ∼5×1010 cm−2 eV−1 were attained with activation anneal at 750 °C. A high level of gate leakage current was observed at the activation temperatures over 750 °C 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 (<50×50 μm2), fortunately, the electrical degradation by further severe silicidation does not occur up to an 800 °C anneal in N2 for 30 min.

Thickness dependence of structural and electrical characteristics of ZrO2 thin films as grown on Si by chemical-vapor deposition

“…It is in- teresting to observe that the effective fixed charge density, (Q SiO x /Si ϩQ ZrO 2 /SiO x ), in the stacked dielectric changes from negative to positive when increasing the film thickness of ZrO 2 above 6.0 nm. A similar sign change of fixed charge was also observed by Houssa et al 15 and Lim et al 33 in the postdeposition oxidation anneal of ZrO 2 /SiO x stacked dielectrics. Houssa et al suggested that the change of fixed charge from negative to positive was caused by the generation of hydrogen-induced overcoordinated oxygen centers by oxidation at high temperature.…”

Impact of Si substrate nitridation on electrical characteristics of Ta2O5stack capacitors

“…Given the weak temperature dependence it is suggested that some kind of tunnelling operates in this case. It is found that the curve is well fitted by a field-assisted tunnelling which is represented by the equation [41,42] J ∝ E 2 t exp − 8π 3h…”

The Effects of Postdeposition Annealing on the Crystallization and Electrical Characteristics of HfO2 and ZrO2 Gate Dielectrics

“…10 Several studies have already reported the effect of postdeposition annealing (PDA) on the insulating properties of HfO 2 and ZrO 2 . 11,12 It has been reported that the PDA generally degrades the dielectric performance (decrease the capacitance density and increase the leakage current) of these films. However, a comparative study of two films deposited by atomic layer deposition (ALD) using similar precursors and process conditions has not been systematically reported.…”