Charge Trapping Behavior in Al2O3-Au Interlayer

초록

Recently, nonvolatile charge storage layer is widely used as for semiconductor gating structure such as flash memory device. A trapping layer and blocking layer in charge storage structure are mostly based on SiN4 and Al2O3, SiO2 respectively. In addition, research for trapping layer using metallic nanoparticles has been reported. In here, we investigated electrical behavior of charge trapping device composed of Au nanocluster, Al2O3 and silicon substrate. To make this device, we firstly deposited 10 nm of Al2O3 on bare silicon wafer with atomic layer deposition method as a tunneling layer. Then Au cluster was formed on Al2O￢3 using thermal evaporator as a charge trapping layer. Finally, we deposited 50 nm of Al2O3 on Au charge trapping layer as a blocking oxide layer. Charge injection process were conducted with conductive atomic force microscopy. Trapped electrons were injected two different shape such as 0D and 1D. After electron was injected into trapping layer with 1D line shape by moving AFM tip with +8V bias, electric potential of surface was measured by Scanning Kelvin Probe Microscopy. It exhibited surface voltage of ~2.1 V in 24 mins. We also conducted 0D-shape process. In this case, it showed surface voltage of ~2.7 V in 24 mins. Analyzing remained charges over time, we found that trapped electrons are exponentially decayed. The Percent of remained charges were found to be inversely proportional to maximum voltage of initial charge injection.