控制氧化层对双势垒纳米硅浮栅存储结构性能的影响

在等离子体增强化学气相沉积(PECVD)系统中，利用逐层淀积非晶硅(a-Si)和等离子体氧化相结合的方法制备二氧化硅(SiO₂)介质层.电容电压(C-V)和电导电压(G-V)测量结果表明：利用该方法在低温(250 ℃)条件下制备的SiO₂介质层均匀致密，其固定氧化物电荷和界面态密度分别为9×10¹¹cm^-2和2×10¹¹cm^-2·eV^-1，击穿场强达4.6 MV/cm，与热氧化形成的SiO₂介质层的性质相当.将该SiO₂介质层作为控制氧化层应用在双势垒纳米硅(nc-Si)浮栅存储结构中，通过调节控制氧化层的厚度，有效阻止栅电极与nc-Si之间的电荷交换，延长存储时间，使存储性能得到明显改善. 关键词： 等离子体氧化 二氧化硅 纳米硅 控制氧化层

Effect of control oxide on the performance of nanocrystalline silicon based double-barrier floating gate memory structure

The silicon dioxide (SiO₂) film was fabricated from layer-by-layer depositing amorphous silicon (a-Si) film combined with step-by-step plasma oxidation in the plasma-enhanced chemical vapor deposition (PECVD) system. The capacitance-voltage(C-V) and conductance-voltage(G-V) characteristics show that the fixed charge and interface state densities of the SiO₂ film are 9×10¹¹ cm^-2 and 2×10¹¹ cm^-2·eV^-1, respectively. Furthermore, the breakdown field strength is as high as 4.6 MV/cm, which is comparable to that formed by hot oxidation. The prepared SiO₂ is employed as control oxide in nc-Si based double-barrier floating gate memory structure and is found to be an effective way to prevent the charge exchange between the gate electrode and nc-Si, which also lead to an enhancement in the retention time. The improved performance of the memory is discussed and is ascribe to the moderate-thickness of SiO₂ as well as its excellent electrical properties.