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介绍了当今业界流行的两种隧穿氧化层淀积预清洗工艺:改进的RCA预清洗工艺以及HF-last预清洗工艺。通过实验对比各自优缺点,分析差异产生的根本原因。相对于改进的RCA预清洗工艺,HF-last预清洗工艺使SONOS存储器阈值电压窗口增大约600mV。但可靠性测试结果表明,HF-last工艺会降低器件的耐烘烤和耐擦写循环能力。进一步的电荷泵对比实验结果表明,HF-last工艺引起的耐烘烤和耐擦写循环能力的降低,分别由Si-SiO2界面态增加和隧穿氧化层变薄引起。
Two popular pre-cleaning tunneling oxide tunneling processes are introduced in the industry today: the improved RCA pre-cleaning process and the HF-last pre-cleaning process. By comparing the advantages and disadvantages of each experiment, the root causes of the differences are analyzed. Compared to the improved RCA pre-cleaning process, the HF-last pre-cleaning process increases the SONOS memory threshold voltage window by about 600mV. However, the reliability test results show that the HF-last process will reduce the ability of the device to resist baking and rewinding cycles. Further charge-pump comparison results show that the reduction of resistance to baking and flash-proof cycling caused by HF-last process is caused by the increase of Si-SiO2 interfacial states and the thinning of the tunneling oxide layer, respectively.