SHH应力下超薄栅氧PMOS器件退化研究

Degradation of PMOSFET with ultra-thin gate oxide under SHH stress

对超薄栅氧PMOS器件衬底热空穴(SHH)应力下SILC(应力感应泄漏电流)特性和机理进行研究。研究结果表明:在SHH应力下,栅电流在开始阶段减小,这是正电荷在氧化层中积累的结果;随后栅电流慢慢地增加,最后,当在氧化层中积累的正电荷密度达到一个临界值时,栅上漏电流迅速跳变到较大数量级上,说明器件被击穿;当注入空穴通过Si—O网络时,随着注入空穴流的增加,化学键断裂的概率增加;当1个Si原子的2个Si—O键同时断裂时,将会导致Si—O网络不可恢复;Si—O键断裂导致氧化层网络结构发生改变和损伤积累,最终导致氧化层破坏性被击穿。

The stress induced leakage current（SILC） characteristic and mechanism in PMOSFET with ultra-thin gate under substrate-hot-hole（SHH） stress were studied.The results show that the gate current decreases with the stress time due to the positive charge buildup in the oxide in the first stage during SHH stress.Then the leakage current increases slowly.And finally,when the density of positive charges accumulated in the oxide reaches a critical value,the gate leakage current rapidly jumps to a larger magnitude and breakdowns occurred in the device.Since the injected holes move through the Si—O network,the probability of the chemical bond breakage increases with the increase of the injected hole flux.The simultaneous breakage of two Si—O bonds in a Si atom leads to irreversible relaxation of the network.The structure of the oxide network changes upon the breakage of the Si—O bonds,and the accumulation of the damage finally leads to the destructive oxide breakdown.