存储器循环擦写耐久性与数据保持可靠性

Reliability of FLASH Program/Erase Cycling and Data-Retention

工艺能力的不断提升使得高密度大容量存储器成为可能,伴随着存储器单元尺寸和芯片面积的不断缩小,介电质绝缘层厚度随之变薄,可靠性窗口不断变小,存储器循环擦写耐久性与长时间数据保持等可靠性问题变得敏感突出,面临严峻挑战。循环擦写耐久性评估存储器的可反复擦写性能,数据保持测试表征存储器在不带电或带电情况下长时间数据保持能力,考核浮栅存储电荷的保持能力。文章通过对存储器擦写耐久性和数据保持测试数据的分析比较,初步探讨了两者的失效机理,最后介绍了影响存储器擦写耐久性和数据保持能力的其他可能因素。

The process integration is greatly developed,which makes it possible to high-density flash memory fabrication,with the memory cell and chip area scaling down,thinner transfer oxide is widely used,flash reliability window constantly decreased,especially the flash reliability issues of endurance and longtime data retention become sensitive and aggressively challenged.Endurance is used to evaluate the flash ability of erase and program repeatedly,while data retention test is used to characterize the ability of device to hold data for a long time without bias or with bias condition,which is assessing the ability of floating gate to hold charge.In this paper,both endurance and data retention test data are compared and analyzed,then the failure mechanism is discussed,and finally the other possible factors that affect endurance and data retention are discussed at the last.