Length Dependence Effect in 40nm Cu Low-k Dielectric Breakdown

• Main Authors: Song, Zhuo, Han, Kun, Zhang, Liwen, Atman, Zhao Y., Wang, York
• Format: Conference Proceeding
• Language: English
• ISSN: 1938-5862; 1938-6737
• DOI: 10.1149/1.3694441

Voltage breakdown (Vbd) and time-dependent dielectric breakdown (TDDB) of low-k dielectrics is considered as a key reliability concern for advanced technologies. The lifetime projection to a real chip application requires a more accurate model to avoid over-optimistic or over- conservative result. Length dependence, a study aimed to clarify the relationship between time to fail (TTF) on test structures experimental and lifetime extrapolated on chip wideness level, can not be treated simply by area scaling with Weibull distribution slope due to obvious slope change among structures along with various lengths (and also Weibull slope less than 1 sometimes). Based on Vbd and TDDB test result with various structures of 40nm low-k dielectrics (k~2.75), this work illustrates the effect of the test structure length which alters the Weibull distribution as well as lifetime. By theoretical and experimental analysis, line edge roughness (LER) is taken as the dominated factor to this length dependence effect.