Time dependent dielectric breakdown (TDDB) is a major concern for newly emerging low-k organosilicate (SiCOH) dielectrics. TDDB degradation can be caused by changes in electrical, chemical, and mechanical properties of the dielectric materials.[i] [ii] [iii] [iv] In order to examine the effect of plasma exposure on TDDB degradation, time-to-breakdown measurements were made on porous SiCOH before and after exposure to a variety of plasma exposure conditions. Plasma parameters were changed between exposures such that each sample was subjected to different charged particle and vacuum ultraviolet photon fluxes in order to determine how TDDB degradation was affected by each of them during plasma exposure. By utilizing a capillary-array window to separate charged particle and photon bombardment, it is possible to show that each process is responsible for causing different types of TDDB degradation.

 

A constant voltage TDDB measurement technique was implemented to analyze unexposed, VUV-irradiated and plasma (charged-particle and photon bombardment) exposed samples to examine the degradation in TDDB. It was observed that the time to breakdown reduces as the electric field stress in increased, which is consistent with what has been previously predicted. It was also found that the unexposed samples exhibit longer time-to-breakdown, indicating highest reliability. Capillary-array-window covered samples exhibited marked degradation in leakage currents and time-to-breakdown relative to the unexposed samples. However, samples exposed to both charged particle and VUV photon bombardment exhibited the most significant degradation, resulting in substantially reduced breakdown times and increased leakage currents. Thus both charged particle and photon bombardment degrade TDDB.

 

This work has been supported by the Semiconductor Research Corporation under Contract 2008-KJ-1871 and by the National Science Foundation under Grant CBET-1066231.

 

[i] E. T. Ogawa, J. Kim, G. S. Haase, H. C. Mogul, and J. W. McPherson, Proc. IEEE Int. Rel. Physics Symp., p. 166. (2003)

[ii] Kok-Yong Yiang, H. W. Yao, A. Marathe, and O. Aubel, Reliability Physics Symposium Proceedings, 44th Annual IEEE International (2009).

[iii] F. Chen, O. Bravo, K. Chanda, P. McLaughlin, T. Sullivan, J. Gill, J. Lloyd, R. Kontra, J. Aitken, Reliability Physics Symposium Proceedings, 44th Annual IEEE International (2006)

[iv] C. Guedj, E. Martinez and G. Imbert, Mater. Res. Soc. Symp. Proc. 990 (2007)