Stress evolution due to electromigration in confined metal lines

Abstract

Articles you may be interested inThe effects of the stress dependence of atomic diffusivity on stress evolution due to electromigration Stress evolution during stress migration and electromigration in passivated interconnect lines AIP Conf. Proc. 305, 231 (1994); 10.1063/1.45694 Microstructure based statistical model of electromigration damage in confined line metallizations in the presence of thermally induced stressesElectromigration is an important concern in very large scale integrated circuits. In narrow, conilned metal interconnects used at the chip level, the electromigration flux is resisted by the evolution of mechanical stresses in the interconnects. Solutions for the differential equation governing the evolution of back stresses are presented for several representative cases, and the solutions are discussed in the light of experimental as well as theoretical developments from the literature.

Modeling the electromigration failure time distribution in short copper interconnects

“…This is not that much of an issue here as it is the shape of the distribution that is important here. The main assumptions regard the use of the stress evolution model of Korhonen et al, 24 which has been used many times in the past to examine EM behavior and seems a reasonable choice here and also the choice of the distribution of diffusivity values. Here this involved fast and slow distributions with probabilities ͑1− p͒ and p, respectively.…”

“…In addition the stress which develops in the line during the nucleation phase determines the start condition for the growth phase. Stresses are assumed to evolve according to the 1D model of Korhonen et al 24 which may be written, in dimensionless units, as…”

X-ray microdiffraction study of Cu interconnects

“…[9][10][11][12][13] However, experimental verification is very difficult mainly because of the challenge of stress measurement in the extremely small volumes of lines with micron or submicron spatial resolution. In addition, interconnect lines must be studied in a realistic IC environment, thus limiting the applicability of surface sensitive techniques 14,15 since the complex structure requires a probe capable of penetrating several microns of dielectrics while maintaining a good spatial resolution.…”

Measurement of strain in Al–Cu interconnect lines with x-ray microdiffraction

“…[6][7][8][9][10] However, experimental verification has proved more difficult mainly because of the difficulty of stress measurement with micron or submicron scale spatial resolution. Indirect measurements have concentrated on measurement of stress through its effects on the substrate material such as Raman spectroscopy 11 and transistor gain modification.…”