1/f noise measurements for faster evaluation of electromigration in advanced microelectronics interconnections

Abstract

The use of 1/f noise measurements is explored for the purpose of finding faster techniques for electromigration (EM) characterization in advanced microelectronic interconnects, which also enable a better understanding of its underlying physical mechanisms. Three different applications of 1/f noise for EM characterization are explored. First, whether 1/f noise measurements during EM stress can serve as an early indicator of EM damage. Second, whether the current dependence of the noise power spectral density (PSD) can be used for a qualitative comparison of the defect concentration of different interconnects and consequently also their EM lifetime t50. Third, whether the activation energies obtained from the temperature dependence of the 1/f noise PSD correspond to the activation energies found by means of classic EM tests. In this paper, the 1/f noise technique has been used to assess and compare the EM properties of various advanced integration schemes and different materials, as they are being explored by the industry to enable advanced interconnect scaling. More concrete, different types of copper interconnects and one type of tungsten interconnect are compared. The 1/f noise measurements confirm the excellent electromigration properties of tungsten and demonstrate a dependence of the EM failure mechanism on copper grain size and distribution, where grain boundary diffusion is found to be a dominant failure mechanism.

Low-Frequency Electronic Noise in Quasi-1D TaSe3 van der Waals Nanowires

“…Table I summarizes the electromigration activation energy estimated using the 1/f noise measurements for different interconnects. The values of the electromigration activation energy for the Cu and Al interconnects determined from the 1/f noise measurements are 0.76-1.10 eV and 0.67-1.14 eV, respectively [21,22,24,38,39]. Our data suggest that quasi-1D TaSe3 nanowires have similar EA values.…”

“…The inset to Figure 4 shows the resistivity change in the temperature range from 298 K to 450 K. The gradual and relatively slow resistance increase below 420 K is due to increasing electron-phonon scattering, which is common in metals. The sharp increase in resistance at the temperatures above 420 K is likely related to the onset of electromigration as commonly observed in the conventional interconnect reliability tests [24,34]. The TaSe3 nanowire noise spectral density and the frequency exponent  rapidly grows with temperature (see Figure 4).…”

“…The frequency dependence and temperature characteristics of the spectral density of the low-frequency noise have been used as reliability metrics for interconnects in Si complementary metal-oxide-semiconductor (CMOS) technology. The low-frequency noise data at elevated temperatures are directly correlated with the electromigration failure mechanisms in interconnects [22][23][24]. It was suggested that the low-frequency noise at high temperatures originates from the vacancy migration along the grain boundaries [22,25].…”

“…where A is a constant, j is the biasing current density and EA is the activation energy related to [21,23,24,37]. The noise measurements have specific advantages over the conventional reliability tests, which require time-dependent resistance measurements of interconnects under high temperature and high current stress for long periods of time (typically from 10 to 100 hours for each set).…”

“…They are also be non-destructive. It was found that the noise level often increases rapidly before the sharp resistance increase, which was defined as the interconnect failure [24]. Figure 6 shows the Arrhenius plot of T×SI/I 2 vs. 1000/T for f=10 Hz.…”