Stress-driven diffusive voiding of aluminum conductor lines

The trend to miniaturize silicon integrated circuits has brought with it a thermal stress-induced void formation problem in the aluminum conductor lines of these circuits. Here, local stress relaxation has been included quantitatively in the construction of a wedge-like void growth model. It is shown that under stress relaxation conditions, the stress-induced grain boundary diffusion equation transforms into the diffusion equation. With the use of appropriate boundary conditions and the initial conductor line stress profile, the diffusion equation is solved numerically. This solution yields the temporal history of void size and local stress. It is shown that two types of stress relaxation moderate and limit the growth of voids. From this analysis, a useful expression which relates final void size and initial stress is derived. With these results conservative estimates of the lifetime of aluminum conductor lines can be made.<<ETX>>

[1]  G. Hill,et al.  Silicon Inclusions in Aluminum Interconnects , 1984, 22nd International Reliability Physics Symposium.

[2]  R. A. Oriani,et al.  The Thermodynamics of Stressed Solids , 1966 .

[3]  Steven B. Herschbein,et al.  Effect of Silicon Inclusions on the Reliability of Sputtered Aluminum-Silicon Metallization , 1984, 22nd International Reliability Physics Symposium.

[4]  T. Turner,et al.  The Influence of Stress on Aluminum Conductor Life , 1985, 23rd International Reliability Physics Symposium.

[5]  R. Stevens Grain boundary sliding and diffusion creep , 1972 .

[6]  R.V. Taylor,et al.  Stress Induced Voids in Aluminum Interconnects During IC Processing , 1985, 23rd International Reliability Physics Symposium.

[7]  Conyers Herring,et al.  Diffusional Viscosity of a Polycrystalline Solid , 1950 .

[8]  Jon Klema,et al.  Reliability Implications of Nitrogen Contamination During Deposition of Sputtered Aluminum/Silicon Metal Films , 1984, 22nd International Reliability Physics Symposium.

[9]  H. Koyama,et al.  Suppression of Stress Induced Aluminum Void Formation , 1986, 24th International Reliability Physics Symposium.

[10]  Robert E. Jones Line Width Dependence of Stresses in Aluminum Interconnect , 1987, 25th International Reliability Physics Symposium.

[11]  J. Curry,et al.  New Failure Mechanisms in Sputtered Aluminum-Silicon Films , 1984, 22nd International Reliability Physics Symposium.