Three-dimensional finite element calculations of thermal stress in aluminum interconnect with tungsten via-studs

Lloyd G. Burrell; Amit X. Kapur

doi:10.1117/12.145479

21 May 1993 Three-dimensional finite element calculations of thermal stress in aluminum interconnect with tungsten via-studs

Lloyd G. Burrell, Amit X. Kapur

Author Affiliations +

Proceedings Volume 1805, Submicrometer Metallization: Challenges, Opportunities, and Limitations; (1993) https://doi.org/10.1117/12.145479
Event: Microelectronic Processing '92, 1992, San Jose, CA, United States

Abstract

The multilevel interconnect to be investigated consist of a first level aluminum line (M1) connected to a second level aluminum line (M2) by a tungsten via-stud (S1). In the manufacturing process, thermal voiding is often observed in passivated aluminum lines near the via-stud. The purpose of this work is to calculate the thermal stresses in a typical passivated multilevel metal-stud-metal structure using the finite element method. Variations of stresses with the tungsten via-stud intersect area, height, and its alignment with respect to M1 have been considered. It is shown that the local stresses in the aluminum line (M1) increase by 25%, the maxima located under the tungsten via-stud. The stresses further increase if the via- stud is misaligned to abut the end of the line. The average stress in the line is not significantly influenced by variation in stud dimensions of 30% about the nominal case, indicating that the stress response is dominated by the passivation. Higher stresses are calculated for SiN_x passivation as compared to SiO₂ since the former is twice as stiff.

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Lloyd G. Burrell and Amit X. Kapur "Three-dimensional finite element calculations of thermal stress in aluminum interconnect with tungsten via-studs", Proc. SPIE 1805, Submicrometer Metallization: Challenges, Opportunities, and Limitations, (21 May 1993); https://doi.org/10.1117/12.145479

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