Effect of Line-Shape on Threshold Current Density of Electromigration Damage in Bamboo Lines

Author(s):  
Kazuhiko Sasagawa ◽  
Shigeo Uno ◽  
Nao Yamaji ◽  
Masumi Saka

It is known that there is the threshold current density of the electromigration damage in the via-connected line. The evaluation of the threshold current density is one of the great interests from the viewpoint of IC reliability. In this study, a metal line with two-dimensional shape, i.e. an angled metal line is treated. The evaluation method of the threshold current density is applied to the metal line. The method is based on the numerical simulation of the building-up process of the atomic density distribution in the bamboo line by using the governing parameter for electromigration damage. Comparing the evaluated results with that of straight-shaped line, the effect of line-shape on threshold current density of electromigration damage is discussed. Furthermore, the obtained difference in the threshold current density is verified experimentally.


Author(s):  
Kazuhiko Sasagawa ◽  
Shota Fukushi

As silicon integrated circuits (ICs) continue to scale down, several reliability issues have emerged. Electromigration — the transportation of metallic atoms by the electron wind — has been recognized as one of the key damage mechanisms in metallic interconnects. It is known that there is the threshold current density of the electromigration damage in the via-connected line. The evaluation of the threshold current density is one of the great interests from the viewpoint of IC reliability. In this study, metal lines with two-dimensional shape, i.e. angled metal lines are treated. The evaluation method of the threshold current density is applied to the metal line. The method is based on the numerical simulation of the building-up process of the atomic density distribution in the bamboo line by using the governing parameter for electromigration damage. Comparing the evaluated results of the angled line with that of straight-shaped line, the effects of corner position and line length on threshold current density of electromigration damage are discussed.



2007 ◽  
Vol 353-358 ◽  
pp. 2958-2961
Author(s):  
K. Sasagawa ◽  
N. Yamaji ◽  
S. Fukushi

As silicon ICs continue to scale down, several reliability issues have emerged. Electromigration- the transportation of metallic atoms by the electron wind- has been recognized as one of the key damage mechanisms in metallic interconnects. It is known that there is a threshold current density of electromigration damage in via-connected lines. The evaluation of the threshold current density is a matter of the great interest from the viewpoint of IC reliability. In this study, Al polycrystalline lines with two-dimensional shape, i.e. angled lines are experimentally treated for the evaluation. Comparing the experimental result with that of straight-shaped line, the effect of line-shape on the threshold current density of electromigration damage is discussed.



Author(s):  
Hiroki Kikuchi ◽  
Kazuhiko Sasagawa ◽  
Kazuhiro Fujisaki

Metal lines used in integrated circuits (ICs) become narrow for raising the device performance. Due to scaling down of the ICs, current density and Joule heating are increased, which induces electromigration (EM) damage. EM is transportation phenomena of metallic atoms caused by electron wind under high current density. EM leads to hillock and void formation in the metal line, thus EM should be considered to evaluate the performances of the device safe. It is known that a value of threshold current density which is critical current density of the EM damage exists in via-connected and passivated lines. In this study, the effect of line geometry on the threshold current density is discussed in the case of taper-shaped line. The evaluation method of threshold current density is conducted based on numerical simulation technique with building-up processes of atomic density distribution in the metal line by using a governing parameter of EM damage. As the simulation results, threshold current density increased in the cases of shorter line length, lower temperature, and wider width in cathode side. Furthermore, a new parameter was proposed for simplified evaluation of the threshold current density in taper-shaped lines. The evaluation method is able to apply various line shapes and conditions and it is expected to use for confirmation of the reliability of the lines in circuit design processes.





Author(s):  
Masataka Hasegawa ◽  
Kazuhiko Sasagawa ◽  
Masumi Saka ◽  
Hiroyuki Abe´

Recently, a governing parameter for electromigration damage, AFD*gen, was identified and, utilizing the parameter, a prediction method of electromigration failure was developed for the passivated polycrystalline line. The parameter AFD*gen was formulated considering the divergence of atomic flux due to electromigration in grain boundary network, and the boundary condition of metal line ends was not taken into account. So far, therefore, failure prediction was exclusively done for the metal line connected by electric-current input/output pads at both ends, not for the line connected by vias at both ends. It is known that there is threshold current density, jth, below which no electromigration damage appears, in the line connected by vias. In this study, first, a governing parameter for electromigration damage on the ends of passivated polycrystalline line is expressed considering the boundary condition of line ends concerning the atomic diffusion. Next, the way to estimate the threshold current density of the metal line with vias is shown based on the numerical simulation using the governing parameter.



Author(s):  
Kazuhiko Sasagawa ◽  
Akihiko Kirita ◽  
Takehiro Abo ◽  
Abdul Hafiz Nor Hassan

As silicon integrated circuits (ICs) continue to scale down, several reliability issues have emerged. Electromigration — the transportation of metallic atoms by the electron wind — has been recognized as one of the key damage mechanisms in metallic interconnects. It is known that there is the threshold current density of electromigration damage in via-connected line. The evaluation of the threshold current density is one of the great interests from the viewpoint of IC reliability. Recently, the threshold current density in interconnect tree was evaluated. However, it might not be so accurate because of evaluation of two-dimensional structure by combining one-dimensional analysis. In this study, the evaluation method of the threshold current density based on the numerical simulation is applied to several kinds of interconnect tree.





Sign in / Sign up

Export Citation Format

Share Document