Analysis for Evaluation of Threshold Current Density of Electromigration Damage in Taper-Shaped Metal Line

2017 ◽  
Author(s):  
Hiroki Kikuchi ◽  
Kazuhiko Sasagawa ◽  
Kazuhiro Fujisaki
Keyword(s):  
Integrated Circuits ◽  
Current Density ◽  
Evaluation Method ◽  
High Current Density ◽  
Void Formation ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Cathode Side ◽  
Metal Line ◽  
Governing Parameter

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.

Evaluation of Threshold Current Density of Electromigration Damage in Angled Bamboo Lines

2007 ◽  
Author(s):  
Kazuhiko Sasagawa ◽  
Shota Fukushi
Keyword(s):  
Integrated Circuits ◽  
Current Density ◽  
Evaluation Method ◽  
Threshold Current ◽  
Line Length ◽  
Threshold Current Density ◽  
Metal Line ◽  
Governing Parameter ◽  
Scale Down ◽  
Dimensional Shape

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.

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

2005 ◽  
Author(s):  
Kazuhiko Sasagawa ◽  
Shigeo Uno ◽  
Nao Yamaji ◽  
Masumi Saka
Keyword(s):  
Numerical Simulation ◽  
Current Density ◽  
Line Shape ◽  
Evaluation Method ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Two Dimensional ◽  
Metal Line ◽  
Governing Parameter ◽  
Dimensional Shape

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.

Expression of a Governing Parameter for Electromigration Damage on Metal Line Ends

2003 ◽  
Author(s):  
Masataka Hasegawa ◽  
Kazuhiko Sasagawa ◽  
Masumi Saka ◽  
Hiroyuki Abe´
Keyword(s):  
Boundary Condition ◽  
Current Density ◽  
Prediction Method ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Atomic Diffusion ◽  
Metal Line ◽  
Governing Parameter ◽  
Atomic Flux ◽  
Current Input

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.

Numerical Simulation of Threshold Current Density of Electromigration Damage in Cu Interconnect Tree

2009 ◽  
Author(s):  
Kazuhiko Sasagawa ◽  
Akihiko Kirita ◽  
Takehiro Abo ◽  
Abdul Hafiz Nor Hassan
Keyword(s):  
Numerical Simulation ◽  
Integrated Circuits ◽  
Current Density ◽  
Evaluation Method ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Dimensional Structure ◽  
Silicon Integrated Circuits ◽  
Scale Down ◽  
Cu Interconnect

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.

Relationship Between Threshold Current Density of Electromigration Damage Considering Void and Hillock Formation and Reservoir Shape in Interconnect Line

2017 ◽  
Author(s):  
Ryuji Takaya ◽  
Kazuhiko Sasagawa ◽  
Kazuhiro Fujisaki ◽  
Takeshi Moriwaki
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Void Formation ◽  
Threshold Current ◽  
Critical Value ◽  
Threshold Current Density ◽  
Atomic Density ◽  
Density Distributions ◽  
Hillock Formation ◽  
Reservoir Length

Reservoir structures are often constructed in the interconnection to prevent the electromigration damages. In this study, a numerical simulation technique for analyzing the atomic density distributions in the line under high current density was used to evaluate the effects of reservoir length and location on the threshold current density considering void and hillock generations. The threshold current density is determined when the local atomic density in the line reaches the upper critical value for hillock creation or the lower critical value for void generation. Atomic density distributions in the line were simulated when cathode and anode reservoir lengths were changed. The threshold current density considering void formation became higher with longer cathode reservoir and shorter anode reservoir. However, opposite results obtained in the case of hillock formation. It was found that there was an optimum value of reservoir length, corresponding to both critical values of hillock and void initiation.

Numerical Analysis of Allowable Current Density for Electromigration of Interconnect Tree Structure With Reservoir

2015 ◽  
Author(s):  
Kazuhiro Fujisaki ◽  
Hikaru Narita ◽  
Kazuhiko Sasagawa
Keyword(s):  
Integrated Circuits ◽  
Electric Current ◽  
Current Density ◽  
Lower Layer ◽  
High Current Density ◽  
Threshold Value ◽  
Threshold Current ◽  
Tree Structure ◽  
High Current ◽  
Line Material

The high current density induces electromigration (EM) in metal lines used for electric wirings in integrated circuits. The growth of voids formed by EM in the line material leads to the line failure. Recently, multilevel interconnections are widely used in the circuit in electronics devices and MEMS. Metal lines aligned on upper and lower layer are connecting through the vias in the multilevel interconnections. The reservoir structure is often constructed in the line structure to prevent the EM damages. There is a threshold current density relating to the EM damage of the lines in the interconnection with vias. It is important to evaluate the threshold value for determination of an allowable electric current of the line. In this study, a numerical simulation technique for analyzing the atomic density distributions in the line material under high current density was used to evaluate the EM risks of metal lines in the several cases of interconnect tree structure with reservoir. The thresholds of current density leading to EM damage were calculated in the simulations considering the reservoir locations and pattern of electric current flow in the tree.

Low Threshold Current Density (100) GaInAsP/InP Double-Heterostructure Lasers for Wavelength 1.3 µm

1979 ◽  
Vol 18 (9) ◽  
pp. 1795-1805 ◽  
Author(s):  
Yoshio Itaya ◽  
Yasuharu Suematsu ◽  
Shinya Katayama ◽  
Katsumi Kishino ◽  
Shigehisa Arai
Keyword(s):  
Current Density ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Double Heterostructure ◽  
Low Threshold
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