Simulations of Dislocation Dynamics in Aluminum Interconnects

2002 ◽  
Vol 731 ◽  
Author(s):  
Lucia Nicola ◽  
Erik Van der Giessen ◽  
Alan Needleman
Keyword(s):  
Thermal Stress ◽  
Cross Section ◽  
Dislocation Dynamics ◽  
Local Concentration ◽  
Small Cross Section ◽  
Discrete Dislocation ◽  
Thermal Stress Field ◽  
Strain Formulation ◽  
Edge Dislocations ◽  
Aluminum Interconnects

AbstractA discrete dislocation simulation of plastic deformation in metallic interconnects caused by thermal stress is carried out. The calculations are carried out using a two dimensional plane strain formulation with only edge dislocations. A boundary value problem is formulated and solved for the evolution of the thermal stress field and the evolution of the dislocation structure in the cross-section of the line as cooling proceeds. For lines with a small cross section (height or width less than 1 μm), the local concentration of stresses due to dislocation patterning strongly affects the overall stress build up and relaxation. The results show a clear dependence of the transverse stress development on the line aspect ratio.

Plasticity in Polycrystalline Thin Films: a 2D Dislocation Dynamics Approach

2003 ◽  
Vol 779 ◽  
Author(s):  
Lucia Nicola ◽  
Erik Van der Giessen ◽  
Alan Needleman
Keyword(s):  
Thin Films ◽  
Dislocation Dynamics ◽  
Stress Evolution ◽  
Polycrystalline Thin Films ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Strain Formulation ◽  
The Difference ◽  
Film Substrate ◽  
Edge Dislocations

AbstractThermal stress evolution in polycrystalline thin films is analyzed using discrete dislocation plasticity. Stress develops in the film during cooling from a stress-free configuration due to the difference in thermal expansion coefficient between the film and its substrate. A plane strain formulation with only edge dislocations is used and each grain of the polycrystal has a specified set of slip systems. The film–substrate interface and the grain boundaries are impenetrable for the dislocations. Results are presented for two film thicknesses, with higher hardening seen for the thinner films.

scholarly journals Relaxation of Thermal Stress by Dislocation Motion in Passivated Metal Interconnects

2004 ◽  
Vol 19 (4) ◽  
pp. 1216-1226 ◽  
Author(s):  
Lucia Nicola ◽  
Erik Van der Giessen ◽  
Alan Needleman
Keyword(s):  
Dislocation Motion ◽  
Slip Systems ◽  
Stress Evolution ◽  
Discrete Dislocation ◽  
Passivation Layers ◽  
Strain Formulation ◽  
On Line ◽  
Pitch Length ◽  
Metal Interconnects ◽  
Edge Dislocations

The development and relaxation of stress in metal interconnects strained by their surroundings (substrate and passivation layers) is predicted by a discrete dislocation analysis. The model is based on a two-dimensional plane strain formulation, with deformation fully constrained in the line direction. Plastic deformation occurs by glide of edge dislocations on three slip systems in the single-crystal line. The substrate and passivation layers are treated as elastic materials and therefore impenetrable for the dislocations. Results of the simulations show the dependence of the stress evolution and of the effectiveness of plastic relaxation on the geometry of the line. The dependence of stress development on line aspect ratio, line size, slip plane orientation, pitch length, and passivation layer thickness are explored.

Effect of Plastic Flattening on the Shearing Response of Metal Asperities: A Dislocation Dynamics Analysis

2015 ◽  
Vol 82 (7) ◽  
Author(s):  
Fengwei Sun ◽  
Erik Van der Giessen ◽  
Lucia Nicola
Keyword(s):  
Shear Stress ◽  
Contact Area ◽  
Dislocation Dynamics ◽  
Dynamics Analysis ◽  
Rectangular Shape ◽  
Lower Shear ◽  
Discrete Dislocation ◽  
Plastic Shearing ◽  
Edge Dislocations

Discrete dislocation (DD) plasticity simulations are carried out to investigate the effect of flattening and shearing of surface asperities. The asperities are chosen to have a rectangular shape to keep the contact area constant. Plasticity is simulated by nucleation, motion, and annihilation of edge dislocations. The results show that plastic flattening of large asperities facilitates subsequent plastic shearing, since it provides dislocations available to glide at lower shear stress than the nucleation strength. The effect of plastic flattening disappears for small asperities, which are harder to be sheared than the large ones, independently of preloading. An effect of asperity spacing is observed with closely spaced asperities being easier to plastically shear than isolated asperities. This effect fades when asperities are very protruding, and therefore plasticity is confined inside the asperities.

scholarly journals Diffusion and interaction of prismatic dislocation loops simulated by stochastic discrete dislocation dynamics

2019 ◽  
Vol 3 (7) ◽  
Author(s):  
Yang Li ◽  
Max Boleininger ◽  
Christian Robertson ◽  
Laurent Dupuy ◽  
Sergei L. Dudarev
Keyword(s):  
Dislocation Dynamics ◽  
Dislocation Loops ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation

Case Analysis on PTH Fracture Caused by Twin Copper

2014 ◽  
Vol 1061-1062 ◽  
pp. 431-435
Author(s):  
Xiao He
Keyword(s):  
Thermal Analysis ◽  
Thermal Stress ◽  
Theoretical Analysis ◽  
Cross Section ◽  
Current Density ◽  
Case Analysis ◽  
Actual Case ◽  
Soldering Process ◽  
Root Cause ◽  
Section Analysis

An actual case of PTH fracture after soldering process was studied. By means of cross section analysis using metallography microscope and SEM, together with thermal analysis results, root cause of PTH fracture was concluded that a high density of twin copper weakened the mechanical strength so seriously that PTHs could not undergo thermal stress from soldering process, and higher CTE was attributed to an accelerative factor. Moreover, it is recommended to enhance current density properly and make sure the effectiveness of electroplating additives to prevent twin copper by theoretical analysis.

Plastic Ploughing of a Sinusoidal Asperity on a Rough Surface

2015 ◽  
Vol 82 (7) ◽  
Author(s):  
H. Song ◽  
R. J. Dikken ◽  
L. Nicola ◽  
E. Van der Giessen
Keyword(s):  
Friction Stress ◽  
Dislocation Dynamics ◽  
Two Dimensional ◽  
Unit Process ◽  
Contact Models ◽  
Self Similar ◽  
Dynamics Simulations ◽  
Micrometer Scale ◽  
Edge Dislocations ◽  
Flat Contact

Part of the friction between two rough surfaces is due to the interlocking between asperities on opposite surfaces. In order for the surfaces to slide relative to each other, these interlocking asperities have to deform plastically. Here, we study the unit process of plastic ploughing of a single micrometer-scale asperity by means of two-dimensional dislocation dynamics simulations. Plastic deformation is described through the generation, motion, and annihilation of edge dislocations inside the asperity as well as in the subsurface. We find that the force required to plough an asperity at different ploughing depths follows a Gaussian distribution. For self-similar asperities, the friction stress is found to increase with the inverse of size. Comparison of the friction stress is made with other two contact models to show that interlocking asperities that are larger than ∼2 μm are easier to shear off plastically than asperities with a flat contact.

Sign in / Sign up

Export Citation Format

Share Document