Analysis of Geometrical and Microstructural Effects on Void Formation in Metallization: Observation and Modelling

1996 ◽  
Vol 428 ◽  
Author(s):  
W. C. Shih ◽  
A. Ghiti ◽  
K. S. Low ◽  
A. L. Greer ◽  
A. G. O'Neill ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Void Formation ◽  
Grain Structure ◽  
Flux Divergence ◽  
Damage Development ◽  
Temperature Variations ◽  
Atomic Flux ◽  
Grain Structures ◽  
Microstructural Effects

AbstractThis paper reports the analysis of geometrical and microstructural effects on void formation in interconnects. Ion-beam machining is used to define segments for study at the cathode end of test lines. Scanning electron microscopy is used to observe damage development, focused ion beam microscopy to observe the corresponding grain structure. Finite-element calculations of self-consistent current density and temperature distributions in the conductor are used to predict damage locations both for a continuum material and for simulated grain structures. Cross-section changes in the line give temperature variations leading to divergences in atomic flux. Regions of high flux divergence are favoured for electromigration damage, but the precise sites of damage are determined by the grain structure, as shown both in the experiment and in the modelling.

Characterization of Plated Cu Thin Film Microstructures

1999 ◽  
Vol 564 ◽  
Author(s):  
L. M. Gignac ◽  
K. P. Rodbel ◽  
C. Cabral ◽  
P. C. Andricacos ◽  
P. M. Rice ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Grain Structure ◽  
Grain Structures ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Gaussian Fit ◽  
Cu Thin Film ◽  
Log Normal ◽  
Electron Imaging

AbstractElectroplated Cu was found to have a fine as-plated microstructure, 0.05 ± 0.03 μm, with multiple grains through the film thickness and evidence of twins and dislocations within grains. Over time at room temperature, the grains grew to greater than 1 μm in size. Studied as a function of annealing temperature, the recrystallized grains were shown to be 1.6 ± 1.0 μm in size, columnar and highly twinned. The grain growth was directly related to the time dependent decrease in sheet resistance. The initial grain structure was characterized using scanning transmission electron microscopy (STEM) from a cross-section sample prepared by a novel focused ion beam (FIB) and lift-out technique. The recrystallized grain structures were imaged using FIB secondary electron imaging. From these micrographs, the grain boundary structures were traced, and an image analysis program was used to measure the grain areas. A Gaussian fit of the log-normal distribution of grain areas was used to calculate the mean area and standard deviation. These values were converted to grain size diameters by assuming a circular grain geometry.

Characterization of Plated Cu Thin Film Microstructures

1999 ◽  
Vol 562 ◽  
Author(s):  
L. M. Gignac ◽  
K. P. Rodbell ◽  
C. Cabral ◽  
P. C. Andricacos ◽  
P. M. Rice ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Grain Structure ◽  
Grain Structures ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Gaussian Fit ◽  
Cu Thin Film ◽  
Log Normal ◽  
Electron Imaging

ABSTRACTElectroplated Cu was found to have a fine as-plated microstructure, 0.05 ±0.03 μm, with multiple grains through the film thickness and evidence of twins and dislocations within grains. Over time at room temperature, the grains grew to greater than 1 μm in size. Studied as a function of annealing temperature, the recrystallized grains were shown to be 1.6 ± 1.0 μm in size, columnar and highly twinned. The grain growth was directly related to the time dependent decrease in sheet resistance. The initial grain structure was characterized using scanning transmission electron microscopy (STEM) from a cross-section sample prepared by a novel focused ion beam (FIB) and lift-out technique. The recrystallized grain structures were imaged using FIB secondary electron imaging. From these micrographs, the grain boundary structures were traced, and an image analysis program was used to measure the grain areas. A Gaussian fit of the log-normal distribution of grain areas was used to calculate the mean area and standard deviation. These values were converted to grain size diameters by assuming a circular grain geometry.

Direct Correlation Between Grain Configuration and Electromigration Damage Development

1996 ◽  
Vol 428 ◽  
Author(s):  
W. C. Shih ◽  
A. Ghiti ◽  
K. S. Low ◽  
A. L. Greer ◽  
A. G. O'Neill ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Boundary Misorientation ◽  
Concentration Gradients ◽  
Damage Development ◽  
Cu Content ◽  
Grain Structures ◽  
Simulation Based ◽  
Atom Migration ◽  
First Time

AbstractThe development of electromigration-induced voids and hillocks in Al - 4 wt. % Cu interconnects is monitored by scanning electron microscopy during interrupted testing and is correlated directly with the actual grain configuration including precipitates. The short segments under study and their grain structures are defined and observed using focused ion beam microscopy. The Cu content in precipitate grains is swept away before electromigration damage, and at most such grains there is subsequent grain thinning. The observations are compared with the results from a computer simulation based on a finite-element calculation of self-consistent current density and temperature distributions. For the first time the simulation uses the actual grain configuration and incorporates Cu atom migration, and back-fluxes driven by stress and concentration gradients. In the simulation the grain-boundary diffusivity is taken to be independent of boundary misorientation or is varied according to randomly assigned orientations. The comparison of the voiding in these two simulated cases and the observations shows that some grain configurations are very susceptible to electromigration damage whatever the diffusivities. For most configurations, however, the misorientation dependence of grainboundary diffusivity is significant and must be included if simulations are to be realistic.

3D-EBSD Studies of Deformation, Recrystallization and Phase Transformations

2012 ◽  
Vol 715-716 ◽  
pp. 41-50 ◽  
Author(s):  
Michael Ferry ◽  
Wan Qiang Xu ◽  
M. Zakaria Quadir ◽  
Nasima Afrin Zinnia ◽  
Kevin J. Laws ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Thermomechanical Processing ◽  
Electron Backscatter Diffraction ◽  
Ion Beam ◽  
Void Formation ◽  
Data Generation ◽  
Serial Sectioning ◽  
Resolution Electron ◽  
Plastic Forming ◽  
Backscatter Diffraction

A focused ion beam (FIB) coupled with high resolution electron backscatter diffraction (EBSD) has emerged as a useful tool for generating crystallographic information in reasonably large volumes of microstructure. In principle, data generation is reasonably straightforward whereby the FIB is used as a high precision serial sectioning device for generating consecutive milled surfaces suitable for mapping by EBSD. The successive EBSD maps generated by serial sectioning are combined using various post-processing methods to generate crystallographic volumes of the microstructure. This paper provides an overview of the use of 3D-EBSD in the study of various phenomena associated with thermomechanical processing of both crystalline and semi-crystalline alloys and includes investigations on the crystallographic nature of microbands, void formation at particles, phase redistribution during plastic forming, and nucleation of recrystallization within various regions of the deformation microstructure.

A New Technique For Visualizing The Displacement Field Of Indentations: The Case Of A Soft Film On A Hard Substrate

1997 ◽  
Vol 505 ◽  
Author(s):  
Joost J. Vlassak ◽  
T. Y. Tsui ◽  
W. D. Nix
Keyword(s):  
Titanium Nitride ◽  
Displacement Field ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Grain Structure ◽  
New Technique ◽  
Hard Substrate ◽  
Film Material ◽  
Pile Up ◽  
A New Technique

ABSTRACTWe have developed a new technique for visualizing displacement fields of indentations in thin films. In this technique, the indented film consists of alternating layers of two different materials. One of the materials serves as a marker for visualizing the plastic flow induced by the indentation. Focused Ion Beam (FIB) milling is used to cross-section the indentation, revealing the deformed layers. This technique can be used to study how the presence of the substrate affects the plastic displacement field around the indentation. The technique is applied to a multilayered film of aluminum and titanium nitride on a silicon substrate. The titanium nitride layers are much thinner than the aluminum layers and serve the function of marker. Pile-up of the film material around the indenter and the effect of the hard substrate are easily revealed and a mechanism for pile-up is suggested. The technique also shows that the grain structure in the deformed zone around the indentation is altered profoundly.

The Challenges of FIB Chip Repair and Debug Assistance in the 0.25μm Copper Interconnect Millennium

1998 ◽  
Author(s):  
S.B. Herschbein ◽  
L.S. Fischer ◽  
T.L. Kane ◽  
M.P. Tenney ◽  
A.D. Shore
Keyword(s):  
High Performance ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Grain Structure ◽  
Long Term Storage ◽  
Wagon Wheel ◽  
Sram Cell ◽  
Oxide Deposition ◽  
Reliable Isolation

Abstract Copper will probably replace aluminum alloys as the interconnect metallurgy of choice for high performance semiconductor devices. This transition will challenge the suitability of established practices in focused ion beam (FIB) chip repair. A fundamental rethink in methodology, techniques, and process gases will be required to deal with the new metal films. This paper discusses the results of recent experiments in the areas of FIB exposure, cuts and connections to buried copper lines. While copper tends to mill faster than aluminum, etch rate variations due to grain structure tend to make reliable isolation cuts more difficult. The films also have been shown to suffer regrowth and surface reactions during long term storage following FIB exposure. Attempts at halogen gas assisted etch (GAE) mills result in undesirable removal characteristics, and in the case of bromine, the spontaneous destruction of all exposed copper in the immediate area. Resistance measurements and reliability of deposited tungsten connections to copper lines are also presented. In addition, the latest techniques developed for aluminum wiring isolation and device characterization are shown. These include 'cleanup' methods for achieving good circuit isolation without the extensive use of local oxide deposition, and the latest multilevel version of the FIB ‘wagon wheel’ for SRAM cell characterization. Also included is preliminary data from a custom built FIB chamber four manipulator prober module.

Effect of temperature on GaSb nanocell lattice fabrication by void formation and development utilizing a focused ion beam

2019 ◽  
Vol 58 (6) ◽  
pp. 065003 ◽  
Author(s):  
Koji Shigematsu ◽  
Kenji Morita ◽  
Kazuhiro Yokoyama ◽  
Noriko Nitta ◽  
Masafumi Taniwaki
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Void Formation ◽  
Effect Of Temperature

Grain growth study of Al(Cu) lines by focused ion beam microscopy and Transmission Electron Microscopy

1995 ◽  
Vol 53 ◽  
pp. 296-297
Author(s):  
M.H. Sohn ◽  
D.A. Smith ◽  
K.P. Rodbell ◽  
Roy Izai
Keyword(s):  
Integrated Circuits ◽  
Grain Boundary ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Pure Aluminum ◽  
Point Of View ◽  
Grain Structure ◽  
Critical Ratio ◽  
Boundary Properties ◽  
Bamboo Structure

Interconnects for integrated circuits now have widths which are of the same order as the grain size. Consequently, their reliability is sensitive to the specific grain boundary properties and configurations rather than being averaged over many grains as in earlier technology when the line width was much greater than the grain diameter. From the point of view of electromigration resistance a bamboo grain structure is desirable. However, the conditions for forming a bamboo structure are not established. Walton et al. developed a model which predicts that the grain structure of aluminum lines becomes a bamboo structure, which is stagnant, upon annealing after particular time at specific temperature when the width to height ratio of the line is lower than a critical ratio (2.1-3.0). The precise value of the critical ratio depends on the ratio of the surface and grain boundary energies. Based on the modeling, we expect that the grain structure of pure aluminum stagnates after annealing at 500 °C for 2.3 hrs.

The Behaviour of Au-Au Wire Bonds in Extreme Environments

2010 ◽  
Vol 2010 (HITEC) ◽  
pp. 000114-000121 ◽  
Author(s):  
D. Shepherd ◽  
P.S. Grant ◽  
C. Johnston ◽  
S. Riches
Keyword(s):  
Yield Strength ◽  
Focused Ion Beam ◽  
High Reliability ◽  
Ion Beam ◽  
Extreme Environments ◽  
Stable Solution ◽  
Thermal Ageing ◽  
Grain Structure ◽  
Microstructural Stability ◽  
Wire Bonds

Microelectronics are being required to show high reliability within aero-engines, oil-gas wells and other extreme applications where devices can experience over 250°C, 1000bar, corrosive environments and significant vibration. Currently operation may be only possible for a small number of hours, which necessitates expensive shut-down and replacement. Wire bond interconnects continue to be critical to overall reliability though previous studies have shown that traditional Au-Al bonds fail in such environments due to microstructural instability. Au-Au bonds offer a potentially stable solution that is increasingly desirable as microelectronics are required to endure ever harsher conditions. Au ball bonds on two representative substrates with Au surfaces and ceramic bases have been exposed to 250 and 300°C in N2 for up to 2000 hours. Substrate 1 was a high temperature co-fired ceramic (HTCC) with a Au coating above Ni-Co and W layers, and Substrate 2 was a Au thick film on alumina. Wire pull and ball shear tests for both sample types significantly exceeded industry specifications, though a decrease in yield strength was observed. Key samples were cross-sectioned and grain structure was revealed by ion channelling contrast within a focused ion beam (FIB) system. The yield strength decrease was attributed to the Hall-Petch effect through elimination of twin grains formed during bonding deformation. Electron probe microanalysis (EPMA) of underlying Ni showed little interdiffusion into the Au. Hence the mechanical robustness and microstructural stability of Au-Au wire bonds in extreme environments has been demonstrated and understanding of thermal ageing mechanisms has been improved.

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