Diffusional Hillock Formation in Al Thin Films Controlled by Creep

1999 ◽  
Vol 594 ◽  
Author(s):  
Deok-kee Kim ◽  
William D. Nix ◽  
Eduard Arzt ◽  
Michael D. Deal ◽  
James D. Plummer
Keyword(s):  
Power Law ◽  
Original Film ◽  
Stress Measurement ◽  
Grain Structure ◽  
Surrounding Area ◽  
Hillock Formation ◽  
Columnar Grain ◽  
Sputter Deposited ◽  
Power Law Creep ◽  
Microstructural Studies

AbstractThermal hillocks in sputter-deposited Al films have been studied as a part of a broad study of stress-induced diffusional processes in Al. Trace amounts of the impurities Ti, W, and O were incorporated into the films during deposition, causing them to be much stronger than most sputter deposited Al films. Stress measurement during thermal cycling, using the wafer curvature method, showed that these Al films are very strong; this finding was corroborated by hardness measurements. Microstructural studies using TEM and FIB showed that the hillocks start to form at the Al/SiO2 interface and grow under the original Al film, with its columnar grain structure. In some cases, the film fails as hillocks grow completely through the original film. The Al film on top of the hillocks appears to inhibit hillock growth by creating a back pressure associated with power law creep of the film. We modeled this form of hillock formation by modifying the boundary conditions in Chaudhari's hillock model [1]. Our model describes hillock formation by diffusion of Al atoms from the surrounding area into isolated hillocks, assuming that the original Al film on top of hillocks deforms following power law creep. Our model can be applied to many different situations by using different creep laws for the top Al film.

Creep-controlled Diffusional Hillock Formation in Blanket Aluminum Thin Films as a Mechanism of Stress Relaxation

2000 ◽  
Vol 15 (8) ◽  
pp. 1709-1718 ◽  
Author(s):  
Deok-Kee Kim ◽  
William D. Nix ◽  
Michael D. Deal ◽  
James D. Plummer
Keyword(s):  
Thin Films ◽  
Grain Structure ◽  
Formation Model ◽  
Surrounding Area ◽  
Grain Sizes ◽  
Hillock Formation ◽  
Diffusional Relaxation ◽  
New Type ◽  
Columnar Grain ◽  
Sputter Deposited

Hillock formation, a stress-induced diffusional relaxation process, was studied in sputter-deposited Al films. The grain sizes in these films were small compared to those in other sputter-deposited Al films, and impurities (O, Ti, W) were incorporated during the preparation of the films. Stress and hardness measurements both indicate that the Al films were strengthened by the small grain size and incorporated impurities. We observed a new type of hillock in these Al thin films after annealing for 2 h at 450 °C in a forming gas ambient. The hillocks were composed of large Al grains created between the substrate and the original Al film with its columnar grain structure, apparently by diffusion from the surrounding area. By modifying the boundary conditions of Chaudhari's hillock formation model [P. Chaudhari, J. Appl. Phy. 45, 4339 (1974)], we have created a new model that can describe the experimentally observed hillocks. Our model seems to explain the experimentally observed abnormal hillock formation and may be applied to other types of hillock formation using different creep laws.

Microstructure and Reliability of Sputter Deposited Cr-Crcu-Cu thin Films for Flip-Chip Applications

1996 ◽  
Vol 445 ◽  
Author(s):  
Na Zhang ◽  
Mark Mcnicholas ◽  
Neil Colvin
Keyword(s):  
Cross Sections ◽  
Thermal Cycle ◽  
Flip Chip ◽  
Grain Structure ◽  
Transmission Electron ◽  
Alloy Solder ◽  
Solder Balls ◽  
Columnar Grain ◽  
Sputter Deposited ◽  
Bond Pads

AbstractThe Cr‐CrCu‐Cu metal scheme, as a terminal multistructure metallization for flip chip applications, has been investigated utilizing PVD sputter deposition varying the conditions of deposition power and temperature, and film thickness. A modified Controlled Collapse Chip Connection (C4) process was utilized in order to evaluate the aforementioned deposition of the Cr‐CrCu‐Cu multilayers and the effect of film microstructure on the parameters of shear strength and thermal cycle reliability. Thermal cycle reliability results proved to be a function of both the CrCu alloy and the Cu overlayer thickness. Transmission electron microscopy (TEM) cross‐sections of the Cr‐CrCu‐Cu multilayers suggests that the columnar grain structure of the CrCu layer may provide a sacrificial thermal diffusion barrier between the PbSn alloy solder balls and the Al bond pads during the thermal‐cycle tests.

TEM studies of solid-state reactions in sputter-deposited Nb/Al multilayer thin films

1996 ◽  
Vol 54 ◽  
pp. 1020-1021
Author(s):  
F. Ma ◽  
S. Vivekanand ◽  
K. Barmak ◽  
C. Michaelsen
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Stoichiometric Composition ◽  
Analytical Electron Microscopy ◽  
Grain Structure ◽  
Solid State Reactions ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sputter Deposited

Solid state reactions in sputter-deposited Nb/Al multilayer thin films have been studied by transmission and analytical electron microscopy (TEM/AEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The Nb/Al multilayer thin films for TEM studies were sputter-deposited on (1102)sapphire substrates. The periodicity of the films is in the range 10-500 nm. The overall composition of the films are 1/3, 2/1, and 3/1 Nb/Al, corresponding to the stoichiometric composition of the three intermetallic phases in this system.Figure 1 is a TEM micrograph of an as-deposited film with periodicity A = dA1 + dNb = 72 nm, where d's are layer thicknesses. The polycrystalline nature of the Al and Nb layers with their columnar grain structure is evident in the figure. Both Nb and Al layers exhibit crystallographic texture, with the electron diffraction pattern for this film showing stronger diffraction spots in the direction normal to the multilayer. The X-ray diffraction patterns of all films are dominated by the Al(l 11) and Nb(l 10) peaks and show a merging of these two peaks with decreasing periodicity.

Ionic Conductivities of Doped CeO2 Thin Films as Related to Their Microstructure

1995 ◽  
Vol 411 ◽  
Author(s):  
Chunyan Tian ◽  
Siu-Wai Chan
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Ionic Conductivities ◽  
Dielectric Constants ◽  
Grain Structure ◽  
X Ray Diffraction ◽  
Fine Grain ◽  
Brick Layer Model ◽  
Columnar Grain ◽  
Beam Deposition

ABSTRACTThin films of 4% Y2O3 doped CeO2/Pd film/(001)LaA103 with a very low pinhole density were successfully prepared using electron-beam deposition technique. The microstructure of the films was characterized by x-ray diffraction and the electrical properties were studied as a function of temperature with AC impedance spectroscopy. A brick layer model was adopted to correlate the electrical properties to the microstructure of the films, which can be simplified as either a series or a parallel equivalent circuit associated with either a fine grain or a columnar grain structure, respectively. The conductivities of the films fell between the conductivities derived from the two circuit models, suggesting that the films are of a mixed fine grain and columnar grain structure. The measured dielectric constants of the films were found smaller than that of the bulk.

Columnar Grain Structure in Cobalt Films Evaporated Obliquely at Low Substrate Temperatures

2006 ◽  
Vol 45 (4A) ◽  
pp. 2534-2538 ◽  
Author(s):  
Kikuo Itoh ◽  
Fusao Ichikawa ◽  
Yoshinori Takahashi ◽  
Kei Tsutsumi ◽  
Yoshie Noguchi ◽  
...  
Keyword(s):  
Grain Structure ◽  
Cobalt Films ◽  
Columnar Grain ◽  
Substrate Temperatures

scholarly journals Three Regions in the Power-Law Creep Regime of TiAl

1992 ◽  
Vol 33 (12) ◽  
pp. 1182-1184 ◽  
Author(s):  
Yukio Ishikawa ◽  
Kouichi Maruyama ◽  
Hiroshi Oikawa
Keyword(s):  
Power Law ◽  
Power Law Creep ◽  
Creep Regime

Columnar grain structure of iron films deposited obliquely by sputtering

1990 ◽  
Vol 86 (2-3) ◽  
pp. 247-253 ◽  
Author(s):  
K. Itoh ◽  
K. Okamoto ◽  
T. Hashimoto ◽  
H. Fujiwara
Keyword(s):  
Grain Structure ◽  
Iron Films ◽  
Columnar Grain

A simple FE approach to study microstructural influences in power-law creep

2012 ◽  
Vol 52 (1) ◽  
pp. 73-76 ◽  
Author(s):  
Cornelia Pein ◽  
Christof Sommitsch
Keyword(s):  
Power Law ◽  
Power Law Creep
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