Structure Evolution in Plated Cu Films

2005 ◽  
Vol 863 ◽  
Author(s):  
D.P. Field ◽  
NJ Park ◽  
PR Besser ◽  
JE Sanchez

AbstractStructure evolution in plated Cu films is a function of sublayer stacking, film thickness, plating chemistry, plating parameters, and temperature. The present work examines grain growth and texture evolution in annealed plated Cu on a 25 nm thick Ta sublayer for films of 480 and 750 nm in thickness. These results are compared against those obtained from damascene Cu lines fabricated from a similar process, using a series of line widths. The results show that the initial structures of the plated films are similar, with slightly weaker (111) texture, a higher fraction of twin boundaries, and larger grains in the thicker films. The microstructure of the Cu within the trench constraints is a strong function of line geometry with the propensity for twin boundary development controlling structural evolution.

2007 ◽  
Vol 990 ◽  
Author(s):  
Chia-Jeng Chung ◽  
David Field ◽  
No-Jin Park ◽  
Christy Woo

ABSTRACTGrain growth in polycrystalline films is controlled by the energetics of the surface, interface and grain boundaries as well as strain energy. The unique character of damascene lines fabricated from electroplated Cu films introduces the additional considerations of bath chemistry and geometric constraints. The moderate stacking fault energy of Cu allows for the development of a substantial twin fraction for certain growth conditions. This paper discusses in-situ observation of grain growth in Cu films and lines under various processing conditions. It is shown that for thicker films and for structures constrained within damascene trenches the energetics of twin boundary formation play a large role in texture development of these structures.


1994 ◽  
Vol 356 ◽  
Author(s):  
R.-M. Keller ◽  
S. Bader ◽  
R. P. Vinci ◽  
E. Arzt

AbstractThe substrate curvature technique was employed to study the mechanical properties of 0.6 μm and 1.0 μm Cu films capped with a 50 nm thick Si3N4 layer and to compare them with the mechanical properties of uncapped Cu films. The microstructures of these films were also investigated. Grain growth, diffusional creep and dislocation processes are impeded by the cap layer. This is evident in the form of high stresses at high temperatures on heating and at low temperatures on cooling. At intermediate temperatures on heating and cooling, stress plateaus a relatively low stresses exist. This can be explained by the so-called Bauschinger effect. A film thickness dependence of the stresses in the film could not be observed for capped Cu films.


1999 ◽  
Vol 564 ◽  
Author(s):  
Qing-Tang Jiang ◽  
Michael E. Thomas ◽  
Gennadi Bersuker ◽  
Brendan Foran ◽  
Robert Mikkola ◽  
...  

AbstractTransformations in electroplated Cu films from a fine to course grain crystal structure (average grain sizes went from ∼0.1 µm to several microns) were observed to strongly depend on film thickness and geometry. Thinner films underwent much slower transformations than thicker ones. A model is proposed which explains the difference in transformation rates in terms of the physical constraint experienced by the film since grain growth in thinner films is limited by film thickness. Geometrical constraints imposed by trench and via structures appear to have an even greater retardation effect on the grain growth. Experimental observations indicate that it takes much longer for Cu in damascene structures to go through grain size transformations than blanket films.


2003 ◽  
Vol 766 ◽  
Author(s):  
D.P. Field ◽  
M.M. Nowell ◽  
O.V. Kononenko

AbstractRecrystallization, grain growth and crystallographic texture evolution in Cu films is an area of importance for IC interconnect fabrication as the film characteristics influence the resulting line microstructure. This study examines Cu films deposited by partially ionized beam deposition onto a sublayer of tantalum nitride and additionally onto alpha- C:H. The films were annealed in-situ in the SEM chamber and intermittent orientation imaging was used to characterize the grain growth and crystallographic texture evolution in the films. Both initial and final textures are weak in each of the films analyzed, but are a function of sublayer material and thickness. Grain size in the Cu films is significantly smaller for the tantalum nitride sublayer than for the á-C:H sublayer.


2001 ◽  
Vol 672 ◽  
Author(s):  
C.E. Murray ◽  
K.P. Rodbell

ABSTRACTAn investigation of the microstructural evolution of Al(Cu) thin films deposited on a variety of interlevel dielectric (ILD) layers was performed. A combination of X-ray texture measurements and scanning electron microscopy (SEM) was employed to link the texture behavior of the as-deposited Al(Cu) films at different thicknesses to the observed morphological development within the films. Three regimes of texture were revealed, corresponding to (1): Al(Cu) island growth and individual island coalescence, (2): fully coalesced film and the onset of grain growth and (3): extensive grain growth. The first and last of these regimes exhibited offset (111) texture, in which the maximum diffracted intensity from Al (111) is offset from the substrate normal. However, the position of maximum offset texture differed between the first and third stages of growth, indicating that two different mechanisms were responsible. The offset (111) texture observed in the third regime of Al(Cu) film microstructure was due to the faceting of grain surfaces. The time required for the films to reach these three stages depended on the effective diffusivity of the Al atoms on the ILD surfaces, which differed in chemistry and topography.


2006 ◽  
Vol 15-17 ◽  
pp. 982-988
Author(s):  
Sang Hoon Lee ◽  
No Jin Park ◽  
David P. Field ◽  
Paul R. Besser

For optimum fabrication and usage of Cu films, an understanding of the relationship between processing and microstructure is required. The existence of twins is another significant factor for texture development in Cu films. Texture character and strength in the Cu film is dependent on the twin boundary development that is a function of processing conditions and film thickness. In this study, determination of grain growth and texture in the sputtered and electroplated Cu films during annealing was performed for films of 100, 480 and 850 nm in thickness deposited on a Ta(25 nm)/Si wafer. The texture was measured by X-ray pole figure. The effect of film thickness on the annealing texture in the sputtered and electroplated Cu films is examined and discussed.


2004 ◽  
Vol 467-470 ◽  
pp. 1289-1294 ◽  
Author(s):  
Svetlana Malysheva ◽  
Gennady A. Salishchev ◽  
S.Yu. Mironov ◽  
Sergei Ya. Betsofen

The paper considers the structure evolution during annealing of submicrocrystalline (SMC) titanium with a mean grain size of 0.2 µm, processed by severe plastic “abc” deformation. Electron microscopic studies have revealed that the microstructure of the SMC titanium is heterogeneous and of a mixed type. One can observe a high density of dislocations, grains, subgrains, elements of a banded structure and areas comprising coarse (up to 1-2µm) and fine (up to 0.1µm) grains. The grain boundary misorientation spectrum is presented by low angle and high angle boundaries of random and special types. Three stages of annealing of SMC titanium have been revealed. The second stage is connected with the intense SMC grain growth and the value of activation energy of grain growth at this stage is twice less than the value of activation energy of grain boundary diffusion in titanium. The latter is caused by acceleration of diffusion processes at SMC grain boundaries having an atom-disordered structure. The texture evolution with annealing temperature is characterized by weakening of predominantly basal texture in the as-received SMC state and strengthening of a prismatic component. The weakening of the basal component is connected with the growth of SMC grains first of all, as well as the increase of the volume fraction of special boundaries.


1994 ◽  
Vol 343 ◽  
Author(s):  
J. A. Floro ◽  
C. V. Thompson

ABSTRACTAbnormal grain growth is characterized by the lack of a steady state grain size distribution. In extreme cases the size distribution becomes transiently bimodal, with a few grains growing much larger than the average size. This is known as secondary grain growth. In polycrystalline thin films, the surface energy γs and film/substrate interfacial energy γi vary with grain orientation, providing an orientation-selective driving force that can lead to abnormal grain growth. We employ a mean field analysis that incorporates the effect of interface energy anisotropy to predict the evolution of the grain size/orientation distribution. While abnormal grain growth and texture evolution always result when interface energy anisotropy is present, whether secondary grain growth occurs will depend sensitively on the details of the orientation dependence of γi.


1999 ◽  
Vol 594 ◽  
Author(s):  
R. Spolenak ◽  
C. A. Volkert ◽  
K. Takahashi ◽  
S. Fiorillo ◽  
J. Miner ◽  
...  

AbstractIt is well known that the mechanical properties of thin films depend critically on film thickness However, the contributions from film thickness and grain size are difficult to separate, because they typically scale with each other. In one study by Venkatraman and Bravman, Al films, which were thinned using anodic oxidation to reduce film thickness without changing grain size, showed a clear increase in yield stress with decreasing film thickness.We have performed a similar study on both electroplated and sputtered Cu films by using chemical-mechanical polishing (CMP) to reduce the film thickness without changing the grain size. Stress-temperature curves were measured for both the electroplated and sputtered Cu films with thicknesses between 0.1 and 1.8 microns using a laser scanning wafer curvature technique. The yield stress at room temperature was found to increase with decreasing film thickness for both sets of samples. The sputtered films, however, showed higher yield stresses in comparison to the electroplated films. Most of these differences can be attributed to the different microstructures of the films, which were determined by focused ion beam (FIB) microscopy and x-ray diffraction.


2011 ◽  
Vol 306-307 ◽  
pp. 116-119
Author(s):  
Masahiko Demura ◽  
Ya Xu ◽  
Toshiyuki Hirano

This article presents the texture evolution and the ductility improvement of the cold-rolled foils of boron-free Ni3Al during the recrystallization and the subsequent grain growth. The cold-rolled foils had sharp {110} textures. After the recrystallization at 873K/0.5h, the texture was disintegrated with several texture components. Interestingly, most of them had a single rotation relationship. i.e. 40˚ around <111>. With the progress of the grain growth, however, the texture returned to the sharp, cold-rolled textures. This two-stage texture evolution, called as “Texture memory effect”, was explained assuming a high mobility of the grain boundary with the 40˚<111> rotation relationship. The texture returning was highly effective to improve the ductility of the foils.


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