scholarly journals Residual Stress and Microstructure of Electroplated Cu Film on Different Barrier Layers

2001 ◽  
Vol 695 ◽  
Author(s):  
Alex A. Volinsky ◽  
Meike Hauschildt ◽  
Joseph B. Vella ◽  
N.V. Edwards ◽  
Rich Gregory ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Vacuum ◽  
Temperature Cycling ◽  
Copper Films ◽  
Stress Distributions ◽  
Cu Films ◽  
Barrier Layers ◽  
Cu Film ◽  
Processing Step ◽  
Stress Mapping

ABSTRACTCopper films of different thicknesses between 0.2 and 2 microns were electroplated on adhesion-promoting TiW and Ta barrier layers on <100> single crystal 6-inch silicon wafers. The residual stress was measured after each processing step using a wafer curvature technique employing Stoney's equation. Large gradients in the stress distributions were found across each wafer. Controlled Cu grain growth was achieved by annealing films at 350 C for 3 minutes in high vacuum. Annealing increased the average tensile residual stress by about 200 MPa for all the films, which is in agreement with stress-temperature cycling measurements.After aging for 1 year wafer stress mapping showed that the stress gradients in the copper films were alleviated. No stress discrepancies between the copper on Ta and TiW barrier layers could be found. However, X-ray pole figure analysis showed broad and shifted (111) texture in films on a TiW underlayer, whereas the (111) texture in Cu films on Ta is sharp and centered.

Stress development and relaxation in copper films during thermal cycling

1993 ◽  
Vol 8 (8) ◽  
pp. 1845-1852 ◽  
Author(s):  
M.D. Thouless ◽  
J. Gupta ◽  
J.M.E. Harper
Keyword(s):  
Thermal Cycling ◽  
Integrated Circuit ◽  
Temperature Hysteresis ◽  
Copper Films ◽  
Cu Films ◽  
Dislocation Glide ◽  
Temperature Range ◽  
Cu Film ◽  
Relaxation Of Stresses ◽  
Power Law Creep

The reliability of integrated-circuit wiring depends strongly on the development and relaxation of stresses that promote void and hillock formation. In this paper an analysis based on existing models of creep is presented that predicts the stresses developed in thin blanket films of copper on Si wafers subjected to thermal cycling. The results are portrayed on deformation-mechanism maps that identify the dominant mechanisms expected to operate during thermal cycling. These predictions are compared with temperature-ramped and isothermal stress measurements for a 1 μm-thick sputtered Cu film in the temperature range 25–450 °C. The models successfully predict both the rate of stress relaxation when the film is held at a constant temperature and the stress-temperature hysteresis generated during thermal cycling. For 1 μm-thick Cu films cycled in the temperature range 25–450 °C, the deformation maps indicate that grain-boundary diffusion controls the stress relief at higher temperatures (>300 °C) when only a low stress can be sustained in the films, power-law creep is important at intermediate temperatures and determines the maximum compressive stress, and that if yield by dislocation glide (low-temperature plasticity) occurs, it will do so only at the lowest temperatures (<100 °C). This last mechanism did not appear to be operating in the film studied for this project.

Stress Gradients Observed in Cu Thin Films Induced by Capping Layers

2009 ◽  
Vol 1156 ◽  
Author(s):  
Conal E. Murray ◽  
Paul R. Besser ◽  
Christian Witt ◽  
Jean L. Jordan-Sweet
Keyword(s):  
Deposition Temperature ◽  
Morphological Changes ◽  
Film Surface ◽  
Stress Distributions ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Cu Films ◽  
Transmission Electron ◽  
Cu Film

AbstractGlancing-incidence X-ray diffraction (GIXRD) has been applied to the investigation of depth-dependent stress distributions within electroplated Cu films due to overlying capping layers. 0.65 μm thick Cu films plated on conventional barrier and seed layers received a CVD SiCxNyHz cap, an electrolessly-deposited CoWP layer, or a CoWP layer followed by a SiCxNyHz cap. GIXRD and conventional X-ray diffraction measurements revealed that strain gradients were created in Cu films possessing a SiCxNyHz cap, where a greater in-plane tensile stress was generated near the film / cap interface. The constraint imposed by the SiCxNyHz layer during cooling from the cap deposition temperature led to an increase in the in-plane stress of approximately 180 MPa from the value measured in the bulk Cu. However, Cu films possessing a CoWP cap without a SiCxNyHz layer did not exhibit depth-dependent stress distributions. Because the CoWP capping deposition temperature was much lower than that employed in SiCxNyHz deposition, the Cu experienced elastic deformation during the capping process. Cross-sectional transmission electron microscopy indicated that the top surface of the Cu films exhibited extrusions near grain boundaries for the samples undergoing the thermal excursion during SiCxNyHz deposition. The conformal nature of these caps confirmed that the morphological changes of the Cu film surface occurred prior to capping and are a consequence of the thermal excursions associated with cap deposition.

Understanding stress gradients in microelectronic metallization

2012 ◽  
Vol 27 (2) ◽  
pp. 92-98 ◽  
Author(s):  
Conal E. Murray ◽  
E. Todd Ryan ◽  
Paul R. Besser ◽  
Christian Witt ◽  
Jean L. Jordan-Sweet ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Large Scale ◽  
Void Formation ◽  
Plastic Behavior ◽  
Stress Distributions ◽  
Cu Films ◽  
Cu Film ◽  
Large Scale Integration ◽  
Reliability Issue ◽  
Scale Integration

The manufacture of ultra-large scale integration technology can impose significant strain within the constituent metallization because of the mismatch in coefficients of thermal expansion between metallization and its surrounding environment. The resulting stress distributions can be large enough to induce voiding within Cu-based metallization, a key reliability issue that must be addressed. The interface between the Cu and overlying capping layers is a critical location associated with void formation. By combining conventional and glancing-incidence X-ray diffraction, depth-dependent stress distributions that develop in Cu films and patterned features are investigated. In situ annealing and as-deposited measurements reveal that strain gradients are created in capped Cu structures, where an increased in-plane tensile stress is generated near the Cu/cap interface. The interplay between plasticity in Cu and the constraint imposed by capping layers dictates the extent of the observed gradients. Cu films possessing caps deposited at temperatures where Cu experienced only elastic deformation did not exhibit depth-dependent stress distributions. However, all capped Cu samples exposed to temperatures that induce plastic behavior developed greater tensile stress at the Cu/cap interface than in the bulk Cu film after cooling, representing a clear concern for the mitigation of metallization voiding.

Texture and microtexture of copper films prepared by the self-ion assisted deposition technique on barrier layers with different structure

2002 ◽  
Vol 721 ◽  
Author(s):  
Oleg V. Kononenko ◽  
Victor N. Matveev ◽  
Andrei G. Vasiliev ◽  
Ivan Khorin ◽  
Tejodher Muppidi ◽  
...  
Keyword(s):  
Barrier Layer ◽  
Layer Structure ◽  
Microstructural Analysis ◽  
Orientation Imaging Microscopy ◽  
Silicon Substrates ◽  
Copper Films ◽  
Deposition Technique ◽  
Cu Films ◽  
Barrier Layers ◽  
Orientation Imaging

AbstractCu may diffuse into the active areas of semiconductors resulting in degradation of the devices. Therefore Cu is isolated from silicon wafers by barrier layers. In this study, copper films were deposited onto silicon substrates coated using polycrystalline Ta3N5 and amorphous α-C:H barrier by the partially ionized beam deposition technique at 6 kV bias, to investigate an influence of barrier layer structure on texture and microstructure of Cu films. After deposition, films were annealed under vacuum. Texture of the films was studied by X-ray diffraction and further microstructural analysis of the copper films was performed by orientation imaging microscopy. Results of the structural analysis reveal large (100) grains in films deposited on α-C:H barrier layer and a bi-modal texture in films on Ta3N5.

EXPERIMENTAL OBSERVATIONS OF ORDERLY STRUCTURES IN COPPER FILMS DEPOSITED ON LIQUID SUBSTRATES

2009 ◽  
Vol 16 (03) ◽  
pp. 359-365 ◽  
Author(s):  
MIAO-GEN CHEN ◽  
SEN-JIANG YU ◽  
YUAN-XIN FENG ◽  
ZHI-WEI JIAO ◽  
BO YANG
Keyword(s):  
Deposition Rate ◽  
Microscopy Study ◽  
Copper Films ◽  
Film System ◽  
Cu Films ◽  
Characteristic Boundary ◽  
Cu Film ◽  
Characteristic Boundary Condition ◽  
Solid Liquid Interface ◽  
Solid Liquid

In this paper, an optical microscopy study of orderly structures, namely bands, which are observed in a nearly free sustained copper ( Cu ) film system, is presented. The band is composed of a large number of parallel key-formed domains with different width w but nearly uniform length L. This study shows that the morphologies of the Cu films are very susceptible to the deposition rate, i.e. with the increase in the deposition rate f, the bands with rectangular domains first become irregular gradually and then disappear completely. The experiment indicates that the growth mechanism of the orderly patterns can be explained in terms of the relaxation of the internal stress in the films, which is related to the characteristic boundary condition of the films on the liquid substrates and the nearly zero adhesion of the solid–liquid interface.

AN INVESTIGATION OF SMOOTH NANOSIZED COPPER FILMS ON GLASS SUBSTRATE BY IMPROVED ELECTROLESS PLATING

2006 ◽  
Vol 13 (04) ◽  
pp. 471-478 ◽  
Author(s):  
HUIPING ZHANG ◽  
ZHONGHAO JIANG ◽  
XIANLI LIU ◽  
JIANSHE LIAN
Keyword(s):  
Grain Size ◽  
Film Thickness ◽  
Electroless Plating ◽  
Glass Substrate ◽  
Deposition Time ◽  
Copper Films ◽  
Diffraction Intensity ◽  
Cu Films ◽  
Fine Grain ◽  
Cu Film

Thin nanocrystalline Cu films (< 1 μm) are deposited on a glass substrate using an improved electroless plating technique. The deposition course of the Cu film is illustrated by the variation of surface morphology with different deposition time. The results show that a more uniform and continuous nanocrystalline Cu film with very small nodules can be formed on a glass substrate at the deposition time over 1 min. The roles of SDBS as an additive in the bath are also discussed. According to the relation of the film thickness and the deposition time, it is obvious that the film thickness nearly linearly varies with the deposition time in the present work. An enhanced (111) texture with the diffraction intensity ratio (I(111)/I(200)) of about 4.0 and the very fine grain size of 15–28 nm determined by X-ray results has been observed. The variations of the resistivity show that it is strongly affected by the film thickness and grain size.

Mechanical behavior of thin Cu films studied by a four-point bending technique

2001 ◽  
Vol 673 ◽  
Author(s):  
Volker Weihnacht ◽  
Winfried Brückner
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
High Vacuum ◽  
Misfit Dislocations ◽  
Plastic Strains ◽  
Yield Behavior ◽  
Cu Films ◽  
Si Substrates ◽  
Four Point Bending ◽  
Tension And Compression

ABSTRACTFour-point bending experiments in combination with thermal cycling of thin films on substrates were performed in a dedicated apparatus. Strains up to ±0.8% could be imposed into Cu films of 0.2, 0.5, and 1.0 μm thickness on Si substrates by bending the substrates at various temperatures in high vacuum. After relief of the bending, the residual stress was measured by the wafer-curvature method. At temperatures below 250°C, the yield behavior is asymmetric in tension and compression. The amount of plastic strain introduced by external bending increases with film thickness, but the absolute values of the introduced plastic strains are very low throughout. At higher temperatures, there is no clear thickness dependence and no asymmetry in tension and compression. The results are discussed in connection with the formation of misfit dislocations during plastic deformation of thin films.

Impact of Low-Temperature Anneals of Electroplated Copper Films on Copper CMP Removal Rates

1999 ◽  
Vol 566 ◽  
Author(s):  
Konstantin Smekalin ◽  
Qing-Tang Jiang
Keyword(s):  
Room Temperature ◽  
Rate Increase ◽  
Removal Rate ◽  
Inert Gas ◽  
Copper Films ◽  
Cu Films ◽  
Film Hardness ◽  
Cu Film ◽  
Electroplated Copper ◽  
Over Time

CMP removal rate (RR) of electrodeposited Cu film was found to increase by 35% over time after plating. The RR increase was attributed to Cu film hardness reduction of 43% and grain growth from the initial 0.1urn at as-deposit to lum at the final stage at room temperature. The removal rate increase will translate to variations in manufacturing environment and are therefore unacceptable. It was found that annealing at ∼100C for 5 minutes in inert gas will stabilize Cu films and provide consistent CMP removal rate.

Influence of Film Thickness and Capping Layer on the Mechanical Properties of Copper Films

1995 ◽  
Vol 391 ◽  
Author(s):  
R.-M. Keller ◽  
W.-M. Kuschke ◽  
A. Kretschmann ◽  
S. Bader ◽  
R.P. Vinci ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Dislocation Density ◽  
Film Thickness ◽  
Copper Films ◽  
Peak Width ◽  
Capping Layer ◽  
X Ray ◽  
Cu Films ◽  
Cu Film

AbstractSubstrate curvature and X-ray technique were used to study the mechanical properties of Cu films. Stress-temperature curves were measured using both methods. An additional analysis of the X-ray peak width allows us to estimate grain size and dislocation density as a function of temperature. It can be shown that a capping layer changes the mechanical properties of a Cu film strongly and that in capped films dislocation processes seem to be more important than diffusion at high temperatures.

The Microstructure and Electrical Property of Porous Cu Film on Soft PVDF Substrate

2012 ◽  
Vol 472-475 ◽  
pp. 1451-1454
Author(s):  
Xue Hui Wang ◽  
Wu Tang ◽  
Ji Jun Yang
Keyword(s):  
Electrical Properties ◽  
Film Surface ◽  
X Ray Diffraction ◽  
Si Substrate ◽  
X Ray ◽  
Cu Films ◽  
Cu Film ◽  
Diffraction Peaks ◽  
Sputtering Pressure ◽  
Effect Method

The porous Cu film was deposited on soft PVDF substrate by magnetron sputtering at different sputtering pressure. The microstructure and electrical properties of Cu films were investigated as a function of sputtering pressure by X-ray diffraction XRD and Hall effect method. The results show that the surface morphology of Cu film is porous, and the XRD revealed that there are Cu diffraction peaks with highly textured having a Cu-(220) or a mixture of Cu-(111) and Cu-(220) at sputtering pressure 0.5 Pa. The electrical properties are also severely influenced by sputtering pressure, the resistivity of the porous Cu film is much larger than that fabricated on Si substrate. Furthermore, the resistivity increases simultaneously with the increasing of Cu film surface aperture, but the resistivity of Cu film still decreases with the increasing grain size. It can be concluded that the crystal structure is still the most important factor for the porous Cu film resistivity.

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