Effect of barrier layers on the texture and microstructure of Copper films

2003 ◽  
Vol 766 ◽  
Author(s):  
Tejodher Muppidi ◽  
David P Field
Keyword(s):  
Barrier Layer ◽  
Copper Film ◽  
Copper Films ◽  
Microstructure Development ◽  
Deposition Technique ◽  
Barrier Layers ◽  
Barrier Films ◽  
Final Microstructure ◽  
Layer Stacking ◽  
Interconnect Material

AbstractThe microstructure of interconnect material is know to influence its electromigration and stress-voiding properties. In addition to many factors responsible for the microstructure development, the barrier layer could be a major contributing factor as it forms the substrate for the copper films above. The microstructure of the barrier films based on its deposition technique could determine the final microstructure of the copper film. In the present work we examine the effect of two different barrier layers (Ta and TaN) and different stackings of these two materials on the microstructure on the copper seed (PVD) and electroplated films using EBSD, AFM and XRD. The results show that the plated films have a predominantly (111) texture and uniform grain size. But the (111) texture maximum varied with the barrier layer stacking underneath the plated film.

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.

Textures of thin copper films

1998 ◽  
Vol 13 (10) ◽  
pp. 2962-2968 ◽  
Author(s):  
W-M. Kuschke ◽  
A. Kretschmann ◽  
R-M. Keller ◽  
R. P. Vinci ◽  
C. Kaufmann ◽  
...  
Keyword(s):  
Copper Film ◽  
Annealing Treatment ◽  
Copper Films ◽  
Deposition Method ◽  
Deposition Technique ◽  
X Ray Diffraction ◽  
Barrier Material ◽  
X Ray ◽  
Pole Figures ◽  
Cap Layer

The textures of thin copper films were determined quantitatively by measuring (111) pole figures with x-ray diffraction. Measurements were performed on a variety of samples, differing in copper film thickness and deposition technique, diffusion barrier material, and the presence or absence of a cap layer. Texture changes due to an annealing treatment were also recorded and correlated with stress measurements by the wafer-curvature technique. It is found that the deposition method (PVD vs CVD) has a strong effect on texture, barrier layer effects range from negligible to significant depending on the barrier material, and the effect of a cap layer is insignificant.

Properties and Barrier Material Interactions of Electroless Copper used for Seed Enhancement

2003 ◽  
Vol 766 ◽  
Author(s):  
C. Witt ◽  
K. Pfeifer
Keyword(s):  
At Risk ◽  
Physical Vapor Deposition ◽  
Copper Ion ◽  
Copper Film ◽  
Copper Films ◽  
Hydrogen Incorporation ◽  
Barrier Materials ◽  
Barrier Films ◽  
Electroless Copper ◽  
Electroplated Copper

AbstractThe conventionally used sequence for copper damascene metallization consists of barrier deposition, physical vapor deposition (PVD) Cu seed and electroplated copper. Due to the limited step coverage of PVD copper, the extendibility of this sequence to feature dimensions below 90 nm is at risk. To reduce the risk of pinch-off of very small features, the PVD layer thickness will be reduced well below 100 nm, the drawback being poor seed coverage at the bottom of the features. Void free fill by electroplating is hence at risk by both pinch-off and discontinuous seed coverage (3-5). In this paper, the use of a conformal metal deposition method, electroless copper, to enhance PVD seed layers as thin as 10 nm is presented. It is demonstrated that sparse, discontinuous copper films provide a catalytic surface for electroless copper deposition. With electroless copper, void-free copper fill of 12.5 aspect ratio (AR) trenches (70 nm width) and 8.3 AR vias is achieved. Furthermore, 6 nm thin electroless copper films were integrated in a dual damascene process and electrically characterized. A yield of approximately 85% was achieved on via chains (360000 links, 0.25 by 1.1 μm vias), with 10 nm PVD seed. This was comparable to the yield when using 100 nm PVD seed. Hydrogen, generated as a byproduct during the electroless copper ion reduction, was found in the copper deposits as well as in the barrier films underneath. In some cases, spontaneous blistering in the plated copper film was observed, and is believed to be due to hydrogen incorporation. The interaction of electroless copper films with various barrier materials (PVD Ta, PVD TaN, CVD TiN(Si) and combinations) is discussed. Electromigration test results presented in this paper indicate that the failure mechanism is not qualitatively different from reference samples with the conventional PVD seed.

Adhesion mechanisms of copper films deposited onto laser-irradiated alumina

1997 ◽  
Vol 12 (11) ◽  
pp. 3174-3181 ◽  
Author(s):  
Jae-Won Park ◽  
Anthony J. Pedraza ◽  
Douglas H. Lowndes ◽  
William R. Allen
Keyword(s):  
Laser Irradiation ◽  
Copper Film ◽  
Alumina Substrate ◽  
Interfacial Region ◽  
Transitional Region ◽  
Copper Films ◽  
High Adhesion ◽  
Strong Adhesion ◽  
Oxygen Excess ◽  
Higher Temperature

Strong adhesion between a deposited copper film and an alumina substrate takes place when the substrate is laser-irradiated prior to deposition. A post-deposition annealing is required to achieve the strong bonding. In this work, the interfacial region between the copper film and the alumina substrate was analyzed using Auger Electron Spectroscopy (AES). It was found that a transitional region is always present in couples that have a high adhesion strength, while little or no transitional region was found in weakly bonded couples. The transitional region depends on the laser irradiation atmosphere. In the case of laser irradiation in air, oxygen excess was found on the surface of the alumina substrate, and in the copper/alumina couple the transitional region consists of a copper oxide and a Cu–Al double oxide. When the laser irradiation was performed in a reducing atmosphere (Ar–4% H2), substoichiometric alumina and metallic aluminum were found on the surface of the substrate and also a reaction between copper and the substoichiometric aluminum oxide was detected in the subsurface. Although the substoichiometric alumina is formed on the surface irradiated in Ar–4% H2, a stable Al2O3 thin layer is formed on the outmost surface because the irradiated substrate is exposed to the atmosphere before deposition. This reoxidized layer remains whole at the interface of the couple upon low temperature (at least up to 300 °C) annealing, while it is ruptured upon higher temperature annealing (500 °C in this work). In the latter case, the copper film can contact and react with the substoichiometric alumina formed in the subsurface of the substrate irradiated in the Ar–4% H2 atmosphere. It is concluded that the Cu–Al–O interfacial compound formed in the transitional region causes the strong adhesion between the copper film and the alumina substrate.

Constitutive Response of Passivated Copper Films: Experiments and Analyses

2001 ◽  
Vol 695 ◽  
Author(s):  
Y.-L. Shen ◽  
U. Ramamurty
Keyword(s):  
Thermal Loading ◽  
Silicon Oxide ◽  
Kinematic Hardening ◽  
Copper Film ◽  
Temperature Response ◽  
Copper Interconnects ◽  
Constitutive Law ◽  
Copper Films ◽  
Rate Dependent ◽  
Constitutive Response

ABSTRACTThe constitutive behavior of passivated copper films is studied. Stresses in copper films of thickness ranging from 1000 nm to 40 nm, passivated with silicon oxide on a quartz or silicon substrate, were measured using the curvature method. The thermal cycling spans a temperature range from - 196 to 600°C. It is seen that the strong relaxation at high temperatures normally found in unpassivated films is nonexistent for passivated films. The copper film did not show any rate-dependent effect over a range of heating/cooling rate from 5 to 25°C/min. Further analyses showed that significant strain hardening exists during the course of thermal loading. In particular, the measured stress- temperature response can only be fitted with a kinematic hardening model, if a simple constitutive law within the continuum plasticity framework is to be used. The analytic procedures for extracting the film properties are presented. Implications to stress modeling of copper interconnects in actual devices are discussed.

Thermomechanical Stresses in Copper Films at Elevated Temperature

2010 ◽  
Vol 2010 (HITEC) ◽  
pp. 000129-000135 ◽  
Author(s):  
Martin Lederer ◽  
Javad Zarbakhsh ◽  
Rui Huang ◽  
Thomas Detzel ◽  
Brigitte Weiss
Keyword(s):  
Elevated Temperature ◽  
Thermal Cycling ◽  
Copper Film ◽  
Film Stress ◽  
Elastic Response ◽  
Copper Films ◽  
Thermomechanical Stress ◽  
Wafer Curvature ◽  
Electronic Parts ◽  
Stoney Formula

Thermomechanical stresses in metallic films are a root cause for material fatigue which limits the lifetime of electronic devices. Since the yield stress of metals is temperature dependent, plastic deformations during thermal cycling are increased at elevated temperature. This effect reduces the reliability of electronic parts. In order to investigate this problem, a 20μm thick copper film was deposited on a silicon wafer. After annealing at 400°C, the sample was exposed to thermal cycles in the temperature range between room temperature and 600°C. The different values for the CTE of copper and silicon lead to a curvature of the sample. The wafer curvature was measured by a multi-laser beam method. On the basis of the experimental results, a new theoretical model was developed, which describes the stress evolution in the film during thermal cycling. In this investigation, the relation between wafer curvature and film stress is calculated by analogy to a model by Freund [1] which is an improvement to the well known Stoney formula. In addition to the elastic response, the new model considers plasticity of the copper film as well as temperature dependence of creep. It is demonstrated that the model can well describe the experiment and thus thermomechanical stress in copper films.

Room Temperature Self-Annealing of Electroplated and Sputtered Copper Films

1999 ◽  
Vol 562 ◽  
Author(s):  
Michelle Chen ◽  
Suraj Rengarajan ◽  
Peter Hey ◽  
Yezdi Dordi ◽  
Hong Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Copper Film ◽  
Copper Films ◽  
Organic Additives ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electroplated Copper ◽  
Effect Of Copper

ABSTRACTSelf-annealing properties of electroplated and sputtered copper films at room temperature were investigated in this study, in particular, the effect of copper film thickness, electrolyte systems used, as well as their level of organic additives for electroplating. Real-time grain growth was observed by transmission electron microscopy. Sheet resistance and X-ray diffraction measurements further confirmed the recrystallization of the electroplated copper film with time. The recrystallization of electroplated films was then compared with that of sputtered copper films.

scholarly journals Molybdenum trioxide thin film recombination barrier layers for dye sensitized solar cells

RSC Advances ◽  
2017 ◽  
Vol 7 (77) ◽  
pp. 48853-48860 ◽  
Author(s):  
Aditya Ashok ◽  
S. N. Vijayaraghavan ◽  
Shantikumar V. Nair ◽  
Mariyappan Shanmugam
Keyword(s):  
Thin Film ◽  
Charge Transport ◽  
Barrier Layer ◽  
Molybdenum Trioxide ◽  
Dye Sensitized Solar Cells ◽  
Electron Hole ◽  
Barrier Layers ◽  
Dye Sensitized ◽  
Sensitized Solar Cells ◽  
Hole Recombination

MoO3 thin film recombination barrier layer suppresses electron–hole recombination at the FTO–TiO2 interface and facilitates charge transport.

scholarly journals Performance of Cu–Ag Thin Films as Diffusion Barrier Layer

Coatings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1087
Author(s):  
Po-Hsien Sung ◽  
Tei-Chen Chen
Keyword(s):  
Barrier Layer ◽  
Diffusion Barrier ◽  
Glass Forming Ability ◽  
Dynamics Simulation ◽  
Quenching Rate ◽  
Barrier Layers ◽  
Glass Forming ◽  
Diffusion Barrier Layer ◽  
Diffusion Simulation ◽  
Lower Electrical Resistivity

It is well-known that Cu–Sn intermetallic compounds are easily produced during reflow process and result in poor reliability of solder bump. Recently, amorphous metallic films have been considered to be the most effective barrier layer because of the absence of grain boundaries and immiscibility with copper. Since Cu–Ag alloys are characterized by their lower electrical resistivity and superior glass-forming ability, they are appropriate to be used as the diffusion barrier layers. In this study, molecular dynamics simulation was performed to investigate the effects of composition ratio and quenching rate on the internal microstructure, diffusion properties, and the strength of the interface between polycrystalline Cu and Cu–Ag barrier layers. The results showed that Cu40Ag60 and Cu60Ag40 present more than 95% of the amorphous at quenching rate between 0.25 and 25 K/ps, indicating a good glass-forming ability. Diffusion simulation showed that a better barrier performance can be achieved with higher amorphous ratio. For the sample of Cu20Ag80 with quenching rate of 25 K/ps, a void is initially generated in amorphous Cu–Ag layer during the tensile test. This indicates the strength of amorphous Cu–Ag is weaker than Cu–Ag/Cu interface and the polycrystalline Cu layer.

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