Dale P. Barkey

High-Aspect-Ratio Copper-Via-Filling for Three-Dimensional Chip Stacking II. Reduced Electrodeposition Process Time

Through-chip electrodes for three-dimensional packaging can offer short interconnection and reduced signal delay. Formation of suitable vias by electrodeposition into cavities presents a filling problem similar to that encountered in the damascene process. Because via dimensions for through-chip filling are larger and have a higher aspect ratio relative to features in damascene, process optimization requires modification of existing superconformal plating baths and plating parameters. In this study, copper filling of high-aspect-ratio through-chip vias was investigated and optimized with respect to plating bath composition and applied current wavetrain. Void-free vias 70 mu m deep and 10 mu m wide were formed in 60 min using additives in combination with pulse-reverse current and dissolved-oxygen enrichment. The effects of reverse current and dissolved oxygen on the performance of superfilling additives is discussed in terms of their effects on formation, destruction, and distribution of a Cu(I) thiolate accelerant. (c) 2005 The Electrochemical Society. All rights reserved.

Roughness Development in Metal Electrodeposition I . Experimental Results

The authors report copper electroforms of thicknesses of several hundred micrometers produced by deposition on a rotating cylinder at rates of up to 5.0 A/cm/sup 2/, corresponding to 110 pm/min. Digitalized surface profiles were analyzed by Fourier transform. Decline of roughness wavelength is observed with increasing current density at constant fraction of limiting current, in agreement with stability theory. Decline in roughness amplitude was also observed. This decline is due to an increase in the number density of nuclei. A comparison of the growth of features inside and outside the hydrodynamic boundary layer is presented.

Roughness Development in Metal Electrodeposition II . Stability Theory

A stability analysis of metal electrodeposition on a smooth surface has been formulated and applied to copper deposition on a rotating cylinder

Surface Adsorption of PEG and Cl − Additives for Copper Damascene Electrodeposition

Copper plate was observed by atomic force microscopy (AFM) after it was immersed in acid electrolyte with polyethylene glycol (PEG) and chloride ions (Cl - ). The AFM image confirmed the existence of adsorbed particles, which are in a flat-cone shape with a bottom radius of 15-25 nm and a height of 2-4 nm. The intermediate complex of copper dissolution/deposition was investigated by means of an electrochemical quartz crystal microbalance through detecting the simultaneous mass change of the electrode during cyclic voltammetric (CV) measurement. The two current peaks in the CV curves illustrate the generation and consumption of intermediate complex Cu + . Cl - . PEG on the copper electrode.

Copper electrodeposition for nanofabrication of electronics devices

Preface (Kazuo Kondo) PART 1 Copper electrodepositon and additive chemistry Chapter 1 - Copper electrodeposition (Masayuki Yokoi) Chapter 2 - Suppression effect and Additive Chemistry (Masayuki Yokoi) Chapter 3- Acceleration effect (Dale P. Barkey) Chapter 4- Modeling and Simulation ( Yutaka Kaneko) PART 2 Copper on chip metallization Chapter 5- Frontiers of Cu Electrodeposition and Electroless Plating for On-Chip Interconnects (James R. Rohan) Chapter 6- Microstructure of Evolution of Copper in Nano-scale Interconnect Features (James Kelly, Christopher Parks, James Demarest, and Christopher Penny) Chapter 7- Direct Copper Plating (Aleksandar Radisic and Philippe M. Vereecken) Part 3 - Through Silicon Via and Other Methods Chapter 8- Through Silicon Via (Kazuo Kondo) Chapter 9- Build-up Printed Wiring board (Kiyoshi Takagi a and Toshkazu Okubo) Chapter 10- Copper Foil Smooth on Both Sides for Lithium Ion Battery (Akitoshi Suzuki and Jun Shinozaki) Chapter 11- Through hole plating (Wei-Ping Dow)

Pattern Formation in Anodic Aluminum Oxide Growth by Flow Instability and Dynamic Restabilization

The viscous flow of oxide driven by the electrostriction force during the growth of anodic aluminum oxide is treated by linear stability and scale analysis. A uniform oxide film is unstable to a periodic deformation. The restabilization of pore growth is examined by scale analysis of the steady pore diameter. The pattern spatial period and pore radius predicted by the analysis are compared with experimental observations reported in the literature.

NMR Spectral Studies of Interactions Between the Accelerants SPS and MPS and Copper Chlorides

Proton and C-13 NMR spectroscopic studies of possible interactions of the copper electroplating accelerant disodium bis(3-sulfopropyl)disulfide (SPS) and its reduced form sodium 3-mercaptopropylsulfonate (MPS) with both cuprous chloride and cupric chloride were carried out in 0.25 M D 2 SO 4 /D 2 O with reagent concentrations between millimolar and 0.1 M under anaerobic conditions. It was confirmed that MPS reacted with CuCl to yield Cu(I)―thiolate products. No evidence for formation of a solution Cu(I)―SPS complex from CuCl and SPS was found. Instead, a redox reaction yielded a Cu(I)―thiolate along with Cu(II) with an estimated equilibrium constant of 5.2 × 10 ―3 M ―1 . The previously reported reaction of aqueous cupric chloride with MPS was investigated further under anaerobic conditions. In addition to SPS, Cu(I)―thiolate products similar to those from the CuCl/MPS reaction were identified. The reaction was found to be complete only upon addition of over 2 equiv of MPS. No evidence for any interaction between CuCl 2 and SPS was observed.

Influence of Additives on the Growth Velocity and Morphology of Branching Copper Electrodeposits

Copper electrodeposition in acid-sulfate plating baths with chloride, 3-mercapto-1-propane sulfonic acid (MPSA) and poly(ethylene glycol) (PEG) was investigated in a thin-layer electrolysis cell. Quasi-2D, branched deposits were produced at various potentials and additive compositions. At large overpotentials in the absence of PEG, dendritic structures were obtained. In the presence of PEG, the morphology varied from tip-splitting at lower MPSA concentration to dendritic at higher MPSA concentration. A PEG/MPSA concentration ratio was found in which the additives in combination distribute the current density away from branch tips, resulting in lower growth velocities and more compact deposits than are produced by the inhibitor PEG alone. An interpretation of the influence of additives on the pattern formation process based on mass transport and adsorption is proposed.

CORROSION OF STEEL REINFORCEMENT IN CONCRETE ADJACENT TO SURFACE REPAIRS

Reinforced concrete may be damaged by chloride-induced corrosion of steel reinforcement, resulting in spalling and delamination as corrosion products accumulate. A surface repair entails removal of damaged concrete and its replacement with repair material. The resulting inhomogeneity between the repair material and remaining chloride-contaminated concrete, however, may produce active-passive corrosion macrocells that drive rapid anodic dissolution of the metal. This experimental study was conducted to characterize the geometry, current distribution, and controlling resistance of corrosion macrocells driven by differences in the electrochemical environment in repair material and contaminated concrete. Additional influences such as galvanic contact between the test reinforcement bar and remote cathode bars were also considered. The tests were based on ASTM G 109, with modifications to incorporate simulated repairs.

Branched copper electrodeposition on a substrate

Abstract We have investigated electrochemical deposition of copper on a two-dimensional substrate. This method gives almost two-dimensional robust deposits which can be withdrawn from the electrolyte. We present a preliminary study on the morphology as a function of different parameters: current density, cell thickness and substrate anisotropy.