Showing papers on "Electroplating published in 2000"

Method for electrochemically depositing metal on a semiconductor workpiece

Abstract: A process for metallization of a workpiece, such as a semiconductor workpiece. In an embodiment, an alkaline electrolytic copper bath is used to electroplate copper onto a seed layer, electroplate copper directly onto a barrier layer material, or enhance an ultra-thin copper seed layer which has been deposited on the barrier layer using a deposition process such as PVD. The resulting copper layer provides an excellent conformal copper coating that fills trenches, vias, and other microstructures in the workpiece. When used for seed layer enhancement, the resulting copper seed layer provide an excellent conformal copper coating that allows the microstructures to be filled with a copper layer having good uniformity using electrochemical deposition techniques. Further, copper layers that are electroplated in the disclosed manner exhibit low sheet resistance and are readily annealed at low temperatures.

Wafer scale packaging scheme

Abstract: A process and a package for achieving wafer scale packaging is described. A layer of a polymeric material, such as polyimide, silicone elastomer, or benzocyclobutene is deposited on the surface of a chip. Via holes through this layer connect to the top surfaces of the studs that pass through the passivating layer of the chip. In one embodiment, the polymeric layer covers a redistribution network on a previously planarized surface of the chip. Individual chip-level networks are connected together in the kerf so that conductive posts may be formed inside the via holes through electroplating. After the formation of solder bumps, the wafer is diced into individual chips thereby isolating the individual redistribution networks. In a second embodiment, no redistribution network is present so electroless plating is used to form the posts. In a third embodiment, there is also no redistribution network but electroplating is made possible by using a contacting layer. Solder bumps attached to the posts are then formed by means of electroless plating, screen or stencil printing.

Method and apparatus for forming a sputtered doped seed layer

Abstract: The present invention generally provides a method and apparatus for forming a doped layer on a substrate to improve uniformity of subsequent deposition thereover. Preferably, the layer is deposited by a sputtering process, such as physical vapor deposition (PVD) or Ionized Metal Plasma (IMP) PVD, using a doped target of conductive material. Preferably, the conductive material, such as copper, is alloyed with a dopant, such as phosphorus, boron, indium, tin, beryllium, or combinations thereof, to improve deposition uniformity of the doped layer over the substrate surface and to reduce oxidation of the conductive material. It is believed that the addition of a dopant, such as phosphorus, stabilizes the conductive material surface, such as a copper surface, and lessens the surface diffusivity of the conductive material. The overall surface diffusivity of copper is reduced such that the tendency to agglomerate or to become discontinuous is reduced, thereby allowing the deposition of a smoother conductive film and thereby reducing localized agglomeration of the conductive material. The smoother film is highly desirable for subsequent deposition processes. A conductive material, such as copper, can be deposited on the deposited doped layer by a variety of processes including PVD, chemical vapor deposition (CVD), electroplating, electroless deposition and other deposition processes.

Apparatus for electroplating alloy films

Abstract: An electroplating bath includes two electrolytes that are separated by a low ionic mobility barrier substance. Electroplating substrates can be transferred between the two electrolytes, through the barrier substance. Successive layers can be deposited by alternately electroplating in the two electrolytes. The substrate need not be brought through an air-liquid interface in transferring it between the two electrolytes. More than one anode can be provided in each electrolyte for depositing alloy film layers. A dummy electrode can be provided in each electrolyte to be used in lieu of the substrate in order to change concentrations of compounds in each electrolyte so that sharp compositional transitions between successive layers deposited on the substrate can be obtained.

Method and apparatus for electroplating and electropolishing

Abstract: The present invention deposits a conductive material from an electrolyte solution to a predetermined area of a wafer. The steps that are used when making this application include applying the conductive material to the predetermined area of the wafer using an electrolyte solution disposed on a surface of the wafer, when the wafer is disposed between a cathode and an anode, and preventing accumulation of the conductive material to areas other than the predetermined area by mechanically polishing the other areas while the conductive material is being applied.

Method of forming lead-free bump interconnections

Abstract: A method of forming solder bumps on a chip or wafer for flip-chip applications comprises the steps of providing a chip or wafer having a plurality of metal bonds pads which provide electrical connection to the chip or wafer, and applying a solder bump comprising pure tin or a tin alloy selected from tin-copper, tin-silver, tin-bismuth or tin-silver-copper by an electroplating technique, and melting the solder bumps by heating to a temperature above the bump melting point to effect reflow

Method of copper electroplating

Abstract: An electroplating process for filling damascene structures on substrates, such as wafers having partially fabricated integrated circuits thereon, includes immersing a substrate, under bias, into a copper plating solution to eliminate thin seed layer dissolution and reduce copper oxide, an initiation step to repair discontinuities in a copper seed layer, superfill plating to fill the smallest features, reverse plating to remove the adsorbed plating additives and their by-products from the substrate, a second superfill plating to fill intermediate size features, a second reverse plating to remove adsorbed plating additives and their by-products from the substrate, and a bulk fill plating with high current density to fill large features. The superfill and reverse plating operations may be repeated more than twice prior to bulk filling in order to provide the desired surface morphology.

The Electrodeposition of Composite Coatings based on Metal Matrix-Included Particle Deposits

Abstract: SUMMARYHistorically, the origins of composite (or inclusion) electrodeposition can be traced back to the early 1900s although the majority of modern developments can be considered to have taken place over the last 40 years. The increasing demands of industrial surface engineering have provided a driving force for rapid developments over the last decade. Co-deposition techniques can be used to produce a wide range of metal matrix-included particle coatings.The thickness of the overall coating can range from sub-micron to tens of microns while the included particles typically have sizes in the range 0.05-50 microns. The metal matrices (which include Ni. Co, Cu, Pb and Cr) can be deposited by electroplating or by electroless plating; particles range from hard materials (e.g., SiC, WC, Al2O3. CrC and BN), to self-lubricating ones (e.g., PTFE, C, MoS2 and encapsulated oils) and second metal powder phases.These deposits combine the advantages of the metal matrix and the included particles. For example, the meta...

Copper electroplating apparatus

Abstract: An electroplating apparatus prevents anode-mediated degradation of electrolyte additives by creating a mechanism for maintaining separate anolyte and catholyte and preventing mixing thereof within a plating chamber The separation is accomplished by interposing a porous chemical transport barrier between the anode and cathode The transport barrier limits the chemical transport (via diffusion and/or convection) of all species but allows migration of ionic species (and hence passage of current) during application of sufficiently large electric fields within electrolyte

Method for forming a copper layer over a semiconductor wafer

Abstract: A method for electroplating a copper layer (118) over a wafer (20) powers a cathode of an electroplating system (10) in a manner that obtains improved copper interconnects. A control system (34) powers the cathode of the system (10) with a mix of two or more of: (i) positive low-powered DC cycles (201 or 254); (ii) positive high-powered DC cycles (256 or 310); (iii) low-powered, pulsed, positive-power cycles (306 or 530); (iv) high-powered, pulsed, positive-powered cycles (212, 252, 302, or 352); and/or (v) negative pulsed cycles (214, 304, 510, 528, or 532). The collection of these cycles functions to electroplate copper or a like metal (118) onto the wafer (20). During electroplating, insitu process control and/or endpointing (506, 512, or 520) is performed to further improve the resulting copper interconnect.

Submicron diameter nickel filaments and their polymer-matrix composites

Abstract: Discontinuous nickel filaments of diameter 0.4 μm and having a carbon core of diameter 0.1 μm were fabricated by electroplating nickel on discontinuous carbon filaments. They exhibited a grain size of 0.016 μm and electrical resistivity of about 5 × 10−6 Ω·cm. In an amount as low as 7 vol.% in a polymer (polyether sulfone) matrix, they resulted in a composite exhibiting electromagnetic interference shielding effectiveness of 87 dB and reflection coefficient 0.95 at 1–2 GHz, tensile strength 52 MPa, tensile ductility 1.0%, and density 1.87 g/cm3.

Study of nickel-cobalt alloy electrodeposition from a sulfamate electrolyte with different anion additives

Abstract: Nickel-cobalt alloys exhibit a spectrum of physical properties that have led to the widespread use of these materials in a variety of high-technology applications. The recent emergence of microstructure- and microsystem-fabrication by electroplating through thick three-dimensional complex-shape electroformed molds illustrates the potential for new challenging applications of these alloys. Magnetic recording tapes, composite coatings, and devices for photothermal conversion of solar energy are only a few examples of nondecorative uses of nickel-cobalt electrodeposition. 1-6 The magnetic, mechanical, and corrosion properties of Ni-Co deposits are dictated by the structure and alloy composition. These parameters, in turn, are affected by processing variables such as plating-bath chemistry, pH, temperature, and applied current density. It is well established that the electrodeposition of iron-group alloys is followed by a local pH rise near the electrode surface. This pH rise is favored when H 2 is evolved simultaneously with alloy deposition. 7-11 In addition it was found that in the absence of boric acid in the electrolyte, the oxygen content in electrodeposited nickel and nickel-iron alloys increases with increasing applied current density. 11 This is explained by the surface precipitation and occlusion of hydroxides in the growing deposit resulting from an increase in the pH of the solution adjacent to the cathode (pHs). A near-electrode pH rise influences the reduction of cations that is supposed to be preceded by dehydration or decomposition of Ni 21 and Co 21 complexes. The importance of knowing the surface concentration of the reacting species in the electrochemical reaction, including that of the hydronium ion in the near-electrode layer, was realized long ago. 12 Deposition of Ni-Co alloys with predictable properties, therefore, depends in large part on understanding the effects of electrode polarization and near-electrode phenomena. The kinetics of single iron-group metal deposition has been studied by many authors and excellent reviews are available. 7-11,13,14 The deposition of cobalt is greatly favored over the deposition of nickel. 10,11,14,15-20 This behavior, the opposite of that which would be predicted from thermodynamics alone (E8 Ni21 5

Electroplating Copper onto Resistive Barrier Films

Abstract: An analytical solution for the metal resistance-controlled plating current distribution on circular wafers is obtained for determining the conditions under which a uniform metal film can be electrodeposited on a resistive film. Results indicate that, when using conventional copper plating solutions, uniform films cannot be deposited on 500 A thick barrier layers consisting of Ta (or more resistive metals) on 200 mm wafers, regardless of plating current density or the use of pulse reverse plating. Uniformity can be characterized by a dimensionless polarization parameter that reflects the influences of current density and physical and chemical properties. Of these properties, the only one that can be varied enough to allow Cu plating on a barrier film is the plating exchange current density, i 0 . By lowering the copper concentration and thus i 0 in the plating bath by one or two orders of magnitude below levels that are commonly employed, the terminal effect can be reduced to the point where a uniform conformal conduction layer can be electrodeposited. Subsequently, the bulk copper film can be plated at high rates.

Studies of Electroplating Using an EQCM. I. Copper and Silver on Gold

Abstract: The electroplating of silver and copper has been studied using an electrochemical quartz crystal microbalance (EQCM). Deposition of Ag on Ag follows the expected behavior. For deposition of Cu, the linearity between frequency shift and added mass is maintained, but the slope is smaller (in absolute value). This is attributed to the formation of ions, which diffuse in part into the bulk of the solution, without being further reduced. Pourbaix‐type diagrams have been developed, showing the regions of thermodynamic stability of the cuprous ions in aqueous solutions, in the absence of complexing agents. In the early stages of deposition of both metals on a gold surface, large deviations of the frequency shift from its calculated value are observed. For Ag, this deviation is due to the difference in the interaction of Au and Ag with the solvent. When Cu is deposited on gold, the deviation is also due to stress in the deposit. This stress, resulting from the difference in crystal parameters between gold and copper, can be relaxed partially at open circuit at room temperature. © 2000 The Electrochemical Society. All rights reserved.

Preparation and characterization of microporous Ni coatings as hydrogen evolving cathodes

Abstract: A number of industrial electrochemical processes employ high surface area Ni electrodes. These include the use of Ni anodes in alkaline or molten carbonate fuel cells [1‐3], NiO(OH) cathodes in nickel‐cadmium and nickel‐hydrogen batteries [4] and hydrogen evolving Ni cathodes in alkaline water electrolysis [5] as well as in electrochemical hydrogenation of organics [6]. There are various types of high surface area Ni electrodes and an even larger variety of preparation methods. Sintered microporous Ni coatings are usually manufactured according to the ceramic foil-casting technology, by mixing of a micrometer size nickel powder with an organic binder, which is subsequently thermally decomposed with further sintering at elevated temperatures in a hydrogen atmosphere [3]. The methods for the production of nanoporous Raney‐Ni coatings include cold rolling, plasma spraying, annealing, sherardizing and cathodic codeposition of the Raney‐nickel precursor alloys (Ni/Al or Ni/Zn) on a nickel support [7]. PolyHIPE Polymer (PHP) [8, 9] is a microporous material produced through the formation of a high internal phase water-in-oil emulsion, in which the volume of the aqueous dispersed phase is greater than about 75%, and the subsequent polymerization (at 60 C) of the oil phase which contains the monomer (styrene and occasionally other monomers too) and the cross-linker (divinylbenzene). This results in the production of a porous polymer matrix due to the evaporation of the water droplets, which were present in the precursor emulsion. The structure of PHP is characterized by the presence of numerous cells (of 1‐100 lm diameter) interconnected by smaller pores (of 0:1‐10 lm diameter).We have recently reported the incorporation of Ni into the PHP matrix by electroplating through its pores and onto a thin Au layer electrode pasted on one side of a polymer sample [10] or onto a Ni mesh in a Ni/ PHP/Ni composite cell [11]. Thermal decomposition of the polymer resulted in a granular Ni structure of BET surface areas in the range of 1‐50 m 2 g ˇ1 depending on the method and plating current density. The main advantages of this process for producing nickel coatings of morphology comparable to that of sintered Ni are the inexpensive raw materials for the polymer matrix production and the relatively low temperature processing. Furthermore, the high surface area coating can be deposited on a variety of substrate electrode materials (e.g., stainless steel, reticulated vitreous carbon) and on substrates of diAerent geometries. The work presented here introduces a further modification of the technique, whereby only the Ni cathode wire is immersed into the precursor emulsion and finally entrapped into a well-defined PHP coating after polymerization. A preliminary characterization of the porous Ni coating, produced after electroplating and polymer decomposition, with respect to hydrogen evolution from alkaline solutions is also presented.

Semiconductor device having semiconductor element with copper pad mounted on wiring substrate and method for fabricating the same

Abstract: After a copper diffusion preventing film 4 is formed on a copper pad 1 , a barrier metal including a titanium film 5 , a nickel film 6 , and a palladium film 7 is formed on the copper diffusion preventing film 4 . The copper diffusion preventing film formed on the copper pad suppresses diffusion of copper. Even when a solder bump is formed on the copper pad, diffusion of tin in the solder and copper is suppressed. This prevents formation of an intermetallic compound between copper and tin, so no interface de-adhesion or delamination occurs and a highly reliable connection is obtained. This structure can be realized by a simple fabrication process unlike a method of forming a thick barrier metal by electroplating. In this invention, high shear strength can be ensured by connecting a solder bump, gold wire, or gold bump to a copper pad without increasing the number of fabrication steps.

Method and apparatus for determination of additives in metal plating baths

Abstract: An apparatus and method for the indirect determination of concentrations of additives in metal plating electrolyte solutions, particularly organic additives in Cu-metalization baths for semiconductor manufacturing. The apparatus features a reference electrode housed in an electrically isolated chamber (2) and continuously immersed in the base metal plating solution (4) (without the additive to be measured). An additive concentration determination method comprises electroplating a test electrode (1) in a two-phase process in a mixing chamber wherein the base metal plating solution is mixed with small volumes of the sample and various calibration solutions containing the additive to be measured. The first phase of the electroplating process is a nucleation pulse comprising electroplating with a high plating current density for a short duration (milliseconds), the second phase is electroplating at a constant or known current density. Plating potentials between the electrodes are measured and plotted for each of the solution mixtures, and data are extrapolated to determine the concentration of both accelerator and suppressor organic additives in Cu plating solution in a single test suite.

Eutectic Sn-Ag solder bump process for ULSI flip chip technology

Abstract: A novel eutectic Pb-free solder bump process, which provides several advantages over conventional solder bump process schemes, has been developed. A thick plating mask can be fabricated for steep wall bumps using a nega-type resist with a thickness of more than 50 /spl mu/m by single-step spin coating. This improves productivity for mass production. The two-step electroplating is performed using two separate plating reactors for Ag and Sn. The Sn layer is electroplated on the Ag layer. Eutectic Sn-Ag alloy bumps can be easily obtained by annealing the Ag/Sn metal stack. This electroplating process does not need strict control of the Ag to Sn content ratio in alloy plating solutions. The uniformity of the reflowed bump height within a 6-in wafer was less than 10%. The Ag composition range within a 6-in wafer was less than /spl plusmn/0.3 wt.% Ag at the eutectic Sn-Ag alloy, analyzed by ICP spectrometry. SEM observations of the Cu/barrier layer/Sn-Ag solder interface and shear strength measurements of the solder bumps were performed after 5 times reflow at 260/spl deg/C in N/sub 2/ ambient. For the Ti(100 nm)/Ni(300 nm)/Pd(50 nm) barrier layer, the shear strength decreased to 70% due to the formation of Sn-Cu intermetallic compounds. Thicker Ti in the barrier metal stack improved the shear strength. The thermal stability of the Cu/barrier layer/Sn-Ag solder metal stack was examined using Auger electron spectrometry analysis. After annealing at 150/spl deg/C for 1000 h in N/sub 2/ ambient, Sn did not diffuse into the Cu layer for Ti(500 nm)/Ni(300 nm)/Pd(50 nm) and Nb(360 nm)/Ti(100 nm)/Ni(300 nm)/Pd(50 nm) barrier metal stacks. These results suggest that the Ti/Ni/Pd barrier metal stack available to Sn-Pb solder bumps and Au bumps on Al pads is viable for Sn-Ag solder bumps on Cu pads in upcoming ULSIs.

Fabrication of composite coatings using a combination of electrochemical methods and reaction bonding process

Abstract: The major difficulty in fabricating ceramic coatings on metal substrates using the electrophoretic deposition process (EPD) is problems caused by the volume shrinkage during the sintering of the green form ceramic coatings produced by EPD. Numerous cracks normally form in the EPD coating during sintering. In this work, we have developed the reaction bonding process to fabricate crack-free and dense ceramic coatings, where the volume shrinkage is compensated by the volume expansion due to the oxidation of aluminium in the green form coatings during sintering in air. Both EPD and electroplating were used here to produce green form coatings which contain aluminium particles and, in some cases, an intermediate nickel layer. During the subsequent heat treatment, melting and oxidation of the metals in the green form coating promote densification during sintering. By these means, relatively dense composite coatings have been fabricated on metal substrates.

Modified plating solution for plating and planarization and process utilizing same

Abstract: A modified plating solution that can be used to electroplate a high quality conductive material that can be effectively polished and planarized includes (1) a solvent, (2) an ionic species of the conductive material to be deposited, (3) at least one additive to improve electrical and structural properties, and (4) a modifying agent.

Removal of Zn(II) from chloride medium using a porous electrode: current penetration within the cathode

Abstract: An electrolytic process for the removal of zinc from aqueous solutions using a flow-through cell with a reticulated vitreous carbon cathode is proposed. The operational conditions for the reactor were optimized as a function of the electrolyte pH, the cathode porosity and the solution flow rate. Both a synthetic solution and a real effluent from an industrial electroplating plant were processed until zinc concentration dropped from 50 to 0.1 mg dm−3 and from 152 to 0.5 mg dm−3, respectively. After the processing of the real effluent, tomographic images of the cathode were taken in order to investigate the current depth penetration during electrolysis. Results have shown that the current density decreases from the outer surface to the centre of the RVC cathode.

Method of manufacturing a semiconductor device having copper interconnects

Abstract: A copper interconnect is formed by creating an opening in a dielectric layer. Copper is then deposited in a non-conformal electroplating process to fill a portion of the opening. A second electroplating process is then performed to conformally deposit copper in the remaining unfilled portion of the opening. The resulting deposition of the copper is more uniform and planar, thereby facilitating subsequent planarization of the semiconductor device.

Electrolytic copper plating solutions

Abstract: The present invention provides inter alia copper electroplating compositions, methods for use of the compositions and products formed by the compositions. Electroplating compositions of the invention contain an increased brightener concentration that can provide effective copper plate on difficult-to-plate aperture walls, including high aspect ratio, small diameter microvias.

Effects of chloride, bromide and iodide ions on internal stress in films deposited during high speed nickel electroplating from a nickel sulfamate bath

Abstract: The effects of chloride, bromide and iodide additions on the internal stress developed in nickel films deposited during high speed electroplating from nickel sulfamate baths operated close to the nickel ion limiting current density were investigated. The variations in internal strain in the films were detected in situ using a resistance wire-type strain gauge placed on the reverse side of the copper substrate. The film resistance on the as-plated electrodes was measured using an electronic current interrupter technique. The effects of chloride, bromide, and iodide additions could be classified into two groups: (a) chloride and bromide ions, and (b) iodide ions. For chloride and bromide additions over the concentration range of 0.1 to 0.5 M, the nickel deposits exhibited a block- and pyramid-like texture with a (200) crystal orientation. The internal tensile stress developed in 20 μm thick nickel films deposited in the presence of these two halides was as low as 140–170 MPa. Conversely, for additions of iodide, at iodide concentrations greater than 0.1 M the deposited nickel exhibited a fine granular texture of disordered crystal orientation. The internal tensile stress developed in 20 μm thick nickel films deposited from these latter baths tended to rise with increasing iodide concentration to values considerably higher than those observed at similar concentrations of NiCl2 or NiBr2.

Tin-copper alloy electroplating bath and plating method using the same

Abstract: PROBLEM TO BE SOLVED: To provide a tin-copper alloy electroplating bath which contains one or >=2 kinds selected from at least a water-soluble tin salt, water-soluble copper salt inorganic acid, and organic acid as well as their water-soluble salts and which contains thiourea and its derivative, 2-mercapto group-containing aromatic compound and nonionic surfactant and a plating method using the same. SOLUTION: The univalent copper ions in the plating bath are stably subjected to complex formation to suppress the substitution reaction of copper and the precipitation of a copper compound, by which the management of the bath may be made easy and the stability of the bath may be enhanced. The tin-copper alloy plating film which imparts effective solderability to parts constituting electronic apparatus, such as chip parts, terminal parts, pressed parts, crystal oscillators, bumps, connectors, connector pins, lead frames, various hoop materials, lead pins of packages, pin grid arrays, ball grid arrays and circuits of printed circuit boards and is effective for etching resist may be eventually formed as a substitute for tin-lead alloy plating.

Method of forming an active-element containing aluminide as stand alone coating and as bond coat and coated article

Abstract: A process is disclosed for forming an improved aluminide coating which includes one or more oxygen active elements. A metallic substrate is coated with an overlay coating, such as an MCrAl coating, including one or more oxygen active elements such as yttrium, hafnium and silicon, by a conventional overlay process such as low pressure plasma spray. A metal, preferably a Series VIII transition metal such as platinum, is applied to the substrate, for example by electroplating. The substrate is then aluminized, for example by chemical vapor deposition, and is preferably heat treated. A ceramic thermal barrier may also be applied. The present invention provides an active element containing aluminide coating having a more consistent composition and having improved durability, either as a standalone coating or as a bond coat for a subsequently-applied thermal barrier coating.

Copper electroplating for future ultralarge scale integration interconnection

Abstract: Copper has received considerable attention during the past few years because of its low electrical resistivity, high melting temperature, and high electromigration resistance. Since electrochemical plating has several advantages compared to physical vapor deposition and chemical vapor deposition due to its low cost and low processing temperature, it becomes the most attractive technique for the implementation of Cu metallization. In this article, we report an electroplating scheme for Cu deposition and study aspects of copper electroplating related to chemical additives effected on Cu deposition. A low resistivity Cu film (∼2 μΩ cm) could be obtained when metallic ion concentration is decreased or current density is increased. The detailed correlation between film resistivity, electrolyte concentration, current density, and film morphology is given in this study. In addition, chemical additives in electrolyte solutions also play important roles in copper electroplating. In this report, thiourea and polyet...