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IBM Journal of Research and Development

Issue 5 • Date Sep. 1998

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Displaying Results 1 - 14 of 14
  • Applications of electrochemical microfabrication: An introduction

    Publication Year: 1998 , Page(s): 563 - 566
    Cited by:  Papers (2)  |  Patents (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    Global competitive pressures and the ever-increasing demand for faster, smaller, less expensive electronic systems have produced fundamental changes in processing technologies. A variety of microelectronic components are manufactured with high-yield, cost-effective electrochemical processing. Electrochemical microfabrication uses electrochemical methods to create thin- and thick-film-patterned microstructures. View full abstract»

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  • Damascene copper electroplating for chip interconnections

    Publication Year: 1998 , Page(s): 567 - 574
    Cited by:  Papers (38)  |  Patents (44)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (757 KB)  

    Damascene Cu electroplating for on-chip metallization, which we conceived and developed in the early 1990s, has been central to IBM's Cu chip interconnection technology. We review here the challenges of filling trenches and vias with Cu without creating a void or seam, and the discovery that electrodeposition can be engineered to give filling performance significantly better than that achievable with conformal step coverage. This attribute of superconformal deposition, which we call superfilling, and its relation to plating additives are discussed, and we present a numerical model that represents the shape-change behavior of this system. View full abstract»

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  • Electrochemical process for advanced package fabrication

    Publication Year: 1998 , Page(s): 575 - 586
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (962 KB)  

    Interconnections for high-end applications are essentially low-resistance transmission-line structures with precisely controlled cross-sectional shapes and dimensions. The relatively thick copper conductors—typically 6 µm or more—combined with the stringent control required on the 10–20-µm-wide cross sections stretches the capabilities of the subtractive etch and lift-off processes that are typically used in semiconductor fabrication to pattern evaporated and sputtered metal films. Electroplating through a photoresist mask, which has proven itself to be a highly effective, precision manufacturing process for thin-film magnetic recording heads, is, however, capable of meeting and far exceeding the requirements of package fabrication. This paper describes the fabrication of a package structure that integrates traditional dry-process technologies with electrolytic copper plating to form the conductors, polyimide backfill and planarization steps to form the dielectric, and electroless deposition to selectively clad the copper lines to prevent adverse reaction of the copper with water generated during the polyimide cure. The discussion highlights salient issues which are pertinent to the compatibility of the individual process steps and to the extension of the technology to more demanding packaging structures and to other applications. View full abstract»

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  • Metallization by plating for high-performance multichip modules

    Publication Year: 1998 , Page(s): 587 - 596
    Cited by:  Papers (5)  |  Patents (11)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (858 KB)  

    Electrolytic plating is used to produce the interconnect wiring on the current generation of high-performance multichip modules used in IBM S/390® and AS/400® servers. This paper reviews the material and manufacturing requirements for successful implementation of a multilayer high-density wiring pattern involving electroplated copper metal and polyimide ielectric. Various strategies for the construction of thin-film structures (planarized and nonplanarized) are outlined, and the advantages of electrolytic plating over dry deposition techniques are described. View full abstract»

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  • Thin-film multichip module packages for high-end IBM servers

    Publication Year: 1998 , Page(s): 597 - 606
    Cited by:  Papers (9)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (790 KB)  

    A new generation of multilevel thin-film packages has been developed for IBM high-end S/390® and AS/400® systems. Thin-film structures in these packages are nonplanar and can be fabricated by either pattern electroplating or subtractive etching. Selection criteria for choice of fabrication methods are discussed in terms of electrical performance requirements, ground rules, manufacturability, and cost issues. Two problems encountered in the development phase of the nonplanar thin-film structures were 1) accelerated etching of plated Cu features during Cu seed etching, and 2) corrosion of the bottom-surface metallurgy during etching of Cr at the top surface. Effective solutions were developed on the basis of underlying electrochemical phenomena. Finally, reliability stress procedures used to qualify these packages and results of these procedures are presented. View full abstract»

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  • Electrolessly deposited diffusion barriers for microelectronics

    Publication Year: 1998 , Page(s): 607 - 620
    Cited by:  Papers (9)  |  Patents (24)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1213 KB)  

    Electrolessly deposited materials were investigated as possible diffusion barrier layers for multilayer microelectronic structures. Attention was focused on selective deposition of barrier layers on various surfaces, the barrier's capability to inhibit Cu diffusion, changes in Cu resistivity caused by barrier material diffusion into Cu, and adhesion between a polyimide film and the barrier layer. Electroless Co(P) was the most effective barrier to Cu diffusion at elevated temperature, even at Co(P) thicknesses as low as 500 Å. Diffusion-barrier effectiveness of electrolessly deposited materials decreased in the following order: Co(P) > Ni-Co(P) ≃ Ni(P) ≫ pure metals Co, Ni). Although a polyimide film bonded strongly to electrolessly deposited Ni(P) layers and only weakly to as-deposited Co(P), electroless Ni(P) significantly increased the Cu resistivity through interdiffusion. Polyimide adhesion to Co(P) was improved by oxidizing a Co(P) surface immediately after deposition to grow a passive film 50–75 Å thick, yielding a surface to which the polyimide adheres strongly and reproducibly. A low-energy-beam, scanning electron microscopy/energy-dispersive X-ray analysis technique (SEM/EDX) was developed to measure the nonoxidized thin Co(P) barrier layer thickness. View full abstract»

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  • Polarographic methods of monitoring addition agents in the electroplating of Sn-Pb solders

    Publication Year: 1998 , Page(s): 621 - 628
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (706 KB)  

    The electrochemical techniques typically used to monitor organic addition agents in electroplating baths work poorly in Sn-Pb solder plating baths. These electrochemical monitoring methods are based on the principle that additives act through their effects on the kinetics of the metal-deposition reaction, and thus the reaction Mn+ + ne → M can be used as a probe to determine the additive concentration. The heavy metal ions in solder plating baths readily poison probe electrodes, however, and thus electrochemical methods on solid electrodes are irreproducible and unreliable in these systems. A polarographic technique, which uses a renewable Hg drop electrode, can be used for the quantitative analysis of addition agents in solder plating solutions, even though the chemical identity of these species may not be known to the user of the plating solution. View full abstract»

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  • Photoelectrochemical etching of semiconductors

    Publication Year: 1998 , Page(s): 629 - 638
    Cited by:  Papers (2)  |  Patents (8)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (790 KB)  

    Photoelectrochemical (PEC) etching of III–V semiconductors has been used to fabricate unique structures in electronic and photonic devices, such as integral lenses on light-emitting diodes, gratings on laser structures, and through-wafer via connections in field-effect transistors. The advantages and characteristics of PEC etching are reviewed, and the extension of this processing technique to silicon is addressed. Three-dimensional structures are of great interest in silicon for electronic and micromechanical devices. Silicon is a challenging material to PEC-etch because the oxides formed during etching inhibit the dissolution rate and decrease the spatial resolution. In addition, the long carrier lifetime permits holes to react at unilluminated sites. Nonaqueous solvents provide a processing environment where oxides do not interfere with the spatial resolution and free fluoride is no longer needed in the dissolution of silicon. View full abstract»

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  • Electrochemical microfabrication by laser-enhanced photothermal processes

    Publication Year: 1998 , Page(s): 639 - 653
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1385 KB)  

    Laser-enhanced processes have found an increasingly important role as the interest in microfabrication continues to grow. An especially attractive feature of laser processing in liquids is the ability to obtain maskless patterning in the form of material deposition or dissolution, dictated by the path of the focused laser on the sample. In the present discussion we review theoretical and experimental aspects of laser-enhanced plating and etching for a variety of materials. Some of the substrates readily etched with the help of the laser are extremely difficult to process by conventional methods. Even though the laser processes can handle materials only in a serial manner, the plating and etching rates in certain instances are sufficiently rapid to make them competitive with batch processing methods. This is particularly interesting as it pertains to laser-enhanced jet plating of copper and gold, where rates as high as 50 and 20 µm/s have respectively been obtained. View full abstract»

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  • Microfabrication by electrochemical metal removal

    Publication Year: 1998 , Page(s): 655 - 670
    Cited by:  Papers (2)  |  Patents (12)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1478 KB)  

    Recent advances in the development of electrochemical metal-removal processes for microfabrication are reviewed in this paper. After a brief description of the process, several important parameters are identified that determine the material-removal rate, shape control, surface finishing, and uniformity. The influence of surface film properties, mass transport, and current distribution on microfabrication performance are discussed. Several examples of microelectronic component fabrication are presented. These examples demonstrate the challenges and opportunities offered by electrochemical metal removal in microfabrication. View full abstract»

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  • Future directions in electroplated materials for thin-film recording heads

    Publication Year: 1998 , Page(s): 671 - 680
    Cited by:  Papers (13)  |  Patents (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (971 KB)  

    The need for recording heads to write on high-coercivity media at high frequencies has created new requirements for the write-head material that cannot be met by Ni80Fe20, the nickel-iron alloy traditionally used in the fabrication of the device. Electroplating through a mask, the method of choice for depositing nickel-iron alloys, makes it possible to pattern and orient the magnetic film more readily than by other methods. We review here research performed mostly in the United States and in Japan to develop electroplated magnetic materials that can meet the new challenges of data storage technology. High-iron nickel-iron alloys (Ni45Fe55) have higher magnetic moment and resistivity than their low-iron counterparts and are increasingly being used in head fabrication. The addition of impurities in a controlled manner has been shown to produce drastic improvement in the properties of electroplated materials. And technology has been developed to fabricate laminated materials by electroplating from a single plating solution. Despite these advances in the electrodeposition of magnetic alloys, more research is required for electroplating processes to meet all of the challenges of data storage technology. View full abstract»

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  • Integrated, variable-reluctance magnetic minimotor

    Publication Year: 1998 , Page(s): 681 - 694
    Cited by:  Papers (2)  |  Patents (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1308 KB)  

    The use of lithography and electroplating to fabricate variable-reluctance, nearly planar, integrated minimotors with 6-mm-diameter rotors on silicon wafers is described. The motors consist of six electroplated Permalloy® horseshoe-shaped cores that surround the rotor. Copper coils are formed around each core. The Permalloy and copper electroplating baths, electroplating seed layers, and through-mask plating techniques are similar to those used to fabricate inductive thin-film heads. High-aspect-ratio optical lithography or X-ray lithography was used to form the various resist layers. The rotors were fabricated separately, released from the substrate, and then slipped onto the shaft, which was plated as part of the stator fabrication process. The fabrication processes for stator and rotor are described in this paper, and initial minimotor operation data are presented. View full abstract»

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  • Recent publications by IBM authors

    Publication Year: 1998 , Page(s): 695 - 710
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1181 KB)  

    The information listed here is supplied by the Institute for Scientific Information and other outside sources. Reprints of the papers may be obtained by writing directly to the first author cited. Journals are listed alphabetically by title; papers are listed sequentially for each journal. View full abstract»

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  • Recent IBM patents

    Publication Year: 1998 , Page(s): 711 - 722
    Save to Project icon | PDF file iconPDF (791 KB)  
    Freely Available from IEEE

Aims & Scope

The IBM Journal of Research and Development is a peer-reviewed technical journal, published bimonthly, which features the work of authors in the science, technology and engineering of information systems.

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Meet Our Editors

Editor-in-Chief
Clifford A. Pickover
IBM T. J. Watson Research Center