Electrodeposition of Gold: Depolarization Effects Induced by Heavy Metal Ions

McIntyre, J. D. E.; Peck, W. F.

doi:10.1149/1.2132700

Cited by 102 publications

(76 citation statements)

References 30 publications

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“…[6] In a similar fashion, sub-monolayer concentrations of Pb are known to accelerate Au deposition. [7,32] Bottom-up feature filling with gold by the two-step derivatization and plate process is in excellent agreement with shape change simulation, as shown in Figure 13. [7] The CEAC superfilling process has also been shown to apply to dry chemically-mediated deposition processes.…”

Section: Superconformal Cu Electrodepositionsupporting

confidence: 75%

Superconformal Electrodeposition for 3‐Dimensional Interconnects

Moffat

Josell

2010

Israel Journal of Chemistry

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Electrodeposition is a key fabrication process used in the state‐of‐the‐art multilevel Cu metallization of microelectronic interconnects, from transistor to circuit board length scale. Recent electrochemical surface science and feature filling studies have provided mechanistic insight into the role of additives in superconformal film growth responsible for void‐free filling of recessed surface features. These studies have shown that a physical model based on mass conservation of accelerating surfactant species during area change very effectively describes feature filling of Cu, Ag, and Au from different electrolytes. This paper presents a selective and cursory review of some relevant developments underway in our laboratory.

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Section: Superconformal Cu Electrodepositionsupporting

confidence: 75%

Superconformal Electrodeposition for 3‐Dimensional Interconnects

Moffat

Josell

2010

Israel Journal of Chemistry

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“…At lower pH, sulfite-based electrolytes suffer from disproportionation, SO 2 formation, and/or dithionnite-based decomposition. [47][48][49][50][51] The instability can be mitigated through the use of additives such as ethylenediamine, and/or electrolyte modification such as the use of thiosulfate, to enable operation at pH values as low as 4.0. [49][50][51][52][53] Similar to cyanide electrolytes, metal deposition from sulfite solutions is constrained by the formation of inhibiting species on the deposit surface.…”

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confidence: 99%

Morphological Transitions during Au Electrodeposition: From Porous Films to Compact Films and Nanowires

Josell

Levin

Moffat

2015

J. Electrochem. Soc.

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Gold electrodeposition was studied in a sulfite electrolyte to which micromolar concentrations of Tl 2 SO 4 were added. Hysteresis and a regime of negative differential resistance (NDR) evident in electroanalytical measurements are correlated with deposit morphology and interpreted through measurements of thallium underpotential deposition (upd). Deposit morphologies range from specular surfaces to highly faceted dendrite-like grains of moderate aspect ratio and, for potentials within the NDR region, sub-50 nm diameter, high aspect ratio 110 oriented single crystal nanowires. The nanowires exhibit an epitaxial relationship to the substrate that permits one step fabrication of surfaces densely covered with high aspect ratio nanowires having controlled orientations. The NDR and nanowires are a consequence of the non-monotonic relationship between Tl coverage and growth velocity; at low coverage Tl accelerates Au deposition while at higher coverage it inhibits deposition. Immiscibility of the Tl and Au supports on-going surface segregation during area expansion that accompanies nanowire growth leading to greater dilution of the additive coverage and more rapid growth at the nanowire tips, while the sidewalls remain passivated by a saturated Tl coverage. Interest in nanostructures is driven by the unique properties associated with high surface area to volume materials that express quantum or mesoscale phenomena of importance to diverse subjects ranging from biology and medicine 1-3 to optics and energy conversion. [4][5][6][7] Of particular interest is the substantial literature on solution or vapor processing to yield a wide variety of nanostructures including high aspect ratio nanowires. 4,8,9 Solution-based, chemical reduction processes are attractive because they are inexpensive and scalable.9-18 Subsequent processing involving particle packing and/or substrate interactions can lead to higher order organization and colloidal crystals.19 Alternatively, nanostructures can be grown on or in surfaces that have been shaped by lithography or other means to obtain control of orientation and/or placement.8 Electrochemical processing may involve throughmask plating in patterned templates 20,21 or superconformal electrodeposition of metals and alloys [22][23][24][25][26][27][28][29][30][31] including gold 32-34 in high aspect ratio features. However, these processes require nanoscale patterned topography to create such structures and the associated patterning often comes with increased processing complexity.Controlled anisotropic growth and orientation, if not position, is possible through vapor-liquid-solid (VLS) growth processes. Fabrication of semiconductor and oxide nanowires typically uses dewetting of a low melting point metal catalyst where the resulting clusters set the feature size while epitaxy to the underlying substrate can control the growth orientation. 5,[35][36][37] More recently, an electrochemical electrolyte-liquid-solid analog has been demonstrated for growth of Ge nanowires. [38][39][40] In another ap...

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“…Adding a Depolarizer It is well known that the addition of a small amount of Pb 2 þ or Tl þ depolarizes the gold electrode in the electrolytic soft gold plating bath [18]; namely these ions shift the gold deposition potential in the positive direction. These ions are known to undergo the so-called underpotential deposition (UPD) on gold, in which the strongly adsorbed metal atoms form on gold at potentials considerably less negative than corresponding equilibrium potentials.…”

Section: Methods Of Increasing the Plating Ratementioning

confidence: 99%

Electroless Deposition of Gold

Okinaka

Kato

2010

Modern Electroplating

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The term electroless plating was originally used by Brenner and Riddell [1], inventors of the well-known autocatalytic nickel and cobalt plating processes using hypophosphite as the reducing agent. A literature survey indicates, however, that this term is currently being used to describe three mechanistically different, nonelectrolytic processes for depositing metals and alloys: (1) galvanic displacement plating (also called immersion plating or cementation), (2) substrate-catalyzed plating, and (3) autocatalytic plating. In this chapter only autocatalytic gold plating processes are reviewed.The first autocatalytic, electroless gold plating bath was developed in 1970 at Bell Laboratories [1a] to plate thick, pure soft gold on semiconductors and circuit boards without employing an external source of electric current. The bath contained potassium cyanoaurate (I), KAu(CN) 2 , as the source of gold, potassium borohydride, KBH 4 , or dimethylamine borane, (CH 3 ) 2 NHÁBH 3 , as the reducing agent, potassium cyanide, and potassium hydroxide. Typical bath compositions are given in Table 21.1. The original baths did not contain stabilizing additives, and they were sensitive to minute amounts of impurities, which tended to lead to spontaneous decomposition. Nevertheless, those baths were employed successfully with sufficient stability under carefully controlled conditions [2-5], yielding highly pure, soft gold useful for the purpose of bonding semiconductor devices [6]. Other successful applications documented in the open literature include (1) metallization of GaAs microwave field-effect transistors [7], (2) formation of ohmic contacts consisting of Pd/Sn/Au films on n-GaAs [8], (3) metallization of polyvinylidene fluoride (PVDF) films used for making piezoelectric devices [9], (4) deposition of a conducting layer on the interior surface of waveguide tubes made of an aluminum alloy [10], and (5) deposition of a gold layer on tungsten-metallized ceramics for packaging semiconductor devices [11].More recently the accelerating trend of miniaturization and the need for greater reliability of electronic components have resulted in the development of new technologies for mounting devices on circuit boards, which in turn created new requirements for compatibility of the plating process with substrate materials and also for properties of gold films to be deposited on semiconductors and circuit boards. Quite generally, the method of electroplating has inherent advantages over that of electroless plating in terms of the ease of maintaining the bath and controlling the film thickness and properties. On the other hand, electroless plating has, in principle, a distinct advantage over electroplating in its capability of minimizing the number of processing steps when gold is needed in areas which are electrically isolated from each other. Under these circumstances, efforts have been made to improve the original borohydride and dimethylamine borane (DMAB) baths, especially in their stability and plating rate, and such improved baths are...

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Electrodeposition of Gold: Depolarization Effects Induced by Heavy Metal Ions

Cited by 102 publications

References 30 publications

Superconformal Electrodeposition for 3‐Dimensional Interconnects

Superconformal Electrodeposition for 3‐Dimensional Interconnects

Morphological Transitions during Au Electrodeposition: From Porous Films to Compact Films and Nanowires

Electroless Deposition of Gold

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