Megasonic agitation for enhanced electrodeposition of copper

Kaufmann, Jens Georg; Desmulliez, Marc Phillipe Yves; Tian, Yingtao; Price, Dennis; Hughes, Michael; Strusevich, N.; Bailey, C.; Liu, Changqing; Hutt, David A.

doi:10.1007/s00542-009-0886-2

Cited by 28 publications

(9 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Research on US agitation has included rigorous investigations to define its impact when used for metal surfaces (Verdan et al , 2003; Cravotto et al , 2013). In contrast, little research has been carried out on the impact of MS-assisted plating on Cu topography, excepting work highlighting that a polycrystalline finish was favoured (Kaufmann et al , 2009). In response to this, the following article provides a design of experiments which studies the impact of MS agitation on the PCB surface during standard Cu electroplating.…”

Section: Introductionmentioning

confidence: 99%

Morphology and acoustic artefacts of copper deposits electroplated using megasonic assisted agitation

Jones¹,

Flynn²,

Desmulliez³

et al. 2016

Self Cite

View full text Add to dashboard Cite

Purpose ± A study of the influence of megasonic (MS) assisted agitation on Printed Circuit Boards (PCBs) electroplated using copper electrolyte solutions, to improve plating efficiencies through enhanced ion transportation. Design/methodology/approach-The impact of MS assisted agitation on topographical properties of the electroplated surfaces studied, through a Design of Experiments (DOE), by measuring surface roughness, characterised by values of the parameter Ra as measured by white light phase shifting interferometry and high resolution scanning electron microscopy. Findings ± An increase of Ra from 400 nm to 760 nm measured after plating, for an increase to acoustic power from 45 W to 450 W. Roughening increase due to micro-bubble cavitation energy, supported through direct imaging of the cavitation. Current thieving effect by the MS transducer induced low-currents, leading to large Cu grain frosting reducing the board quality. Current thieving was negated in plating trials through specific placement of transducer. Wavy electroplated surfaces, due to surface acoustic waves, also observed reducing the uniformity of the deposit. Research limitations/implications ± The formation of unstable transient cavitation and variation of the topology of the copper surface are unwanted phenomena. Further plating studies using megasonic agitation are needed, along with fundamental simulations, to determine how the effects can be reduced or prevented. Practical implications ± Identify manufacturing settings required for high-quality MS assisted plating and promote areas for further investigation, leading to the development of an MS plating manufacturing technique. Originality/value ± Quantification of the topographical changes to a PCB surface in response to megasonic agitation and evidence for deposited copper artefacts due to acoustic effects.

show abstract

Section: Introductionmentioning

confidence: 99%

Morphology and acoustic artefacts of copper deposits electroplated using megasonic assisted agitation

Jones¹,

Flynn²,

Desmulliez³

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…where ν is the Rayleigh streaming acoustic velocity, ρ is the density of the medium and ω is equal to f/2π; where f is the acoustic frequency. Using this approximation, increases to the acoustic frequency bring further reductions to the diffusion layer, improving the diffusion mass transfer of the Cu ions [12].…”

Section: Phenomena Responsible For the Enhanced Agitation Of Electrol...mentioning

confidence: 99%

“…The application of high frequency acoustics induces streaming mechanisms which have the ability to improve the transport of plating solution down microfeatures [5][6][7], improving the Cu plated thickness down vias over existing agitation techniques. A MS wave is used to deliver a uniform acoustic wave to the surface of the PCB, cathode, to investigate the influence of acoustic agitation within the electrolyte solution [8][9][10][11][12]. Increases in Cu deposition depth and improved uniformity of the Cu filling were obtained for high thickness-to-width aspect ratio (ar) vias, of the order of 8:1 and 3:1 for the THV and BV, respectively, as shown in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Copper electroplating of PCB interconnects using megasonic acoustic streaming

Jones

Bernassau

Flynn

et al. 2018

Ultrasonics Sonochemistry

Self Cite

View full text Add to dashboard Cite

In this research experimental and simulated analysis investigates the influence of megasonic (MS; 1 ± 0.05 MHz) acoustic-assisted electroplating techniques, with respect to the fabrication of through-hole via (THV) and blind-via (BV) interconnects for the Printed Circuit Board (PCB) industry. MS plating of copper down THV and BV interconnects was shown to produce measurable benefits such as increased connectivity throughout a PCB and cost savings. More specifically, a 700% increase of copper plating rate was demonstrated for THVs of 175 µm diameter and depth-to-width aspect ratio (ar) of 5.7:1, compared with electrodeposition under no-agitation conditions. For BVs, a 60% average increase in copper thickness deposition in 150 µm and 200 µm, ar 1:1, was demonstrated against plating under standard manufacturing conditions including bubble agitation and panel movement. Finite element modelling simulations of acoustic scattering revealed 1st harmonic influence for plating rate enhancement.

show abstract

“…Acoustic streaming is a truly ubiquitous phenomenon observed not only in Newtonian fluids, but also in superfluid helium [13] and non-Newtonian viscoelastic liquids [14]. It is used in many different applications: thermoacoustic engines [15], enhancement of electrodedeposition [16], mixing in microfluidics [17,18], enhancement of particle trapping [19,20], micropumping [21], biofouling removal [22], and lysing of vesicles [23]. Given its widespread appearance, a fundamental question naturally arises: is it possible to suppress acoustic streaming?…”

mentioning

confidence: 99%

Suppression of Acoustic Streaming in Shape-Optimized Channels

Bach

Bruus

2020

Phys. Rev. Lett.

View full text Add to dashboard Cite

Acoustic streaming is an ubiquitous phenomenon resulting from time-averaged nonlinear dynamics in oscillating fluids. In this theoretical study, we show that acoustic streaming can be suppressed by two orders of magnitude in major regions of a fluid by optimizing the shape of its confining walls. Remarkably, the acoustic pressure is not suppressed in this shape-optimized cavity, and neither is the acoustic radiation force on suspended particles. This basic insight may lead to applications, such as acoustophoretic handling of nm-sized particles, which is otherwise impaired by the streaming.

show abstract

Megasonic agitation for enhanced electrodeposition of copper

Cited by 28 publications

References 8 publications

Morphology and acoustic artefacts of copper deposits electroplated using megasonic assisted agitation

Morphology and acoustic artefacts of copper deposits electroplated using megasonic assisted agitation

Copper electroplating of PCB interconnects using megasonic acoustic streaming

Suppression of Acoustic Streaming in Shape-Optimized Channels

Contact Info

Product

Resources

About