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Van Eisden J.,Atotech United States Inc. | Adolf J.,Atotech United States Inc.
Journal of the Electrochemical Society | Year: 2013

Common open-source suppressors for copper filling of damascene interconnects include polyethylene glycol (PEG), polypropylene glycol (PPG), or a copolymer structure of both. Differences in the structure of these suppressors generate variations in polarization strength, surface adsorption rate, and SPS displacement rate. These properties were measured by electrochemical transient analysis and coupled with the results of time-evolved partial fill plating experiments on 32 nm and 45 nm node features to determine the effect of electrochemical property variations on the gap-fill characteristics. The high polarization strength of PPG, along with its greater dependence on concentration was found to greatly increase the bottom-up growth rate during copper filling, while the improved resistance to accelerator displacement of PEG resulted in better sidewall protection. Both these gap-fill characteristics were evident when PEG and PPG were combined together as a homopolymer mixture or in copolymer structures, although the overall influence was dependent on the size and configuration of each component. These data sets provided a more fundamental understanding of PEG, PPG and their different configurations role in the metallization of damascene interconnects. The relative gap-fill performance can also be inferred to screen new suppressor candidates and reduce the quantity of plating experiments by comparison of the electrochemical properties. © 2013 The Electrochemical Society. All rights reserved.


Volov I.,Columbia University | Swanson E.,Columbia University | Van Den Boom R.,Atotech United States Inc. | West A.C.,Columbia University
Journal of the Electrochemical Society | Year: 2012

The electrodeposition of Cu-Ag alloys was studied as a possible application for interconnect technology, where Cu-Ag alloys may be less susceptible to electromigration than Cu alone. The presence of chloride in state-of-the-art copper plating electrolytes limited the solubility of Ag. However, pulse-plating approach enabled a wide range of Cu-Ag alloy compositions at substantial chloride concentration levels. The deposition of Ag was driven by the displacement reactions between the metallic copper and ionic silver during the off-time. Measured alloy compositions were consistent with theoretical estimates at various electrolyte concentrations, electrode rotation speeds, pulse frequencies and duty cycles. However, organic additives decreased incorporation of Ag into the alloy. It was also discovered that CuSO4 · 5H2O from a number of major chemical suppliers contained Ag as an impurity. The roughness of the films was significant when produced by pulsed plating, but was shown to be substantially reduced in the presence of a leveling agent. Additionally, the concentration of chloride in the electrolyte was shown to significantly affect surface quality of the deposited Cu-Ag thin films. Copyright © 2012 The Electrochemical Society.


Shi P.,Atotech United States Inc. | Wu J.,Atotech United States Inc.
ECS Transactions | Year: 2013

Electrochemical nucleation of Cu on Ru in commercial chemistries was studied. The results show that Cu nucleation behavior is highly dependent on the suppressor species and concentrations, the acidity of the electrolyte, and the state of Ru surface. With an excellent suppressor and intermediate acid electrolyte, the Cu nucleation density as high as 1 ×1013 cm-2 can be achieved without the need of a pretreatment of the Ru surface. Direct plating of Cu on Ru with both damascene and through-silicon via structures using this highly suppressive chemistry is demonstrated. Copyright © 2013 by ECS - The Electrochemical Society.


Snyder D.L.,Atotech United States Inc.
Metal Finishing | Year: 2012

Electrodeposition of decorative chromium is the principal means of imparting the physical and chemical properties of chromium to the surface of less expensive and easier-to-form materials such as steel and plastics. The most desirable properties of chromium as a metal coating are its inherent protective and decorative characteristics. The deposit's high reflectivity is retained in service because of chromium's excellent lubricity and resistance to tarnish, corrosion, wear and scratches. For example, the cost for hexavalent chromium solutions is typically lower than that for trivalent. However, the fluoride used in many hexavalent chromium processes will etch substrates, such as copper and steel, resulting in metallic contamination of the plating bath which could increase operating problems and rejects. Trivalent chromium processes typically do not contain fluoride but will dissolve copper and iron. However, metallic contamination is easier to remove from a trivalent chromium electrolyte.


Volov I.,Columbia University | Sun X.,Columbia University | Gadikota G.,Columbia University | Shi P.,Atotech United States Inc. | West A.C.,Columbia University
Electrochimica Acta | Year: 2013

The electrodeposition of copper-tin alloy thin films was studied as a potential application for on-chip interconnection, where Cu-Sn alloys may be less susceptible to failure caused by electro- and stress-migration than pure copper. Alloys with variable Sn content were plated from acidic copper sulfate electrolytes by polarizing copper deposition into the region where Sn deposition became possible. The effective polarization was demonstrated by means of several halogen-polyether pairs, with Br-EPE (poly(ethylene glycol)-block- poly(propylene glycol)-block-poly(ethylene glycol)) pair exhibiting the strongest polarization. Alloy content of Sn between 0 and 7 at% was obtained above the reduction potential of Sn2+, which can be attributed to UPD mechanism. Higher Sn content of up to 20 at% was achieved when Cu deposition was suppressed below the reduction potential of Sn2+ by the combination of Br- and EPE. A positive correlation between Sn content and concentration of Sn2+ in the electrolyte was observed. At low rotation speeds of a disk electrode (i.e. 25 rpm versus 100 rpm) the tin content in the alloy was higher, possibly due to stronger suppression of copper deposition at low rotation speeds. The relationship between Sn content and the applied current density was specific to the employed additive chemistry. © 2012 Elsevier Ltd. All Rights Reserved.


Hsieh M.,Atotech United States Inc. | Libman E.,Atotech United States Inc. | Brandt L.,Atotech United States Inc.
Proceedings - 2014 47th International Symposium on Microelectronics, IMAPS 2014 | Year: 2014

The continuing demands of the electronics industry for faster and/or smaller products have been driving the necessity for the size reduction of all subsystems and components. This continuing trend in miniaturization leads to challenges in circuitry as adhesion of the conductor to the dielectric substrates has historically been achieved by the roughening of the substrate. This adhesion technique limits the line width because a highly roughened surface which will have strong adhesion to the copper may lead to poor line definition and compromise electrical performance and signal transfer. Alternatively, a less roughened surface with precise line definition may have poor adhesion of the copper to the substrate leading to reliability issues. It is evident that an alternative method for creating adhesion of copper to dielectric substrates is necessary. SNaP, a nanoparticle-based chemical adhesion process, will be introduced as a method to impart adhesion of electroless-deposited copper onto dielectric substrates with minimal roughening. The wide range of dielectric substrates to which this process can be applied will also be demonstrated. Copyright © 2014 IMAPS - International Microelectronics Assembly and Packaging Society All Rights Reserved.


Mukai K.,Atotech United States Inc. | Eastep B.,Atotech United States Inc. | Kim K.,Atotech United States Inc. | Gaherty L.,Atotech United States Inc. | Kashyap A.,Atotech United States Inc.
Proceedings - Electronic Components and Technology Conference | Year: 2016

Plating on molding compound is a relatively new field whichcould open up new package designs. One major application is conformal self EMI shielding (package level shielding) of ICs. Generally, EMI shielding is done mainly by metallic cans, however, this technique increases the space requirements and reduces flexibility of component layout on the PCB, that would not be suitable to handset products. An alternative and more space saving approach is "Conformal Self EMI Shielding (package level shielding)". A popular method to provide a metallic seed layer for"Conformal Self EMI Shielding" is sputtering and conductive paste, however, in order to make it more cost effective and feasible for mass production, there is a need for classical electroless plating metallization along with adhesion enhancement process. While in some instances conductive paste and sputtering metallization will provide adequate adhesion-it has the technical drawbacks of poorsidewall coverage and limited metal layer thickness that would not fulfill for lower frequency noise shield. As a result, scale-up for mass production is relatively difficult and costly. Classical electroless and electrolytic plating metallization are much more desirable but have been so far limited by insufficient adhesion by existing chemical treatment, due to the presence of extremely high ratio (80-90%wt.) and irregular size (from few μm to tens of μm) offillers. In this paper we will present a new "Adhesion nhancementProcess" approach that is based on an innovative combination of mechanical anchoring by selective resin etching and chemical adhesion promoter along with adhesion results and shielding effectiveness results. This adhesion enhancement technology is applicable to various kinds of molding compounds. Extending this technology to new package design (Embedded PoP/SiP) can be other reaching applications. © 2016 IEEE.


Wafula F.,Atotech United States Inc. | Pattanaik G.,Atotech United States Inc. | Enloe J.,Atotech United States Inc. | Hummler K.,SEMATECH | Sapp B.,SEMATECH
2014 IEEE International Interconnect Technology Conference / Advanced Metallization Conference, IITC/AMC 2014 | Year: 2014

In this paper, physical and electrical results of full wafer direct Cu plating of 2×40 μm TSVs with thin Ru seed are presented. Physical vapor deposition of about 100 nm Cu in the field is shown to improve plating non-uniformity across the structured wafer. TSV plating using Atotech's TSV III chemistry results in bottom-up growth with strong TSV sidewall suppression and void free TSV fill. Early results for in-line electrical test and voltage ramp dielectric breakdown reliability testing are discussed. © 2014 IEEE.


Gu X.,Case Western Reserve University | Gu X.,Atotech United States Inc. | Michal G.M.,Case Western Reserve University | Ernst F.,Case Western Reserve University | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2014

Unusual composition-depth profiles have been observed after low-temperature nitrocarburization of austenitic stainless steels. When nitridation is performed after carburization, the carbon concentration in the nitrogen diffusion zone is reduced from ≈10 to ≈2 at. pct. Conversely, the carbon concentration in advance of the nitrogen diffusion zone is as high as 10 at. pct. This has been called a "push" effect of nitrogen on carbon, but this concept is non-physical. The profiles can be better understood from conventional thermodynamic principles, recognizing that (1) diffusion always occurs in response to gradients in chemical potentials and (2) the diffusivity of interstitial solutes in austenite is strongly concentration dependent, increasing dramatically with higher solute concentrations. Parameters from the CALPHAD literature quantitatively indicate that interstitial nitrogen and carbon in austenitic stainless steel mutually increase their chemical potentials. Based on these data, we have conducted numerical simulations of composition-depth profiles that correctly account for the chemical potential gradients and the concentration dependence of the diffusion coefficients for nitrogen and carbon. The simulations predict the "push" effect observed on nitridation after carburization, as well as the corresponding composition-depth profiles for other scenarios, e.g., carburization followed by nitridation or simultaneous nitridation and carburization (nitrocarburization). © 2014 The Minerals, Metals & Materials Society and ASM International.


Gu X.,Case Western Reserve University | Gu X.,Atotech United States Inc. | Michal G.M.,Case Western Reserve University | Ernst F.,Case Western Reserve University | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2014

The diffusion coefficient of carbon in austenite depends on the local carbon concentration. This concentration dependence is particularly noticeable during low-temperature "paraequilibrium" carburization. A critical review of the extensive literature on this topic reveals that an early paper by Asimow provides an excellent description of this substantial concentration dependence. The present analysis suggests that the marked concentration dependence of carbon diffusivity is most likely due to interstitial carbon decreasing the activation energy for carbon jumps from one interstitial site to its neighbor. © The Minerals, Metals & Materials Society and ASM International 2014.

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