Electron Microscope Investigation of Mixed Stannous Chloride/ Palladium Chloride Catalysts for Plating Dielectric Substrates

Feldstein, N.; Schlesinger, M.; Hedgecock, N. E.; Chow, S. L.

doi:10.1149/1.2401901

Cited by 63 publications

(48 citation statements)

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“…The final active sites initiating metal deposition have been discussed with some results of electron diffraction (3,4), MSssbauer (5), and Rutherford scattering spectroscopies (6). By electron diffraction analysis Feldstein et al (3) showed the fcc diffraction patterns which were due to Pd3Sn. Cohen et al (5) using MSssbauer spectroscopy constructed a model in which the colloidal particles consist of Pd-Sn alloy core with a stabilizing layer of adsorbed Sn(II) ions.…”

mentioning

confidence: 99%

An Electron Diffraction Study on Mixed PdCl2 / SnCl2 Catalysts for Electroless Plating

Osaka

Nagasaka

Goto

1980

J. Electrochem. Soc.

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The activated or catalyzed surface conditions for initiating electroless metal deposition were studied by means of transmission electron microscopy and electron diffraction analysis. Four mixed PdC1JSnC12 catalysts, including two commercial samples, and five accelerators (NaOH, HC1, H2SO4, NH4OH, and NI-I4BF4) were used in this study. The acceleration with NaOH gave the finest remaining particles which were almost bare active nuclei, while the acceleration with ammonate group (NH4OH and NI-I4BF4) coagulated small particles to produce high density particles. The electron diffraction patterns after activation, for the catalysts prepared in our laboratory, showed amorphous broad diffraction rings which were explained as fcc structure, while for the commercial catalysts, they showed relatively sharp and netlike profiles which could be attributed to orthorhombic structure. The electron diffraction patterns after acceleration with NaOH became the sharper profiles of fcc structure, however in the case of ammonate group, they showed the complicated profiles of non-fcc structure. Finally the catalytically active sites or nuclei are discussed.There have been two groups of investigations of the PdC12/SnC12 catalyst solution initiating electroless plating onto nonmetallic substrates, namely, to focus on whether the catalytic activity is due to Pd-Sn solute complexes or to the presence of colloidal particles in the catalyst solution. Matijevid et al. (1) concluded that colloidal particles in solution exhibit catalytic activity on the basis of colloid science measurements. The present authors (2) also showed the colloidal states to be active by photospectroscopy (u.v. and vl) and electron microscopy. The final active sites initiating metal deposition have been discussed with some results of electron diffraction (3, 4), MSssbauer (5), and Rutherford scattering spectroscopies (6). By electron diffraction analysis Feldstein et al.(3) showed the fcc diffraction patterns which were due to Pd3Sn. Cohen et al. (5) using MSssbauer spectroscopy constructed a model in which the colloidal particles consist of Pd-Sn alloy core with a stabilizing layer of adsorbed Sn(II) ions. Meek (6) indicated from Rutherford scattering measurement that the Pd/Sn ratio becomes(~ <) 1 after activation and ___3 after acceleration and finally ~6 at the initial stage of copper plating. The present authors (2) derived the conclusion from x-ray photoelectron spectroscopy that the Pd/Sn ratio after acceleration depends on the catalyst activity and that it is less than unity. In this communication, we will discuss the surface conditions of Pd-Sn particles on the substrate revealed by electron diffraction study and also investigate the acceleration effect on surface conditions. ExperimentalThree samples of PdC1JSnCI~ catalysts which were employed in the previous study (2) and the commercial sample "F" were used and the detailed preparations and compositions were previously shown in Ref.(2). The sample "A" (low catalytic activity) and "D" (high catalytic activity)...

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confidence: 99%

An Electron Diffraction Study on Mixed PdCl2 / SnCl2 Catalysts for Electroless Plating

Osaka

Nagasaka

Goto

1980

J. Electrochem. Soc.

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“…The uncatalyzed PET film revealed a smooth surface (R a <0.05 µm) with a root-mean-square roughness (R rms ) value of 0.525 nm. The R rms is calculated from the TMAFM data for a chosen area using the formula R rms = [Σ(Z i -Z av ) 2 /N] 0.5 [1] where Z i is the height of an individual pixel, Z av is the average height within a boxed area (frame), and N is the total number of pixels. For the PET substrate catalyzed and activated in our laboratory at 200°C for 45 min, the R rms roughness values for these films were in the range of 0.241-1.68 nm.…”

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confidence: 99%

“…[1][2][3][4][5] The conventional techniques of catalyzation are the two-step process consisting of sensitization with SnCl 2 /HCl followed by acceleration with PdCl 2 /HCl solution, and the one-step process which involves dipping the substrate in a colloid containing Pd/Sn salts. The entire substrate is catalyzed and photolithography or photomasks are used to activate a selected portion of the substrate.…”

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Tapping Mode Atomic Force Microscopy Analysis of a Novel Catalyzation Technique on Nonconducting Substrates

Kuruganti

1999

Electrochem. Solid-State Lett.

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A novel catalyzation technique involving direct printing of catalyst patterns on a nonconducting polymer substrate followed by thermal activation is investigated. The effects of time and temperature of activation on the nature and distribution of catalyst particles on the substrate was studied quantitatively using tapping mode atomic force microscopy (TMAFM). The TMAFM results indicate that a minimum amount of energy (integral of time and temperature) of activation were to be maintained for the initiation of catalyst particle formation on the nonconducting substrate.

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“…To obtain a continuously even Ag film, a high density of Pd particles is critical. Sn sensitization is a surface-wetting process that improves the hydrophilic character of various surfaces [17][18][19][20][21][22][23] by the adsorption of colloidal particles a few nanometers in size. In one study, after Sn sensitization, the sample was immersed in a solution of Pd ions, and the electron transfer between Sn 2+ and Pd 2+ generated Pd clusters on Sn colloids.…”

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confidence: 99%

Ag Seed-Layer Formation by Electroless Plating for Ultra-Large-Scale Integration Interconnection

Koo

Kim

Cho

et al. 2008

J. Electrochem. Soc.

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A high density of Pd catalytic particles is an important factor for obtaining a uniform and continuous Ag seed layer in electroless plating. Adequate surface pretreatment is critical for the formation of such a Pd catalytic particle population. In this study, electroless plating of Ag thin films on TiN substrates was performed using Sn sensitization and Pd activation as pretreatment methods. Sn surface sensitization improves surface wetting and aids in the formation of a Pd catalytic layer in surface-oxidative Pd activation. The Pd activation supported by Sn sensitization also accelerated the formation of a continuous thin Ag film. Furthermore, a thin Ag seed layer deposited on a patterned structure showed excellent conformality. © 2008 The Electrochemical Society. ͓DOI: 10.1149/1.2948365͔ All rights reserved.Manuscript submitted March 26, 2008; revised manuscript received May 29, 2008. Published July 8, 2008 Because chip size has shrunk in ultra-large-scale integration, resistance-capacitance delay has become a critical factor that limits the overall performance of devices.1 Ag is considered to be the ultimate interconnection material in the metallization process of the semiconductor industry due to its very low resistivity, low diffusivity into silicon, and its high resistance against oxidation. 2-4Electroless plating is the autocatalytic process of depositing a metal in the absence of an external source of electric current. In electroless plating, electrons generated by oxidation of a reducing agent on the catalytic surface reduce metal ions.5 Once a continuous metal layer is formed, the metal layer itself acts as a catalyst. [6][7][8][9][10] Electroless plating has high potential for use in the metallization process, especially for the formation of a seed layer for electroplating, due to excellent step coverage, simple processing, low resistivity of the deposited film, and no requirement for an external current supply.11-13 Most work in electroless plating has focused on using this method to form a seed layer for complementary metal oxide semiconductor interconnection. However, there have been few reports about bottom-up filling by Ag electroplating.14,15 Furthermore, no research investigating the use of an electroless plated Ag seed layer for bottom-up filling has been done.In electroless plating, pretreatment steps, where the catalytic particle layer is generated, are very important for obtaining smooth and continuous film morphology. 16 In this study, Pd is adopted as the catalytic material. Pd activation involves the formation of catalytic Pd particles by the reduction of Pd on the substrate surface using electrons generated by the oxidation of the substrate. To obtain a continuously even Ag film, a high density of Pd particles is critical. Sn sensitization is a surface-wetting process that improves the hydrophilic character of various surfaces [17][18][19][20][21][22][23] by the adsorption of colloidal particles a few nanometers in size. In one study, after Sn sensitization, the sample was immersed in a...

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Electron Microscope Investigation of Mixed Stannous Chloride/ Palladium Chloride Catalysts for Plating Dielectric Substrates

Cited by 63 publications

References 7 publications

An Electron Diffraction Study on Mixed PdCl2 / SnCl2 Catalysts for Electroless Plating

An Electron Diffraction Study on Mixed PdCl2 / SnCl2 Catalysts for Electroless Plating

Tapping Mode Atomic Force Microscopy Analysis of a Novel Catalyzation Technique on Nonconducting Substrates

Ag Seed-Layer Formation by Electroless Plating for Ultra-Large-Scale Integration Interconnection

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