A Novel Patterning Method of Low-resistivity Metals

Noh, Chang-Ho; Son, Hae-Jung; Kim, Jin‐Young; Hwang, Ok-Chae; Song, Ki-Yong; Byk, T. V.; Sokolov, V. G.; Kim, Jin-Baek

doi:10.1246/cl.2005.82

Cited by 4 publications

(3 citation statements)

References 7 publications

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“…The photodeposition process is initiated when light with energy larger than the bandgap of amorphous TiO 2 ͑3.92 eV 15,16 ͒ is absorbed by the photolayer, forming electron-hole pairs as illustrated by Eq. 1…”

Section: Resultsmentioning

confidence: 99%

Photochemical Deposition of Ni–Cu Patterns onto Conducting Substrates Employing TiO[sub 2]–Pd[sup 2+] Layers

Byk¹,

Sokolov²,

Gaevskaya³

et al. 2007

Electrochem. Solid-State Lett.

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The metal photopatterning process employing a thin film of amorphous TiO 2 doped with Pd 2+ and oxalic acid has been developed. The exposure of this photolayer to UV light is believed to yield Pd͑I͒ stabilized in a titanium oxide matrix, while subsequent washing results in formation of Pd nanoparticles through disproportionation. The Pd centers at the exposed areas are capable of inducing electroless nickel plating yielding the adhesive nickel pattern. The electroless copper deposition over patterned Ni allows generation of metal patterns with a resistivity of 4-12 ⍀ cm and a resolution of 7 m on the conducting substrates ͑indium-tin oxide glass, Si͒.Titanium dioxide is known as an excellent heterogeneous photocatalyst. 1-3 Titania-catalyzed photochemical processes involve absorption of suprabandgap photons by semiconductor resulting in the generation of photoexcited electrons ͑e − ͒ and holes ͑h + ͒. The photoelectrons and photoholes diffuse to the surface of the semiconductor where they are consumed due to the interfacial chargetransfer reactions involving adsorbed acceptor and donor molecules and ions. Thus, photoholes can oxidize the organic substances, whereas ions of noble metals ͑Pd, Ag, etc.͒ and some transition metals, having a sufficiently positive electrochemical potential ͑e.g., Cu͒, can be reduced to their elemental forms by the photogenerated electrons. 4-6 The photocatalytically derived metal centers may induce electroless deposition of another metal which thus occurs as a photoselective deposition. 7-10 Different versions of photocatalytic lithography permitting the generation of metal patterns at the dielectric substrates were proposed. 8,10-14 However, these phototechnological processes employing photosensitive layers based on titania microdispersions in synthetic adhesive compositions 7,8,10-12 or annealed polycrystalline TiO 2 layers 10,13,14 which cannot be removed from free areas after metal pattern generation are unsuitable for many potential applications, e.g., production of large-area flat panel displays and microelectronic devices.In our previous papers, 15,16 a photopatterning process permitting the generation of Ni-Cu patterns of 10-12 m resolution with the use of a photosensitive layer consisting of amorphous TiO 2 and water-soluble polyvinyl alcohol was proposed. The main drawback of this phototechnology is that the metal pattern generation cannot be performed on conducting substrates ͓indium-tin oxide ͑ITO͒, n-Si, etc.͔ due to spreading of the photoinduced charges. The aim of the present work was to investigate the possibility of photoselective metal deposition utilizing thin films of hydrated titanium oxide containing both chemical sensitizer ͑photohole scavenging agent͒ and metal ions capable of yielding metal centers which exhibit catalytic activity toward further electroless metal deposition. Such a photolayer, that enables generation of latent metallic image in a single step, is favorable for the formation of metal patterns on conducting substrates and permits one to simplify t...

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Section: Resultsmentioning

confidence: 99%

Photochemical Deposition of Ni–Cu Patterns onto Conducting Substrates Employing TiO[sub 2]–Pd[sup 2+] Layers

Byk¹,

Sokolov²,

Gaevskaya³

et al. 2007

Electrochem. Solid-State Lett.

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“…Some organic compounds such as acetic acid and triethanolamine (TEA) are known to increase the photocatalytic activity of TiO 2 particles in water. 10,15,18 In this study, 0.05 M oxalic acid and 0.01M TEA were added to the solution of PVA to increase the photosensitivity of photocatalytic layers. The thickness of the PVA layer was adjusted to 200-400 nm.…”

Section: Preparation Of Photocatalyst Layersmentioning

confidence: 99%

“…In this study, we used photocatalytic layers consisting of an amorphous TiO 2 film and a film of water-soluble polyvinyl alcohol (PVA) for the patterning of low-resistivity metals as shown in Figure 1. 14,15 The new procedure consists of four key steps as shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

A novel patterning method of low-resistivity metals

et al. 2005

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A new metal patterning process using photocatalyst was developed to reduce the number of chemical processing steps and to obtain high resolution. Films of amorphous TiO 2 and water-soluble polyvinyl alcohol were used as photocatalytic layers. UV light was illuminated through a photomask onto the photocatalytic layers. Pd(II) in an aqueous solution was reduced to Pd(0) by the exposed TiO 2 and deposited on the exposed regions. Selective electroless Ni/Cu plating on the Pd patterns showed high resolution metal patterns. Process parameters such as exposure dose and postexposure time delay were optimized to confirm the feasibility of this method. It was established that high resolution metal patterns of low resistivity with good adhesion were formed only at a small process steps without using high cost materials and equipments. Selective growth of carbon nanotubes on the Ni patterns was carried out by plasma-enhanced chemical vapor deposition. It's expected that this methods will have several benefits for fabricating the microelectronic devices, especially in the large size flat panel display.

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