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Method for patterned electroless deposition of metal and alloys

IP.com Disclosure Number: IPCOM000010781D
Original Publication Date: 2003-Jan-21
Included in the Prior Art Database: 2003-Jan-21
Document File: 3 page(s) / 109K

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Disclosed is a strategy to direct the metallization of a nonconductive substrate by combining microcontact printing (5CP) and electroless deposition (ELD). Such strategy provides an interesting alternative to conventional microfabrication procedures that otherwise would include the deposition of a metal in vacuum and patterning it using photolithography.

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Method for patterned electroless deposition of metal and alloys

  Microcontact printing uses a micropatterned, elastomeric stamp that is made of polydimethylsiloxane (PDMS), and which is inked, dried and placed onto a substrate to localize a chemical reaction between molecules in the ink and the substrate in the zones of contact [1,2]. This technique is the method of choice to pattern self-assembled monolayers of alkanethiols on metals such as Au, Ag, Cu, and Pd [1].

ELD is a convenient method for obtaining thin metallic films on insulating substrates at low cost. This method uses metastable solutions that contain a reducing agent and complexed metal ions as the source of the metal. The presence of a catalyst on the substrate is required to initiate ELD, which then proceeds under autocatalytic conditions. ELD of a metal on a glass substrate necessitates the pretreatment of the glass with a linker that can bind the catalyst. The strategy described here employs a colloidal Pd/Sn catalyst, which is immobilized from solution onto the glass substrate via an amino-functionalized silane such as 3-(2-aminoethylamino)-propyl-trimethoxysilane (EDA-Si).

Figure 1 illustrates one strategy of how to direct the metallization of a glass substrate with NiB by combining µCP and ELD. This strategy relies on activating the glass with the Pd/Sn colloids homogeneously and on deactivating the catalyst selectively by microcontact-printing eicosanethiol (ECT). The procedure starts by derivatizing the glass substrate homogeneously with EDA-Si by immersing the substrate into an aqueous solution of EDA-Si for several minutes, which is followed by rinsing with deionized water, and drying the substrate. Prior to the grafting of EDA-Si, the glass substrate can be covered on the back with an adhesive foil to ensure having ELD of NiB on one face of the substrate only. The EDA-Si-treated glass substrate is then immersed into a solution containing the Pd/Sn colloids that bind to the EDA-Si grafted to the glass. After removal and rinsing with deionized water, the substrate is exposed to an accelerator solution containing HBF4 to activate the catalyst by dissolving part of the Sn from the colloids. The substrate is rinsed with deionized water, dried, and then used immediately for µCP. The stamp is inked by covering i...