Electroless Plating of Silicon Nitride Using (3-Aminopropyl) Triethoxysilane

Abstract

In this work we demonstrate electroless Cu and Ni-P ͑using both alkaline and acidic solutions͒ metallization of a silicon nitride surface. This was done by surface pretreatment with NH 2 functionalization via silanization, followed by adsorption of Pd/Sn nanoparticles onto the surface. Using this method, films of Ni-P and Cu were created and characterized. As a possible application we demonstrate metallization of atomic force microscope probes by Ni-P and Au ͑on top of the Ni-P from the acidic solution͒. Silicon nitride ͑Si 3 N 4 ͒ is an important industrial material due to its unique qualities of high-temperature strength, 1,2 excellent shock and wear resistance, 2,3 low dielectric constant, and chemical stability. It is commonly used in the manufacture of gas turbines, 4 balls and bearings, 5 and in insulation and passivation in microelectronics. 6-9 Efficient metallization techniques can help overcome some of the disadvantages attributed to Si 3 N 4 , mainly its bad fracture, and enable new applications for this material. One possible plating technique, which is commonly used to plate other dielectric materials, is electroless plating.Electroless plating presents an easy, cost-effective, and efficient technique for plating conductive as well as nonconductive materials. It is widely used in many industrial fields, such as oil and gas, aviation, automotives, and microelectronics. [10][11][12][13][14][15] Standard electroless plating of nonconductive substrates requires preliminary surface treatment for effective absorption of the catalyst. For example, NaOH was previously used for the preliminary surface treatment of Si 3 N 4 . 16 This procedure etches the surface and increases its roughness. These effects might be problematic in some applications, especially where the thickness of the substrate is small and minimal damage is preferable. In addition, the catalyst placed over the roughened surface adheres rather poorly due to the absence of chemical bonding between the two.Recently, there has been growing use of organosilane molecules to improve the absorption of metallic nanoparticles/colloids to surfaces. 17-27 Several studies have been performed using mainly aminosilane and mercaptosilane molecules, in order to improve catalyst adsorption for electroless plating. In this way, various metals have been plated over glass, 17,18 silicon-oxide, 19-23 mica, 24 polyimide, 25 and poly͑tetrafluoroethylene͒. 26,27 In this work ͑3-aminopropyl͒ triethoxysilane ͑APTES, Fig. 1c͒ is used as the binding agent between the catalyst and the substrate. For better APTES coverage, the Si 3 N 4 was treated with HNO 3 , which increases the number of OH groups on the surface. 28 The catalyst used in this work is Pd/Sn colloids. The colloidal solution of the catalyst is acidic, as it contains HCl. Once a substrate, covered with APTES, is immersed in the catalyst solution, the amine group of the APTES is protonated and becomes positively charged. It is well known that the catalyst colloids are negatively charged ͑probably due to SnCl 3 ...

Formation and characterization of low resistivity sub-100nm copper films deposited by electroless on SAM

“…The = 4 ± 0.4 cm achieved in our work [11] for 35-55 nm Cu films deposited by electroless and then vacuum annealed at 220 • C, 4 h is about 3 times lower compared to that for ELD Cu on SAMs reported in literature [6,12]. Nevertheless, it is still 2.2 times higher than the bulk resistivity bulk Cu .…”

“…There are only few reports on catalyzed [6,7,12] and non-catalyzed [8,9] ELD of thin Cu films on SAMs. Too small was known until very recently about electrical properties of sub-100 nm Cu films deposited by ELD on SAM and the relation between their resistivity , microstructure and fabrication route [10,11].…”

“…The electrical resistivity of such films was significantly larger compared to that of pure bulk Cu bulk Cu = 1.8 cm. Moreover, to our best knowledge the minimum values which have ever been obtained for sub-100 nm ELD films on SAMs are 13.7 cm and 11 cm for Cu films with the thickness of 40 nm [6] and 70 nm [12], respectively. in the 45-40 nm 1/2 pitch first level metallization for microprocessor units projected by the International Technology Roadmap for Semiconductors (ITRS) for 2010-2011 years [1].…”

Atomic Force Spectroscopy Evidence of Non-Specific Adhesion of <I>Aggregatibacter actinomycetemcomitans</I>

“…26 27 APTES attaches to the Si 3 N 4 cantilever through silane bonds and leaves amine groups available for binding with the fimbriae. 28 Fimbriae were attached to the cantilever by suspending the cantilever in the fimbriae solution for 1 hour. The amine groups of the APTES molecule bind to the C-terminus of the Flp1 protein, leaving the hydrophobic N -terminus free to bind to other surfaces.…”

Enhanced polymeric encapsulation for MEMS based multi sensors for fisheries research

“…The functionalisation procedure of silane molecules to silicon nitride surfaces is well described in the literature and does normally involve wet chemical cleaning and oxidation by RCA1 (5H 2 O:1H 2 O 2 :1NH 4 OH) and 10% nitric acid (HNO 3 ) solutions [20,21]. HNO 3 is used to prepare the surface with hydroxyl groups that the (3-aminopropyl) triethoxysilane can form covalent bonds with.…”