Nanoseeding via Dual Surface Modification of Alkyl Monolayer for Site-Controlled Electroless Metallization

Abstract

In this work, an attempt to fabricate nanostructured metallization patterns on SiO(2) dielectric layers is made by using plasma-patterned self-assembled monolayers (SAMs), in conjunction with a novel aqueous seeding and electroless process. Taking octadecyltrichlorosilane (OTS) as a test material, the authors demonstrate that optimizing the N(2)-H(2) plasma conditions leads to the successive conversion of the topmost aliphatic chains of alkyl SAMs to carboxyl (COOH) and hydroxyl (C-OH) functional groups, which was previously found in alkyl SAMs only by exposure to "oxygen-based" plasma. Further modifying the plasma-exposed (either COOH or C-OH terminated) regions with an aqueous solution (SC-1) creates surface functionalities that are viable for site-controlled metallic seeding (e.g., Co or Ni) with an adsorption selectivity of greater than 1000:1. Neither the combination of costly PdCl(2) and complex additives nor the demerits of the associated aqueous chemistry (e.g., seed agglomeration and seed sparseness) are involved. Therefore, the seed particles are only 3 nm in size. Simultaneously, there are sufficient particle densities previously unattainable for electroless deposition to trigger highly resolved Cu metallization patterns with a film thickness of less than 10 nm. The formation of the seed-adsorbing sites is discussed, based on a plasma-dissociated, water-mediated chemical oxidation route.

Site-Selective Electroless Metallization on Porous Organosilica Films by Multisurface Modification of Alkyl Monolayer and Vacuum Plasma

“…As presented before, fractional coverage of the OTS monolayers was monitored by the evolution of contact angles of water droplets; those angles were analyzed as a function of immersion time since a well-ordered, uniformly coated monolayer gives a saturated contact angle of 110°. , Coating of the OTS monolayers was reconfirmed by X-ray absorption spectroscopy.…”

“…We have recently developed a nanoseeding process via dual surface modification of alkyl SAM for site-controlled electroless metallization on thermally oxidized SiO 2 dielectrics . Herein, we take a step further by selecting chemical vapor deposited porous SiOCH (p-SiOCH) films and octadecyltrichlorosilane (C 18 H 37 SiCl 3 ; OTS) films as test cases to elucidate the plasma-induced reaction pathways between porous carbon-doped organosilicate glasses and alkyl-based SAMs.…”

“…We have recently developed a nanoseeding process via dual surface modification of alkyl SAM for site-controlled electroless metallization on thermally oxidized SiO 2 dielectrics. 18 Herein, we take a step further by selecting chemical vapor deposited porous SiOCH (p-SiOCH) films and octadecyltrichlorosilane (C 18 H 37 SiCl 3 ; OTS) films as test cases to elucidate the plasmainduced reaction pathways between porous carbon-doped organosilicate glasses and alkyl-based SAMs. Particular attention is given to developing a damage-free multisurface modification process involving vacuum plasma, SAM, and chemical solution for the dielectric films to yield active surface functional groups for site-selective seeding, subsequently acting as templates for spatially controlled electroless metallization.…”

Solution-Based Photo-Patterned Gold Film Formation on Silicon Nitride

“…7 Systematic studies of surface sensitizer preparations have clearly established principles to control the plated film grain size and grain size distribution, and these can be explored for patterning, as well. 23 The degree of infilling shown here is high in the context of low-process-overhead patterned metallization steps, 30 and particularly when targeting suitability for use with structured surfaces incompatible with more involved conventional patterning, such as in enclosed micro-and nanofluidic channels. We developed a solution-based method to form spatially patterned metal features on silicon-rich SiNx thin films.…”

Area-Selective ALD of TiO2 Nanolines with Electron-Beam Lithography

“…Selective deposition of sacrificial layer for double patterning (e.g., hard-mask layer for FIN or any other critical dimension) would be useful as a simple, cheap, and reliable process. Self-assembled monolayers (SAMs), an important subgroup of organic molecules spontaneously adsorbed on solid substrates, have not only been employed to control surface properties, − such as wettability, adhesion, and lubrication, but also considered as ultrathin materials suitable for surface patterning with nanoscale dimensions. − Depending on their terminal head groups, SAMs can either enhance or prevent chemical-reaction-based deposition due to their highly hydrophilic or hydrophobic nature. Area-selective deposition can be achieved by selectively alternating the functional groups of the SAMs, which determine nucleation and growth during the deposition process.…”