Platinum metallization on silicon and silicates

Abstract

Thin films of platinum deposited by physical vapor deposition (PVD) processes such as evaporation and sputtering are used in many academic and industrial settings, for example to provide metallization when tolerance to corrosive thermal cycling is desired, or in electrocatalysis research. In this review, various practical considerations for platinum (Pt) metallization on both Si and SiO 2 are placed in context with a comprehensive data review of diffusion measurements. The relevance of diffusion phenomena to the development of microstructure during deposition as well as the effect of microstructure on the properties of deposited films are discussed with respect to the Pt-Si system. Since Pt and Si readily form silicides, diffusion barriers are essential components of Pt metallization on Si, and various failure modes for diffusion barriers between Pt and Si are clarified with images obtained by electron microscopy. Adhesion layers for Pt films deposited on SiO 2 are also considered.

Adhesion Microscopy as a Nanoscale Probe for Oxidation and Charge Generation at Metal-Oxide Interfaces

“…High electric fields can also drive the diffusion of metal into oxide, and given that the applied field in our experiments is as high as ∼20 MV/cm, a possible path leading to increased adhesion is the formation of a silicide at the Pt–SiO 2 interface by field-driven diffusion from the Pt tip into the SiO 2 at positive bias. We consider this unlikely because Pt does not react with SiO 2 at RT or form alloys, even when heated at 800 °C vacuum . Further, HRTEM studies of ReRAM filament formation show that although field-induced migration of noble metals can occur in evaporated or sputtered SiO x film, , no migration can be observed in high-quality oxides, as used here.…”

“…The alternative mechanisms of encapsulation (i.e., the mass transport of oxide to cover or immerse adsorbed NP) or the diffusion of metal into the SiO 2 to form interfacial alloys or silicides require annealing at high temperatures (typically >∼600 °C). 51 High temperatures are not expected in our experiments because the low current used (0.1−10 nA) ensures Joule heating is small. 2 High electric fields can also drive the diffusion of metal into oxide, and given that the applied field in our experiments is as high as ∼20 MV/cm, a possible path leading to increased adhesion is the formation of a silicide at the Pt−SiO 2 interface by fielddriven diffusion from the Pt tip into the SiO 2 at positive bias.…”

“…A redox mechanism, i.e., oxidation of the electrode material, appears to be the most likely explanation of our results as it is the only mechanism involving oxygen mass transfer at room temperature (RT). The alternative mechanisms of encapsulation (i.e., the mass transport of oxide to cover or immerse adsorbed NP) or the diffusion of metal into the SiO 2 to form interfacial alloys or silicides require annealing at high temperatures (typically >∼600 °C) . High temperatures are not expected in our experiments because the low current used (0.1–10 nA) ensures Joule heating is small .…”

Sputtered (Fe,Mn)3O4 Spinel Oxide Thin Films for Micro-Supercapacitor

“…The Al 2 O 3 layer was deposited by Atomic Layer Deposition (ALD) in a PicoSun R200 reactor and acts as a diffusion barrier layer to prevent the platinum silicide (Pt-Si) formation occurring during the annealing process. 2,[23][24][25] The Cr and Pt layers were successively evaporated on the oxide layer by Plassys MEB 550 S equipment, acting as adhesive (between the oxide and Pt) and current collector layers respectively. The spinel Mn-films were subsequently deposited from an equimolar Mn/Fe (50/50) metallic single target (diameter 4 inch, 99.95%, Neyco) on the Pt current collector using magnetron sputtering cluster CT200 from Alliance Concept.…”

Printed Platinum Nanoparticle Thin-Film Structures for Use in Biology and Catalysis: Synthesis, Printing, and Application Demonstration

“…14−18 The most conventional method for homogeneous deposition of platinum thin films is physical vapor deposition (PVD). 19,20 However, the process of creating platinum thinfilm structures is complicated and expensive due to the costs and complexity associated with patterning and etching platinum using lithography, lift-off, etching, etc.…”