Reaction of 1,1,1,5,5,5‐Hexafluoro‐2,4‐pentanedione (H+hfac) with CuO , Cu2 O  , and Cu Films

Abstract

The interactions of copper and copper oxide layers with 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (H+hfac) have been investigated. The results provide supporting evidence for proposed reactions of copper with H § which are thought to be responsible for the vapor-phase etching of copper. Specific reaction products depend on the chemical state of the copper in the film. Reaction of H § with Cu 2 § yields volatile reaction products of Cu~(hfac)2 and H20, while Cu 1 § yields the same products with a change in the chemical state of the surface to Cu(% No reaction is observable between H*hfac and Cu ~~ at temperatures studied in these experiments.

Solid–Liquid–Vapor Etching of Semiconductor Nanowires

“…The term “anisotropic” etching is used since our process acts only in the axial direction and does not impact the nanowire sidewall. We describe the process as “chemical” since precursors react with and remove Ge atoms from the catalyst droplet, which is quite distinct from reports of nanowire dissolution via evaporation at high temperature. , The well-known ability of dicarbonyls to chelate a range of metal atoms, including beryllium, zinc, and copper, − suggests that molecules such as BD would be capable of binding to and removing atoms from the catalyst.…”

“…One or two BD molecules may react with a Ge atom to yield product I or II, respectively. A dicarbonyl species similar to BD, hexafluoroacetylacetone, is known to etch Cu films, and a similar chelation reaction has been hypothesized . The formation of at least two Ge–O bonds, each with a bond strength of ∼14–17 kcal/mol, supports the assumption that the interface reaction is irreversible.…”

Sacrificial Adhesion Promotion Layers for Copper Metallization of Device Structures

“…While we have not established a definitive mechanism for the suppression of Cu oxides at the substrate interface, the literature and additional experimentation provide some insight. It is well-known that Cu oxides can be dry etched from Cu by exposure to volatile acids − and decomposition of PAA is known to produce low molecular weight acidic species . In addition, we have demonstrated that the presence of excess H 2 during Cu SFD suppresses Cu oxidation in the bulk during film deposition 7 and others have shown that H 2 can reduce both CuO and CuO 2 …”

Dealloying Multiphase AgCu Thin Films in Supercritical CO2

“…In order for Cu to dissolve in scCO 2 , it first must be oxidized to a 2+ valence state with H 2 O 2 and then chelated using hfacH. This sequential process is expected to occur via the following two reactions: − Cu ( s ) + normalH 2 normalO 2 ( f ) ↔ CuO ( s ) + normalH 2 normalO ( f ) CuO ( s ) + 2 hfacH ( f ) ↔ Cu false( hfac false) 2 · normalH 2 normalO ( f ) Although Ag is a noble metal, it could potentially oxidize to AgO, rendering it susceptible to attack by hfacH as well. However, recent studies using X-ray photoelectron spectroscopy showed that the in situ oxidation process is aggressive enough to oxidize Cu but leaves the Ag atoms in a metal state .…”