Electroless deposition and electrical resistivity of sub-100nm Cu films on SAMs: State of the art

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 .…”

“…The 5 nm mono-dispersed AuNPs were synthesized by the protocol given in Refs. [10,11]; the working pH of the solution was adjusted by sodium hydroxide or sulfuric acid. ELD of Cu films on thus activated surface were performed at room temperature from tartrate/formaldehyde bath [10].…”

“…In the previous works [10,11] we have shown that the size of AuNPs and coverage  of the SAM surface with AuNPs influence the morphology of the ELD film and eventually, affect the of the film. Here, we used X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) depth-profiling to check more directly the integrity of the APTMS at the different stages of the process and to determine to which extent the NH 2 termini of the SAM are oriented outward towards the Au catalyst-the factors which are critical for successful activation of APTMS by AuNPs and subsequent ELD of 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.…”

Complete filling of 41nm trench pattern using Cu seed layer deposited by SAM-modified electroless plating and electron-beam evaporation

“…As a result, when the trench size is less than 70 nm (the size of Pd catalysts is much larger than that of trench width), it is difficult to obtain the Cu seed layer with conformal structure using ELP. To solve this problem, Glickman et al recently introduced an ordered monolayer of mercapto-and amino-silanes with thicknesses of approximately 1-2 nm to be used a coupling agent between the SiO 2 (substrate) and the nanosized Au catalysts (catalysts for Cu ELP) and also as an adhesion enhancer for the Cu/Au/SiO 2 interface [5,6]. Our group also reported fabrication of a conformal Cu seed layer with uniform thickness using an ordered monolayer consisting of 3-aminopropyl-triethoxy silane molecules [7].…”