Microstructure and properties of nanocrystalline Cu–Ta thin films prepared by direct current magnetron sputtering

Abstract

Nanocrystalline (NC) Cu-Ta thin films were successfully fabricated by unbalanced magnetron sputtering on crystal silicon and glass substrates. Thin films doped with different Ta contents were prepared by altering the sputtering current of the Ta target. The micromorphology, microstructure, mechanical properties, electrical properties, and thermal stability of the films were investigated. The results on the microstructure of the as-deposited films demonstrated that Ta forms an FCC Cu (Ta) metastable supersaturated substitutional solid solution in Cu. In addition, with the increase of Ta content, the NC Cu-Ta films tended to be amorphous. Furthermore, the grain size of the post-annealed Cu-Ta films increased slightly due to recrystallization and in the metastable solid solution, Ta was exsolved and precipitated from the Cu matrix. The lowest resistivity (3.165 × 10 −7 Ω•m −1 ) and the highest elastic modulus (125.2 GPa) were obtained with a Ta target current of 0.5 A.

A critical review of copper electroless deposition on glass substrates for microsystems packaging applications

“…The interfacial forces between the metal film and substrate and the mechanical interlocking of metal particles are the two main factors contributing to the adhesion improvement for H 2 SO 4 /K 2 Cr 2 O 7 treated substrates. The mechanical grinding did not improve the adhesion before acid etching (samples [19][20][21][22][23][24]. However, the polished/acid-etched samples showed higher adhesion values than the merely polished samples.…”

“…Several deposition techniques are used to deposit thin (<1 μm) and thick (>1 μm) copper films. Physicalvapour-deposition (PVD) processes [17][18][19][20], like sputtering [21][22][23][24][25] and electron beam evaporation [26][27][28][29], Chemical-vapour-deposition (CVD) [30][31][32][33][34], atomic layer deposition (ALD) [35][36][37][38] methods are used to deposit high-quality, defect-free, continuous films; however, the average thickness of deposited films is generally less than 1 μm. Electroplating is used in those applications where the thick blanket film is required or blind/through holes must be filled.…”

Structure, phase evolution and properties of Ta films deposited using hybrid high-power pulsed and DC magnetron co-sputtering

“…The finer grains and the more grain boundaries behaved so greater, the resistance to the movement of dislocations and other defects that there was the higher of the film hardness. [35][36][37] 115.14…”