Vacancy clustering and its dissociation process in electroless deposited copper films studied by monoenergetic positron beams

Abstract

Positron annihilation was used to probe vacancy-type defects in electroless deposited copper films. For as-deposited films, two different types of vacancy-type defects were found to coexist; these were identified as vacancy aggregates (V3-V4) and larger vacancy clusters (∼V10). After annealing at about 200 °C, the defects started to diffuse toward the surface and aggregate. The same tendency has been observed for sulfur only, suggesting the formation of complexes between sulfur and vacancies. The defect concentration near the Cu/barrier-metal interface was high even after annealing above 600 °C, and this was attributed to an accumulation of vacancy-impurity complexes. The observed defect reactions were attributed to suppression of the vacancy diffusion to sinks through the formation of impurity-vacancy complexes. It was shown that electroless plating has a high potential to suppress the formation of voids/hillocks caused by defect migration.

Effect of Hydrogen on Vacancy Formation in Sputtered Cu Films Studied by Positron Annihilation Spectroscopy

“…In contrast, the 5-m-thick Cu films were investigated using a Kapton-film-sealed 22 NaCl conventional positron source ($1 MBq). A 22 NaCl source emits positrons with a maximum energy of 545 keV, 18) which corresponds to approximately 0.1 mm implantation depth.…”

“…In contrast, the 5-m-thick Cu films were investigated using a Kapton-film-sealed 22 NaCl conventional positron source ($1 MBq). A 22 NaCl source emits positrons with a maximum energy of 545 keV, 18) which corresponds to approximately 0.1 mm implantation depth. Therefore, to prevent positrons from penetrating a sample, 60 sheets of self-standing 5-m-thick Cu films were stacked, and the positron source was inserted between the stacked films.…”

“…2,15) Positron annihilation spectroscopy is a powerful technique for detecting vacancy defects in crystalline materials, [16][17][18] and Cu films have also been investigated by this technique. [19][20][21][22] Past positron annihilation spectroscopy studies have revealed that a large number of vacancy clusters are included in electroplated Cu films. [19][20][21] Similarly, in the argon-hydrogen-sputtered Cu films, there is a possibility that vacancy defects affect the improvement of the Cu embedding property.…”

On crystallization of bisphenol-A polycarbonate thin films upon annealing

“…In recent years, positron annihilation spectroscopy (PAS) has been accepted as a new microanalytical probe for free-volumes in polymeric materials [13,14]. PAS is a powerful, nondestructive tool for the characterization of vacancy-type defects, surface and interface defects and free-volumes [15][16][17][18][19][20]. After being injected in condensed matter, positrons may be localized in vacancy-type defects and free-volume holes due to the Coulomb repulsion from * Corresponding author.…”

Positron annihilation characteristics in mesostructural silica films with various porosities

“…[6][7][8][9][10][11][12][13] It is ideally suited for characterizing thin films on substrates by positron annihilation lifetime spectroscopy, Doppler broadening of positron annihilation radiation (DBAR) spectroscopy, and positronium time-of-flight etc., based on a variable energy slow positron beam. 6,9,[11][12][13][14][15] After being implanted in condensed matter, positrons may be localized in vacancy-type defects and pores during diffusion because of Coulomb repulsion from positively charged ion cores, and are annihilated by either valence or core electrons from surrounding atoms. Annihilation of positrons with core electrons may be less probable depending on the physicochemical environments, which results in narrowing of Doppler broadening of positron annihilation c-ray radiation.…”