Hongchuan Jiang Chaojie Wang Wanli Zhang Xu Si Yanrong Li
材料科学技术（英）
TaNx thin films were deposited on commercial polished Al2O3 ceramic substrates by reactive dc magnetron sputtering. The influences of the film thickness on the electrical properties of the samples were examined in detail. It is found that the film thickness does not influence the phase structures of the TaNx thin films. The sheet resistances of the samples shift from 173 Ω/sq. to 7.5 Ω/sq. with the film thickness shifting from 30 nm to 280 nm. With the increase of the film thickness from 30 nm to 280 nm, the temperature coefficient of resistance (TCR) of the samples shifts from negative value to positive value. When the film thickness is about 100 nm, TaNx thin films exhibits a near-zero TCR value (approximately -15×10-6/°C). This fact implies that TaNx thin films with a null TCR can be obtained by adjusting the film thickness. The variation in the electrical properties of the TaNx thin films with the film thickness can be qualitatively explained by the parallel connection of surface layer with high resistivity and negative TCR and TaNx layer with low resistivity and positive TCR.
关键词:
TaNx thin films
,
Film thickness
,
TCR
,
Sheet resistance
Wei Liu Lei Zhang J.K. Shang
材料科学技术（英）
The thermodynamic conditions for dewetting of a liquid solder drop on copper thin films were examined under a hot-stage optical microscope in a flowing protective atmosphere. Dewetting of liquid solder was found to depend strongly on the copper film thickness and preceded by spalling of Cu6Sn5 intermetallic compounds. However, the loss of interfacial bonding by spalling was not sufficient to cause immediate dewetting of solder drops if the wetting tip was still strongly bonded to the copper film. By introducing a pinning force on the wetting front, a sufficient condition was found from a force balance analysis for dewetting of the liquid solder drop, in general agreement with the experimental results.
关键词:
Dewetting
,
dewetting
,
solder
,
spalling
,
film thickness
