We determined the growth rate, electrical performance and morphology of tantalum (Ta) thin films in a wide range of
back pressure (i.e. 0,003-0,06 mbar) and plasma power P<sub>p</sub> (i.e. 100-900 W) levels at nominally unheated substrate
conditions during deposition. First, Ta thin films with nearly constant thickness (mean value: 230 (±50) nm) were
deposited by varying the sputter time in dependence of the plasma power. Next, we increased the sputter time at constant
plasma power to demonstrate that we get a higher resistivity with increasing film thickness as well as at high back
pressures when depositing Tantalum predominantly in the beta phase. Doing so, the resistivity of the tantalum thin films
can be tailored over two decades at constant film thickness only by tuning these important deposition parameters.
Furthermore, X-ray diffraction (XRD) measurements showed a decreasing grain size at samples with a higher resistivity
proving the physical basis of this finding. All results can be explained based on the variation in microstructure of the thin
films at different deposition parameters such as the grain size. Furthermore, when knowing the growth rate (i.e. film
thickness and sputter time) the corresponding microstructure present in the Ta thin films can be estimated.
To make use of metals with improved conductivity like Ag, AgPd, Au or Cu for metallization pastes in ceramic
multilayer technology, Low-Temperature Co-fired Ceramics (LTCC) are densified at temperatures below 900°C. The
densification mechanism can be attributed to viscous sintering in combination with the crystallization of the glass matrix.
Lifetime prediction and extension of the application range to elevated temperatures strongly depend on the transition
range of the remaining amorphous phase as well as on the final crystallization products. Due to the fact that multilayer
ceramics based on LTCCs are gaining increasing interest in the manufacturing of highly integrated devices for
microelectronic and sensor applications, there is the need to establish a better understanding of their mechanical and
electrical behaviour in the elevated temperature regime. In this study, four commercial LTCC substrate materials in
addition to a test product in the sintered state, namely DP 951, DP 943, both from DuPont, CT 800 and AHT-01, both
from Heraeus, and GC from CeramTec were investigated in respect to the temperature dependence of their mechanical
and electrical properties up to temperatures of 950 °C. Mechanical characterization included three-point bending tests on
single layer substrates. Furthermore, the surface resistivity as a function of temperature up to 500°C was determined
under vacuum for DP 951. Next, these results were correlated to the composition of the glasses, determined by
inductively coupled plasma (ICP) analysis, as well as the crystallization products apparent in the composites, which were
determined by XRD of the sintered substrates and in-situ HT-XRD for DP 951. Results gained from these investigations
of the commercial LTCC products were compared to measurements carried out on glass-ceramic composites developed
in-house exhibiting improved electrical behaviour and good temperature stability.