Thin-Film RF/Microwave
Capacitor Technology
Accu-P
555
Accu-P
Thin-Film Technology
This accuracy sets apart these Thin-Film capacitors from
THE IDEAL CAPACITOR
ceramic capacitors so that the term Accu has been
The non-ideal characteristics of a real capacitor can be
employed as the designation for this series of devices, an
ignored at low frequencies. Physical size imparts inductance
abbreviation for accurate.
to the capacitor and dielectric and metal electrodes result in
resistive losses, but these often are of negligible effect on the
circuit. At the very high frequencies of radio communication
THIN-FILM TECHNOLOGY
1
(>100MHz) and satellite systems (>1GHz), these effects
Thin-film technology is commonly used in producing semi-
become important. Recognizing that a real capacitor will
conductor devices. In the last two decades, this technology
exhibit inductive and resistive impedances in addition to
has developed tremendously, both in performance and in
capacitance, the ideal capacitor for these high frequencies is
process control. Todays techniques enable line definitions of
an ultra low loss component which can be fully characterized
below 1m, and the controlling of thickness of layers at 100
in all parameters with total repeatability from unit to unit.
-2
(10 m). Applying this technology to the manufacture of
Until recently, most high frequency/microwave capacitors
capacitors has enabled the development of components
were based on fired-ceramic (porcelain) technology. Layers
where both electrical and physical properties can be tightly
of ceramic dielectric material and metal alloy electrode paste
controlled.
are interleaved and then sintered in a high temperature oven.
The thin-film production facilities at AVX consist of:
This technology exhibits component variability in dielectric
Class 1000 clean rooms, with working areas under
quality (losses, dielectric constant and insulation resistance),
laminar-flow hoods of class 100, (below 100 particles
variability in electrode conductivity and variability in physical
per cubic foot larger than 0.5m).
size (affecting inductance). An alternate thin-film technology
has been developed which virtually eliminates these vari-
High vacuum metal deposition systems for high-purity
ances. It is this technology which has been fully incorporated
electrode construction.
into Accu-P and Accu-P to provide high frequency capaci-
Photolithography equipment for line definition down to
tors exhibiting truly ideal characteristics.
2.0m accuracy.
The main features of Accu-P may be summarized as follows: Plasma-enhanced CVD for various dielectric deposi-
tions (CVD=Chemical Vapor Deposition).
High purity of electrodes for very low and repeatable
ESR. High accuracy, microprocessor-controlled dicing saws
for chip separation.
Highly pure, low-K dielectric for high breakdown field,
high insulation resistance and low losses to frequencies High speed, high accuracy sorting to ensure strict
above 40GHz. tolerance adherence.
Very tight dimensional control for uniform inductance,
unit to unit.
Very tight capacitance tolerances for high frequency
signal applications.
Orientation Marking
Alumina (Al O )
2 3
Electrode
Seal
(SiNO)
Dielectric (SiO / SiNO)
2
Electrode
Alumina (Al O )
2 3
Terminations
ACCU-P CAPACITOR STRUCTURE
6