Dielectric Properties Analysis in Paraelectric ZrTiO
4
Thin Films
Kyunghae Kim
1
, Jinhee Heo
1
, Taeseok Kim
2
, Byungwoo Park
2
, Junsin Yi
1
1
School of Electrical and Computer Engineering, Sungkyunkwan University,
Suwon, 440-746, Korea
2
School of Materials Science and Engineering, Seoul National University,
Seoul, 151-742, Korea
ABSTRACT
The dielectric constants and dielectric losses of ZrTiO
4
thin films deposited by DC magnetron
reactive sputtering were investigated. The paraelectric properties were measured in the 100kHz
range and compared with an equivalent circuit model. As the deposition temperature increased
(up to 600 ), the dielectric losses (tan ) decreased (down to 0.017 0.007), while the dielectric
constants ( ) were in the range of 35 7. Post annealing at 800 in oxygen for 2h reduced tan
down to 0.005 0.001, higher than those of well-sintered bulk ZrTiO
4
.
INTRDUCTION
With a wide variety of microwave communication applications, such as mobile phones, global
positioning systems(GPS), and satellite communications, the demand for monolithic microwave
integrated circuit technologies (MMIC) has been increasing. For miniaturization of integrated
circuit, microwave dielectric components need improved characteristics, smaller size, and
compatibility with existing circuits.[1-4] Paraelectric materials used as resonators and filters in
microwave circuits require high dielectric constants (resonator size proportional to 1 / ε ), low
dielectric losses (tan ), and low temperature coefficients of resonance frequency (
f
). Since
inferior dielectric properties of fabricated thin films limit the application of these materials in
thin film microwave devices, detailed studies on the correlations between the dielectric
properties and microstructures of thin films are needed.
The bulk ZrTiO
4
phase has a high dielectric constant suitable for microwave devices, low
dielectric losses, and good thermal stability with Sn addition. [5,6] Single-phase ZrTiO
4
structure
is orthorhombic with Ti and Zr ions chemically disordered in half of the eight octahedral sites in
a single unit cell above 1100 .[7] Below this temperature, the equilibrium phase diagram shows
phase separation into ZrO
2
and ZrTi
2
O
6
. [8,9] Single-phase ZrTiO
4
thin films have been studied
previously for the dielectric constants, leakage current, and optical index of refraxtion (n). [10-
13] The dielectric losses of these thin films in the microwave and even low frequency (~1MHz)
ranges, however, have not as yet been investigated. Therefore, in this paper, we report the effects
of deposition temperature and post thermal annealing on the dielectric losses (tan ) and dielectric
Mat. Res. Soc. Symp. Proc. Vol. 666 © 2001 Materials Research Society
F3.7.1