Annealing Effects to Electrode Pt / Ti for PZT
- PDF / 1,568,750 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 25 Downloads / 166 Views
59 Mat. Res. Soc. Symp. Proc. Vol. 318. ©1994 Materials Research Society
RESULT
In Fig.1., we show the XRD spectra, taken in 6 • 20 mode, for the unannealed and annealed electrodes. The data for the annealed electrodes were those taken in situ in the final 20 minutes in the annealing. The Pt layer is {111} oriented before annealing. Although small peaks, corresponding to Pt (200), appear in the electrode annealed at 600'C and 800°C, their signal heights are about 1 % of those of Pt (111). Pt {111} orientation is well conserved even after annealing. This character was also confirmed for the other spectra (not shown), taken in the initial 20 minutes of the annealing and at R.T. after annealing.
IM000-
.............. .
.................................................................
l0- ....... . . . . . ." . . .. . . . .. . . . . . . . . ............ . . .
.................
........................................
. ........... ..... ............. ............................... . . .. . .
............ .. .. .
0C 600
......... .
...... .. ..........
. .. .. .. . ...... .
No Anneal °&'M
X100
40!0
50!0
$0!0
70.00
Fig. 1. XRD spectra in 0 *26 mode for the unannealed and annealed electrodes. The data for the annealed were those taken in the final 20 minutes in the annealing. Oriented films allow us to discuss the stress from the peak shift. The horizontal compressive stress makes the Pt (111) lattice spacing larger. The torsion in the normal direction, e, is expressed as F. = - V Cy/ E, where v and E are Poisson ratio and Young's modulus respectively. The horizontal stresse was denoted by CF.If (3is positive, it is tensile . By measuring the torsion in the normal direction with the Pt (111) peak position, it is possible to evaluate the sign and the magnitude of the horizontal stress, aY. In Fig.2., the heat hysteresis of the Pt (111) lattice spacing is shown. For the powder Pt, the (111) lattice spacing at R.T. is 2.265 A. The thermal expansion coefficent of Pt is 8.8 X 10-6 / deg. at R.T.[12]. Before annealing, the lattice spacing is larger than that of the powder Pt. The Pt layer initially experiences the compressive stress. That was probably caused by the sputtering damage. With E = 1.68)X 101(Pa) and v = 0.377 for Pt [12], we get the initial compressive stress, 1.6 Gpa. After 400'C annealing, the lattice spacing is similar to that of the powder Pt. After 600'C or 800'C annealing, the lattice spacing is smaller than that of the powder Pt. That means the Pt layer feels the tensile stress.
660
2.28
Powder-,O/
02.27
" 400'C annealed
)•
2.26
*-600°C
,
8000C - Powder I
0
1000 500 Temperature ( °C )
Fig.2. Heat Hysteresis of Pt (111) Lattice Spacing. The thermal expansion coefficient for Pt is 8.8 X 10-6 / deg. at R.T. [14]. The thermal expansion coefficient of Pt is larger than that of the substrate Si. During the cooling after annealing, the Pt layer is effectively expanded by the substrate, thereby feels the
horizontal tensile stress. The Pt layer, with its stress released at high temp
Data Loading...
