Evaluating the residual stress in PbTiO₃thin films prepared by a polymeric chemical method

Abstract

We report a study of residual stress in PbTiO 3 (PT) thin films prepared on Si substrates by a polymeric chemical method. The E(1TO) frequency was used to evaluate the residual stress through an empirical equation available for bulk PT. We find that the residual stress in PT films increases as the film thickness decreases and conclude that it originates essentially from the contributions of extrinsic and intrinsic factors. Polarized Raman experiments showed that the PT films prepared by a polymeric chemical method are somewhat a-domain (polar axis c parallel to the substrate) oriented.

Investigation of thickness-dependent stress in PbTiO3 thin films

“…Let us however emphasize that Eq. ͑4͒ is used in the literature regardless of the stress state ͑compres-sive and tensile͒ 11,12,14,16,38 and this although the pressure coefficient is experimentally known only for compression. As a matter of fact, it is difficult to anticipate the tensile pressure coefficient for an anharmonic soft mode from compression data.…”

“…Therefore, the investigation of residual stress helps in predicting physical properties for ferroelectric film-based devices. Optical fluorescence, 6 x-ray diffraction ͑XRD͒, 7 wafer curvature measurements, 8 cantilever beam deflection, 9 laser reflectance, 10 and Raman spectroscopy [11][12][13][14][15][16][17] have been used for stress analysis in ferroelectric materials. Among them, XRD and Raman spectroscopy are most popular, as they are powerful tools for the nondestructive investigation of structure.…”

“…23 Even though epitaxial films often have physical properties superior to those of polycrystalline films ͑i.e., in terms of polarization͒, only a few papers on stress evaluation by Raman spectroscopy are known in such films 15,16 ; most reports concern stress evaluation in polycrystalline films on sapphire or Si substrates. [11][12][13][14] Different theoretical studies analyze the stress state 24 and the possible mechanisms for stress relaxation 23 in epitaxial PTO thin films. Here we report a systematic study of stress and domain structure evolution as a function of film thickness for PTO films by using XRD, Raman spectroscopy, and atomic force microscopy ͑AFM͒.…”

Raman Spectroscopy and X-ray Diffraction Studies of Stress Effects in PbTiO<inf>3</inf> Thin Films

“…In the past, optical fluorescence [12], X-ray diffraction (XRD) [13], wafer curvature measurements [14], cantilever beam deflection [15], laser reflectance [16] and Raman spectroscopy [17][18][19][20][21][22][23][24] have been used for stress analysis of ferroelectric materials. Among them, XRD and Raman 3 spectroscopy are the most popular techniques, as they are powerful tools for non-destructive investigation of structure.…”

Stress development of direct-patternable PZT film for applying to micro-detecting system

“…We measured the residual stress by using Raman spectroscopy because it is nondestructive and simple method [10,11]. The ferroelectric properties and residual stress of conventional film were compared with those of modified film and the application-probability was discussed on the point of view of micro-bio-detecting device, for example, cantilever type.…”