Measuring crystallographic texture in thin films

Preferred crystallographic orientation (texture) in thin films of technologically important materials frequently has a strong effect on the properties of these films. For example, the remanent polarization in ferroelectric films such as PbZr_xTi_1-xO₃ (PZT) is texture-dependent, so the ability to switch domains in a PZT non-volatile memory device (NVRAM) is strongly influenced by the texture. One objective of this project is to provide U.S. industry with fast, quantitative x-ray diffraction tools for measuring crystalline texture in thin films. We have developed techniques that use conventional powder diffractometers to measure texture in thin film and bulk materials. A conventional theta-2theta scan of a Bragg peak from the textured planes is recorded, and also an omega-scan (rocking curve) at the Bragg peak scattering angle. The raw omega-scan data are corrected for defocus using the Bragg peak theta-2theta scan to obtain accurate texture profiles and full-width-at-half-maximum values. These corrections can be substantial, as shown in the figure.

PZT (100) texture profile

Texture measurements have been performed on (Ba,Sr)TiO₃ and PZT films, and on electrodeposited advanced metallization Cu films.

Software is available to calculate texture profiles from raw x-ray data.

Conferences and Workshops

A workshop on "Texture in Electronic Applications" was held at NIST on October 10 and 11, 2000. The workshop featured invited and contributed talks and posters, and a round table discussion was held during the final afternoon. The report is published in the NIST Journal of Research, "Conference Report: Workshop on Texture in Electronic Applications", M. Vaudin and D. Kaiser, J. Res. Nat. Inst. Stand. Technol., Vol. 106, pp. 605-608 , 2001.

To follow up on the workshop, there will be a Symposium (J) on Texture and Microstructure in Electronic and Magnetic Films at the Spring MRS meeting in San Franciso, April 1 to 5, 2002.