Sputter deposition of PZT piezoelectric films on thin glass substrates for adjustable x-ray optics

Abstract

Piezoelectric PbZr(0.52)Ti(0.48)O(3) (PZT) thin films deposited on thin glass substrates have been proposed for adjustable optics in future x-ray telescopes. The light weight of these x-ray optics enables large collecting areas, while the capability to correct mirror figure errors with the PZT thin film will allow much higher imaging resolution than possible with conventional lightweight optics. However, the low strain temperature and flexible nature of the thin glass complicate the use of chemical-solution deposition due to warping of the substrate at typical crystallization temperatures for the PZT. RF magnetron sputtering enabled preparation of PZT films with thicknesses up to 3 μm on Schott D263 glass substrates with much less deformation. X-ray diffraction analysis indicated that the films crystallized with the perovskite phase and showed no indication of secondary phases. Films with 1 cm(2) electrodes exhibited relative permittivity values near 1100 and loss tangents below 0.05. In addition, the remanent polarization was 26 μC/cm(2) with coercive fields of 33 kV/cm. The transverse piezoelectric coefficient was as high as -6.1±0.6 C/m(2). To assess influence functions for the x-ray optics application, the piezoelectrically induced deflection of individual cells was measured and compared with finite-element-analysis calculations. The good agreement between the results suggests that actuation of PZT thin films can control mirror figure errors to a precision of about 5 nm, allowing sub-arcsecond imaging.

Thickness distribution of sputtered films on curved substrates for adjustable x-ray optics

“…The actuators on the back consist of a series of metal (Ti and Pt), piezoelectric Pb 0.995 ðZr 0.52 Ti 0.48 Þ 0.99 Nb 0.01 O 3 (PZT) layers, and then a top Pt electrode is lithographically patterned to form an array of piezoelectric actuators. [18][19][20][21][22] The front (concave side) is then deposited with Cr and Ir coatings for adhesion and x-ray reflection, respectively.…”

Experimental system design for the integration of trapped-ion and superconducting qubit systems

“…However, for actuation purposes it is preferable to have thicker layers to obtain structural stability during flexing. For this reason, a 3 µm thick PZT layer was included in this proposal as this is the maximum thickness achievable from current sputter deposition processes [42]. A 1 µm thick Nb layer was added to the top and bottom of the PZT to form the electrode structures (see Fig.…”

“…The Pt layer serves as an adhesion layer and diffusion barrier between the Nb and PZT layer. (8) The deposition of PZT can be performed through several methods, such as sol-gel coating [45], sputtering [42], hydrothermal deposition [46], screen printing [47] and aerosol deposition [48]. For a 3 µm layer, rf magnetron sputtering provides an established deposition technique, which can utilize the same deposition tools as used for the other layers.…”

Measuring the performance of adjustable x-ray optics with wavefront sensing

“…A ∼ 1.5 µm PZT layer is deposited over the ground electrode. 10 Finally, patterned Pt electrodes are deposited over the PZT layer to form the actuator cells. Each mirror is a segment (∼ 30 degrees) of a Wolter I parabola or hyperbola.…”