In Situ X-ray Measurements to Follow the Crystallization of BaTiO3 Thin Films during RF-Magnetron Sputter Deposition

Peter Walter,Christian Bonar Zeuthen,Uwe Klemradt,Wiebke Ohm,Jantorben Roeh,Markus Ilchen

doi:10.3390/app11198970

Abstract

Here, we report on adding an important dimension to the fundamental understanding of the evolution of the thin film micro structure evolution. Thin films have gained broad attention in their applications for electro-optical devices, solar-cell technology, as well storage devices. Deep insights into fundamental functionalities can be realized via studying crystallization microstructure and formation processes of polycrystalline or epitaxial thin films. Besides the fundamental aspects, it is industrially important to minimize cost which intrinsically requires lower energy consumption at increasing performance which requires new approaches to thin film growth in general. Here, we present a state of the art sputtering technique that allows for time-resolved in situ studies of such thin film growth with a special focus on the crystallization via small angle scattering and X-ray diffraction. Focusing on the crystallization of the example material of BaTiO3, we demonstrate how a prototypical thin film forms and how detailed all phases of the structural evolution can be identified. The technique is shaped to enable a versatile approach for understanding and ultimately controlling a broad variety of growth processes, and more over it demonstrate how to in situ investigate the influence of single high temperature sputtering parameters on the film quality. It is shown that the whole evolution from nucleation, diffusion adsorption and grain growth to the crystallization can be observed during all stages of thin film growth as well as quantitatively as qualitatively. This can be used to optimize thin-film quality, efficiency and performance.

Highlights

The industrial market for thin films requires the production of more efficient layers with better performance, lower energy consumption, and preferably to lower production cost
To follow the preparation of oxide thin films, we were using the characteristic features of the modern synchrotron radiation source PETRA III [7], a compact and low-weight sputtering unit [8], and the investigation techniques in situ grazing incidence small angle
A second single-photon counting pixel detector with 487 × 619 pixel of 172 μm each (Pilatus 300k, Dectris, Baden, Switzerland) was mounted on the detector arm of the diffractometer with SDD = 0.28 m covering the Qrange from 2 Å−1 –4.5 Å−1. With this second 2D detector, we were following the evolution by grazing incidence X-ray powder diffraction (GIXRPD) simultaneously to the grazing incidence small angleX-ray scattering (GISAXS) measurement

Summary

Introduction

The industrial market for thin films requires the production of more efficient layers with better performance, lower energy consumption, and preferably to lower production cost. With an increasing demand of functional thin films the control and influence of the preparation parameters has to be investigated in situ during the thin film production. State of the art thin film research has reached a point where only in situ measurements can help optimizing the thin film production, because this way, the influence of the different sputtering parameters can be followed in real time during the deposition process. To follow the preparation of oxide thin films, we were using the characteristic features of the modern synchrotron radiation source PETRA III [7], a compact and low-weight sputtering unit [8], and the investigation techniques in situ grazing incidence small angle. We follow the crystallization process in situ during the high temperature deposition above the crystallization energy. We deposit BaTiO3 at 600 ◦ C and followed the film evolution from early formation to polycrystalline thin film of around 40 nm

Methods

Results

Conclusion