Barium–strontium–titanate thin films for application in radio-frequency-microelectromechanical capacitive switches

Abstract

In this letter we report the application of barium–strontium–titanate (BST) thin film oxides as the dielectric layer in radio-frequency-microelectromechanical system (rf-MEMS) capacitive switches. BST thin films deposited at ambient temperature by off-axis sputtering have been employed for application in rf-MEMS switches. Their dielectric properties have been characterized in the frequency range from 1 to 20 GHz both on magnesium oxide and on gold metal films. Switches have been fabricated which demonstrate promising on-state capacitance and good dielectric breakdown properties. Dielectric breakdown in excess of 400 kV/cm has been measured on switches cycled in excess of 2000 times during testing.

Structure and electrical properties of Ba0.67 Sr0.33TiO3 thin film fabricated by sol-gel based composite technique

“…In recent years Ba x Sr 1−x TiO 3 (BST) thin films have received intensive research interest for their device applications, such as bolometers [1][2][3], gas sensor [4,5], tunable microwave filters [6] and radio-frequency microelectromechanical (RF-MEMS) capacitive switches [7]. For most of the cases, higher dielectric constant of BST makes it possible to achieve smaller size or better performance of the devices.…”

Parallel-Plate Capacitors

“…After factoring out the series inductance, the high-frequency becomes (3) where has a weak frequency dependence. Thus, the variation in as a function of frequency can be illustrated as shown in Fig.…”

“…The ratio of resistances, i.e., 6.67, is very close to the ratio of the different probe areas, i.e., 6.25. 3 If this resistance results from physical contact with the top electrode, it will not be corrected during instrument calibration. While the shorted structure may be expected to account for this resistance, our devices are more similar to open-circuit loads than short-circuit loads, limiting the ability of the deembedding procedure using a shorted structure alone to fully capture the electrode-related properties [20].…”

Barium Titanate-Based Materials – a Window of Application Opportunities

“…As mentioned earlier, barium strontium titanate is an extensively investigated ferroelectric material due to its good electrical properties in bulk and thin film form being a leading candidate for applications in many electronic devices. Barium strontium titanate is currently considered as an attractive material in sensing, memory, capacitor and RF and microwave applications (Kirchoefer et al, 2002;Acikel et al, 2002;Hwang et al, 1995;Zhu et al, 2004;Tissot, 2003). But many important issues, such as improving dielectric constant values, dielectric loss and leakage, still need further attention in order to improve film quality and device performance.…”