Multilayer thin film capacitors by selective etching of Pt and Ru electrodes

• Process developed to fabricate thin film multilayer capacitors.
• The number of fabrication steps is independent of the number of layers.
• Demonstrated proof-of-concept fabrication of one-, two-, and three-layer capacitors.

Capacitors and other passive components within electronic devices can significantly affect the size of electronic devices. To continue decreasing the size of electronics, the miniaturization and potential integration of capacitors require thin film technologies. However, the number of fabrication steps needed for many thin film multilayer capacitor fabrication methods is proportional to the number of active capacitor layers, rendering them cost and time consuming. To overcome this issue, we developed a method using the highly selective etching capability of platinum and ruthenium for the fabrication of multilayer thin film capacitors, resulting in a process which is independent of the number of capacitive layers. To demonstrate the process, one-, two-, and three-layer 2.5 mm × 2.5 mm devices were fabricated using a proof-of-concept silicon oxycarbonitride dielectric grown by plasma-enhanced chemical vapor deposition. The resulting 278 ± 3 pF, 508 ± 5 pF, and 762 ± 5 pF capacitors showed negligible frequency dispersion up to 1 MHz, and had low dissipation factors of ∼0.001 at 10 kHz. As a demonstration of the versatility of the process, devices with thicker dielectric layers (3.5 μm) were also fabricated with a capacitance of 101 ± 2 pF which could achieve up to 640 V before the devices were permanently damaged. The versatility of the process suggests it is a good candidate for the future integration of multilayer capacitors, since it can potentially be fabricated by a variety of deposition methods, and can be formed on two- or three-dimensional substrates.

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