Piezoelectric Thick Film Deposition via Powder/Granule Spray in Vacuum: A Review

Abstract

Conventional thin-film processing techniques remain inadequate for obtaining superior dense ceramic thick films. The incompatibility of ceramic films prepared via other methods, such as screen printing, spin coating, and sputtering, is a major obstacle in the fabrication of thick film-based ceramic electronic components. The granule spray in vacuum (GSV) processes and aerosol deposition (AD) are important coating approaches for forming dense ceramic thick films featuring nanoscale crystallite structures at room temperature, which offer excellent material properties and facilitate cost-effective production. AD ceramic coatings require the acceleration of solid-state submicron ceramic particles via gas streams with a velocity of a few hundred meters per second, which are then wedged onto a substrate. This process is economical and particularly useful for the fabrication of piezoelectric thick film-based microactuators, energy harvesters, sensors, and optoelectronic devices. More recently, the GSV technique was improved to achieve more uniform and homogeneous film deposition after AD. This review article presents a detailed overview of the AD and GSV processes for piezoelectric thick films in terms of recent scientific and technological applications.

Making powder aerosol deposition accessible for small amounts: A novel and modular approach to produce dense ceramic films

“…2 Developments in the past decade pointed towards a better understanding of the deposition mechanism, 10,[41][42][43][44] possible applications, 36,40,[45][46][47][48] and a scale-up of the spray process. 49 The latter resulted in an enhanced process control and increased coating areas, for example, for PZT on 4-inch wafers, 50 SOFC anode/electrolyte bi-layers up to 1000 cm², 51 Y 2 O 3 transparent films on 500 mm square glass panels, 52 and even larger films using nozzles width of 400 mm up to 1000 mm. 49,53 However, this process improvement comes at the cost of a significantly raised complexity of the coating devices.…”

“…49 The latter resulted in an enhanced process control and increased coating areas, for example, for PZT on 4-inch wafers, 50 SOFC anode/electrolyte bi-layers up to 1000 cm², 51 Y 2 O 3 transparent films on 500 mm square glass panels, 52 and even larger films using nozzles width of 400 mm up to 1000 mm. 49,53 However, this process improvement comes at the cost of a significantly raised complexity of the coating devices. Consequently, expensive moving stages, high-throughput aerosol generation devices, and very large deposition chambers are required.…”

PowderMEMS—A Generic Microfabrication Technology for Integrated Three-Dimensional Functional Microstructures

“…While the desired lateral dimensions are easily achievable using this technique, patterning of layers that exceed a few µm in thickness becomes increasingly challenging. For example, materials such as piezoelectric PZT or hard magnetic NdFeB can be obtained with a thickness of 100 µm via aerosol deposition and pulsed-laser deposition, respectively [ 4 , 5 ]. However, suitable patterning processes have been reported only for 10 µm thick layers of those materials [ 6 , 7 ].…”

Posttreatment of powder aerosol deposited oxide ceramic films by high power LED

“…The thermal interaction depth of the laser irradiation and therefore the annealing depth strongly depend on the wavelength and the scan speed as well as on the laser beam profile (i.e., Gaussian beam profile or flat top beam profile) 19–21 . Laser sources with a wavelength in the range of 400–700 nm are stated to be ideal for 5 μm thick PAD films, depending on the material properties such as the band gap 22–24 …”

“…[19][20][21] Laser sources with a wavelength in the range of 400-700 nm are stated to be ideal for 5 μm thick PAD films, depending on the material properties such as the band gap. [22][23][24] To reduce both, the thermal stress caused by the posttreatment and long process times, this paper focuses on an inexpensive, rapid optothermal posttreatment of PAD films with a minimum required energy input. Therefore, three different high-power light emitting diodes (HP-LED) in the visible light spectrum (blue, green, and amber) are For these films, a high electrical conductivity is required since they are intended to be used, for example, as p-type conductor in thermoelectric generators.…”