This work presents the results obtained with potassium sodium niobate (KNN) biaxial non-resonant microelectromechanical systems (MEMS) mirrors manufactured on a 200 mm silicon substrate. These MEMS mirrors feature various reflector dimensions for the squared shape, ranging from 0.5 × 0.5 to 2 × 2 mm2, and incorporate sputtered potassium sodium niobate ((K0.35Na0.65)NbO3) thin-film piezo-motors from Sumitomo Chemical, with thicknesses varying from 0.5 to 1.5 µm. A comparison of the mirror's performance and static deformation as a function of KNN thickness will be presented and discussed. The results obtained with these non-resonant mirrors, all fabricated using a collective 200 mm silicon manufacturing process, exhibit the following: (a) an arm deformation of 50 to 80 µm corresponding to an estimated tensile residual stress of approximately 120 MPa in the KNN layer, (b) the same level of performance for the 0.5 µm thick lead zirconate titanate (PZT) and KNN at 10 V, and (c) an optical angle up to 8.5° at 40 V for the 2 × 2 mm2 mirror design with 1.5 µm thick KNN. These results indicate that the MEMS mirrors fabricated with the KNN lead-free piezoelectric material offer state-of-the-art performances and open potential applications in a wide range of fields from light detection and ranging (lidar) systems to biomedical applications, thanks to the full biocompatibility of the KNN material.

State-of-the-art (K,Na)NbO3 (KNN) films were integrated into MEMS actuator devices in a 200mm silicon wafer technology environment following industry compatible process. The ferroelectric, dielectric and piezoelectric properties of KNN films with a thickness of 1µm and 1.9µm integrated into capacitors were assessed throughout the whole 200mm wafers. The actuator behaviour was highlighted through electromechanical measurements on KNN based devices such as cantilever beams and membranes. KNN was eventually used to actuate micro-mirrors, one of the main piezoMEMS components that may drive the market in the near future. The results demonstrate that KNN technology is promising for replacing lead content PZT technology in piezoelectric MEMS industry.

We demonstrate the integration of a photonic circuit containing passive and active components into a piezoelectric-actuated micro cantilever. A 16-channel optical phased array operating at a wavelength of 905nm provides beam scanning over a range of 17 degrees in one dimension, while the inclination of the entire circuit and consequently the angle of the output beam in a second dimension can be independently modified over a range of up to 40 degrees via the piezoelectric actuator.

Using wafer level fabrication techniques, we combine silicon photonics and MEMS technologies to demonstrate the integration of an active photonic beam-steering circuit into a piezoelectric actuated micro cantilever. An optical phased array (OPA), operating at a wavelength of 905nm, provides output beam scanning over a range of 17° in one dimension, while the inclination of the entire circuit and consequently the angle of the output beam in a second dimension can be independently modified over a range of up to 40° via the piezoelectric actuator. This combination of existing commercial silicon technologies can provide continuous, low-divergence, solid-state beam scanning for sensing applications, while avoiding the disadvantages associated with the use of a widely tunable source laser.

This work reports the development of an enhanced 2D beam scanning by combining 200 mm silicon (Si) photonics and 200 mm Si MEMS technologies. It demonstrates the fusion of an active photonic beam-steering circuit within a piezoelectrically actuated micro-cantilever. Operating at a wavelength of 905 nm, the optical phased array (OPA) enables beam scanning up to 17 degrees in one dimension. Simultaneously, the circuit's inclination, in a second dimension, can be independently adjusted over a range of up to 40 degrees via the piezoelectric actuator. This paper will focus on the technological process that combines photonics and piezoelectric materials, as well as the possibility of tailoring the cantilever resonance frequencies via the dimensional parameters, to suit various target applications.

AbstractThree dimensional sensing is essential in order that machines may operate in and interact with complex dynamic environments. Solid-state beam scanning devices are seen as being key to achieving required system specifications in terms of sensing range, resolution, refresh rate and cost. Integrated optical phased arrays fabricated on silicon wafers are a potential solution, but demonstrated devices with system-level performance currently rely on expensive widely tunable source lasers. Here, we combine silicon nitride photonics and micro-electromechanical system technologies, demonstrating the integration of an active photonic beam-steering circuit into a piezoelectric actuated micro cantilever. An optical phased array, operating at a wavelength of 905 nm, provides output beam scanning over a range of 17° in one dimension, while the inclination of the entire circuit and consequently the angle of the output beam in a second dimension can be independently modified over a range of up to 40° using the piezoelectric actuator.

This paper presents the thermal behavior of a non-resonant (quasi-static) biaxial piezoelectric MEMS scanner [...]

This paper presents a simulation method based on a lumped element formulation solved using a time discrete scheme able to predict the behavior of biaxial MEMS scanners. To simulate the dynamic behavior on the scanner on both axis, an equivalent electrical circuit is used. From the dimensions and materials of the scanner, the inertial mass, the torsional spring and the coupling factor can be derived. Using a time domain solver, the frequency response as well as the response of the scanner to different signals can be evaluated. This model could easily be extended to include nonlinear effects of the piezoelectric layer, as well as geometric nonlinearities.

This paper presents the thermal behavior of non-resonant (quasi-static) piezoelectric biaxial MEMS scanners with Bragg reflectors. These scanners were developed for LIDAR (LIght Detection And Ranging) applications using a pulsed 1550 nm laser with an average power of 2 W. At this power, a standard metal (gold) reflector can overheat and be damaged. The Bragg reflector developed here has up to 24 times lower absorption than gold, which limits heating of the mirror. However, the use of such a reflector involves a technological process completely different from that used for gold and induces, for example, different final stresses on the mirror. In view of the high requirements for optical power, the behavior of this reflector in the event of an increase in temperature needs to be studied and compared with the results of previous studies using gold reflectors. This paper shows that the Bragg reflector remains functional as the temperature rises and undergoes no detrimental deformation even when heated to 200 °C. In addition, the 2D-projection model revealed a 5% variation in optical angle at temperatures up to 150 °C and stability of 2D scanning during one hour of continuous use at 150 °C. The results of this study demonstrate that a biaxial piezoelectric MEMS scanner equipped with Bragg reflector technology can reach a maximum temperature of 150 °C, which is of the same order of magnitude as can be reached by scanners with gold reflectors.

We report a study of AlN-based piezoelectric micromachined ultrasonic transducers (PMUT) dedicated to biomedical applications. The fabrication, the packaging, the electrical and acoustical characterization of the devices are reported and compared with the expectations. The device exhibits a 35% -3dB bandwidth with a central frequency at 10.4 MHz. The drive sensitivity is measured at 0.63 kPa/V/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and the receive sensitivity at 570 μA/MPa/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . This confirms the potential of PMUT as low-voltage, miniaturized ultrasound transducers for biomedical applications.

Transparent PZT-based membranes were fabricated out of 200 mm silicon wafers thanks to an innovative layer transfer process. The ITO (100 nm)/PZT (1.16 µm)/ITO (150 nm)/SiO2 (8.7 µm) membrane stack shows an average transmission of about 75 % in the visible spectrum. PZT film is highly (100) oriented and measured capacitors exhibit ferroelectric, dielectric and piezoelectric properties comparable to standard non-transparent PZT with metal electrodes. Piezoelectric actuation under applied voltage was verified through both static deflection and acoustic measurements. This first proof of concept opens the way to the fabrication of transparent piezoelectric transducers such as transparent PMUT devices.