Post-CMOS compatible high-throughput fabrication of AlN-based piezoelectric microcantilevers

Abstract

A post-complementary metal oxide semiconductor (CMOS) compatible microfabrication process of piezoelectric cantilevers has been developed. The fabrication process is suitable for standard silicon technology and provides low-cost and high-throughput manufacturing. This work reports design, fabrication and characterization of piezoelectric cantilevers based on aluminum nitride (A1N) thin films synthesized at room temperature. The proposed microcantilever system is a sandwich structure composed of chromium (Cr) electrodes and a sputtered A1N film. The key issue for cantilever fabrication is the growth at room temperature of the A1N layer by reactive sputtering, making possible the innovative compatibility of piezoelectric MEMS devices with CMOS circuits already processed. A1N and Cr have been etched by inductively coupled plasma (ICP) dry etching using a BCl3-Cl2-Ar plasma chemistry. As part of the novelty of the post-CMOS micromachining process presented here, a silicon Si (100) wafer has been used as substrate as well as the sacrificial layer used to release the microcantilevers. In order to achieve this, the Si surface underneath the structure has been wet etched using an HNA (hydrofluoric acid + nitric acid + acetic acid) based solution. X-ray diffraction (XRD) characterization indicated the high crystalline quality of the A1N film. An atomic force microscope (AFM) has been used to determine the Cr electrode surface roughness. The morphology of the fabricated devices has been studied by scanning electron microscope (SEM). The cantilevers have been piezoelectrically actuated and their out-of-plane vibration modes were detected by vibrometry.

Temperature characteristics of SAW resonators on Sc0.26Al0.74N/polycrystalline diamond heterostructures

“…The ScAlN thin films used in this work have been deposited on a 5.8 μm thick polycrystalline diamond substrate using a home built single magnetron sputtering system. The sputtering system is solely devoted to the deposition of AlN (for avoiding cross contamination effects) and recently to ScAlN thin films [28,29]. It consists of two separate chambers, namely a synthesis chamber and a load-lock chamber.…”

Electro-optical characterization of IC compatible microcantilevers

“…Consequently, after the cantilevers are released, the area of cantilever clamping is also underetched, as observed in the scanning electron microscopy (SEM) analysis. This manufacturing process is the result of an optimization process which seeks maximizing the fabrication throughput while keeping it compatible with state of the art CMOS technology standards (Pérez-Campos, Iriarte, Hernando-Garcia, & Calle, 2015).…”

An Identification Method for Dynamic Systems with SCNs Hysteresis Compensator: Application to the Inchworm Piezo Motor

“…For ultra-precision detection and motion systems dedicated to super-resolution microscopy for semiconductor tests [1], ultra-precision micro-machines for manufacturing [2,3], and microrobots for medical assistance technology [4], inchworm piezo motors are commonly used. It should be noted that inchworm piezo motors are particularly useful in semiconductor chip detection systems due to their advantages in terms of their long travel ranges (millimeter scale), nanometer resolution (nanometer scale), and heavy forces (tens of N scale) [5,6].…”