2D PZT MEMS Resonant Scanner Using a Three-Mask Process

TL;DR

This paper introduces a compact 2D resonant MEMS scanner with a novel dual-axis architecture using a three-mask process, achieving high scan angles and bandwidth efficiency suitable for advanced optical applications.

Contribution

It presents a new mechanically coupled dual-axis 2D MEMS scanner fabricated with a simplified three-mask process, enabling high performance in a compact form factor.

Findings

Achieved vertical and horizontal resonant frequencies of 3.6 kHz and 54.2 kHz.

Optical scan angles of 4.8° and 11.5° in vertical and horizontal directions.

High scan bandwidth-efficiency products of 24.2 deg·mm·kHz and 623 deg·mm·kHz.

Abstract

This work presents the design, simulation, fabrication, and characterization of a novel architectural compact two-dimensional (2D) resonant MEMS scanning mirror actuated by thin-film lead zirconate titanate (PZT). The device employs an innovative mechanically coupled dual-axis architecture fabricated using a three-mask process on an SOI-PZT deposited wafer, significantly reducing system complexity while achieving high performance. The scanner integrates a 1 $\times$ 1.4 mm oval mirror within a 7 $\times$ 4.7 mm die, actuated by PZT thin-film elements optimized for resonant operation at 3.6 kHz (vertical) and 54.2 kHz (horizontal) under 12 V$_{\mathrm{p-p}}$ periodic pulse driving. The system achieves optical scan angles of 4.8$^\circ$ and 11.5$^\circ$ in vertical and horizontal directions, respectively, with quality factors of 750 (vertical) and 1050 (horizontal). These values contribute to high scanning bandwidth-efficiency products of 24.2 deg$\cdot$mm$\cdot$kHz (vertical) and 623 deg$\cdot$mm$\cdot$kHz (horizontal), among the higher values reported for 2D PZT-MEMS scanners. Finite element analysis confirmed minimal stress and mirror deformation, and experimental validation demonstrated excellent agreement with simulation results. This architecture demonstrates the feasibility of high-resolution laser scanning, as required in applications such as OCT, LiDAR, and displays, by achieving performance levels in line with those used in such systems.