抄録
Abstract
Piezoresistive microelectromechanical systems (MEMS) multi-axis force sensors are widely utilized owing to their high sensitivity and compact form factor. In multi-axis sensing applications, it is essential to measure forces along each axis simultaneously while minimizing crosstalk. To achieve this, forming piezoresistive layers not only on the device surface for out-of-plane force detection but also on the sidewalls for in-plane force detection is highly effective. However, patterning piezoresistive layers on sidewalls remains technically challenging using conventional lithography-based MEMS fabrication processes, thereby increasing fabrication complexity and limiting design flexibility. In contrast, laser doping enables localized and selective formation of piezoresistive layers, offering a promising approach to overcome these limitations. In this study, we propose a piezoresistive cantilever for in-plane force measurement fabricated using liquid-immersion laser sidewall doping. The proposed process consists of two main steps: device structure formation through laser processing and sidewall piezoresistive layer formation via liquid-immersion laser doping. This approach enables direct and selective patterning of piezoresistive layers on device sidewalls. To verify the effectiveness of the proposed method, the electrical and mechanical characteristics of the fabricated sensor were evaluated. The piezoresistive layer exhibited a gauge factor exceeding 13, demonstrating sufficient performance for practical sensing applications.