硅基电磁式MEMS微扬声器结构设计和制作

Design and fabrication of silicon-based electromagnetic MEMS microspeaker

设计制作了一种高音质电磁微机电系统(MEMS)扬声器,该结构由悬臂梁支撑的硅基薄膜、固定在硅基薄膜上的钐钴磁体以及制作在PCB板上的铜线圈组成。扬声器微结构利用体微加工工艺制作,微梁支撑的硅基薄膜刚度较大,在音频范围内只有三个振动模态,远少于传统电磁式微扬声器使用的聚合物薄膜振动模态数,减少了尖声信号出现,提高了声音的质量。悬臂梁结构可以提供较大的振动幅度以及很好的振动线性度,从而获得更高的声压。扬声器结构硅基薄膜直径1mm,厚度25μm,悬臂梁宽度20μm,厚度25μm,具有音质好、声压大的特点。

An electromagnetic micro-electromechanical systems（MEMS）microspeaker was designed and fabricated, which is composed of a silicon-based membrane suspended by cantilever beams, stacked Sm2Co17 permanent magnet and a copper coil on a PCB board. The bulk micromachined device structure with silicon membrane using shows higher rigidity and better acoustic behavior compared with conventional devices with flexible polymer membranes, and for example, only 3 vibration modes appear in the audio range, improving the quality of the sound. Large vibration amplitude and good vibration linearity provided by the cantilever structure make the structure has a higher sound pressure. Consequently, the structure has the characteristics of better sound quality and higher sound pressure. The diameter of silicon membrane and the width of the cantilever beam are 1mm and 20μm, respectively, and they have the same thickness of 25μm.