基于微电子机械系统技术的高灵敏度电容式微传声器的研制
Study of a highly sensitive miniature condenser microphone based on MEMS technology
-
摘要: 基于微电子机械系统(MEMS)技术的微传声器是当前国际上研究的热点。使用 MEMSI艺制备的薄膜一般有着不可忽视的残余应力,极大的降低了膜的机械灵敏度。理论分析和数值模拟表明,纹膜结构可在不改变工艺条件的前提下,显著的降低残余应力的不良影响,大幅度增加膜的灵敏度。本文提出了一种使用MEMS技术制作的纹膜结构电容式微传声器,其制作工艺简单、重复性好,所用材料也能与 ICI艺很好的兼容。圆片级测试的结果表明,在 10 V的偏置电压下,这种微传声器在 7 kHz以下具有平直的频响,开路灵敏度可达 40 mv/Pa,而其占用的芯片面积仅为 1.5×l.5 mm2。进一步的研究可望将信号处理电路集成于片内,形成完整的微声学系统。Abstract: Nowadays, great enthusiasm is devoted to miniature microphone based on Microelectromechanical System (MEMS). For micromechined membrane, there is significantinternal (residual) stress, which strongly decreases the mechanical sensitivity of membrane. As predicted by theoretical analysis and numerical simulation, the application of corrugated membrane offers the possibility to eliminate the effect of initial stress and thus to increase the sensitivity of membrane without changing process conditions. A MEMS-based condenser miniature microphone with corrugated diaphragm has been presented and realized, the fabrication process is simple, efficient and fully compatible with standard IC process. Wafer level measurement has been carried out. An open circuit sensitivity of 40 mv/Pa up to 7 kHz could be achieved under a low bias voltage of 10 V with only 1.5×1.5 mm2 chip area. The preamplifier and subsequent signal process circuits should be integrated in the same chip to make a complete micro acoustics system.