Abstract:

MEMS devices with movable structures can be influenced by unmatched stress introduced by packaging process, leading to the change of structural reliability. The packaging effects on stability of MEMS structures were studied, and structural unstablity behaviors,such as buckling and adhesion, were observed after packaging. Analytical models of vibration and adhesion of beam structure were set up to predict the unstable behaviors. Experiments on surfaced-micromachined polysilicon structures indicate that compression stress is introduced after bonding, and the resonant frequency and contact resistance change considerably after the stability of devices is changed.

Key words: MEMS packaging, thermal mismatch, structural stability, adhesion

摘要：

由可动结构组成的MEMS器件容易受到封装工艺引入的热失配应力的影响。这种影响不仅会改变器件性能，还会影响其可靠性。从MEMS结构稳定性角度研究封装效应，阐明封装可能彻底改变MEMS的结构稳定性状态，产生屈曲、黏附等可靠性问题。在传统结构黏附模型上，分析了屈曲梁的振动特性和黏附行为。通过表面加工多晶硅梁结构的实验，结合理论模型证明，常规芯片粘接工艺会在梁结构中引入显著压应力，完全改变器件的稳定性状态，并使谐振频率和接触电阻这两个参数发生显著变化。
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关键词: 微机电系统封装, 热失配, 结构稳定性, 黏附