Dielectric surface roughness and top electrode metal asperities tend to affect both the life-time reliability and frequency response of RF MEMS capacitive shunt switches. Down-state (off) capacitance of these switches is considerably affected by interface irregularities and trapped free space. There exists two very contradictory concepts regarding theoretically completely conformal Metal-Insulator-Metal contacts and commercially available RF MEMS capacitive switches. We explained the sole source of this contradiction, and offered a new model that is more accurate to describe RF MEMS switches. With this model we consider the effects of both contact roughness and free space trapped in down-state capacitance. Using the proposed model, different switch characteristics like frequency response and capacitance ratio is evaluated.

中文翻译：

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接触粗糙度和自由空间对RF-MEMS电容分流开关特性的影响

电介质表面粗糙度和顶部电极金属凹凸往往会影响 RF MEMS 电容分流开关的寿命可靠性和频率响应。这些开关的下态（关断）电容受界面不规则性和自由空间的影响很大。关于理论上完全共形的金属-绝缘体-金属触点和商用 RF MEMS 电容开关，存在两个非常矛盾的概念。我们解释了这一矛盾的唯一来源，并提供了一种更准确地描述 RF MEMS 开关的新模型。在这个模型中，我们考虑了接触粗糙度和捕获在低态电容中的自由空间的影响。使用所提出的模型，可以评估不同的开关特性，如频率响应和电容比。