A surface micromachining process utilizing dual metal sacrificial layer for fabrication of RF MEMS switch

We have developed a surface micromachining process utilizing the Cu - Ni dual metal layer as the sacrificial layer to fabricate the metal-contact RF MEMS switch. No seed layer is required for electroplating the structural layer, when the metallic sacrificial layer, such as Ni and Cu, is employed. Some inherit problems were found when using a single metal sacrificial layer. Our experimental results showed that a rough bottom surface of the structural layer would be obtained by use of Cu as the sacrificial layer solely, and an unacceptable stress would be induced by use of Ni. In contrast, applying Cu - Ni dual sacrificial layer led in the smooth structural surface and insignificant residual stress. A fabricated switch was demonstrated here.