A method to enhance the connection strength of suspended membrane leads and substrate contacts is described. A reading circuit chip is provided and a sacrificial layer is formed thereon. Subsequently, an electrical contact window is created in the sacrificial layer to expose a conductive layer of the reading circuit chip. A metal layer is filled into the contact window and a conductive membrane is formed thereon to couple electrically to the metal layer. Afterward, an infrared measuring membrane and an upper dielectric layer are formed thereon.