A micromechanical arm array is provided. The micromechanical arm array comprises: a plurality of micromechanical arms spaced from each other in a first horizontal direction and extending in a second horizontal direction, wherein each micromechanical arm comprises a protrusion at a top of each micromechanical arm and protruding upwardly in a vertical direction; a plurality of protection films, each protection film encapsulating one of the plurality of micromechanical arms; and a metal connection structure extending in the first horizontal direction. The metal connection structure comprises: a plurality of joint portions, each joint portion corresponding to and surrounding the protrusion of one of the plurality of micromechanical arms; and a plurality of connection portions extending in the first horizontal direction and connecting two neighboring joint portions.