MEMS microphone chip based on piezoelectric film and preparation method of suspended film unit

The MEMS microphone chip comprises an MEMS chip substrate, the MEMS chip substrate is provided with a vertically through cavity, the cavity is provided with a suspended film body formed by connecting a plurality of groups of suspended film units in series, the suspended film body covers the cavity in a sealing manner, the suspended film unit takes a piezoelectric layer as a substrate, and the piezoelectric layer is arranged on the substrate. A metal molybdenum layer, a silicon oxide layer and a silicon nitride layer are sequentially stacked on the upper surface and the lower surface of the piezoelectric layer respectively. The suspended membrane body is of a pentagonal structure and is formed by combining and splicing five suspended membrane units, and each suspended membrane unit is triangular. The piezoelectric film is adopted to replace a capacitor, zero-power-consumption monitoring is achieved by means of the piezoelectric effect, the multiple sets of suspension films are arranged and connected in series,