Pressure sensor and manufacturing method thereof

The invention provides a pressure sensor and a manufacturing method of the pressure sensor. The manufacturing method of the pressure sensor comprises the steps that a semiconductor substrate is provided, wherein a CMOS circuit, an interconnection circuit and a bottom plate electrode are embedded in the semiconductor substrate, the CMOS circuit, the interconnection circuit and the bottom plate electrode are arranged in a stacked mode, and the interconnection circuit on the periphery of the bottom plate electrode is exposed from the semiconductor substrate; a sacrificial layer is formed on the position, corresponding to the bottom plate electrode, on the semiconductor substrate; a pressure sensing layer is formed on the sacrificial layer and on the semiconductor substrate; the sacrificial layer is removed, and a cavity is defined by the pressure sensing layer and the semiconductor substrate; a pressure conducting layer is formed on the pressure sensing layer and located above the cavity, wherein the pressure sensing layer is formed by forming a silicon germanium-noncrystalline silicon-silicon germanium stacked structure on the sacrificial layer. Compared with the prior art, due to the fact that the composite stacked structure is adopted by the pressure sensing layer, stress in the pressure sensing layer can be reduced; due to the fact that the stacked structure with multiple layers is adopted, the thickness of membranes, made of the same material, of each layer is reduced, stress is greatly reduced, and the performance of devices is improved.