Axial flow vacuum pump with curved rotor and stator blades

An axial flow vacuum pump for evacuating a chamber in a semiconductor manufacturing process, the axial flow vacuum pump comprising:

• a rotor having a plurality of rotor blades;
• and
• a stator having a plurality of stator blades, wherein the rotor blades and stator blades have a curved aerofoil cross-sectional shape comprising a curved leading edge, a pointed trailing edge, a concaved pressure surface extending from the leading edge to the trailing edge and a curved suction surface extending from the leading edge to the trailing edge, wherein the concaved pressure surface of each rotor faces in a direction of rotation of the rotor;
• wherein an inlet stage of the pump comprises blades having a first radial length and an adjacent downstream stage of the pump comprises blades having a second radial length, wherein the ratio of first radial length to second radial length is 2:1 or greater.