Patent ID: 7852476

Claim:
A particle monitor system for detecting particles in a substrate processing apparatus including a housing chamber in which a substrate is received and processed, an exhausting apparatus for exhausting gas in the housing chamber therefrom to reduce a pressure in the housing chamber, and an exhaust pipe through which the housing chamber is communicated with the exhausting apparatus, comprising: a laser oscillator adapted to irradiate laser light toward inside the exhaust pipe; a light receiving device having a focal point thereof adapted to be located on the laser light, said light receiving device being adapted to receive scattered light or attenuated light of the laser light scattered or attenuated by particles flowing through the exhaust pipe; and a particle converging unit adapted to converge at least part of the particles toward the focal point of said light receiving device, wherein said particle converging unit includes a gas passage through which gas passes from upstream of the exhaust pipe to downstream thereof, and wherein the gas passage of said particle converging unit is adapted to separate a flow of the gas from a flow of the particles such that the gas is introduced toward a location other than the focal point of said light receiving device.