Patent ID: 9691646
Date: 2017-06-27
CPC Classifications: H01L

Claim:
1. A substrate processing apparatus comprising: a substrate holding unit provided in a substrate processing unit with a rotating plate and a substrate support unit configured to support a substrate above the rotating plate; a ring-shaped retro-reflective sheet having a central opening provided on an extended line of a central axis of the substrate holding unit such that the ring-shaped retro-reflective sheet is disposed below the substrate when the substrate is disposed on the substrate holding unit and rotated together with the substrate holding unit; a light projecting and receiving part provided above the substrate when the substrate is supported by the substrate support unit and configured to project incident light having a predetermined incident angle to the ring-shaped retro-reflective sheet from a slanted upper side and receive reflected light reflected in the same direction as the incident angle; a substrate detection unit separately provided from the light projecting and receiving part and configured to detect a presence or an absence of the substrate on the substrate holding unit based on a signal from the light projecting and receiving part, which indicates an intensity of the reflected light received by the light projecting and receiving part; and a supply pipe configured to supply liquid or gas by penetrating through the rotating plate of the substrate holding unit, the supply pipe being provided to penetrate through the central opening of the ring-shaped retro-reflective sheet.