Substrate warpage detection device, substrate warpage detection method, and substrate processing apparatus and substrate processing method using the same

A substrate warpage detection device for detecting warpage of a substrate loaded on a substrate loading region having a recess shape formed on a rotary table along a circumferential direction during rotation of the rotary table, the device comprising:

• a light transmitter configured to transmit a light beam obliquely upward from a side of the rotary table such that a lower portion of the light beam collides with an upper end of a side surface of the rotary table and an upper portion of the light beam positioned more upward than the lower portion of the light beam passes a portion near a surface of the rotary table;
• and
• a light receiver installed to face the light transmitter and configured to receive the light beam passing the portion near the surface of the rotary table so as to detect an amount of received light,
• wherein the light transmitter is disposed such that, when the substrate loaded on the substrate loading region protrudes upward from the surface of the rotary table by a predetermined height, the amount of received light detected by the light receiver becomes less than a predetermined threshold value.