Separating system and separating method

A separating method, comprising:

• placing a first cassette allowed to accommodate a combined substrate in which a first substrate and a second substrate are bonded to each other with a separation layer therebetween, a second cassette allowed to accommodate the first substrate, and a third cassette allowed to accommodate the second substrate in a placing unit configured to place therein the first cassette, the second cassette and the third cassette;
• taking out, by using a transfer device, the combined substrate from the first cassette placed in the placing unit and transferring the taken combined substrate to a removing apparatus configured to remove the separation layer by radiating laser light to the separation layer and allowing the separation layer to absorb the laser light;
• removing the separation layer from the combined substrate by using the removing apparatus, thereby separating the first substrate and the second substrate from the combined substrate;
• detecting a separating state of the combined substrate in the removing apparatus by measuring a distance to a top surface of the combined substrate by using a detector disposed above the combined substrate in the removing apparatus,
• determining that the combined substrate is separated into the first substrate and the second substrate when an absolute value of a difference between the distance detected by the detector before a processing by the removing apparatus and the distance detected by the detector after the processing by the removing apparatus exceeds a threshold value, and
• accommodating, by using the transfer device, the first substrate and the second substrate separated from the combined substrate in the second cassette and the third cassette placed in the placing unit, respectively.