Substrate transfer apparatus, substrate transfer method, and non-transitory storage medium

A substrate transfer method comprising:

• detecting, in a sensor part of a substrate holding part movable in a lateral direction to transfer a circular substrate from a first module to a second module, positions of at least four points of an edge portion of the substrate held by the substrate holding part, the sensor part comprising at least four sensor pairs comprising light source parts applying light to positions different from one another at the edge portion and light receiving parts paired with the light source parts;
• determining for each of the at least four sensor pairs whether the sensor pair is usable or unusable on the basis of a detection result of the light receiving part of the sensor pair;
• detecting positions of the edge portion of the substrate with the substrate holding part holding the substrate received from the first module located at a set position preset with respect to each of the sensor pairs;
• (i) deciding, when four or more sensor pairs are determined to be usable at the determination step, a delivery position of the substrate holding part with respect to the second module on the basis of the positions of the edge portion detected by at least four usable sensor pairs, and
• (ii) deciding, when three sensor pairs are determined to be usable at the determination step, a delivery position of the substrate holding part with respect to the second module on the basis of the positions of the edge portion detected by the three usable sensor pairs;
• and
• driving a drive part to move the substrate holding part relative to the sensor part to the delivery position.

A non-transitory storage medium storing a computer program executable by a controller to cause a controller to:

• detect, in a sensor part of a substrate holding part movable in a lateral direction to transfer a circular substrate from a first module to a second module, positions of at least four points of an edge portion of the substrate held by the substrate holding part, the sensor part comprising at least four sensor pairs comprising light source parts applying light to positions different from one another at the edge portion and light receiving parts paired with the light source parts;
• determine for each of the at least four sensor pairs whether the sensor pair is usable or unusable on the basis of a detection result of the light receiving part of the sensor pair;
• detect positions of the edge portion of the substrate with the substrate holding part holding the substrate received from the first module located at a set position preset with respect to each of the sensor pairs;
• (i) decide, when four or more sensor pairs are determined to be usable at the determination step, a delivery position of the substrate holding part with respect to the second module on the basis of the positions of the edge portion detected by at least four usable sensor pairs, and
• (ii) decide, when three sensor pairs are determined to be usable at the determination step, a delivery position of the substrate holding part with respect to the second module on the basis of the positions of the edge portion detected by the three usable sensor pairs;
• and
• drive a drive part to move the substrate holding part relative to the sensor part to the delivery position.