Substrate bonding apparatus, manufacturing system, and semiconductor device manufacturing method

A substrate bonding apparatus comprising:

• a first chucking stage configured to chuck a first substrate;
• a second chucking stage disposed facing the first chucking stage, and configured to chuck a second substrate;
• and
• an alignment unit configured to be inserted between the first chucking stage and the second chucking stage,
• wherein the alignment unit includes
• a base body including a first main face and a second main face opposite to the first main face,
• a first detection element disposed on the first main face, and
• a second detection element disposed on the second main face,
• wherein the alignment unit is provided with the first detection element and the second detection element to be movable independently of each other,
• the substrate bonding apparatus further comprising a controller configured to operate to perform alignment between a first optical axis of the first detection element and a second optical axis of the second detection element, and to insert the alignment unit between the first chucking stage and the second chucking stage in a state where the first optical axis and the second optical axis are aligned with each other.