Wafer to wafer bonding apparatus and wafer to wafer bonding method

A wafer bonding apparatus, comprising:

• a first stage configured to suction a first wafer;
• a second stage configured to suction a second wafer;
• a stage driver configured to move the first stage and the second stage relative to each other;
• a first mark image sensor on an outer portion of the first stage, the first mark image sensor being configured to image a second alignment mark on the second wafer;
• a second mark image sensor on an outer portion of the second stage, the second mark image sensor being configured to image a first alignment mark on the first wafer;
• a target image sensor on the outer portion of the first stage adjacent to the first mark image sensor;
• and
• a target portion on the outer portion of the first stage, the target portion having a target plate arranged above the target image sensor and spaced apart from the target image sensor by a predetermined distance,
• wherein:
• in an alignment measurement of the first stage and the second stage, the first stage and the second stage are movable so that the target image sensor and the second mark image sensor face each other and the target plate is between the target image sensor and the second mark image sensor facing each other, and
• each of a first distance between the target plate and the target image sensor and a second distance between the target plate and the second mark image sensor is within a range of 5 mm to 15 mm.

A wafer bonding apparatus, comprising:

• a first stage configured to suction a first wafer;
• a second stage configured to suction a second wafer;
• a stage driver configured to move the first stage and the second stage relative to each other;
• a first mark image sensor on an outer portion of the first stage, the first mark image sensor being configured to image a second alignment mark on the second wafer;
• a second mark image sensor on an outer portion of the second stage, the second mark image sensor being configured to image a first alignment mark on the first wafer;
• a target image sensor in the outer portion of the first stage adjacent to the first mark image sensor;
• a target portion on the outer portion of the first stage, the target portion having a target plate arranged above the target image sensor and spaced apart from the target image sensor by a predetermined distance;
• a push rod that is movable upwardly and downwardly through a center hole in a middle portion of at least one of the first stage and the second stage to press a middle region of the first wafer or the second wafer;
• and
• a push rod driver configured to move the push rod upwardly and downwardly,
• wherein, in an alignment measurement of the first stage and the second stage, the first stage and the second stage are movable so that the target image sensor and the second mark image sensor face each other and the target plate is between the target image sensor and the second mark image sensor facing each other.