Apparatuses of bonding substrates and methods of bonding substrates

A substrate bonding apparatus, comprising:

• a lower chuck, the lower chuck configured to support a lower substrate on an upper surface of the lower chuck;
• an upper chuck, the upper chuck configured to face the lower chuck such that a lower surface of the upper chuck faces the upper surface of the lower chuck, the upper chuck configured to support an upper substrate on the lower surface of the upper chuck;
• an electric actuator on a central portion of the upper chuck, the electric actuator configured to lower a bonding pin through the upper chuck to apply a pressure to the upper substrate supported on the lower surface of the upper chuck;
• a pressure sensor at a central portion of the lower chuck such that the pressure sensor is below the upper surface of the lower chuck and is configured to be below the lower substrate supported on the upper surface of the lower chuck, the pressure sensor configured to sense a lowering pressure applied by the bonding pin to the pressure sensor in real time;
• and
• a controller configured to control the lowering pressure applied by the bonding pin to the upper substrate, the controller further configured to
• increase a magnitude of the lowering pressure applied by the bonding pin to the upper substrate to a first pressure to cause a central portion of the upper substrate to be separated from the upper chuck,
• decrease the magnitude of the lowering pressure applied by the bonding pin to the upper substrate to a second pressure smaller than the first pressure subsequently to the central portion of the upper substrate being separated from the upper chuck and pushed towards the lower substrate by the boding pin, and
• increase the magnitude of the lowering pressure applied by the bonding pin to the upper substrate to a third pressure greater than the first pressure subsequently to the lower substrate and the upper substrate being brought into contact with each other.