Vacuum pad, hand, and transfer apparatus

A hand of a transfer apparatus comprising:

• a hand body having a suction channel in which a suction hole is formed;
• and
• a vacuum pad installed in the suction hole and vacuum-absorbing a substrate,
• wherein the vacuum pad includes,
• a piezoelectric element installed on the hand body to cover the suction hole and having a hollow portion;
• and
• a pad member installed in the hollow portion of the piezoelectric element and having a pad hole communicating with the suction hole.

A transfer apparatus comprising:

• a robot arm;
• a hand installed on the robot arm and on which a substrate is mounted;
• and
• a warpage measurement sensor measuring a warpage shape of the substrate and a controller electrically connected to the warpage measurement sensor,
• wherein the hand includes,
• a hand body installed on the robot arm and having a suction channel with a suction hole formed therein;
• and
• a vacuum pad installed in the suction hole and vacuum-absorbing the substrate,
• wherein the vacuum pad includes,
• a piezoelectric element installed on the hand body to cover the suction hole and having a hollow portion;
• and
• a pad member installed in the hollow portion of the piezoelectric element and having a pad hole communicating with the suction hole,
• wherein the piezoelectric element is a bimorph piezoelectric element, and
• the controller controls a voltage applied to the piezoelectric element according to a warpage shape of the substrate measured by the warpage measurement sensor.