Wafer holder and wafer transfer apparatus, system and method

A wafer holder, comprising a holder body and a sucker, wherein

• the holder body defines a first opening;
• and
• the sucker comprises a first skirt, wherein the first skirt is located on a top surface of the holder body and connected to the first opening, a groove, comprising a first side wall, a second side wall, and a bottom surface connecting the first side wall and the second side wall, is formed at a joint between the first skirt and the first opening, and the groove is located at an outer side of the first skirt;
• wherein the first side wall is closer to the first opening than the second side wall;
• the second side wall is slanted away from the first opening,
• wherein the groove extends from the top surface of the holder body into the holder body and ends at the bottom surface.