Dual Substrate Hand Layout to Keep Dry Wafers Free of Liquid

The substrate transfer apparatus is divided into two separate hands: a dry substrate hand for transferring dry substrates and a wet substrate hand for transferring liquid-filled substrates. This segmentation prevents cross-contamination where adhered liquid from the wet hand could wet the dry substrate, thereby maintaining substrate integrity while managing device complexity through functional separation.

The pusher mechanism is extracted from the wet substrate hand and relocated to the dry substrate hand. The wet substrate hand uses only protrusions for gentle substrate support, eliminating the source of liquid scattering. The pusher is then applied exclusively to dry substrates where it provides effective gripping without causing liquid contamination issues.

The vertical positioning of the hands is inverted from the conventional arrangement. Instead of placing the wet substrate hand above the dry substrate hand to save space, the wet substrate hand is positioned below the dry substrate hand. This inversion prevents liquid dripping from contaminating the dry substrate hand and maintains proper functional separation while still utilizing vertical space efficiently.