A flexible vacuum seal pad structure capable of, for example, sealingly securing a bowed substrate to a finger apparatus or "endeffector" used to robotically engage and/or move the substrate from one processing station to another, or capable of securing a wafer to a base member or susceptor during processing of the wafer, i.e., functioning as a chuck. The flexible vacuum seal pad structure of the invention comprises a hollow central post or shank which serves as a mounting or retention mechanism, a flexible arch-like member connected at one end to the central post, and a peripheral ring structure connected to the opposite end of the arch member. The peripheral ring structure contacts and forms a seal with the underside of the wafer, while the arch member provides the flexibility to permit the ring structure to make or form a sealing contact to a bowed wafer, and the central post provides a mechanism through which the flexible vacuum seal pad structure may be secured to the base or finger.