Patent ID: 7169269

Claim:
A plating apparatus comprising: a plating vessel having a cylindrical side wall for containing a plating liquid; a substrate holding mechanism for generally horizontally holding a generally round substrate to be treated; a cathode ring provided in the substrate holding mechanism and having substantially the same inner diameter as the plating vessel for sealing a peripheral edge portion of a lower surface of the substrate, the cathode ring having a cathode to be brought into contact with the substrate held by the substrate holding mechanism; and a rotative driving mechanism for rotating the substrate held by the substrate holding mechanism together with the cathode ring; wherein the plating vessel has an upper edge portion complementary in configuration to a portion of the cathode ring opposed to the plating vessel so that the lower surface of the substrate held by the substrate holding mechanism can approach the plating vessel so as to be substantially flush with an upper edge of the plating vessel without interference between the upper edge portion of the plating vessel and the cathode ring; wherein the cathode ring includes a body and an abutment portion for abutting the lower surface of the substrate, the abutment portion being composed of a rigid material and projecting as tapered inwardly from the body of the cathode ring; and the abutment portion has a sealing surface for sealing the peripheral edge portion of the lower surface of the substrate; wherein the substrate holding mechanism further comprises a substrate back side press plate having a projection composed of a soft material, the substrate back side press plate opposing the abutment portion of the cathode ring; and the substrate holding mechanism is constructed to hold a substrate by the sealing surface of the abutment portion and the projection of the substrate back side press plate.