Patent ID: 7775785

Claim:
A planarization apparatus for planarizing a curable or reflowable coating applied to a substrate, the apparatus comprising: a lower membrane assembly for supporting the substrate thereon, the lower membrane assembly including a lower flexible sheet; an upper membrane assembly including an upper flexible sheet; and a differential pressure assembly operable to create a pressure differential which deflects the upper flexible sheet downward and deflects the lower flexible sheet upward to press an upper surface of the substrate against a lower face of the upper flexible sheet to planarize the coating on the substrate, the differential pressure assembly including an upper pressure chamber positioned above an upper face of the upper flexible sheet, a lower pressure chamber positioned below a lower face of the lower flexible sheet, a central pressure chamber positioned generally between the lower face of the upper flexible sheet and the upper face of the lower flexible sheet, and apparatus for selectively pressurizing, and evacuating the upper, lower, and central pressure chambers.