Apparatus for processing semiconductor wafers

Apparatus for uniform, damage-free precision chemical etching of a plurality of generally circular wafers, said wafers each having substantially the same diameter, said apparatus comprising an etchant tank for containing a body of liquid etchant, a frame adapted for being immersed in said etchant, said frame including a pair of opposed end pieces, a pair of elongate rollers each extending longitudinally between said end pieces, each of said rollers having its respective ends journalled for rotation in said end pieces, said rollers being horizontal, the respective longitudinal axes of said rollers being in spaced, parallel relationship, each of said rollers having a plurality of annular grooves spaced uniformly along the length of the roller, grooves of one roller being laterally aligned wih corresponding grooves of the other roller to provide parallel pairs of laterally aligned grooves, each of said grooves being of sufficient depth and of a cross-section shaped such that each laterally aligned pair of grooves is adapted to provide the sole means for guiding and supporting one of the wafers, the spacing between the longitudinal axes of said rollers being substantially greater than the the diameter of said wafers, said laterally aligned grooves thereby supporting a plurality of said wafers in spaced, parallel relationship, means for rotating said rollers whereby rotation of said rollers causes rotation of each of said wafers while said wafers are maintained in said spaced, parallel relationship while immersed in said etchant and whereby said wafers are prevented from being contacted by each other or by other objects except the surfaces of said grooves, means for circulating the etchant for causing uniform flow of the etchant through the spaces between said wafers, heat exchanger means for maintaining the etchant substantially at a predetermined temperature, and means for metering fresh etchant into said body of etchant.