20 will impinge on the lines 18 and 19 as the wafer is passed first in one direction under the laser beam and then at right angles thereto thus the wafer 10 is mounted for slidable movement with respect to the laser beam such that the beam first passes along the lines 18 and then orthogonal thereto along the lines 19 the wafer 10 is positioned such that the laser beam 21 shown in fig1 will impinge upon the back surface 10b of wafer 10 which surface 10b is the back surface opposite to the front surface 10a in which the active diffisions have been produced typically to achieve the correct alignment of the wafer with the beam the wafer would be calibrated into a desired position on x y positioning table set at a reference set of coordinates after being so positioned the positioning table would be programmed to move at a certain rate along certain coordinates to move the wafer under the laser beam such that the beam passes along the lines 18 and 19 in a preferred embodiment the wafer is positioned by utilizing the apparatus taught in a co pending u s pat application ser no 526 989 entitled semiconductor wafer alignment apparatus filed in the name of gerald gates assigned to the same assignee of the present invention and filed of even date herewith as described in this co pending application the semiconductor wafer is viewed through a split image microscope and positioned with respect to a set of alignment marks after the wafer has been positioned it is inverted while retaining the aligned positioned and transferred on an x y movable table under a laser beam the x y movable table is programmed such that.