9000wm stress measurement system the instrument determines the bow in the wafer before and after it is coated with the ceramic film using the stoney 39 s equation u03c3 r et s 2 6 ue89e 1 v ue89e t ue89e 1 r f 1 r o 4 where e is the young 39 s modulus of the substrate v is poisson 39 s ratio of the substrate t s is the thickness of the substrate t is the thickness of the film and r o and r f are the initial and final radii of curvature of the wafer respectively before and after it is coated with the ceramic film fig6 shows the measured residual film stress u03c3 r of three samples of each wafer type the four point bending test results of the coated and non coated samples are shown in fig7 for each of the tested sample types the mor was calculated referring to fig7 it can be shown that the bare silicon wafer had an average mor of 139 69 mpa the sin coated samples had an average mor of 125 7 144 9 and 145 2 mpa respectively the sio coated samples had an average mor of 134 0 142 4 and 146 8 mpa respectively and the sic coated.