such a manner as shown in fig2 as shown in this figure the high resistance polycrystalline silicon thin film wiring line portion 5 acts as a fuse which is cut by joule heat when an excess current flows therethrough the function provides an affect that when the semiconductor chip 2 fails during a burn in test and a high current flows therethrough the high resistance polycrystalline silicon thin film wiring layer 5 acts like a fuse and disconnects the failed chip from the burn in testing circuit another function resides in that in case the semiconductor chip 2 is rejected by a wafer probing test which is performed before the burn in test an excess current is deliberately supplied to the semiconductor chip 2 at the final stage of the wafer probing test to cut the high resistance polycrystalline silicon thin film wiring line portions 5 so that the failed portion is disconnected in advance from the burn in testing circuit the low resistance polycrystalline thin film wiring line portion 8 does not exhibit any fuse like function as different from the high resistance polycrystalline silicon thin film wiring line portion 5 and the affect of the construction is such that metallic whiskers which may contact upon wire bonding at a later stage with a bonding wire to cause short circuiting are.