layer of polysilicon 42 having a thickness of about 1850 u00e5 the polysilicon 42 is bonded to a tungsten silicide wsi x layer 44 about 1200 u00e5 thick an insulating layer of silicon oxide sio 2 46 lies below the wsi x of about 3300 u00e5 thickness the capacitor dielectric 24 lies between the fuse element 26 and p doped substrate 48 in order to determine the current interruption characteristics of the poly fuse a fuse test setup of fig4 was assembled on a 4 meg dram chip the poly fuse element 26 is shown connected by contacts 20 to metal conductor 50 on one side and to a second aluminum conductor 52 on the other in this test setup the second aluminum conductor 52 is also formed to make a necked down section metal fuse element 54 a third aluminum conductor 56 connects to variable voltage source 58 and has a connection to voltmeter 60 which measures the voltage across the first and third metal conductors when current flows through the two fuses 54 and 26 and is measured by ammeter 62 in this setup the characteristics of both the metal fuse element 54 and poly fuse element 26 can be determined the width 64 of metal fuse in this test was 0 8 u03bcm the minimum width attainable and two sets of poly fuse widths at 66 were tested i e 0 6 u03bcm and 1 5 u03bcm the results of the test are listed in the table below table 1______________________________________ 0 6 u03bcm 1 5 u03bcmdie no mamps mamps______________________________________1 22 28 37 262 24 14 38 653 22 78 38 314 24 84 39 405 37 51 x 23 51 38 22 u03c3 1 18 0 8______________________________________ the data indicates consistently close.