Abstract : The SOS Electrical Overstress Investigations program was initiated to isolate the mechanisms of second breakdown. Tests conducted at Auburn University identified the need for test diodes with specified inherent silicon properties and controlled sets of processed 'defects'. Rockwell International designed and fabricated two wafer lots of SOS p-n diodes with a wide range of physical design variations and process parameter variations to fulfill the need for special test diodes. Design requirements traversed the limits of the state-of-the-art in processing capabilities, but all of the design goals were realized in the final wafer product. 'Defects' as small as one micron were faithfully produced on both wafer lots. Each die on the wafer contains 214 diodes and there are five different substrate doping levels (five different wafers) to yield 1070 diode variations in a wafer lot. The need expressed by Auburn University for special diodes has been fulfilled. (Author)