High density prom

The invention shows how diodes in a modern semiconductor process can be used as a very compact switch element in a Programmable Read Only Memory (PROM) using common integrated circuit fuse elements such as polysilicon and metal. This compact switch element allows very dense PROM arrays to be realized since diodes have the highest conduction density of any semiconductor device. The high conduction density is used to provide the relatively high current needed to blow the fuse element open. Since MOSFETs are typically used as fuse array switch elements, a relatively large area is required for the MOSFET to reach the current needed to blow the fuse element. Since diodes are two terminal switch elements unlike MOSFETs which are three terminal devices, methods are outlined on how to both read and write the arrays using this two terminal switch.