ONE-TIME PROGRAMMABLE MEMORY USING FUSE/ANTI-FUSE AND VERTICALLY ORIENTED FUSE UNIT MEMORY CELLS

摘要

PURPOSE: A one-time programmable memory array is provided to form a high density one-time programmable(OTP) memory at a remarkably low cost by greatly reducing the size of an individual unit memory cell. CONSTITUTION: The OTP memory includes one or more memory arrays stacked on top of each other. The OTP memory array is a cross-point array where unit memory cells are formed at the cross-points. The unit memory cell may include a fuse and an anti-fuse in series with each other or may include a vertically oriented fuse. Unit memory cells are selected and a writing voltage is applied to make a critical voltage drop across the selected cells occur so that the memory is programmed. This causes the anti-fuse of the cell to break down to a low resistance. The low resistance of the anti-fuse causes a high current pulse to be delivered to the fuse, which in turn melts the fuse to an open state. Unit memory cells for reading are selected and a reading voltage is applied to the selected memory cells. Whether current is present or not is measured to read the memory. Equipotential sensing may be used to read the memory.