Abstract: An electrically programmable fuse includes a metal-oxide-semiconductor (MOS) programmable transistor that is gate-source coupled by a resistive element. The resistive element can comprise a gate-source coupled MOS transistor. If the MOS transistor is unprogrammed, then the resistive element ensures that the programmable transistor is turned off during read operations. However, when a programming voltage is applied across the source and drain terminals of the programmable transistor, the resistive element allows the programming voltage to be capacitively coupled to the gate of the programmable transistor from its drain. This turns the programmable transistor on, thereby reducing the snapback voltage of the programmable transistor, and hence, the required programming voltage. Once the snapback mode is entered, current flow through the programmable transistor increases until thermal breakdown occurs and the programmable transistor shorts out.

Abstract: A test structure provides defect information rapidly and accurately. The test structure includes a plurality of lines provided in a parallel orientation, a decoder coupled to the plurality of lines for selecting one of the plurality of lines, and a sense amplifier coupled to the selected line. To analyze an open, a line in the test structure is coupled to the sense amplifier. A high input signal is provided to the line. To determine the resistance of the open, a plurality of reference voltages are then provided to the sense amplifier. A mathematical model of the resistance of the line based on the reference voltage provided to the sense amplifier is generated. Using this mathematical model, the test structure can quickly detect and characterize defect levels down to a few parts-per-million at minimal expense.