1. Field
This disclosure relates generally to semiconductors, and more specifically, to the testing of semiconductors that store data.
2. Related Art
As integrated circuits evolve and incorporate significantly more amounts of circuitry, the ability to reliably manufacture and use reliable fuses is problematic. For example supply voltage values have dramatically been reduced to the point where voltages are not sufficient to reliably blow or open-circuit fuses that rely on an electric current to activate the fuse. An alternative to current or voltage activated fuses is the use of lasers to activate a fuse. However, laser-activated fuses are not an option once an integrated circuit has been packaged. In contrast, fuses that are activated by an operating voltage may be activated after an integrated circuit has been packaged and functionality previously verified. Various advantages exist for waiting until later in the manufacturing process to activate fuses. For example, custom configuration of an integrated circuit may be accomplished wherein certain functions are either enabled or not enabled. Various redundant circuits may be activated. Additionally, fuses may be used by a purchaser of an integrated circuit to implement proprietary security codes in the integrated circuit as well as to create special identification codes for the integrated circuit.
Additional problems associated with existing fuse circuits that are used with storage devices include an inability to easily and quickly test the functionality of fuses, both before the fuses are activated and afterwards. Significant circuit area and test time is typically required to check the functionality of programmable fuses.