Apparatus and method for programming an electronically programmable semiconductor fuse

Abstract

An apparatus for programming an electronically programmable semiconductor fuse applies a programming current to a fuse link as a series of multiple pulses. Application of the programming current as a series of multiple short pulses provides a level of programming current sufficiently high to ensure reliable and effective electromigration while avoiding exceeding temperature limits of the fuse link.

1 . An apparatus for programming a semiconductor fuse structure including a first conductive area and a second conductive area coupled by a fuse link, the apparatus comprising:
 a current supply including circuitry operatively coupled to the semiconductor fuse to deliver a cyclic programming current as a series of pulses, each pulse having an amplitude and a cycle duration,   wherein programming of the semiconductor fuse is completed upon application of the programming current through the series of multiple pulses and wherein the cycle duration is between about 0.01 and about 0.17 times a thermal time constant of the fuse link.   
     
     
         2 . The apparatus of  claim 1 , wherein the cycle duration is less than about 0.05 times the thermal time constant of the fuse link. 
     
     
         3 . An apparatus for programming a semiconductor fuse structure including a first conductive area and a second conductive area coupled by a fuse link, the apparatus comprising:
 a current supply including a programmable pulse generator operatively coupled to the semiconductor fuse and programmed to deliver a cyclic programming current as a series of pulses, each pulse having an amplitude and a cycle duration,   wherein programming of the semiconductor fuse is completed upon application of the programming current through the series of multiple pulses and wherein continuous application of a constant programming current having an amplitude equal to an average of the maximum amplitudes of the series of pulses for a time period equal to a sum of the cycle durations of each of the series of pulses would cause heating of the fuse link to a temperature exceeding a rupture temperature of the fuse link.   
     
     
         4 . An apparatus for programming a semiconductor fuse structure including a first conductive area and a second conductive area coupled by a fuse link, the apparatus comprising:
 a current supply including circuitry operatively coupled to the semiconductor fuse to deliver a cyclic programming current as a series of pulses, each pulse having an amplitude and a cycle duration, an amplitude, and a duty cycle, wherein the current supply supplies current at an amplitude to the semiconductor fuse greater than 120 percent of the current required to initiate electromigration in the fuse link when applied;   wherein programming of the semiconductor fuse is completed upon application of the programming current through the series of multiple pulses, and   wherein during programming, a fuse link temperature does not exceed a rupture temperature.   
     
     
         5 . The apparatus of  claim 4 , wherein the current supply includes a programming FET and the step of applying the programming current includes applying a programming voltage and a gate voltage to the programming FET, wherein the programming voltage and gate voltage are selected to maintain operation of the FET in a saturation operating region of the programming FET. 
     
     
         6 . The apparatus of  claim 4 , wherein the duty cycle of each pulse is substantially equal. 
     
     
         7 . The apparatus of  claim 4 , wherein the cycle duration of each pulse is substantially equal. 
     
     
         8 . The apparatus of  claim 4 , wherein the amplitude of each of the multiple pulses is substantially equal. 
     
     
         9 . The apparatus of  claim 4 , wherein the duty cycle of each pulse is in the range of 0.62 to 0.69. 
     
     
         10 . The apparatus of  claim 4 , wherein the duty cycle of an initial pulse is different from the duty cycle of a final pulse. 
     
     
         11 . The apparatus of  claim 10 , wherein the duty cycle of the initial pulse is less than the duty cycle of the final pulse. 
     
     
         12 . The apparatus of  claim 10 , wherein the duty cycle of the initial pulse is greater than the duty cycle of the final pulse. 
     
     
         13 . The apparatus of  claim 4 , wherein the amplitude of an initial pulse is different from the amplitude of a final pulse. 
     
     
         14 . The apparatus of  claim 12 , wherein the amplitude of the initial pulse is less than the amplitude of the final pulse. 
     
     
         15 . The apparatus of  claim 4 , wherein the amplitude of each programming current pulse is in the range of about four to about ten milliamps. 
     
     
         16 . The apparatus of  claim 4 , wherein the cycle duration is about five nanoseconds to about one hundred nanoseconds. 
     
     
         17 . The apparatus of  claim 4 , wherein the cycle time is less than 30 nanoseconds. 
     
     
         18 . The apparatus of  claim 4 , wherein the cycle duration is between about 0.01 and about 0.17 times a thermal time constant of the fuse link.