Systems and Methods for Controlling of Electro-Migration

Abstract

Systems and methods for controlling electro-migration, and reducing the deleterious effects thereof, are disclosed. Embodiments provide for reversal of an applied voltage to an integrated circuit when a measurement indicative of an extent of electro-migration indicates that a healing cycle of operation is warranted. During the healing cycle, circuits of the integrated circuit function normally, but electro-migration effects are reversed. In one embodiment, micro-electro-mechanical switches are provided at a lowest level of metallization to switch the direction of current through the levels of metallization of the integrated circuit. In another embodiment, if the measurement indicative of the extent of electro-migration exceeds a reference level by a specifiable amount, then the voltage applied to the integrated circuit is reversed in polarity to cause current to switch directions to counter electro-migration. A plurality of switches are provided to switch current directions through a lowest level of metallization so that the circuits function normally even though the polarity of the applied voltage has been reversed.

1 . An integrated circuit with controllable electro-migration characteristics, comprising:
 a resistance comprising metallization affected by electro-migration;   a circuit to produce a measurement voltage indicative of the resistance at a first input of a comparator;   a comparator to compare the measurement voltage to a reference voltage received at a second input of the comparator; and   a plurality of switches to conditionally switch between a forward circuit path and a reverse circuit path, the switches responsive to a condition where the measurement voltage exceeds the reference voltage by a first specifiable amount.   
   
   
       2 . The integrated circuit of  claim 1 , wherein the switches are adapted to switch from a reverse circuit path to a forward circuit path if the measurement voltage is less than the reference voltage by a second specifiable amount. 
   
   
       3 . The integrated circuit of  claim 1 , wherein the switches are adapted to switch from a forward circuit path to a reverse circuit path after a power-down sequence of the integrated circuit. 
   
   
       4 . The integrated circuit of  claim 1 , wherein the switches comprise a plurality of micro-electro-mechanical switches to switch direction of current in a layer of metallization of the integrated circuit. 
   
   
       5 . The integrated circuit of  claim 1 , wherein the resistance comprises multiple separated layers of metallization connected by vias. 
   
   
       6 . The integrated circuit of  claim 1 , wherein, during a forward circuit path condition, a first resistance is measured to produce a measurement voltage, and during a reverse circuit path condition, a second resistance is measured to produce a measurement voltage. 
   
   
       7 . The integrated circuit of  claim 1 , wherein the plurality of switches are adapted to switch from an applied reverse supply voltage condition to an applied forward supply voltage condition if the measurement voltage is less than the reference voltage by a second specifiable amount. 
   
   
       8 . The integrated circuit of  claim 1 , wherein the plurality of switches are adapted to switch from an applied forward supply voltage condition to an applied reverse supply voltage condition after a power-down sequence of the integrated circuit. 
   
   
       9 . The integrated circuit of  claim 2 , wherein the first and second specifiable amounts are equal. 
   
   
       10 . An integrated circuit with controllable electro-migration characteristics, comprising:
 an electro-migration sensor to monitor a resistance and output a measurement voltage indicative of a value of the resistance, the resistance value affected by electro-migration;   circuitry to compare the measurement Voltage to a reference voltage; and   a switching network to conditionally switch between applying a forward supply voltage to at least a portion of wiring of the integrated circuit and applying a reverse supply voltage to the same portion of the wiring of the integrated circuit; the switching network responsive to a condition wherein the measurement voltage is less than the reference voltage by a first specifiable amount.   
   
   
       11 . The integrated circuit of  claim 10 , further comprising switching from an applied forward supply voltage condition to an applied reverse supply voltage condition after a power-down sequence of the integrated circuit. 
   
   
       12 . The integrated circuit of  claim 10 , further comprising situating four micro-electro-mechanical switches in the integrated circuit to switch direction of current in a layer of metallization of the integrated circuit. 
   
   
       13 . The integrated circuit of  claim 10 , wherein the integrated circuit comprises multiple separated layers of metallization connected by vias. 
   
   
       14 . The integrated circuit of  claim 10 , wherein, during a condition of applying a forward voltage, a first resistance is measured and during a condition of applying a reverse voltage, a second resistance is measured.