Resistor tuning

Abstract

A structure for resistors and the method for tuning the same. The resistor comprises an electrically conducting region coupled to a liner region. Both the electrically conducting region and the liner region are electrically coupled to first and second contact regions. A voltage difference is applied between the first and second contact regions. As a result, a current flows between the first and second contact regions in the electrically conducting region. The voltage difference and the materials of the electrically conducting region and the liner region are such that electromigration occurs only in the electrically conducting region. As a result, a void region within the electrically conducting region expands in the direction of the flow of the charged particles constituting the current. Because the resistor loses a conducting portion of the electrically conducting region to the void region, the resistance of the resistor is increased (i.e., tuned).

1 . A resistor structure, comprising: 
 an electrically conductive region;    an electrically conductive liner region in direct physical contact with the electrically conductive region; and    first and second contact regions electrically coupled to the electrically conductive region and the electrically conductive liner region,    wherein the first contact region is in direct physical contact with the electrically conductive liner region, and    wherein in response to a current flowing in the electrically conductive region and from the first contact region to the second contact region, a void region in the electrically conductive region expands due to electromigration so as to increase the resistance of the resistor structure between the first and second contact regions.    
   
   
       2 . The resistor structure of  claim 1 , 
 wherein the current comprises flowing electrons, and    wherein the void region expands in the direction of the flow of the electrons.    
   
   
       3 . The resistor structure of  claim 1 , wherein the electrically conducting region comprises a first plate, wherein the liner region comprises second and third plates, wherein the first plate is sandwiched between the second and third plate, and wherein the second plate is in direct physical contact with both the first and second contact regions.  
   
   
       4 . The resistor structure of  claim 1 , wherein the electrically conducting region comprises first and second portions, and wherein in response to the current, electromigration occurs in the first portion but not in the second portion.  
   
   
       5 . The resistor structure of  claim 4 , wherein in response to the current, the void region expands and replaces the entire first portion of the electrically conducting region.  
   
   
       6 . The resistor structure of  claim 1 , wherein the void region expands and replaces the entire the electrically conducting region.  
   
   
       7 . The resistor structure of  claim 1 , wherein the electrically conductive region comprises a material selected from the group consisting of copper and a silicide.  
   
   
       8 . A method for tuning a resistor structure, the method comprising the steps of: 
 providing (a) an electrically conducting region, (b) a liner region coupled to the electrically conducting region, and (c) first and second contact regions electrically coupled to the electrically conducting region and a liner region; and    flowing a current in the electrically conducting region and from the first contact region to the second contact region such that a void region in the electrically conducting region expands due to electromigration so as to increase the resistance of the resistor structure between the first and second contact regions.    
   
   
       9 . The method of  claim 8 , wherein the electrically conducting region is surrounded by the liner region, and wherein both the electrically conducting region and the liner region are in direct physical contact with the second contact region.  
   
   
       10 . The method of  claim 8 , wherein the current comprises flowing electrons, and wherein the void region expands in the direction of the flow of the electrons.  
   
   
       11 . The method of  claim 8 , wherein the electrically conducting region comprises a first plate, wherein the liner region comprises second and third plate, wherein the first plate is sandwiched between the second and third plate, and wherein the second plate is in direct physical contact with both the first and second contact regions.  
   
   
       12 . The method of  claim 8 , wherein the electrically conducting region comprises first and second portions, and wherein in response to the current, electromigration occurs in the first portion but not in the second portion.  
   
   
       13 . The method of  claim 12 , wherein in response to the current, the void region expands and replaces the entire first portion of the electrically conducting region.  
   
   
       14 . The method of  claim 8 , wherein the void region expands and replaces the entire the electrically conducting region.  
   
   
       15 . The method of  claim 8 , wherein the electrically conducting region comprises a material selected from the group consisting of copper and a silicide.  
   
   
       16 . The method of  claim 8 , further comprising the step of disabling the current when the resistance of the resistor structure between the first and second contact regions is within a pre-determined tolerance of a pre-specified target resistance value.  
   
   
       17 . A method for tuning a resistor structure, the method comprising the steps of: 
 providing in the resistor structure (a) a semiconductor region, (b) an electrically conducting layer formed on the semiconductor region, (c) a plurality of contact regions electrically coupled to the electrically conducting layer;    selecting first and second contact regions of the plurality of contact regions such that if intervals of the electrically conducting layer between the first and second contact regions are replaced by a void region due to electromigration, the resistance of the resistor structure between third and fourth contact regions of the plurality of contact regions is within a pre-determined tolerance of a pre-specified target resistance value; and    applying a voltage difference between the first and second contact regions until the intervals of the electrically conducting layer between the first and second contact regions are replaced by the void region due to electromigration.    
   
   
       18 . The method of  claim 17 , wherein the electrically conducting layer comprises a silicide material.  
   
   
       19 . The method of  claim 17 , wherein the electrically conducting layer comprises first and second layer sections physically separated by the semiconductor region, and wherein the first and second layer sections are in direct physical contact with the third and fourth contact regions, respectively.