Methods for substrate biasing for mr devices

Abstract

A method for setting a voltage (Vsub) of a substrate to about a voltage (Vshield) of a shield of at least one reader formed above the substrate is presented in one embodiment. The method includes passing an MR bias current through each MR sensor of at least one reader formed above a substrate; and setting a voltage (Vsub) of the substrate to about the voltage (Vshield) of a shield of the at least one reader. A method according to another embodiment includes passing a bias current through at least one reader formed above a substrate, the at least one reader further comprising a shield and a magnetoresistive (MR) sensor, the substrate being at about a voltage (Vsub); and operatively adjusting a voltage (Vshield) of the shield of the at least one reader to about match the Vsub. Additional methods are also presented.

1 . A method for setting a voltage (Vsub) of a substrate to about a voltage (Vshield) of a shield of at least one reader formed above the substrate, the at least one reader further comprising a shield and a magnetoresistive (MR) sensor, the method comprising:
 passing an MR bias current through each MR sensor of at least one reader formed above a substrate; and   setting a voltage (Vsub) of the substrate to about the voltage (Vshield) of a shield of the at least one reader.   
   
   
       2 . A method as recited in  claim 1 , wherein the Vsub is set to about match the Vshield of only one reader. 
   
   
       3 . A method as recited in  claim 1 , wherein the Vsub is set to about match an average Vshield of at least two readers. 
   
   
       4 . A method as recited in  claim 1 , further comprising setting a voltage (Vshield) of the shield of the at least one sensor to about a voltage of the MR sensor. 
   
   
       5 . A method as recited in  claim 4 , further comprising adjusting the MR bias current of the at least one reader for independently adjusting the Vshield of the at least one reader to about match the Vsub. 
   
   
       6 . A method as recited in  claim 4 , wherein a bias circuit is coupled to the at least one reader for passing the MR bias current through the MR sensor thereof, wherein the bias circuit of the at least one reader includes a first bias resistor positioned between a current source and the MR sensor and a second bias resistor positioned between the MR sensor and a ground, and further comprising adjusting resistance values of the bias resistors for adjusting the Vshield of the at least one reader to about match the Vsub. 
   
   
       7 . A method as recited in  claim 1 , further comprising adjusting the Vsub between two voltage levels. 
   
   
       8 . A method as recited in  claim 1 , wherein a circuit for setting the Vsub comprises a resistance to ground. 
   
   
       9 . A method as recited in  claim 8 , wherein a bias circuit passes the MR bias current through the MR sensor, the bias circuit comprising a bias resistor, wherein the resistance to ground of the circuit for setting the Vsub has a resistance value in a range of between about 50 and 200 times a resistance value of the bias resistor. 
   
   
       10 . A method as recited in  claim 1 , wherein a circuit for setting the Vsub comprises a conductive path from the shield to the substrate. 
   
   
       11 . A method as recited in  claim 10 , wherein the circuit for setting the Vsub further comprises a resistor on the conductive path and positioned between the shield and the substrate. 
   
   
       12 . A method as recited in  claim 1 , further comprising passing a magnetic recording tape over the at least one reader. 
   
   
       13 . A method, comprising:
 passing a bias current through at least one reader formed above a substrate, the at least one reader further comprising a shield and a magnetoresistive (MR) sensor, the substrate being at about a voltage (Vsub); and   operatively adjusting a voltage (Vshield) of the shield of the at least one reader to about match the Vsub.   
   
   
       14 . A method as recited in  claim 13 , wherein a bias circuit is coupled to the at least one reader for passing the MR bias current through the MR sensor thereof, wherein a second circuit is coupled to the at least one reader for setting a voltage (Vshield) of the shield to about a voltage of the MR sensor, the second circuit being coupled to the bias circuit, wherein the MR bias current of the at least one reader is variable for adjusting the Vshield of the at least one reader to about match the Vsub. 
   
   
       15 . A method as recited in  claim 13 , wherein a bias circuit is coupled to the at least one reader for passing an MR bias current through the MR sensor thereof, wherein the bias circuit of the at least one reader includes a first bias resistor positioned between a current source and the MR sensor and a second bias resistor positioned between the MR sensor and a ground, wherein resistance values of the bias resistors are adjustable for adjusting the Vshield of the at least one reader to about match the Vsub. 
   
   
       16 . A method as recited in  claim 13 , further comprising passing a magnetic recording tape over the at least one reader. 
   
   
       17 . A method, comprising:
 passing a bias current through each of a plurality of readers formed above a common substrate, each of the readers further comprising a shield and a magnetoresistive (MR) sensor;   setting a voltage (Vsub) of the substrate to about a voltage (Vshield) of at least one of the shields; and   setting the Vshield of each of the readers to about a voltage of the MR sensor of the same reader.   
   
   
       18 . A method as recited in  claim 17 , wherein the Vsub is set to about match the Vshield of only one reader. 
   
   
       19 . A method as recited in  claim 17 , wherein the Vsub is set to about match an average Vshield of at least two readers. 
   
   
       20 . A method as recited in  claim 17 , wherein the Vsub is oscillated between two voltage levels.