Profile method in magnetic write head fabrication

1. A method, comprising:

depositing a dielectric hard mask layer above a polymer mask under-layer;

forming a photoresist mask above the hard mask layer;

transferring the image of the photoresist mask onto the hard mask layer using reactive ion etching, thereby defining a hard mask;

determining that a critical dimension bias of the hard mask is within or outside a specification; and

changing a level of an input source power used during a subsequent reactive ion etching step to move the critical dimension bias towards a target critical dimension bias when the critical dimension bias of the hard mask is outside the specification.

2. The method as recited in claim 1 , wherein the level of the input source power is selected based on a linear equation CDB=CDB 0 +A*ISP at a fixed input bias power, where CDB is a critical dimension bias, CDB 0 is a constant representing an intersection of a linear result of the linear equation with the CDB axis, A is a slope of the linear result of the linear equation, and ISP is the input source power.

3. The method as recited in claim 1 , further comprising changing the level of the input source power used during a subsequent reactive ion etching step when the critical dimension bias of the hard mask is inside the specification but away from the target critical dimension bias.

4. The method as recited in claim 1 , wherein the target critical dimension bias corresponds to vertical sidewalls of the hard mask after the reactive ion etching.

5. The method as recited in claim 1 , wherein determining that the critical dimension bias of the hard mask is within or outside the specification includes detecting a critical dimension of the photoresist mask and critical dimension of the hard mask in a direction parallel to a plane of deposition of the hard mask layer, calculating the critical dimension bias using the detected photoresist mask critical dimension and the detected hard mask critical dimension, and determining whether the critical dimension bias falls within a range specified by the specification.

6. The method as recited in claim 5 , wherein the input source power is increased when the critical dimension bias is less than the target critical dimension bias.

7. The method as recited in claim 5 , wherein the input source power is decreased when the critical dimension bias is greater than the target critical dimension bias.

8. The method as recited in claim 1 , further comprising transferring an image of the hard mask onto the underlayer using a second reactive ion etching having a different material selectivity than the reactive ion etching after determining that the critical dimension bias of the hard mask is within the specification.

9. The method as recited in claim 8 , wherein the polymer mask underlayer overlies a magnetic write pole material, further comprising, after performing the second reactive ion etching, performing an ion milling to transfer the image of the under-layer onto the magnetic write pole material, thereby defining a magnetic write pole.

10. The method as recited in claim 1 , further comprising repeating the: depositing the dielectric hard mask layer, forming the photoresist mask, and transferring the image when the critical dimension bias of the hard mask is outside the specification and using the changed level of the input source power.

11. The method as recited in claim 1 , further comprising repeating the method on a second wafer using the changed input source power level.

12. A method for manufacturing a magnetic write head, the method comprising:

providing a wafer;

depositing a magnetic write pole material on the wafer;

depositing an etch stop layer above the magnetic write pole material;

depositing a polymer mask under-layer above the etch stop layer;

depositing a dielectric hard mask layer above the under-layer;

forming a photoresist mask over the dielectric hard mask layer;

transferring the image of the photoresist mask onto the hard mask layer using reactive ion etching, thereby defining a hard mask;

determining that a critical dimension bias of the hard mask is within or outside a specification;

performing subsequent processing on the wafer when the critical dimension bias of the hard mask is within the specification; and

removing the hard mask when the critical dimension bias of the hard mask is outside the specification and repeating the forming the photoresist mask and the transferring using a different level of an input source power for the reactive ion etching, the different level being selected based on the determining.

13. The method as recited in claim 12 , wherein the level of the input source power is selected based on a linear equation CDB=CDB 0 +A*ISP at a fixed input bias power, where CDB is a critical dimension bias, CDB 0 is a constant representing an intersection of a linear result (e.g., line on a chart) of the linear equation with the CDB axis, A is a slope of the linear result of the linear equation, and ISP is the input source power.

14. The method as recited in claim 12 , further comprising changing the level of the input source power used during a subsequent reactive ion etching step on a second wafer when the critical dimension bias of the hard mask is outside the specification, or inside the specification but away from a target critical dimension bias.

15. The method as recited in claim 14 , wherein the target critical dimension bias corresponds to vertical sidewalls of the hard mask after the reactive ion etching.

16. The method as recited in claim 12 , wherein determining that the critical dimension bias of the hard mask is within or outside the specification includes detecting a critical dimension of the hard mask in a direction parallel to a plane of deposition thereof, detecting a critical dimension of the photoresist mask in a direction parallel to a plane of deposition thereof, calculating the critical dimension bias of the hard mask using the detected critical dimensions of the photoresist mask and photoresist mask, and determining whether the critical dimension bias falls within a range specified by the specification.

17. The method as recited in claim 16 , wherein the input source power is increased when the critical dimension bias is less than the target critical dimension bias.

18. The method as recited in claim 16 , wherein the input source power is decreased when the critical dimension bias is greater than the target critical dimension bias.

19. The method as recited in claim 12 , further comprising transferring an image of the hard mask onto the underlayer using a second reactive ion etching having a different material selectivity than the reactive ion etching after determining that the critical dimension bias of the hard mask is within the specification.

20. The method as recited in claim 19 , further comprising, after performing the second reactive ion etching, performing an ion milling to transfer the image of the under-layer onto the magnetic write pole material, thereby defining a magnetic write pole.