Advanced phase shift lithography and attenuated phase shift mask for narrow track width d write pole definition
View Patent ↗A method for patterning a wafer using a phase shifting photolithography that can produce a critical symmetrical 2-dimensional structure such as a magnetic write pole of a magnetic write head. In one aspect of the invention, a photolithographic mask has an opaque portion with narrow, transparent phase shifting regions at either side of the opaque portion. A non-phase shifted region extends beyond the narrow phase shifted portion at either side of the structure. The phase shifted regions are symmetrical about the opaque region so that the image produced on the wafer is completely symmetrical. In another aspect of the invention, a phase shifted region in formed in a transparent medium with non-phase shifted regions at either side of the phase shifted region. The transition between the phase shifted region and non-phase shifted region alone defines a pattern on the wafer, without the need for an opaque structure on the mask.
1. A mask for photolithographic patterning, comprising:
a first mask region having an opaque portion having first and second sides;
first and second transparent phase shifting regions formed at the first and second sides of the opaque portion;
a transparent non-phase shifted region extending beyond the first and second phase shifting portions; and
a second mask region having a narrow phase shifted portion and a non-phase shifted region and having no opaque portion wherein and configured to define a narrow feature by only the phase difference between a phase shift between the phase shifted region and the non-phase shifted region.
2. The mask as in claim 1 wherein the first and second transparent phase shifting portions each have a thickness that light passing through the first and second phase shifting portions is 180 degrees out of phase with light passing through the non-phase shifting portions.
3. The mask as in claim 1 wherein the first and second transparent phase shifting portions have a thickness that is less than a thickness of the transparent non-phase shifting portion.
4. The mask as in claim 1 further comprising a glass medium, wherein the opaque region comprises a layer of opaque material formed over a portion of a surface of the glass medium, and wherein the first and second phase shifting portions further comprise a recess formed in the glass medium such that the glass medium has a thickness in the first and second transparent phase shifting regions that is less than a thickness of the glass medium in the non-phase shifting region.
5. The mask as in claim 1 further comprising a quartz medium, wherein the opaque region comprises a layer of opaque material formed over a portion of a surface of the quartz medium, and wherein the first and second phase shifting portions further comprise a recess formed in the quartz medium such that the glass medium has a thickness in the first and second transparent phase shifting regions that is less than a thickness of the glass medium in the non-phase shifting region.
6. The mask as in claim 1 wherein the opaque portion is in the shape of a magnetic write pole of a magnetic write head.
7. The mask as in claim 1 wherein the phase shifting regions each have a width of 0.05λ-0.60λ, where λ is the exposure wavelength.
8. The mask as in claim 1 wherein the phase shifting regions each have a width of about 0.20, where λ is the exposure wavelength.
9. A mask for photolithographically patterning a feature on a wafer, the mask comprising:
a transparent medium;
a phase shifted region formed in the transparent medium; and
a non-phase shifted region immediately adjacent to the phase shifted region such that a transition between the phase shifted region and non-phase shifted region allows patterning of a feature on the wafer without the need for an opaque feature on the mask.
10. The mask as in claim 9 wherein the phase shifted region comprises an etched recess formed in the transparent substrate.
11. The mask as in claim 9 wherein the phase shifted region has first and second sides defining a width of 0.2λ-0.7λ, where λ is the exposure wavelength, there-between and has a non-phase shifted region at either side.
12. The mask as in claim 9 wherein the phase shifted region has first and second sides defining a width of about 0.40λ, where λ is the exposure wavelength, there-between and has a non-phase shifted region at either side.
13. The mask as in claim 9 wherein the transition between the phase shifted region and the non-phase shifted region defines a narrow structure in a first portion of the mask, and wherein a second portion of the mask includes an opaque region that defines a larger structure.
14. The mask as in claim 9 wherein the transparent substrate comprises glass.
15. The mask as in claim 9 wherein the transparent substrate comprises quartz.
16. The method as in claim 9 wherein the phase shifting region is configured to define a pole tip region of a magnetic write pole.
17. A method for patterning a feature on a wafer, comprising:
providing a wafer;
depositing a layer of photoresist on the wafer;
photolithographically patterning the photoresist using a mask, the mask comprising:
an opaque portion having first and second sides;
first and second transparent phase shifting regions formed at the first and second sides of the opaque portion;
a transparent non-phase shifted region extending beyond the first and second phase shifting portions; and
a second mask region having a narrow phase shifted portion and a non-phase shifted region and having no opaque portion wherein and configured to define a narrow feature by only the phase difference between a phase shift between the phase shifted region and the non-phase shifted region.
18. The method as in claim 17 further comprising, before depositing the photoresist, depositing a magnetic write pole material; and
wherein the photolithographic patterning produces a photoresist mask formed over the magnetic write pole material; and
the method further comprising after photolithographically patterning the photoresist performing an ion milling to remove portions of the magnetic write pole material that are not protected by the photoresist mask.
19. A method for patterning a feature on a wafer, comprising:
providing a wafer;
depositing a layer of photoresist on the wafer;
photolithographically patterning the photoresist using a mask, the mask comprising:
a transparent medium;
a phase shifted region formed in the transparent medium; and
a non-phase shifted region immediately adjacent to the phase shifted region such that a transition between the phase shifted region and non-phase shifted region allows patterning of a feature on the wafer without the need for an opaque feature on the mask.
20. The method as in claim 19 further comprising, before depositing the photoresist, depositing a magnetic write pole material; and
wherein the photolithographic patterning produces a photoresist mask formed over the magnetic write pole material; and
the method further comprising after photolithographically patterning the photoresist, performing an ion milling to remove portions of the magnetic write pole material that are not protected by the photoresist mask.