Reader fabrication method employing developable bottom anti-reflective coating
View Patent ↗Disclosed are methods for making read sensors using developable bottom anti-reflective coating and amorphous carbon (a-C) layers as junction milling masks. The methods described herein provide an excellent chemical mechanical polishing or planarization (CMP) stop, and improve control in reader critical physical parameters, shield to shield spacing (SSS) and free layer track width (FLTW).
1. A method of making an amorphous carbon mill mask, the method comprising:
depositing an amorphous carbon layer on a substrate surface;
applying a developable-soluble bottom anti-reflective coating on at least a portion of an upper surface of the amorphous carbon layer;
applying a photoresist layer on at least a portion of an upper surface of the developable-soluble bottom anti-reflective coating;
developing the photoresist layer and the developable-soluble bottom anti-reflective coating to form a layered structure on an upper surface of the amorphous carbon layer, wherein the photoresist layer and developable-soluble bottom anti-reflective coating are developed under conditions such that the photoresist is developed into a line structure while the developable-soluble bottom anti-reflective coating is underdeveloped such that the developable-soluble bottom anti-reflective coating has a cross-sectional width that is approximately the same as the photoresist where the photoresist contacts the developable-soluble bottom anti-reflective coating, the developable-soluble bottom anti-reflective coating has a cross-sectional width that is wider than the photoresist where the developable-soluble bottom anti-reflective coating contacts the amorphous carbon layer; and
performing a reactive ion etch of the amorphous carbon layer under conditions whereby the cross-sectional width of the photoresist and developable-soluble bottom anti-reflective coating decreases as the amorphous carbon is etched.
2. The method of claim 1 , wherein the substrate comprises a tunneling magnetic resistive (TMR) material.
3. The method of claim 1 , wherein the deposited amorphous carbon layer is about 3 to 10 nm thick.
4. A method of making a read junction for a read sensor, the method comprising:
depositing an amorphous carbon layer on a tunneling magnetic resistive (TMR) substrate surface;
applying a developable-soluble bottom anti-reflective coating on at least a portion of the amorphous carbon layer;
applying a photoresist layer on at least a portion of the developable-soluble bottom anti-reflective coating;
developing the photoresist layer and the developable-soluble bottom anti-reflective coating to form a layered structure on an upper surface of the amorphous carbon layer, wherein the photoresist layer and developable-soluble bottom anti-reflective coating are developed under conditions such that the photoresist is developed into a line structure while the developable-soluble bottom anti-reflective coating is underdeveloped such that the developable-soluble bottom anti-reflective coating has a cross-sectional width that is approximately the same as the photoresist where the photoresist contacts the developable-soluble bottom anti-reflective coating, the developable-soluble bottom anti-reflective coating has a cross-sectional width that is wider than the photoresist where the developable-soluble bottom anti-reflective coating contacts the amorphous carbon layer; and
performing a reactive ion etch of the amorphous carbon under conditions whereby the width of the photoresist and developable-soluble bottom anti-reflective coating decreases as the amorphous carbon is etched.
5. The method of claim 4 , wherein the deposited amorphous carbon layer is about 3 to 10 nm thick.
6. The method of claim 4 , further comprising junction milling after performing the reactive ion etch of the amorphous carbon.
7. The method of claim 6 , further comprising removing developable-soluble bottom anti-reflective coating from the remaining amorphous carbon via a solution based process after completion of junction milling.
8. The method of claim 7 , further comprising chemical mechanical polishing or planarization.
9. The method of claim 7 , further comprising removing the remaining amorphous carbon via reactive ion etching.
10. A read sensor comprising a read junction prepared according to the method of claim 4 .
11. The read sensor of claim 10 , wherein the read junction has a width of between about 15 and 30 nm.
12. The read sensor of claim 10 , wherein the read junction has a width of between about 20 and 30 nm.
13. The read sensor of claim 10 , wherein the read junction has a width of between about 20 and 25 nm.