Method of making an ultra-sharp tip mode converter for a HAMR head

• US 9,202,493 B1
• Filed: 05/27/2014
• Issued: 12/01/2015
• Est. Priority Date: 02/28/2014
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: Western Digital Corporation
• Inventors: Wan, Dujiang, Yi, Ge, Zhao, Lijie, Shi, Zhong, Sun, Hai
• Primary Examiner(s): TRAN, THANG V
• Application Number:
  US14/287,467
• Time in Patent Office: 553 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G11B 2005/0021 Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal
• CPC Class Codes: G11B 5/314 where the layers are extra layers normally not provided in the transducing structure, e.g. optical layers G11B5/3196 takes precedence
• CPC Class Codes: G11B 5/6088 Optical waveguide in or on flying head

Abstract

A mode converter for use in a Heat-assisted magnetic recording (HAMR) read head to couple or bend light (e.g., from an external laser diode) into a tapered waveguide, and subsequently, to a near field transducer is provided. The mode converter may have an ultra-sharp tip, e.g., less than 200 nm to achieve a desired optical output. Manufacturing such a mode converter involves a two-pattern transform process, where overlay control (using a first edge, such as a right edge, as a reference layer relative to which positioning of a second edge, such as a left edge, is measured) allows for aligning of the right and left edges of a tip portion of the mode converter to ultimately create the ultra-sharp tip.

Claims

1. A method of manufacturing a mode converter comprising:

forming a mode converter process film stack comprising a stop layer, a core material, a buffer layer, a first cladding layer, and a hard mask layer;

defining a first edge of the mode converter;

transferring the first edge into the hard mask layer;

defining a second edge of the mode converter, wherein respective ends of the first and second edges define a mode converter tip;

transferring the second edge into the hard mask layer;

forming a temporary mode converter pattern on the hard mask layer;

temporarily transferring the mode converter pattern into the core material to form a final mode converter including the mode converter tip;

removing the hard mask layer and the buffer layer; and

depositing a second cladding layer over the final mode converter including the mode converter tip.

2. The method of claim 1, wherein the mode converter tip is defined by the first and second edges and has a width less than 200 nm.

3. The method of claim 1, wherein the mode converter tip is defined by the first and second edge and has a width ranging from approximately 200 nm to approximately 300 nm.

4. The method of claim 1, wherein the stop layer comprises an Aluminum Oxide (AlOx) reactive ion etch stop layer approximately 2-3 nm thick.

5. The method of claim 1, wherein the core material comprises Tantalum Pentoxide (Ta₂O₅).

6. The method of claim 1, wherein the buffer layer comprises Silicon Dioxide (SiO₂).

7. The method of claim 1, wherein the hard mask layer comprises one of Chromium (Cr), Ruthenium, or other metallic material.

8. The method of claim 1, wherein the hard mask layer is deposited on the buffer layer using a bi-layer lift-off process to produce an open metal seed window.

9. The method of claim 1, wherein the defining of the first edge comprises defining via a first deep ultraviolet scanner photolithography process.

10. The method of claim 9, wherein the transferring of the first edge comprises transferring via a first hard mask reactive ion etch process.

11. The method of claim 10, wherein the defining of the second edge comprises defining via a second deep ultraviolet scanner photolithography process.

12. The method of claim 11, wherein the transferring of the second edge comprises transferring via a second hard mask reactive ion etch process.

13. The method of claim 11, further comprising defining positions of the first and second edges to define the mode converter tip by measuring a position of the second edge relative to the first edge, the first edge acting as a reference layer.

14. The method of claim 1, wherein the second cladding layer comprises SiO₂.

15. A method of manufacturing a mode converter comprising:

defining first and second edges of the mode converter using a sequential dual photolithography process;

transferring the defined first and second edges into a hard mask layer of a mode converter process film stack to form a mode converter tip pattern;

transferring the mode converter tip pattern onto a core material of the mode converter process film stack to form the mode converter;

removing the hard mask layer; and

depositing a protective layer on the mode converter.