Method to make interferometric taper waveguide for HAMR light delivery
View Patent ↗A method for making an interferometric taper waveguide (I-TWG) with high critical dimension uniformity and small line edge roughness for a heat assisted magnetic recording (HAMR) head, wherein the method includes creating an I-TWG film stack with two hard mask layers on top of an I-TWG core layer sandwiched between two cladding layers, defining a photoresist pattern over the I-TWG film stack using deep ultraviolet lithography, transferring the pattern to the first hard mask layer using reactive ion etching (RIE), forming a temporary I-TWG pattern on the second hard mask layer using RIE, transferring the temporary pattern to the I-TWG core using RIE, refilling the cladding layer, and planarizing using chemical mechanical planarization (CMP).
1. A method for manufacturing an interferometric taper waveguide (I-TWG), the method comprising:
depositing a film stack, the film stack comprising a plurality of hard mask layers and a cladding-core sandwich layer, wherein the plurality of hard mask layers is located above the cladding-core sandwich layer, and the cladding-core sandwich layer comprises a top cladding layer, a bottom cladding layer, and a core layer located between the top cladding layer and the bottom cladding layer;
spinning a photoresist layer on a top hard mask layer;
defining with a first microfabrication process an I-TWG pattern in the photoresist layer;
transferring with a second microfabrication process the I-TWG pattern to the top hard mask layer;
removing the photoresist;
forming with a third microfabrication process the I-TWG pattern in a bottom hard mask layer;
transferring with a fourth microfabrication process the I-TWG pattern to the core layer;
refilling cladding material;
removing with a fifth microfabrication process excess cladding material;
planarizing with a sixth microfabrication process a top surface of the I-TWG; and
removing with a seventh microfabrication process the bottom hard mask layer.
2. The method of claim 1 wherein each of the plurality of hard mask layers comprises Ta 2 O 5 , Ta, Cr, or Ru.
3. The method of claim 1 wherein the cladding layers comprise SiO 2 and the core layer comprises Ta 2 O 5 .
4. The method of claim 1 wherein the first microfabrication process comprises using deep ultraviolet lithography.
5. The method of claim 1 wherein the second microfabrication process, the third microfabrication process, and the fourth microfabrication process each comprise using reactive ion etching.
6. The method of claim 1 wherein the fifth microfabrication process comprises using waveguide etching and reactive ion etching.
7. The method of claim 1 wherein the sixth microfabrication process comprises using chemical mechanical planarization.
8. The method of claim 1 wherein the seventh microfabrication process comprises using wet etching.
9. The method of claim 1 wherein the I-TWG pattern comprises a taper waveguide pattern, a directional coupler pattern, and a splitter pattern.