Controlling etch angles by substrate rotation in angled etch tools
Embodiments described herein relate to methods of forming gratings with different slant angles on a substrate and forming gratings with different slant angles on successive substrates using angled etch systems. The methods include positioning portions of substrates retained on a platen in a path of an ion beam. The substrates have a grating material disposed thereon. The ion beam is configured to contact the grating material at an ion beam angle θ relative to a surface normal of the substrates and form gratings in the grating material. The substrates are rotated about an axis of the platen resulting in rotation angles ϕ between the ion beam and a surface normal of the gratings. The gratings have slant angles θ′ relative to the surface normal of the substrates. The rotation angles ϕ selected by an equation ϕ=cos −1 (tan(θ′)/tan(θ)).
1. A grating forming method, comprising:
projecting an ion beam, to a first substrate having a grating material disposed thereon, the ion beam configured to contact the grating material at an ion beam angle ϑ relative to a surface normal of the first substrate, wherein:
the first substrate is positioned at a first rotation angle ϕ between the ion beam and a grating vector of one or more first gratings to be formed by the ion beam contacting the grating material; and
the first rotation ϕ angle is selected to form the one or more first gratings with a first slant angle ϑ′ relative to the surface normal of the first substrate, the first slant angle ϑ′ different than the ion beam angle ϑ.
2. The method of claim 1 , wherein the grating material includes at least one of silicon oxycarbide (SiOC), titanium dioxide (TiO 2 ), silicon dioxide (SiO2), vanadium (IV) oxide (VOx), aluminum oxide (Al 2 O 3 ), indium tin oxide (ITO), zinc oxide (ZnO), tantalum pentoxide (Ta 2 O 5 ), silicon nitride (Si 3 N 4 ), titanium nitride (TiN), and zirconium dioxide (ZrO 2 ) containing materials.
3. The method of claim 2 , wherein the grating material has a refractive index between about 1.5 and about 2.65.
4. The method of claim 1 , wherein the ion beam is a ribbon beam, a spot beam, or a full substrate-size beam.
5. The method of claim 1 , wherein:
the first substrate
is positioned at a second rotation angle ϕ between the ion beam and a grating vector of one or more second gratings to be formed by the ion beam contacting the grating material; and
the second rotation angle ϕ is selected to form the one or more second gratings with a second slant angle ϑ′ 2 relative to the surface normal of the first substrate.
6. The method of claim 5 , wherein the second rotation angle ϕ is different from the first rotation angle ϕ.
7. The method of claim 1 , wherein the ion beam angle ϑ is between is preferably between about 25° and about 75°.
8. The method of claim 1 , wherein the first rotation angle ϕ selected by an equation ϕ=cos −1 (tan(ϑ′)/tan(ϑ)).
9. The method of claim 1 , wherein the first substrate is retained on a platen in a path of the ion beam and the first substrate is positioned at the first rotation angle ϕ by rotation of the platen about an axis of the platen.
10. The method of claim 9 , wherein an angled etch system generates the ion beam and directs the ion beam at an optimized angle α relative to the surface normal of the first substrate.
11. The method of claim 10 , wherein the the platen tilts the first substrate at a tilt angle β relative to an axis of an ion beam chamber so that the ion beam contacts the grating material at the ion beam angle ϑ.
12. A grating forming method, comprising:
projecting an ion beam, to a first substrate having a grating material disposed thereon, the ion beam configured to contact the grating material at an ion beam angle ϑ relative to a surface normal of the first substrate, wherein:
a first portion of the first substrate is positioned at a first rotation angle ϕ 1 between the ion beam and a grating vector of one or more first gratings to be formed by the ion beam contacting the grating material of the first portion;
the first rotation angle ϕ 1 is selected to form the one or more first gratings with a first slant angle ϑ′ 1 relative to the surface normal of the first substrate;
a second portion of the first substrate is positioned at a second rotation angle ϕ 2 between the ion beam and the grating vector of one or more second gratings to be formed by the ion beam contacting the grating material, the second rotation angle ϕ 2 different than the first rotation angle ϕ 1 ; and
the second rotation angle ϕ 2 is selected to form the one or more second gratings have a second slant angle ϑ′ 2 relative to the surface normal of the first substrate, at least one of the first slant angle ϑ′ 1 and the second slant angle ϑ′ 2 are different than the ion beam angle ϑ.
13. The method of claim 12 , wherein the ion beam is a ribbon beam, a spot beam, or a full substrate-size beam.
14. The method of claim 12 , wherein the first rotation angle ϕ 1 and the second rotation angle ϕ 2 are selected by a system of equations ϑ=arctan(tan(ϑ′ 1 )/cos(ϕ 1 )), ϑ=arctan(tan(ϑ′ 2 )/cos(ϕ 2 )), and Δϕ=ϕ 2 −ϕ 1 .
15. The method of claim 12 , wherein the first slant angle ϑ′ and second slant angle ϑ′ are different than the ion beam angle ϑ.
16. The method of claim 12 , wherein the first substrate is retained on a platen in a path of the ion beam and the first substrate is positioned at the first rotation angle ϕ and the second by rotation angle ϕ of the platen about an axis of the platen.
17. A grating forming method, comprising:
projecting an ion beam to a first portion and a second portion of a substrate having a grating material disposed thereon, the ion beam configured to contact the grating material at an ion beam angle ϑ relative to a surface normal of the substrate wherein:
the substrate is positioned at a first rotation angle ϕ 1 between the ion beam and a grating vector of one or more first gratings and a second rotation angle ϕ 2 between the ion beam and a grating vector of one or more second gratings to be formed by the ion beam contacting the grating material;
the first rotation angle ϕ 1 and the second rotation angle ϕ 2 are selected to form the one or more first gratings with a first slant angle ϑ′ 1 and the one or more second gratings with a second slant angle ϑ′ 2 relative to the surface normal of the substrate; and
the first rotation angle ϕ 1 and the second rotation angle ϕ 2 are different and at least one of the first slant angle ϑ′ 1 and second slant angle ϑ′ 2 is different than the ion beam angle ϑ.
18. The method of claim 17 , wherein the first substrate traverses the ion beam in a single pass.
19. The method of claim 17 , wherein the first rotation angle ϕ 1 and the second rotation angle ϕ 2 are selected by a system of equations ϑ=arctan(tan(ϑ′ 1 )/cos(ϕ 1 )), ϑ=arctan(tan(ϑ′ 2 )/cos(ϕ 2 )), and Δϕ=ϕ 2 −ϕ 1 .
20. The method of claim 17 , wherein the ion beam is a ribbon beam, a spot beam, or a full substrate-size beam.