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 . An optical device, comprising:
a first portion of one or more first gratings disposed on a substrate, the first portion corresponding to one of an input coupling region, an intermediate region, or an output coupling region, each first grating of the first portion comprising:
a first grating vector; and
a first slant angle ϑ′ 1 formed at a first rotation angle φ 1 , wherein the first rotation angle φ 1 is between an etch angle t and the first grating vector; and
a second portion of one or more second gratings disposed on the substrate, the second portion corresponding to one of the input coupling region, the intermediate region, or the output coupling region that is different from the one corresponding to the first portion, each second grating of the second portion comprising:
a second grating vector, the second grating vector different than the first grating vector; and
a second slant angle ϑ′ 2 , the second slant angle ϑ′ 2 different than the first slant angle ϑ′ 1 , wherein the second slant angle ϑ′ 2 is formed at a second rotation angle φ 2 , wherein the second rotation angle φ 2 is between the etch angle t and the second grating vector, 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 .
2 . The optical device of claim 1 , wherein:
the first grating vector is a first orientation of each first grating relative to an origin of the substrate defined by the first slant angle; and
the second grating vector is a second orientation of the second grating relative to the origin of the substrate defined by the second slant angle.
3 . The optical device of claim 1 , wherein the first slant angle and second slant angle are between 25° and 75°.
4 . The optical device of claim 1 , wherein each first grating and each second grating are comprised of a grating material of one or more of silicon oxycarbide (SiOC), titanium dioxide (TiO 2 ), silicon dioxide (SiO 2 ), 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), or zirconium dioxide (ZrO 2 ).
5 . The optical device of claim 4 , wherein the grating material of each first grating and each second grating has a refractive index between 1.5 and 2.65.
6 . The optical device of claim 1 , wherein a non-transparent hardmask is disposed over each first grating and each second grating.
7 . The optical device of claim 1 , wherein a transparent etch stop layer is disposed between the substrate and each first grating and each second grating.
8 . The optical device of claim 1 , wherein the etch angle ϑ corresponds to the angle of a beam.
9 . The optical device of claim 8 , wherein the beam is an ion beam.
10 . An optical device, comprising:
a layer of grating material disposed over the substrate;
a first portion of one or more first gratings disposed in the layer of grating material over the substrate, each first grating of the first portion comprising:
a first slant angle ϑ′ 1 formed at a first rotation angle φ 1 , wherein the first rotation angle φ 1 is between an etch angle t and a first grating vector; and
the first grating vector wherein the first grating vector is a first orientation of each first grating relative to an origin of the substrate defined by the first slant angle ϑ′ 1 ; and
a second portion of one or more second gratings disposed in the layer of grating material over the substrate, each second grating of the second portion comprising:
a second slant angle ϑ′ 2 , the second slant angle ϑ′ 2 different than the first slant angle ϑ′ 1 , wherein the second slant angle ϑ′ 2 is formed at a second rotation angle φ 2 , wherein the second rotation angle φ 2 is between the etch angle ϑ and a second grating vector; and
the second grating vector, the second grating vector different than the first grating vector, wherein the second grating vector is a second orientation of the second grating relative to the origin of the substrate defined by the second slant angle, 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 .
11 . The optical device of claim 10 , wherein the first slant angle and the second slant angle are between 25° and 75°.
12 . The optical device of claim 10 , wherein the layer of grating material includes of one or more of silicon oxycarbide (SiOC), titanium dioxide (TiO 2 ), silicon dioxide (SiO 2 ), 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), or zirconium dioxide (ZrO 2 ).
13 . The optical device of claim 12 , wherein the grating material of each first grating and each second grating has a refractive index between 1.5 and 2.65.
14 . The optical device of claim 10 , wherein a non-transparent hardmask is disposed over each first grating and each second grating.
15 . The optical device of claim 10 , wherein a transparent etch stop layer is disposed between the substrate and each first grating and second grating.
16 . The optical device of claim 10 , wherein the first portion of one or more first gratings or the second portion of one or more second gratings are disposed in the layer of grating material and in an additional layer disposed on the layer of grating material.
17 . The optical device of claim 10 , wherein a transparent layer is disposed between the layer of grating material and the substrate.
18 . The optical device of claim 10 , wherein the etch angle ϑ corresponds to the angle of a beam.
19 . The optical device of claim 18 , wherein the beam is an ion beam.
20 . An optical device, comprising:
a first portion of one or more first gratings disposed on a substrate, each first grating of the first portion comprising:
a first grating vector; and
a first slant angle ϑ′ 1 ; and
a second portion of one or more second gratings disposed on the substrate, each second grating of the second portion comprising:
a second grating vector, the second grating vector different than the first grating vector; and
a second slant angle ϑ′ 2 , the second slant angle ϑ′ 2 different than the first slant angle ϑ′ 1 ;
wherein the optical device is formed by a process comprising:
projecting an ion beam to the substrate having a grating material disposed thereon, the ion beam configured to contact the grating material at ion beam angle ϑ relative to a surface normal of the substrate, wherein:
the first portion of the substrate is positioned at a first rotation angle φ 1 between the ion beam and the first 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 the first slant angle ϑ′ 1 relative to the surface normal of the substrate;
the second portion of the substrate is positioned at a second rotation angle φ 2 between the ion beam and the second 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 2 is selected to form the one or more second gratings with the second slant angle ϑ′ 2 relative to the surface normal of the 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 t, 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 .
21 . The optical device of claim 20 , wherein the ion beam angle 9 is between 250 and 750.
22 . The optical device of claim 20 , wherein the grating material is comprised of one or more of silicon oxycarbide (SiOC), titanium dioxide (TiO 2 ), silicon dioxide (SiO 2 ), 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), or zirconium dioxide (ZrO 2 ).
23 . The optical device of claim 20 , wherein the ion beam is a ribbon beam, a spot beam, or a full substrate-size beam.
24 . The optical device of claim 20 , wherein the second rotation angle φ 2 is different from the first rotation angle φ 1 .
25 . The optical device of claim 20 , wherein the substrate traverses the ion beam in a single pass.