Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0065—Manufacturing aspects; Material aspects
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70216—Mask projection systems
  • G03F7/70258—Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system
  • G03F7/70266—Adaptive optics, e.g. deformable optical elements for wavefront control, e.g. for aberration adjustment or correction
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0033—Means for improving the coupling-out of light from the light guide
  • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
  • G02B6/0038—Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
  • G03F1/22—Masks or mask blanks for imaging by radiation of 100nm or shorter wavelength, e.g. X-ray masks, extreme ultraviolet [EUV] masks; Preparation thereof
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
  • G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
  • G03F1/80—Etching
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/0002—Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/0005—Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/20—Dry etching; Plasma etching; Reactive-ion etching
  • H10P50/24—Dry etching; Plasma etching; Reactive-ion etching of semiconductor materials
  • H10P50/242—Dry etching; Plasma etching; Reactive-ion etching of semiconductor materials of Group IV materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P76/00—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography
  • H10P76/40—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising inorganic materials
  • H10P76/408—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising inorganic materials characterised by their sizes, orientations, dispositions, behaviours or shapes
  • H10P76/4085—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising inorganic materials characterised by their sizes, orientations, dispositions, behaviours or shapes characterised by the processes involved to create the masks

Definitions

• Embodiments of the present disclosure generally relate to waveguides for augmented, virtual, and mixed reality. More specifically, embodiments described herein provide for methods of waveguide fabrication from substrates.
• Virtual reality is generally considered to be a computer generated simulated environment in which a user has an apparent physical presence.
• a virtual reality experience can be generated in 3D and viewed with a head-mounted display (HMD), such as glasses or other wearable display devices that have near-eye display panels as lenses to display a virtual reality environment that replaces an actual environment.
• HMD head-mounted display
• Augmented reality enables an experience in which a user can still see through the display lenses of the glasses or other HMD device to view the surrounding environment, yet also see images of virtual objects that are generated for display and appear as part of the environment.
• Augmented reality can include any type of input, such as audio and haptic inputs, as well as virtual images, graphics, and video that enhances or augments the environment that the user experiences.
• audio and haptic inputs as well as virtual images, graphics, and video that enhances or augments the environment that the user experiences.
• Waveguides are used to assist in overlaying images. Generated light is propagated through a waveguide until the light exits the waveguide and is overlayed on the ambient environment. Fabricating waveguides can be challenging as waveguides tend to have non-uniform properties. Accordingly, what is needed in the art are improved augmented waveguides and methods of fabrication.
• a method for forming a waveguide structure includes imprinting a stamp into a resist to form a positive waveguide pattern.
• the resist is disposed on a hard mask formed on a surface of a portion of a substrate.
• the positive waveguide pattern includes a pattern including at least one of a first plurality of grating patterns, a waveguide pattern, and a second plurality of grating patterns. Each of the first plurality of grating patterns and the second plurality of grating patterns have a residual layer and top pattern surfaces.
• a curing process is performed to cure the positive waveguide pattern.
• the stamp is released.
• a first etching process is performed to remove the residual layer and the hard mask disposed under the residual layer and to expose the surface of the substrate.
• the substrate is masked to expose a first unprotected area of the surface of the substrate.
• a second etching process is performed for a first predetermined period of time to form a first plurality of gratings with first depths.
• the substrate is masked to expose a second unprotected area of the surface of the substrate.
• the second etching process is performed for a second predetermined period of time to form a second plurality of gratings with second depths.
• the top pattern surfaces, the waveguide pattern, and the hard mask disposed under the top pattern surfaces and the waveguide pattern are removed to form a waveguide structure including at least one of an input coupling region, a waveguide region, and an output coupling region.
• a method for forming a waveguide structure includes imprinting a stamp into a resist to form a positive waveguide pattern.
• the resist is disposed on a hard mask formed on a surface of a portion of a substrate.
• the positive waveguide pattern includes a pattern including at least one of a first plurality of grating patterns, a waveguide pattern, and a second plurality of grating patterns.
• Each of the first plurality of grating patterns and the second plurality of grating patterns have a residual layer, top pattern surfaces, and sidewall pattern surfaces slanted relative to the surface of the substrate.
• a curing process is performed to cure the positive waveguide pattern.
• the stamp is released.
• a first etching process is performed to remove the residual layer and the hard mask disposed under the residual layer and to expose the surface of the substrate.
• the substrate is masked to expose a first unprotected area of the surface of the substrate.
• Etching at a predetermined angle for a first predetermined period of time forms a first plurality of angled gratings with first depths.
• the substrate is masked to expose a second unprotected area of the surface of the substrate.
• Etching at the predetermined angle for a second predetermined period of time forms a second plurality of angled gratings with second depths;
• the top pattern surfaces, the waveguide pattern, and the hard mask disposed under the top pattern surfaces and the waveguide pattern are removed to form a waveguide structure including at least one of an input coupling region, a waveguide region, and an output coupling region.
• a method for forming a waveguide structure includes imprinting a stamp into a resist to form a positive waveguide pattern, the resist is disposed on a hard mask formed on a surface of a substrate, the positive waveguide pattern includes a pattern including at least one of a first plurality of grating patterns, a waveguide pattern, and a second plurality of grating patterns.
• Each of the first plurality of grating patterns and the second plurality of grating patterns have a residual layer, top pattern surfaces, and sidewall pattern surfaces slanted by relative to the surface of the substrate.
• the positive waveguide pattern is cured by electromagnetic radiation curing.
• the stamp is released.
• the residual layer is removed by plasma ashing.
• the hard mask disposed under the residual layer is reactive ion etched to expose the surface of the substrate.
• the substrate is masked to expose a first unprotected area of the surface of the substrate.
• Directional reactive ion etching (RIE) at a predetermined angle for a first predetermined period of time forms a first plurality of angled gratings with first depths.
• the substrate is masked to expose a second unprotected area of the surface of the substrate.
• Directional RIE at the predetermined angle for a second predetermined period of time forms a second plurality of angled gratings.
• the substrate is masked to expose a third unprotected area of the surface of the substrate.
• Directional RIE at the predetermined angle for a third predetermined period of time forms a third plurality of angled gratings with third depths.
• the top pattern surfaces and the waveguide pattern are removed by plasma ashing.
• Reactive ion etching the hard mask disposed under the top pattern surfaces and the waveguide pattern forms a waveguide structure including at least one of an input coupling region, a waveguide region, and an output coupling region
• Figure 1 is a perspective, frontal view of a waveguide combiner according to an embodiment.
• Figure 2 is a flow chart illustrating operations of a method for forming a waveguide structure according to an embodiment.
• Figures 3A-3E are schematic, cross-sectional views of a waveguide during fabrication according to an embodiment.
• Figures 4A-4E are schematic, cross-sectional views of a waveguide during fabrication according to an embodiment.
• Figure 5 is a flow chart illustrating operations of a method for forming a waveguide structure according to an embodiment
• Figures 6A-6E are schematic, cross-sectional views of a waveguide during fabrication according to an embodiment.
• Embodiments described herein relate to methods for fabricating waveguide structures from substrates.
• the waveguide structures are formed having input coupling regions, waveguide regions, and output coupling regions formed from substrates.
• the regions are formed by imprinting stamps into resists disposed on hard masks formed on surfaces of the substrates to form positive waveguide patterns. Portions of the positive waveguide patterns and hard masks disposed under the portions are removed.
• the substrates are masked and etched to form gratings in the input coupling regions and the output coupling regions. Residual portions of the positive waveguide pattern and the hard masks disposed under the residual portions are removed to form waveguide structures having input coupling regions, waveguide regions, and output coupling regions formed from substrates.
• the substrates include at least one of glass and plastic materials.
• the substrates have a refractive index between about 1.5 and about 2.5.
• FIG. 1 is a perspective, frontal view of a waveguide combiner 100. It is to be understood that the waveguide combiner 100 described below is an exemplary waveguide combiner.
• the waveguide combiner 100 includes an input coupling region 102 defined by a plurality of gratings 108, a waveguide region 104, and an output coupling region 106 defined by a plurality of gratings 110.
• the input coupling region 102 receives incident beams of light (a virtual image) having an intensity from a microdisplay.
• Each grating of the plurality of gratings 108 splits the incident beams into a plurality of modes, each beam having a mode.
• Zero-order mode (TO) beams are refracted back or lost in the waveguide combiner 100, positive first-order mode (T1) beams undergo total-internal-reflection (TIR) through the waveguide combiner 100 across the though the waveguide region 104 to the output coupling region 106, and negative first-order mode (T-1) beams propagate in the waveguide combiner 100 a direction opposite to the T1 beams.
• TO zero-order mode
• T1 positive first-order mode
• TIR total-internal-reflection
• T-1 beams propagate in the waveguide combiner 100 a direction opposite to the T1 beams.
• the T1 beams undergo total-internal-reflection (TIR) through the waveguide combiner 100 until the T1 beams come in contact with the plurality of gratings 110 in the output coupling region 106.
• TIR total-internal-reflection
• the T1 beams contact a grating of the plurality of gratings 110 where the T1 beams are split into TO beams refracted back or lost in the waveguide combiner 100, T1 beams that undergo TIR in the output coupling region 106 until the T1 beams contact another grating of the plurality of gratings 110, and T-1 beams coupled out of the waveguide combiner 100.
• FIG. 2 is a flow diagram illustrating operations of a method 200 for forming a waveguide structure.
• waveguide structure 300 corresponds to at least one of the input coupling region 102, the waveguide region 104, and the output coupling region 106 of the waveguide combiner 100.
• a stamp having a negative waveguide pattern is imprinted into a resist that is disposed on a hard mask formed on a surface of a portion of a substrate to form a positive waveguide pattern.
• the positive waveguide pattern includes a pattern.
• the pattern includes at least one of an input coupling portion, a waveguide portion, and an output coupling portion to result in the formation of at least one of the input coupling region 102, the waveguide region 104, and the output coupling region 106 of the waveguide combiner 100.
• the pattern includes a plurality of gratings patterns including a residual layer and top pattern surfaces. In one embodiment, the pattern includes plurality of gratings patterns and a waveguide pattern.
• a curing process is performed to cure the positive waveguide pattern.
• the stamp is released from the resist.
• the residual layer and the hard mask disposed under the residual layer are removed by performing a first etching process to expose the surface of the portion of the substrate.
• the substrate is masked to expose a first unprotected area of the surface of the substrate.
• a first plurality of gratings with first depths is formed by performing a second etching process for a first predetermined period of time.
• the first plurality of gratings are a first portion of at least one of the plurality of gratings 108 of the input coupling region 102 and the plurality of gratings 110 of the output coupling region 106. In another embodiment, the first plurality of gratings are at least one of the plurality of gratings 108 of the input coupling region 102 and the plurality of gratings 110 of the output coupling region 106.
• the substrate is masked to expose a second unprotected area of the surface of the substrate.
• a second plurality of gratings with second depths is formed by performing the second etching process for a second predetermined period of time.
• the second plurality of gratings are a second portion of at least one of the plurality of gratings 108 of the input coupling region 102 and the plurality of gratings 110 of the output coupling region 106.
• the second plurality of gratings are at least one of the plurality of gratings 108 of the input coupling region 102 and the plurality of gratings 110 of the output coupling region 106.
• the top pattern surfaces, the waveguide pattern, and the hard mask disposed under the top pattern surfaces and the waveguide pattern are removed to form a waveguide structure.
• the waveguide structure includes at least one of the input coupling region 102, the waveguide region 104, and the output coupling region 106 of the waveguide combiner 100.
• a stamp 326 is imprinted into a resist 325 disposed on a hard mask 303 formed on a surface 302 of a portion 330 substrate 301 to form a positive waveguide pattern 313.
• the stamp 326 has a negative waveguide pattern
• the stamp 312 that includes an inverse pattern 331.
• the inverse pattern 331 includes at least one of an input coupling portion 314, an inverse waveguide portion 316, and an inverse output coupling portion 318.
• the stamp 326 is fabricated from a waveguide master having a master pattern.
• the master pattern includes at least one of a master input coupling portion, a master waveguide portion, and a master output coupling portion.
• the stamp 326 is molded from the waveguide master.
• the stamp 326 may include a semi-transparent material such as fused silica or polydimethylsiloxane (PDMS) to allow the positive waveguide pattern 313 to be cured by exposure to radiation, such as infrared (IR) radiation or ultraviolet (UV) radiation at operation 202.
• the resist 325 comprises a UV curable material (such as mr-N210 available from Micro Resist Technology) that is nano imprintable by the stamp 326 including PDMS.
• the surface 302 of the substrate 301 is prepared for spin coating of the UV curable material by UV ozone treatment, oxygen (0 2 ) plasma treatment, or by application of a primer (such as mr-APS1 available from Micro Resist Technology).
• the resist 325 includes a thermally curable material that may be cured by a solvent evaporation curing process.
• the solvent evaporation curing process may include thermal heating or infrared illumination heating.
• the resist 325 may be disposed on the surface 302 using a liquid material pour casting process, a spin-on coating process, a liquid spray coating process, a dry powder coating process, a screen printing process, a doctor blading process, a physical vapor deposition (PVD) process, a chemical vapor deposition (CVD) process, a flowable CVD (FCVD) process, or an atomic layer deposition (ALD) process.
• PVD physical vapor deposition
• CVD chemical vapor deposition
• FCVD flowable CVD
• ALD atomic layer deposition
• the positive waveguide pattern 313 includes a pattern 322.
• the pattern 322 includes at least one of an input coupling portion 315, a waveguide portion 317, and an output coupling portion 319.
• the pattern 322 includes at least one of a first plurality of grating patterns 305, a waveguide pattern 333, and a second plurality of grating patterns 327.
• Each of the first plurality of grating patterns 305 and the second plurality of grating patterns 327 has a residual layer 311 , oftentimes referred to as bottom pattern surfaces, and top pattern surfaces 307 parallel to the surface 302 of the substrate 301 and sidewall pattern surfaces 309 oriented normal to the surface 302 of the substrate 301.
• Figure 3B illustrates a schematic, cross-sectional view after the stamp 323 has been released at operation 203.
• the stamp 326 can be mechanically removed by a machine tool or by hand peeling as the stamp 326 may be coated with a mono-layer of anti-stick surface treatment coating, such as a fluorinated coating.
• the stamp 326 may comprise a polyvinyl alcohol (PVA) material that is water soluble in order for the stamp 326 to be removed by dissolving the stamp 326 in water.
• the stamp 326 comprises a rigid backing sheet, such as a sheet of glass, to add mechanical strength.
• Figure 3C is a schematic, cross-sectional view after the first etching process removes the residual layer 311 and the hard mask 303 disposed under the residual layer 311 and exposes the surface 302 of the substrate 301 at operation 204.
• the residual layer 311 may be removed by plasma ashing, oftentimes referred to as plasma descumming, using an oxygen gas (0 2 ) containing plasma, a fluorine gas (F 2 ) containing plasma, a chlorine gas (Cl 2 ) containing plasma, and/or a methane (CH 4 ) containing plasma.
• a first radio frequency (RF) power is applied to 0 2 and an inert gas, such as argon (Ar) or nitrogen (N), until the residual layer 311 is removed.
• the hard mask 303 disposed under the residual layer 311 may be removed by ion etching, reactive ion etching (RIE), or highly selective wet chemical etching.
• the hard mask 303 may have a first layer comprising a first material and a second layer comprising a second material, where the second layer is formed on the first layer disposed on the surface 302 of the substrate 301.
• the second layer may be removed by utilizing a high etch selectivity of the second material over the first material and materials of the substrate 301.
• the first layer may be removed by utilizing a high etch selectivity of the first material over the materials of the substrate 301.
• the hard mask 303 comprises a silicon containing layer (such as OptiStack® HM825-302.6 available from Brewer Science) disposed on a carbon containing layer (such as OptiStack® SOC110D available from Brewer Science).
• the silicon containing layer disposed under the residual layer 311 is removed by RIE using a F 2 containing plasma, and the carbon containing layer disposed under the residual layer 311 is removed by RIE using a 0 2 containing plasma.
• the hard mask 303 comprises a chromium containing layer disposed on a silicon dioxide (Si0 2 ) containing layer.
• the chromium containing layer disposed under the residual layer 311 is removed by RIE using a Cl 2 containing plasma, such as BCI3, and the silicon dioxide containing layer is removed by RIE using a F 2 containing plasma or CFU containing plasma.
• Figure 3D is a schematic, cross-sectional view after operations 205-208.
• the second etching process is performed for a first predetermined period of time after the substrate 301 is masked to expose the first unprotected area of the surface 302 of the substrate 301 and the second etching process is performed for a second predetermined period of time after the substrate 301 is masked to expose a second unprotected area of the surface 302 of the substrate 301.
• a chamber mounted etch end point detection system is used.
• Masking the substrate 301 may include placing a shadow mask in physical contact with the surface 302 of the substrate 301 or aligning a photomask over the substrate 301 to expose the first unprotected area.
• the shadow mask is metal and may be used repeatedly.
• the first unprotected area corresponds to a first region and the second unprotected area corresponds to a second region of the resulting waveguide structure 300. In another embodiment, the first unprotected area corresponds to the first region and the second region, and the second unprotected area corresponds to the second region.
• the first region is the input coupling region 102 and the second region is the output coupling region 106. In another embodiment, not shown, the first region and the second region are regions of the input coupling region 102 or the output coupling region 106.
• the second etching process may include etching processes such as ion implantation, ion etching, RIE, directional RIE such as directed ribbon-beam ion etching, microblasting, waterjet cutting, and laser etching for the first predetermined period of time to form a first plurality of gratings 304 with first depths 321.
• etching processes such as ion implantation, ion etching, RIE, directional RIE such as directed ribbon-beam ion etching, microblasting, waterjet cutting, and laser etching for the first predetermined period of time to form a first plurality of gratings 304 with first depths 321.
• ion implantation apparatus is the Varian VIISTA® Trident, available from Applied Materials, Inc., Santa Clara, Calif.
• Ion etching may be in the presence of an etch gas to improve the ion etching rate
• the first plurality of gratings 304 further includes top surfaces 306 and bottom surfaces 328 corresponding to the surface 302 of the substrate 301 and sidewall surfaces 308 oriented normal to the surface 302 of the substrate 301.
• the shadow mask may be relocated or the photomask may be realigned to expose the second unprotected area.
• Performing the second etching process for a second predetermined period of time forms the second plurality of gratings 310 with second depths 323.
• the second plurality of gratings 310 further includes the top surfaces 306, the bottom surfaces 328, and the sidewall surfaces 308.
• FIG. 3E is a schematic, cross-sectional view of the waveguide structure 300 formed after operation 209.
• the top pattern surfaces 307, the waveguide pattern 333, and the hard mask 303 disposed under the top pattern surfaces 307 and waveguide pattern 333 at operation 207 are removed to form the waveguide structure 300 including at least one of the input coupling region 102, the waveguide region 104, and the output coupling region 106 of the waveguide combiner 100.
• the top pattern surfaces 307 and the waveguide pattern 333 may be removed by plasma ashing using the 0 2 containing plasma, the F 2 containing plasma, the Cl 2 containing plasma and/or the CFU containing plasma.
• a second radio frequency (RF) power is applied to 0 2 and an inert gas, such as argon (Ar) or nitrogen (N), until the top pattern surfaces 307 and the waveguide pattern 333 are removed.
• the hard mask 303 disposed under the top pattern surfaces 307 and waveguide pattern 333 may be removed by ion etching, RIE, or highly selective wet chemical etching.
• the hard mask 303 includes the silicon containing layer disposed on the carbon containing layer. The silicon containing layer is removed by RIE using the F 2 containing plasma, and the carbon containing layer is removed by RIE using the 0 2 containing plasma.
• the hard mask 303 comprises the chromium containing layer disposed on the Si0 2 containing layer.
• the chromium containing layer is removed by RIE using the Cl 2 containing plasma and the silicon dioxide containing layer is removed by RIE using the F 2 containing plasma or the CH 4 containing plasma.
• the hard mask 303 is not removed and the hard mask 303 comprises materials, such as Si0 2 and titanium dioxide (Ti0 2 ), with controlled refractive indices between about 1.5 and about 2.5.
• the waveguide structure 300 resulting from the method 200 has a substantially uniform refractive index. Utilizing materials having a refractive index of between about 1.5 and about 2.5 for the substrate 301 , as compared to the refractive index of air (1.0), total internal reflection, or at least a high degree thereof, is achieved to facilitate light propagation through the waveguide structure 300.
• a stamp 426 is imprinted into a resist 425 disposed on a hard mask 403 formed on a surface 402 of a portion 430 of a substrate 401 to form a positive waveguide pattern 413.
• the stamp 426 has a negative waveguide pattern 412 that includes an inverse pattern 431.
• the inverse pattern 431 includes at least one of an inverse input coupling portion 414, an inverse waveguide portion 416, and an inverse output coupling portion 418.
• the positive waveguide pattern 413 is cured.
• the positive waveguide pattern 413 includes a pattern 422.
• the pattern 422 includes at least one of includes an input coupling portion 415, a waveguide portion 417, and an output coupling portion 419.
• the pattern 422 includes at least one of a first plurality of grating patterns 405, a waveguide pattern 433, and a second plurality of grating patterns 427.
• Each of the first plurality of grating patterns 405 and the second plurality of grating patterns 427 has a residual layer 411 , oftentimes referred to as bottom pattern surfaces, and top pattern surfaces 407 parallel to the surface 402 of the substrate 401 and sidewall pattern surfaces 409 slanted by an amount relative to the surface 402 of the substrate 401.
• the stamp 426 is released from the resist 425.
• the residual layer 411 and the hard mask 403 disposed under the residual layer 411 are removed by performing a first etching process to expose the surface 402 of the substrate 401.
• the substrate 401 is masked to expose a first unprotected area of the surface 402 of the substrate 401.
• Masking the substrate 401 may include placing a shadow mask in physical contact with the surface 402 of the substrate 401 or aligning a photomask over the substrate 401 to expose the first unprotected area.
• the first unprotected area corresponds to a first region and the second unprotected area corresponds to a second region of the resulting waveguide structure 400.
• the first unprotected area corresponds to the first region and the second region, and the second unprotected area corresponds to the second region.
• the first region is the input coupling region 102 and the second region is the output coupling region 106. In another embodiment, not shown, the first region and the second region are regions of the input coupling region 102 or the output coupling region 106.
• performing the second etching process at a predetermined angle for a first predetermined period of time of time forms a first plurality of gratings 404 with first depths 421 and sidewall surfaces 408 slanted by an amount relative to the surface 402 of the substrate 401.
• the predetermined angle may be determined by computer simulation to maximize the light coupling efficiency of the waveguide structure 400 and the predetermined angle may range from about 15 degrees to about 75 degrees.
• the first plurality of gratings 404 further includes top surfaces 406 parallel to the surface and bottom surfaces 328 corresponding to the surface 302.
• Etching at the predetermined angle may include etching processes such as angled ion implantation, angled ion etching, and directional RIE such as directed ribbon-beam ion etching.
• Angled ion implantation includes accelerating ions towards the surface 402 of the substrate 401 at the predetermined angle relative to the surface 402 of the substrate 401 and bombarding the substrate 401 with ions at the predetermined angle to selectively remove material to form the first plurality of gratings 404.
• introduction of an etch gas close to an ion generation source will improve the ion etching rate.
• an angled ion implantation apparatus is the Varian VIISTA® Trident, available from Applied Materials, Inc., Santa Clara, Calif.
• the substrate 401 is masked to expose a second unprotected area of the surface 402 of the substrate 401.
• the shadow mask may be relocated or the photomask may be realigned to expose the second unprotected area.
• a second plurality of angled gratings 410 with second depths 423 is formed by etching at the predetermined angle for a second predetermined period of time.
• the second plurality of angled gratings 410 further includes top surfaces 406 and bottom surfaces 428 and sidewall surfaces 408 slanted by an amount relative to the surface 402 of the substrate 401.
• the top pattern surfaces 407, the waveguide pattern 433, and the hard mask 403 disposed under the top pattern surfaces 407 and the waveguide pattern 433 are removed to form the waveguide structure 400 having the input coupling region 102, the waveguide region 104, and the output coupling region 106.
• the top pattern surfaces 407 and the waveguide pattern 433 may be removed to form the waveguide structure 400 including at least one of the input coupling region 102, the waveguide region 104, and the output coupling region 106 of the waveguide combiner 100.
• the hard mask 403 is not removed and the hard mask 403 comprises materials with controlled refractive indices between about 1.5 and about 2.5.
• the waveguide structure 400 resulting from the method 200 has substantially uniform refractive index.
• FIG. 5 is a flow diagram illustrating operations of a method 500 for forming a waveguide structure 600 as shown in Figures 6A-6E.
• waveguide structure 600 corresponds to at least one of the input coupling region 102, the waveguide region 104, and the output coupling region 106 of the waveguide combiner 100.
• a stamp 626 is imprinted into a resist 625 disposed on a hard mask 603 formed on a surface 602 of a portion 630 of a substrate 601 to form a positive waveguide pattern 613.
• the stamp 626 has a negative waveguide pattern 612 that an inverse pattern 631.
• the inverse pattern 631 includes at least one of an inverse input coupling portion 614, an inverse waveguide portion 616, and an inverse output coupling portion 618.
• the positive waveguide pattern 613 includes a pattern 622.
• the pattern 622 includes at least one of an input coupling portion 615, a waveguide portion 617, and an output coupling portion 619.
• the pattern 622 includes at least one of a first plurality of grating patterns 605, a waveguide pattern 633, and a second plurality of grating patterns 627.
• Each of the first plurality of grating patterns 605 and the second plurality of grating patterns 627 has a residual layer 611 , oftentimes referred to as bottom pattern surfaces, and top pattern surfaces 607 parallel to the surface 602 of the substrate 601 and sidewall pattern surfaces 609 slanted by an amount relative to the surface 602 of the substrate 601.
• the positive waveguide pattern 613 is cured by exposure to electromagnetic radiation, such as infrared (IR) radiation and ultraviolet (UV) radiation.
• electromagnetic radiation such as infrared (IR) radiation and ultraviolet (UV) radiation.
• the stamp 626 is released from the resist 625.
• the residual layer 611 is removed by plasma ashing until the residual layer 611 is removed.
• the hard mask 603 disposed under the residual layer 611 is removed by ion etching, reactive ion etching (RIE), and highly selective wet chemical etching.
• the substrate 601 is masked to expose a first unprotected area of the surface 602 of the substrate 601.
• Masking the substrate 601 may include placing a shadow mask in physical contact with the surface 602 of the substrate 601 or aligning a photomask over the substrate 601 to expose the first unprotected area.
• the first unprotected area corresponds to a first region
• the second unprotected area corresponds to a second region
• a third unprotected area corresponds to a third region of the resulting waveguide structure 600.
• the first unprotected area corresponds to the first region, the second region, and the third region
• the second unprotected area corresponds to the second region and the third region
• the third unprotected area corresponds to the third region.
• the first region is the input coupling region 102
• the second region and the third region are the output coupling region 106.
• the first region, the second region, and the third region are regions of the input coupling region 102 or the output coupling region 106.
• a first plurality of gratings 604 with first depths 621 is formed by directional reactive ion etching (RIE) at a predetermined angle for a first predetermined period of time to a first etch depth.
• the first plurality of gratings 604 further includes top surfaces 606 parallel to the surface 602 of the substrate 601 , bottom surfaces 628 corresponding to the surface 602 of the substrate 601 , sidewall surfaces 608 slanted by an amount relative to the surface 602 of the substrate 601.
• the substrate 601 is masked to expose a second unprotected area of the surface 602 of the substrate 601.
• the shadow mask may be relocated or the photomask may be realigned to expose the second unprotected area.
• the second unprotected area corresponds to a first portion 634 of the output coupling region 106.
• the second unprotected are corresponds to the first portion 634 and a second portion 635 of the output coupling region 106.
• a second plurality of angled gratings 610 with second depths 623 in the first portion 634 is formed by directional RIE at the predetermined angle for a second predetermined period of time.
• the second plurality of angled gratings 610 further includes top surfaces 606, bottom surfaces 628, and sidewall surfaces 608 slanted by an amount relative to the surface 602 of the substrate 601.
• the substrate 601 is masked to expose a third unprotected area of the surface 602 of the substrate 601.
• the shadow mask may be relocated or the photomask may be realigned to expose the third unprotected area.
• the third unprotected area corresponds to the second portion 635 of the output coupling region 106.
• a third plurality of angled gratings 632 with third depths 629 is formed by directional RIE at the predetermined angle for a third predetermined period of time.
• the third plurality of angled gratings 632 further includes top surfaces 606 and bottom surfaces 628 parallel to the surface 602 of the substrate 601 and sidewall surfaces 608 slanted by an amount relative to the surface 602 of the substrate 601.
• the top pattern surfaces 607, the waveguide pattern 633, and the hard mask 603 disposed under the top pattern surfaces 607 and the waveguide pattern 633 are removed by plasma ashing.
• the hard mask 603 disposed under the top pattern surfaces 607 and waveguide pattern 633 is removed by ion etching, RIE, or highly selective wet chemical etching to form the waveguide structure 600 having the input coupling region 102, the waveguide region 104, and the output coupling region 106.
• the hard mask 603 is not removed and the hard mask 603 comprises materials with controlled refractive indices between about 1.5 and about 2.5.
• the waveguide structure 600 resulting from the method 500 has substantially uniform refractive index.

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• 2018
  • 2018-11-13 CN CN202310338255.8A patent/CN116520644A/zh active Pending
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