Method for manufacturing a blazed grating

Abstract

This disclosure relates to a method 100 for manufacturing a blazed grating. The method 100 includes steps 110 of preparing a substrate and a patterned mask layer on the substrate, step 120 of performing a primary dry etch of the substrate such that primary ions are accelerated in a primary etch direction and impinge on the substrate, and step 150 of performing a secondary dry etch of the substrate such that secondary ions are accelerated in a secondary etch direction and impinge on the substrate. A primary projection of the primary etch direction and a secondary projection of the secondary etch direction on the grating cross section extend perpendicular to one and the other of the blaze facet direction and the anti-blaze facet direction, respectively, and the ions accelerated in a projection direction perpendicular to the blaze facet direction on the grating cross section are collimated to form a collimated ion beam for etching the substrate.

Description

[Technical field]

[0001] This disclosure relates to diffraction gratings, and in particular to blazed gratings. [Background technology]

[0002] A typical surface relief grating, a so-called binary grating, comprises a number of ridges and grooves, with the tops of the ridges and the bottoms of the grooves running parallel to one another. Well-known manufacturing processes exist for producing such binary gratings. In the case of such binary gratings, normally incident light is diffracted, resulting in equal diffraction efficiency for both negative and positive diffraction orders. This effect occurs due to the mirror symmetry of the cross-sectional shape of the binary grating.

[0003] In many applications, for example in many waveguide-based display structures, preferential diffraction into one or more specific diffraction orders may be desired, and diffraction into other diffraction orders may be considered as light loss. In order to preferentially direct light into specific diffraction orders, gratings with non-mirror symmetric cross-sectional shapes must be used. One example of such an asymmetric grating is the so-called blazed grating, which has a triangular or sawtooth cross-sectional shape.

[0004] Blazed gratings are typically fabricated using processes based on grayscale lithography. Although such processes have been improved to produce gratings with acceptable properties, the features of blazed gratings produced using grayscale lithography, particularly the vertices, are generally relatively rounded due to the low contrast of typical grayscale lithography resists. Such deviations from the ideal blazed shape can reduce the diffraction efficiency of blazed gratings produced using grayscale lithography and / or increase the light scattering caused by such gratings. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above, it may be desirable to develop new solutions for blazed gratings. [Means for solving the problem]

[0006] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0007] Provided herein is a method for manufacturing a blazed grating comprising ridges having blaze facets facing in a blaze facet direction and anti-blaze facets facing in an anti-blaze facet direction, the blaze facet direction and the anti-blaze facet direction extending along a cross section of the grating, the method comprising the steps of providing a substrate and a patterned mask layer on the substrate, performing a primary dry etch of the substrate such that primary ions are accelerated in the primary etch direction and impinge on the substrate, and performing a secondary dry etch of the substrate such that secondary ions are accelerated in the secondary etch direction and impinge on the substrate.

[0008] The primary projection of the primary etching direction onto the grating cross section and the secondary projection of the secondary etching direction onto the grating cross section extend perpendicular to one of the blaze facet direction and the anti-blaze facet direction, respectively, and the ions (primary ions and secondary ions) accelerated in a projection direction perpendicular to the blaze facet direction onto the grating cross section are collimated to form a collimated ion beam for etching the substrate.

[0009] The present disclosure will be better understood from the following detailed description in light of the accompanying drawings, in which: [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 illustrates a method for manufacturing a blazed grating. [Figure 2A] 1A-1C show a series of subsequent steps in a method for manufacturing a blazed grating. [Figure 2B] 1A-1C show a series of subsequent steps in a method for manufacturing a blazed grating. [Figure 2C] 1A-1C show a series of subsequent steps in a method for manufacturing a blazed grating. [Figure 2D] 1A-1C show a series of subsequent steps in a method for manufacturing a blazed grating. [Figure 2E] 1A-1C show a series of subsequent steps in a method for manufacturing a blazed grating. [Figure 3A] 10A-10C show a series of subsequent steps of another method for manufacturing a blazed grating. [Figure 3B] 10A-10C show a series of subsequent steps of another method for manufacturing a blazed grating. [Figure 3C] 10A-10C show a series of subsequent steps of another method for manufacturing a blazed grating. [Figure 3D] 10A-10C show a series of subsequent steps of another method for manufacturing a blazed grating. [Figure 3E] 10A-10C show a series of subsequent steps of another method for manufacturing a blazed grating. [Figure 3F] 10A-10C show a series of subsequent steps of another method for manufacturing a blazed grating. [Figure 3G] 10A-10C show a series of subsequent steps of another method for manufacturing a blazed grating. [Figure 3H] 10A-10C show a series of subsequent steps of another method for manufacturing a blazed grating. [Figure 4A] 11A-11D show a series of subsequent steps in yet another method for manufacturing a blazed grating. [Figure 4B] 11A-11D show a series of subsequent steps in yet another method for manufacturing a blazed grating. [Figure 4C] 11A-11D show a series of subsequent steps in yet another method for manufacturing a blazed grating. [Figure 4D] 11A-11D show a series of subsequent steps in yet another method for manufacturing a blazed grating. [Figure 4E] 11A-11D show a series of subsequent steps in yet another method for manufacturing a blazed grating. [Figure 4F] 11A-11D show a series of subsequent steps in yet another method for manufacturing a blazed grating. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Unless specifically noted otherwise, any of the foregoing drawings may not be drawn to scale, and therefore any element of the drawing may be drawn in inaccurate proportion to other elements of the drawing, in order to emphasize certain structural aspects of the embodiments of the drawing.

[0012] Corresponding elements of the embodiments presented in the drawings, e.g., identical or similar elements, are referenced using the same reference numerals. Corresponding elements of the previous drawings may be out of proportion to each other in this drawing to emphasize particular structural aspects of the embodiment in this drawing.

[0013] 1 shows a method 100 for making a blazed grating having ridges with blaze facets facing in a blaze facet direction and anti-blaze facets facing in an anti-blaze facet direction, where the blaze facet direction and the anti-blaze facet direction extend along a cross section of the grating. Methods for making blazed gratings in other embodiments may be the same as, similar to, or different from method 100 of the embodiment of FIG.

[0014] In the embodiment of FIG. 1, the method 100 includes step 110 of providing a substrate and a patterned mask layer on the substrate, step 120 of performing a primary dry etch of the substrate such that primary ions are accelerated in a primary etch direction and impinge on the substrate, and step 150 of performing a secondary dry etch of the substrate such that secondary ions are accelerated in a secondary etch direction and impinge on the substrate.

[0015] Throughout this specification, "dry etching" can refer to the removal of material by exposure to a bombardment of ions. Typical dry etching techniques include reactive ion etching (RIE), deep reactive ion etching (DRIE), inductively coupled plasma reactive ion etching (ICP-RIE), ion milling, ion beam etching (IBE), reactive ion beam etching (RIBE), and variations thereof.

[0016] In this specification, performing dry etching of a substrate such that certain ions are "accelerated" in a particular direction to impact the substrate may refer to the ions being subjected to an average velocity, e.g., drift velocity, in a particular direction. Such ions may typically be accelerated in a particular direction by an electric field.

[0017] In the embodiment of Figure 1, the primary projection of the primary etching direction onto the grating cross section and the secondary projection of the secondary etching direction onto the grating cross section extend perpendicular to one or the other of the blaze facet direction and the anti-blaze facet direction, respectively, and the ions (primary ions and secondary ions) accelerated onto the grating cross section in a projection direction perpendicular to the blaze facet direction are collimated to form a collimated ion beam for etching the substrate. Generally, with such primary and secondary etching directions and by utilizing a collimated ion beam perpendicular to the blaze facet direction for etching the substrate, blazed gratings with sharper or less rounded features, such as vertices and / or facets, can be readily produced.

[0018] As used herein, a "collimated ion beam" may refer to a beam of ions propagating from a collimator in a particular etching direction, e.g., a primary etch direction or a secondary etch direction. Additionally or alternatively, an ion beam propagating from a collimator in a particular etching direction may be referred to as a collimated ion beam if the ion beam has a maximum angular error of, for example, 4°, 3°, or 2° from the primary etch direction. When a collimated ion beam is formed to etch a substrate, such maximum angular error may be determined at the position of the substrate.

[0019] Performing 120 a first dry etch may optionally include forming 124 grooves extending in the substrate along the first etch direction, as shown in FIG. 1 using dashed lines, the method 100 may optionally include depositing 130 a first material in the grooves to form interstitial features, and performing 150 a second dry etch may optionally include 154 using the interstitial features as an etch stop. In general, using the interstitial features as an etch stop when performing the second dry etch may facilitate the production of blazed gratings with sharper, less rounded features and / or smoother and / or more uniform facets. The method of producing a blazed grating may or may not have one or more of such features in other embodiments.

[0020] In this specification, a "process" can refer to a sequence of one or more steps leading to an end result. A process can therefore be a single-step process or a multi-step process. A process can further be divisible into multiple sub-processes, each of which may or may not share a common step.

[0021] As used herein, a "step" can refer to an action taken to achieve a predefined result. For example, an "atomic layer deposition step" can refer to a process step in which a layer is formed by atomic layer deposition.

[0022] Method 100 may optionally include exposing 140 the ridged portions of the substrate prior to performing 150 the secondary dry etch, also as shown in FIG. 1 using dashed lines. Generally, exposing the ridged portions of the substrate prior to performing the secondary dry etch facilitates the formation of a blazed grating without a post-processing step, whereby the released portions of the substrate are removed during the step of performing the secondary dry etch. Methods of fabricating a blazed grating may or may not include exposing the ridged portions of the substrate prior to performing the secondary dry etch in other embodiments.

[0023] Additionally, depositing 130 the first material in the trenches may optionally include an atomic layer deposition step 131. Generally, depositing 130 the first material in the trenches may include an atomic layer deposition step to facilitate forming interstitial features in narrower trenches and / or with greater uniformity. Depositing 130 the first material in the trenches may or may not include an atomic layer deposition step in other embodiments.

[0024] 1 using dashed lines, the step 110 of preparing a substrate and a patterned mask layer may optionally include a step 111 of providing a plurality of elongated through holes in a coating disposed on the substrate to form a mask layer, the plurality of elongated through holes extending perpendicular to the lattice cross section. The step of preparing a substrate and a patterned mask layer may or may not include a step of providing a plurality of elongated through holes in a coating disposed on the substrate to form a mask layer in other embodiments.

[0025] The method of manufacturing a blazed grating, in one embodiment, includes steps that correspond to steps of the embodiment of method 100 of Figure 1. The method of manufacturing a blazed grating, in other embodiments, may include steps that correspond to non-optional steps of the embodiment of method 100 of Figure 1. The method of manufacturing a blazed grating may generally include any number of additional steps or steps not disclosed herein in conjunction with the embodiment of method 100 of Figure 1.

[0026] The steps of the method of fabricating a blazed grating that perform steps corresponding to any of the steps of method 100 of the embodiment of Figure 1 need not be performed in a fixed order, but any step of method 100 performing a step corresponding to providing a substrate and a patterned mask layer step 110 may generally be performed before any step of method 100 performing a step corresponding to any of performing a first dry etch step 120 and performing a second dry etch step 150, any step of method 100 performing a step corresponding to forming grooves extending through a substrate step 124 may generally be performed before any step of method 100 performing a step corresponding to depositing a first material in the grooves step 130, and any step of method 100 performing a step corresponding to depositing a first material in the grooves step 130 may generally be performed before any step of method 100 performing a step corresponding to utilizing interstitial features as an etch stop step 154.

[0027] Figures 2A to 2E, collectively referred to throughout this specification as Figure 2, show diagrammatically a sequence of subsequent steps of a method for manufacturing a blazed grating 200 comprising a ridge 210 having blaze facets 211 facing in a blaze facet direction 212 and anti-blaze facets 213 facing in an anti-blaze facet direction 214, where according to one embodiment the blaze facet direction 212 and the anti-blaze facets 213 extend along a grating cross section 215. In Figure 2, the grating cross section 215 extends perpendicularly to the plane of the drawing of Figures 2A to 2E. The method for manufacturing a blazed grating may in other embodiments include a sequence of steps similar to or different from the steps of the method of the embodiment of Figure 2.

[0028] The embodiment of Figure 2 may conform to any of the embodiments disclosed with reference to and / or in conjunction with Figure 1. The embodiment of Figure 2 may additionally or alternatively have any functionality not explicitly described below but generally of any of the embodiments disclosed with reference to and / or in conjunction with Figure 1.

[0029] 2E, the blazed grating 200 comprises a plurality of ridges 210, each of which has a blaze facet 211 facing in a blaze facet direction 212 and an anti-blaze facet 213 facing in an anti-blaze facet direction 214. The blazed grating can comprise at least one such ridge, or a plurality, i.e. at least two, of such ridges in other embodiments.

[0030] 2A and 2B, the method includes providing a substrate 220 and a patterned mask layer 230 on the substrate 220. The step of providing the substrate 220 and the patterned mask layer 230 includes providing a coating 232 on the substrate 220 and providing a plurality of elongated through holes 231 in the coating 232 to form the mask layer 230. The plurality of elongated through holes 231 extend perpendicular to the lattice cross section 215.

[0031] 2 may be formed of a high refractive index polymeric material using any suitable application method, such as spin coating, spray coating, and / or inkjet printing. The substrate may, in other embodiments, comprise any suitable material and may be formed using any suitable process.

[0032] The mask layer 230 in the embodiment of FIG. 2 may be formed of aluminum oxide (AlO2) deposited by electron beam evaporation. The mask layer may be formed of any suitable material in other embodiments, such as aluminum oxide (AlO2 / AlO x ), titanium oxide (TiO2 / TiO2), silicon oxide (SiO2 / SiO x ), and / or silicon nitride (Si2N3 / SiN x The insulating layer may comprise inorganic materials, including oxide and / or nitride materials, such as SiO 2 , and may be formed using any suitable process, such as, for example, sputtering, evaporation, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), inductively coupled plasma chemical vapor deposition (ICP-CVD), atomic layer deposition (ALD), and / or variations thereof.

[0033] 2 embodiment may constitute one example of a method for fabricating a blazed grating whereby a blazed grating is formed on a face of a waveguide for coupling light into and / or out of the waveguide. Substrate 220 may thus be disposed on face 271 of waveguide 270. A blazed grating may be formed on a face of a waveguide in other embodiments for any suitable use in any suitable application, such as for coupling light into and / or out of the waveguide.

[0034] When substrate 220 is disposed on face 271 of waveguide 270, blazed grating 200 of the embodiment of Figure 2 is formed in an additional layer of material disposed on waveguide 270. A blazed grating may, in other embodiments, be formed on the face of the waveguide to couple light into and / or out of the waveguide, and this blazed grating may or may not be disposed on such additional layer of material. A blazed grating may, in some such embodiments, be formed directly in the waveguide.

[0035] "Waveguide" in this disclosure may refer to an optical waveguide. A waveguide may additionally or alternatively refer to a two-dimensional waveguide, where light is confined along the thickness of the waveguide.

[0036] Additionally, a "face" of a waveguide may refer to a portion of the surface of the waveguide that is visible from or faces a particular line of sight direction. A face of a waveguide may additionally or alternatively refer to a surface that is suitable or configured to confine light within the waveguide by total internal reflection.

[0037] The method includes, referring to FIG. 2C, performing a primary dry etch of a substrate 220 such that primary ions 121, shown diagrammatically as white dots, are accelerated in a primary etching direction 122 and impinge on the substrate 220.

[0038] 2, the primary projection 123 of the primary etching direction 122 onto the grating cross section 215 extends perpendicular to the anti-blaze facet direction 214. The primary projection of the primary etching direction onto the grating cross section can extend perpendicular to the blaze facet direction or the anti-blaze facet direction in other embodiments.

[0039] 2 includes forming grooves 240 extending in substrate 220 along primary etch direction 122. Performing a primary dry etch may or may not include forming such grooves in other embodiments.

[0040] As shown in Figures 2B and 2C, the interface 222 between the substrate and the mask layer extends along the base plane 260, and the primary projection 123 extends perpendicular to the base plane 260. The base plane 260 extends perpendicular to the grating cross section 215. In general, a primary or secondary projection extending perpendicular to the base plane may enable the formation of a blazed grating with upright anti-blazed facets, which may improve diffraction efficiency. The primary or secondary projection may or may not extend perpendicular to the base plane in other embodiments.

[0041] As used herein, a "base plane" can refer to an imaginary surface along which the interface between the substrate and the mask layer extends. The base plane can be planar, e.g., in the case of a flat interface, or curved, e.g., in the case of a curved interface.

[0042] In the embodiment of FIG. 2, the primary etch direction 122 may extend parallel to the grating cross section 215. Thus, the primary etch direction 122 may extend perpendicular to the base plane 260. In general, a primary or secondary etch direction extending perpendicular to the base plane may enable the use of a wider range of dry etching techniques, including reactive ion etching (RIE) and ion milling. The primary or secondary etch direction may or may not extend perpendicular to the base plane in other embodiments. For example, in some embodiments, each of the first projection and the second projection may extend obliquely to the base plane. In general, a primary and secondary projection extending obliquely to the base plane may enable the formation of a blazed grating with tilted anti-blazed facets, which may facilitate spatial tuning of, for example, the diffraction efficiency of the blazed grating.

[0043] 2 may include an RIE step, since the primary etch direction 122 may extend perpendicular to the base plane 260. During the RIE step, the substrate 220 may be etched using, for example, an oxygen plasma. In other embodiments where the primary etch direction or the secondary etch direction extends perpendicular to the base plane, the step of performing the primary dry etch may include any suitable steps, such as an RIE step and / or an ion milling step.

[0044] The method includes, referring to FIG. 2D , performing a secondary dry etch of a substrate 220 such that secondary ions 151, shown diagrammatically as black dots, are accelerated in a secondary etching direction 152 and impinge on the substrate 220.

[0045] 2, the secondary projection 153 of the secondary etching direction 152 onto the grating cross section 215 extends perpendicular to the blaze facet direction 212. The secondary projection of the secondary etching direction onto the grating cross section can extend perpendicular to the blaze facet direction or the anti-blaze facet direction in other embodiments.

[0046] 2, the secondary ions 151 are collimated to form a collimated secondary ion beam for etching the substrate 220. In other embodiments, the primary ions and / or secondary ions can be collimated to form a collimated primary ion beam and / or a collimated secondary ion beam for etching the substrate.

[0047] 2, performing a secondary dry etch can include a RIBE step, during which the substrate 220 can be etched using, for example, oxygen ions. In other embodiments, performing a dry etch can include any suitable steps, such as an IBE step and / or a RIBE step, in which ions are accelerated onto the grating cross section in a projected direction perpendicular to the blaze facet direction and the ions are collimated to form a collimated ion beam for etching the substrate.

[0048] 2E, the method further includes a post-processing step whereby during the step of performing a second dry etch, the released portions of the substrate 220 are removed to form a plurality of ridges 210. The method of manufacturing a blazed grating may or may not include such a post-processing step in other embodiments.

[0049] The post-treatment step in the embodiment of Figure 2 can be performed as a wet cleaning step, such as a water immersion step. In other embodiments, the method of manufacturing a blazed grating includes a post-treatment step whereby during the step of performing a second dry etch, the released portions of the substrate are removed to form one or more ridges, and the post-treatment step can be performed in any suitable manner, for example as a wet cleaning step, such as a water immersion step.

[0050] In the embodiment of FIG. 2, under primary etching conditions (i.e., in the process of performing a primary dry etch), the primary ions 121 can exhibit a first primary chemical reactivity with the mask layer 230 and a second primary chemical reactivity with the substrate 220 that is higher than the first primary chemical reactivity. Additionally, under secondary etching conditions (i.e., in the process of performing a secondary dry etch), the secondary ions 151 can exhibit a first secondary chemical reactivity with the mask layer 230 and a second secondary chemical reactivity with the substrate 220 that is higher than the first secondary chemical reactivity. Generally, the use of such reactive ions in etching the substrate can increase the selectivity of the dry etching process and can facilitate the production of blazed gratings with sharper and less rounded features. Examples of dry etching techniques in which such reactive ions are used include RIE, DRIE, ICP-RIE, RIBE, and variations thereof. In other embodiments, the primary ions may or may not exhibit a first primary chemical reactivity with the mask layer and a second primary chemical reactivity with the substrate under primary etch conditions that is higher than the first primary chemical reactivity, and / or the secondary ions may or may not exhibit a first secondary chemical reactivity with the mask layer and a second secondary chemical reactivity with the substrate under secondary etch conditions that is higher than the first secondary chemical reactivity.

[0051] Figures 3A to 3H, collectively referred to throughout this specification as Figure 3, show a schematic sequence of subsequent steps of a method for manufacturing a blazed grating 200 comprising a ridge 210 having blaze facets 211 facing in a blaze facet direction 212 and anti-blaze facets 213 facing in an anti-blaze facet direction 214, where according to one embodiment the blaze facet direction 212 and the anti-blaze facets 213 extend along a grating cross section 215. In Figure 3, the grating cross section 215 extends perpendicularly to the plane of the drawing of Figures 3A to 3H. The method for manufacturing a blazed grating may in other embodiments include a sequence of steps similar to or different from the steps of the method of the embodiment of Figure 3.

[0052] The embodiment of Figure 3 may conform to any of the embodiments disclosed with reference to and / or in conjunction with any of Figures 1 and 2. The embodiment of Figure 3 may additionally or alternatively have any suitable features of any of the embodiments disclosed with reference to and / or in conjunction with any of Figures 1 and 2, generally not described explicitly below.

[0053] 3A to 3C, the method includes the steps of preparing a substrate 220 and a patterned mask layer 230 on the substrate 220, the preparing step including the steps of applying a coating 232 on the substrate 220 and providing a plurality of elongated through holes 231 in the coating 232 to form the mask layer 230, and the method also includes the steps of performing a primary dry etching of the substrate 220 such that primary ions 121, shown diagrammatically as white dots, are accelerated in a primary etching direction 122 and impinge on the substrate 220.

[0054] In the embodiment of Figure 3, the primary projection 123 of the primary etch direction 122 onto the grating cross section 215 extends perpendicular to the anti-blaze facet direction 214. Additionally, performing the primary dry etch of the embodiment of Figure 3 includes forming grooves 240 that extend into the substrate 220 along the primary etch direction 122.

[0055] The steps of preparing a substrate and a patterned mask layer and performing the first dry etch of the embodiment of FIG. 3 can be performed in accordance with those disclosed above with reference to FIG. 2, and therefore further details of these steps are omitted here for the sake of brevity and simplicity.

[0056] 3D and 3E, the method includes depositing a first material 250 into the grooves 240 to form interstitial features 251, and removing the patterned mask layer 230 prior to depositing the first material 250 into the grooves 240. In other embodiments, the method of manufacturing a blazed grating may or may not include depositing a first material into the grooves to form interstitial features. In embodiments, when the method of manufacturing a blazed grating includes depositing a first material into the grooves to form interstitial features, the method may or may not include removing the patterned mask layer prior to depositing the first material into the grooves.

[0057] The first material 250 in the embodiment of FIG. 3 is aluminum oxide (AlO or AlO) deposited by plasma enhanced chemical vapor deposition (PECVD). x The mask layer may be, in other embodiments, any suitable material, such as aluminum oxide (AlO2 / AlO), that may be formed using any suitable process. x ), titanium oxide (TiO2 / TiO2), silicon oxide (SiO2 / SiO x ) or silicon nitride (Si2N3 / SiN x The first material may include an oxide or nitride material, such as, for example, a SiO 2 film, a SiO 3 film, a SiO 4 film, or a mixture thereof. The first material may generally be deposited using any suitable deposition method, such as, for example, sputtering, evaporation, chemical vapor deposition (CVD), PECVD, inductively coupled plasma chemical vapor deposition (ICP-CVD), atomic layer deposition (ALD), and / or variations thereof.

[0058] 3F, the method includes exposing the ridge portions 221 of the substrate 220 prior to performing the secondary dry etch. The method of manufacturing a blazed grating may or may not include exposing the ridge portions of the substrate prior to performing the secondary dry etch in other embodiments.

[0059] 3, the step of exposing the ridge portions 221 of the substrate 220 can include an additional dry etching step. In other words, at least a portion of the first material 250 covering the ridge portions 221 can be etched using a dry etching method. The method of manufacturing a blazed grating, in other embodiments, includes the step of exposing the ridge portions of the substrate, and this step of exposing the ridge portions can be performed in any suitable manner.

[0060] The method includes, with reference to Figure 3G, performing a secondary dry etching of a substrate 220 such that secondary ions 151, shown diagrammatically by black dots, are accelerated in a secondary etching direction 152 to impinge on the substrate 220. The secondary ions 151 are collimated to form a collimated secondary ion beam for etching the substrate 220.

[0061] Performing a secondary dry etch includes using the interstitial features 251 as an etch stop in the embodiment of Figure 3. Performing a secondary dry etch may or may not include using the interstitial features as an etch stop in other embodiments.

[0062] 3, the interstitial features 251 are disposed in the anti-blaze facet direction 214 from the ridge portion 221. The interstitial features may be disposed in the blaze facet direction or in the anti-blaze facet direction from the ridge portion in other embodiments. In other embodiments, the secondary projection of the secondary etch direction onto the grating cross section extends perpendicular to one of the blaze facet direction and the anti-blaze facet direction, and the interstitial features may be disposed in the other of the blaze facet direction and the anti-blaze facet direction from the ridge portion.

[0063] The method further includes a post-processing step, with reference to Figure 3H, whereby the interstitial features 251 are removed. Such a step may be implemented, for example, as a wet etching step. The method of manufacturing a blazed grating may or may not include such a post-processing step in other embodiments.

[0064] Figures 4A to 4F, collectively referred to throughout this specification as Figure 4, show a schematic sequence of subsequent steps of a method for manufacturing a blazed grating 200 comprising ridges 210 having blaze facets 211 facing in a blaze facet direction 212 and anti-blaze facets 213 facing in an anti-blaze facet direction 214, where according to one embodiment the blaze facet direction 212 and the anti-blaze facets 213 extend along a grating cross section 215. In Figure 4, the grating cross section 215 extends perpendicularly to the plane of the drawing of Figures 4A to 4F. The method for manufacturing a blazed grating may in other embodiments include a sequence of steps similar to or different from the steps of the method of the embodiment of Figure 4.

[0065] The embodiment of Figure 4 may conform to any of the embodiments disclosed with reference to any of Figures 1 to 3 and / or in conjunction with any of Figures 1 and 2. The embodiment of Figure 4 may additionally or alternatively have any features not explicitly described below but generally of any of the embodiments disclosed with reference to any of Figures 1 to 3 and / or in conjunction with any of Figures 1 to 3.

[0066] The method includes, with reference to Figure 4A, providing a substrate 220 and a patterned mask layer 230 on the substrate 220. The embodiment method of Figure 2 may constitute an example of a method for manufacturing a blazed grating, whereby the blazed grating is formed on a contact surface of a nano-imprinting stamp. Thus, the embodiment substrate 220 of Figure 2 may be a nano-imprinting stamp 280 having a contact surface 281.

[0067] The nano-imprinting stamp 280 may be formed of single crystal silicon in the embodiment of Figure 4. The nano-imprinting stamp may be formed of or include any suitable material in other embodiments. For example, the nano-imprinting stamp may include multiple stacks formed of different materials in some embodiments.

[0068] As shown in FIG. 4A, the interface 222 between the substrate 220 and the mask layer 230 extends along a base plane 260 that extends perpendicular to the grating cross section 215 .

[0069] The method performs a primary dry etching of a substrate 220 such that, with reference to Fig. 4B, primary ions 121, shown diagrammatically by white dots, are accelerated in a primary etching direction 122 and impinge on the substrate 220. The primary ions 121 are collimated to form a collimated primary ion beam in the embodiment of Fig. 4 for etching the substrate 220. The primary ions may or may not be collimated to form a collimated primary ion beam in other embodiments for etching the substrate.

[0070] In the embodiment of Figure 4, the primary projection 123 of the primary etch direction 122 onto the grating cross section 215 extends perpendicular to the blaze facet direction 212. Additionally, performing the primary dry etch of the embodiment of Figure 4 includes forming grooves 240 that extend into the substrate 220 along the primary etch direction 122.

[0071] 4C, the method includes depositing a first material 250 in the grooves 240 to form interstitial features 251. In other embodiments, the method of manufacturing a blazed grating may or may not include depositing a first material in the grooves to form interstitial features.

[0072] In the embodiment of FIG. 4, the step of depositing the first material 250 in the grooves 240 comprises an atomic layer deposition step. In other words, at least a portion of the first material 250 deposited in the grooves 240 is deposited using atomic layer deposition. The first material 250 in the embodiment of FIG. 3 is aluminum oxide (AlO2 or AlO x ). The step of depositing the first material in the trench may in other embodiments include an atomic layer deposition step, and any suitable type of first material may be used.

[0073] 4D, the method includes exposing the ridge portion 221 of the substrate 220 prior to performing the second dry etch. In the embodiment of FIG. 4, exposing the ridge portion 221 of the substrate 220 may include, for example, a lift-off step to remove the mask layer 230 and the first material 250 covering the ridge portion 221.

[0074] The method includes performing a secondary dry etch of the substrate 220 such that secondary ions 151, shown diagrammatically as black dots with reference to Figure 4E, are accelerated in a secondary etch direction 152 to impact the substrate 220. Performing the secondary dry etch includes utilizing interstitial features 251 as an etch stop. The interstitial features 251 are disposed in a blaze facet direction 212 from the ridge portion 221.

[0075] In the embodiment of Figure 4, the secondary etching direction 152 can extend parallel to the grating cross section 215. The secondary etching direction 152 can therefore extend perpendicular to the base plane 260. Because the secondary etching direction 152 can extend perpendicular to the base plane 260, the process of performing the primary dry etch of the embodiment of Figure 4 can include a RIE step.

[0076] The method finally further comprises, with reference to FIG. 3F, a post-processing step whereby the interstitial features 251 are removed, for example by wet etching.

[0077] It should be understood that the above-described embodiments can be used in combination with each other. Some of the embodiments can be combined to form further embodiments.

[0078] It is obvious to those skilled in the art that with the advancement of technology, the basic idea of ​​the present invention can be realized in various ways. Therefore, the present invention and its embodiments are not limited to the examples described above, but can be modified within the scope of the claims.

[0079] It will be understood that any of the benefits and advantages described above may pertain to one embodiment or to several embodiments, and the embodiments are not limited to those that solve some or all of the described problems or have some or all of the described benefits and advantages.

[0080] The term "comprising" is used in this specification to mean including the subsequent feature or act without excluding the presence of one or more additional features or acts. It will be further understood that a reference to "an" or "an" item refers to one or more of such items. [Explanation of symbols]

[0081] 100 ways 110. Preparing a Substrate and a Patterned Mask Layer 111 Providing a plurality of elongated through holes in the coating 120 Step of performing a first dry etching 121 Primary ions 122 1st etching direction 123 Primary projection 124 Step of forming an extending groove in a substrate 130 Depositing a first material in the groove 131 Atomic layer deposition 140 Step to expose the protrusion 150 Step of performing a second dry etching 151 Secondary ions 152 Secondary etching direction 153 Secondary projection 154 Using interstitial features as an etch stop 200 Blazed Lattice 210 protrusion 211 Blaze Facet 212 Blaze Facet Direction 213 Anti-blaze facets 214 Anti-blaze facet direction 215 Grid cross section 220 Substrate 221 Projection part 222 Interface 230 Mask Layer 231 Through hole 232 Coating 240 Groove 250 First Ingredient 251 Interstitial Form 260 base plane 270 Waveguide 271 sides 280 Nanoimprint Stamp 281 Contact surface

Claims

1. A method (100) for manufacturing a blazed grating comprising ridges having blaze facets facing in a blaze facet direction and anti-blaze facets facing in an anti-blaze facet direction, the blaze facet direction and the anti-blaze facet direction extending along a grating cross section, the method comprising: - providing (110) a substrate and, on said substrate, a patterned mask layer; - performing (120) a primary dry etching of said substrate, such that primary ions are accelerated in a primary etching direction and impinge on said substrate; performing (150) a secondary dry etching of the substrate, such that secondary ions are accelerated in a secondary etching direction and impinge on the substrate; a primary projection of the primary etching direction onto the grating cross section extends perpendicular to an anti-blaze facet direction, a secondary projection of the secondary etching direction onto the grating cross section extends perpendicular to the blaze facet direction, and ions accelerated in a projection direction perpendicular to the blaze facet direction onto the grating cross section are collimated to form a collimated ion beam for etching the substrate, The method (100), wherein the method (100) does not include exposing a protruding portion of the substrate prior to the step (150) of performing a secondary dry etch, and the mask layer comprises an inorganic material.

2. 10. The method (100) of claim 1, wherein the step (120) of performing a first dry etch includes forming (124) trenches extending in the substrate along the first etch direction, the method (100) includes depositing (130) a first material in the trenches to form interstitial features, and the step (150) of performing a second dry etch includes utilizing (154) the interstitial features as an etch stop.

3. The method (100) of claim 2, wherein the step (130) of depositing a first material in the trench comprises an atomic layer deposition (131) step.

4. 4. The method (100) according to any one of claims 1 to 3, wherein the interface between the substrate and the mask layer extends along a base plane and the primary projection or the secondary projection extends perpendicular to the base plane.

5. The method (100) of claim 4, wherein the primary etch direction or the secondary etch direction extends perpendicular to the base plane.

6. 4. The method (100) of claim 1, wherein the interface between the substrate and the mask layer extends along a base plane, and the primary projection and the secondary projection extend obliquely relative to the base plane.

7. 4. The method (100) of any one of claims 1 to 3, wherein the step (110) of preparing a substrate and a patterned mask layer comprises the step (111) of providing a mask layer with a plurality of elongated through holes in a coating disposed on the substrate, the plurality of elongated through holes extending perpendicular to the lattice cross-section.

8. 4. The method (100) of any one of claims 1 to 3, wherein the primary ions exhibit a first primary chemical reactivity with the mask layer and a second primary chemical reactivity with the substrate under primary etching conditions that is higher than the first primary chemical reactivity, and / or the secondary ions exhibit a first secondary chemical reactivity with the mask layer and a second secondary chemical reactivity with the substrate under secondary etching conditions that is higher than the first secondary chemical reactivity.

9. 4. The method (100) of any one of claims 1 to 3, wherein the blazed grating is formed on a face of the waveguide for coupling light into and / or out of the waveguide.

10. The method (100) of any one of claims 1 to 3, wherein the blazed grating is formed on a contact surface of a nanoimprinting stamp.

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