Method for manufacturing diffractive optical waveguide, diffractive optical waveguide and AR device

Abstract

This invention provides a method for fabricating a diffractive optical waveguide, comprising: providing a waveguide substrate; forming a patterned imprinted adhesive layer on the surface of the waveguide substrate; using the patterned imprinted adhesive layer as a first mask, performing a first-stage etching on the waveguide substrate to form an embedded structure in a first region, and simultaneously forming a remaining patterned imprinted adhesive layer in a second region; forming a second mask using the remaining patterned imprinted adhesive layer; and etching the waveguide substrate using the second mask as a mask to form an detached structure; wherein the depth of the detached structure is greater than the depth of the embedded structure. This solution solves the problem of ensuring the formation of embedded and detached structures of unequal depths on the waveguide substrate while meeting the requirement that the relative positions of the embedded and detached structures have no significant deviation; and is suitable for mass production.

Description

Technical Field

[0001] This invention relates to the field of diffractive waveguides, and more particularly to a method for fabricating a diffractive waveguide, the diffractive waveguide itself, and an AR device. Background Technology

[0002] Typically, diffractive waveguides can be divided into two parts based on their functional regions: the coupling grating region and the coupling grating region. Depending on the performance requirements of different functional regions, the coupling grating region and the coupling grating region usually employ grating structures with different morphologies. For example, the coupling region requires high-efficiency coupling, so a blazed grating is usually chosen for the coupling grating region; the coupling region requires uniform coupling, so a straight-tooth grating is usually chosen for the coupling grating region.

[0003] According to the design requirements of diffractive waveguides, structures with varying coupling depths need to be achieved on the target material, and the waveguide must possess good transmission efficiency and certain optical properties. Generally, the fabrication of blazed gratings is difficult and the process is complex, especially during etching. Longer etching times (or deeper etching depths) have a greater impact on the grating surface morphology. If blazed gratings and toothed gratings are formed simultaneously through etching, the etching of the toothed gratings is severely limited by the etching conditions of the blazed gratings. This is particularly pronounced when there is a difference in grating depth between the blazed and toothed gratings. Furthermore, the depth of the toothed grating is usually greater than that of the blazed grating, making it impossible to simultaneously achieve the performance of both blazed and toothed gratings, resulting in a diffractive waveguide that fails to meet the expected performance.

[0004] In existing technologies, blazed gratings and straight-tooth gratings are formed by etching separately, which can easily lead to relative positional deviations in the coupling in and coupling out, thus affecting the overall performance of the diffractive waveguide.

[0005] Therefore, developing a fabrication process for a waveguide that can ensure the structural forming of diffracted optical waveguides with unequal coupling depths and simultaneously meet the requirement of no deviation in the relative positions of the coupling in and coupling out has become a key technical issue that urgently needs to be addressed by those skilled in the art. Summary of the Invention

[0006] This invention provides a method for fabricating a diffractive optical waveguide, the diffractive optical waveguide, and an AR device, to solve the problem of how to ensure the formation of coupling-in and coupling-out structures of different depths on the waveguide substrate while meeting the requirement that the relative positions of the coupling-in and coupling-out structures have no significant deviation.

[0007] According to a first aspect of the present invention, a method for fabricating a diffractive optical waveguide is provided, comprising:

[0008] Provide a waveguide substrate;

[0009] A patterned imprinted adhesive layer is formed on one surface of the waveguide substrate; the patterned imprinted adhesive layer includes a first patterned imprinted structure and a second patterned imprinted structure; the first patterned imprinted structure is formed in a first region of the surface, and the second patterned imprinted structure is formed in a second region of the surface; the thickness of the second patterned imprinted structure is greater than the thickness of the first patterned imprinted structure.

[0010] Using the patterned imprinted adhesive layer as a first mask, the waveguide substrate is etched in the first stage to form a coupling structure on the waveguide substrate in the first region, while the remaining patterned imprinted adhesive layer on the waveguide substrate in the second region maintains the pattern of the second patterned imprinted structure.

[0011] The remaining patterned imprinted adhesive layer is used to form a second mask, and the waveguide substrate is etched in a second stage based on the second mask to form a coupling structure in the second region;

[0012] The second mask covers the coupling structure to protect it from etching during the second stage of etching. The coupling structure and the coupling outlet structure have different structural forms, and the depth of the coupling outlet structure is greater than the depth of the coupling structure.

[0013] Optionally, the etching depths of the coupling structures are equal, or the etching depths of different regions of the coupling structures are not equal.

[0014] Optionally, the step of forming a second mask using the remaining patterned imprinted adhesive layer, and performing a second stage of etching on the waveguide substrate based on the second mask to form a coupling structure in the second region, includes:

[0015] A first hard mask layer is formed; the first hard mask layer is formed on the surface of the waveguide substrate and covers the coupling structure and the remaining patterned imprinted adhesive layer;

[0016] Remove the remaining patterned embossing adhesive layer and the first hard mask layer covering the remaining patterned embossing adhesive layer to form the second mask;

[0017] The waveguide substrate is etched in a second stage using the second mask as a mask to form a coupling structure in the second region.

[0018] Optionally, the second stage of etching the waveguide substrate using the second mask as a mask to form a coupling structure in the second region includes: performing a first stage of etching the waveguide substrate using the second mask as a mask to form a coupling structure with equal etching depth.

[0019] The photoresist layer is formed in N steps; each photoresist layer covers a portion of the coupling structure, where N is an integer greater than or equal to 1.

[0020] After each photoresist layer is formed, the photoresist layer formed this time and the remaining patterned imprinting adhesive are used as a mask to etch the part of the coupling structure that was not covered by the photoresist layer this time, until after the Nth etching, the coupling structure with N+1 different etched areas is formed.

[0021] Remove the photoresist and the second mask.

[0022] Optionally, the material of the first hard mask layer is Cr, Al, SiO2 or Si3N4.

[0023] Optionally, the step of forming a second mask using the remaining patterned imprinted adhesive layer, and performing a second stage of etching on the waveguide substrate based on the second mask to form a coupling structure in the second region, includes:

[0024] A coupling protective layer is formed on the surface of the coupling structure;

[0025] Using the coupling protective layer and the remaining patterned imprinted adhesive layer as a second mask, the waveguide substrate is etched in a second stage based on the second mask to form a coupling structure in the second region.

[0026] Optionally, the coupling protective layer is a photoresist layer.

[0027] Optionally, forming a coupling protective layer on the surface of the coupling structure includes:

[0028] A predetermined amount of photoresist is dropped into the area where the coupling structure is located;

[0029] Under vacuum and negative pressure conditions, the photoresist is made to flow uniformly and cover the surface of the coupling structure;

[0030] The photoresist is cured to form the photoresist layer.

[0031] Optionally, the thickness of the coupling protective layer is greater than the thickness of the remaining patterned embossing adhesive layer.

[0032] Optionally, forming a patterned imprinted adhesive layer on one surface of the waveguide substrate specifically includes:

[0033] An impression master is provided; the impression master is provided with a first master graphic structure and a second master graphic structure; wherein, the first master graphic structure corresponds to the coupling-in structure; and the second master graphic structure corresponds to the coupling-out structure;

[0034] An imprinting adhesive is coated onto the waveguide substrate;

[0035] The printing master is pressed onto the printing adhesive to form the patterned printing adhesive layer; wherein the pattern of the patterned printing adhesive layer corresponds to the pattern of the first master graphic structure and the pattern of the second master graphic structure;

[0036] Separate the embossing master and the graphic embossing adhesive layer.

[0037] Optionally, the step of imprinting the master image onto the imprinting adhesive to form the patterned imprinting adhesive layer specifically includes:

[0038] The printing master is pressed onto the printing adhesive;

[0039] The embossing adhesive is cured to form the patterned embossing adhesive layer.

[0040] Optionally, the thickness of the imprinting adhesive is adapted to the maximum depth of the graphics in the first master graphic structure and the second master graphic structure.

[0041] According to a second aspect of the present invention, a diffractive optical waveguide is provided, which is fabricated by the method for fabricating a diffractive optical waveguide according to any one of the first aspects of the present invention.

[0042] According to a third aspect of the present invention, an AR device is provided, comprising the diffractive waveguide described in the second aspect of the present invention.

[0043] This invention provides a method for fabricating a diffractive optical waveguide. Utilizing a patterned imprinted adhesive layer formed on a waveguide substrate, the method first performs a first-stage etching on the waveguide substrate using the patterned imprinted adhesive layer as a first mask to form an embedded structure in a first region, while simultaneously forming the remaining patterned imprinted adhesive layer in a second region. Secondly, this invention creatively proposes to use the remaining patterned imprinted adhesive layer to form a second mask to protect the embedded structure; and to use the second mask as a mask to perform a second-stage etching on the waveguide substrate to form an detached structure in the second region. Through these two steps, this invention can ultimately form embedded and detached structures of different depths; and the relative positions of the formed detached and embedded structures do not deviate significantly from the preset relative positions. Therefore, the technical solution provided by this invention solves the problem of ensuring the formation of embedded and detached structures of varying depths on the waveguide substrate while meeting the requirement of no significant deviation in the relative positions of the embedded and detached structures; and is suitable for mass production. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic flowchart of a method for fabricating a diffractive optical waveguide according to an embodiment of the present invention;

[0046] Figure 2-11 This is a schematic diagram of the device structure at different process stages fabricated according to the fabrication method of diffractive waveguide provided in a specific embodiment of the present invention;

[0047] Figure 12-13 This is a schematic diagram of the device structure at different process stages fabricated according to the fabrication method of diffractive waveguide provided in another specific embodiment of the present invention;

[0048] Figure 14 This is a schematic diagram of the structure of a vacuum dish provided in an embodiment of the present invention;

[0049] Explanation of reference numerals in the attached figures:

[0050] 101 - Waveguide substrate;

[0051] 1011-coupled structure;

[0052] 1012, 1013 - Coupling structure;

[0053] 102 - Imprinting adhesive;

[0054] 103 - Patterned embossed adhesive layer;

[0055] 1031 - First graphic imprint structure;

[0056] 1032 - Second patterned embossing structure;

[0057] 104 - Imprinting Master;

[0058] 105 - Remaining patterned embossing adhesive layer;

[0059] 106 - First hard mask layer;

[0060] 107 - Second Mask;

[0061] 108 - Photoresist layer;

[0062] 109 - Coupling protective layer;

[0063] 110-Vacuum dish;

[0064] 1101 - Vacuum dish base;

[0065] 11011 - Sealing ring;

[0066] 11012 - Vacuum port for extraction / discharge;

[0067] 1102 - Vacuum dish lid. Detailed Implementation

[0068] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0069] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0070] Typically, diffractive waveguides can be divided into two parts based on their functional regions: the coupling grating region and the coupling grating region. Depending on the performance requirements of different functional regions, the coupling grating region and the coupling grating region usually employ grating structures with different morphologies. For example, the coupling region requires high-efficiency coupling, so a blazed grating is usually chosen for the coupling grating region; the coupling region requires uniform coupling, so a straight-tooth grating is usually chosen for the coupling grating region.

[0071] According to the design requirements of diffractive waveguides, structures with varying coupling depths need to be achieved on the target material, and the waveguide must possess good transmission efficiency and certain optical properties. Generally, the fabrication of blazed gratings is difficult and the process is complex, especially during etching. Longer etching times (or deeper etching depths) have a greater impact on the grating surface morphology. If blazed gratings and toothed gratings are formed simultaneously through etching, the etching of the toothed gratings is severely limited by the etching conditions of the blazed gratings. This is particularly pronounced when there is a difference in grating depth between the blazed and toothed gratings. Furthermore, the depth of the toothed grating is usually greater than that of the blazed grating, making it impossible to simultaneously achieve the performance of both blazed and toothed gratings, resulting in a diffractive waveguide that fails to meet the expected performance.

[0072] In existing technologies, blazed gratings and straight-tooth gratings are formed by etching separately, which can easily lead to relative positional deviations in the coupling in and coupling out, thus affecting the overall performance of the diffractive waveguide.

[0073] In view of this, this application simultaneously forms patterns corresponding to the preset coupling-in structure and the preset coupling-out structure on the surface of the waveguide substrate in one imprint, so as to meet the requirement that the relative positions of the coupling-in and coupling-out are basically without deviation. At the same time, by cleverly setting the mask, the coupling-in structure and the coupling-out structure are etched in two stages to form the coupling-in structure and the coupling-out structure respectively, thus achieving a structure with different coupling-in and coupling-out depths.

[0074] Furthermore, in the first stage of etching to form the coupling structure, this application controls the remaining adhesive layer at the predetermined location of the coupling structure to retain the pattern reflecting the coupling structure. Then, the remaining adhesive layer is used to form a second mask, and the waveguide substrate is etched in the second stage based on the second mask to form the coupling structure. Moreover, the second mask covers the coupling structure, protecting the morphology of the coupling structure from being affected during the second stage of etching. Therefore, the method provided in this application can ensure the formation of structures with unequal depths of the coupling and coupling structures in the diffractive waveguide, while simultaneously meeting the requirement of no deviation in the relative positions of the coupling and coupling structures, and is suitable for mass production.

[0075] Furthermore, this application ingeniously utilizes a solvent extraction process to form a hard mask on the waveguide substrate. This hard mask is then used to etch the waveguide substrate in the coupling region, creating a coupling structure with a different depth than the coupling-in structure. Compared to existing technologies, the relative positions of the coupling and coupling structures formed using this method show no significant error. Moreover, using a hard mask to etch the coupling structure allows for different etching depths in different regions.

[0076] Alternatively, in this application, the coupling structure can be protected by coating the top of the already formed coupling structure with photoresist, and the remaining imprinted adhesive can be used as a mask to etch the waveguide substrate of the coupling region to form the coupling structure, which can also achieve a similar effect.

[0077] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0078] According to an embodiment of the present invention, a method for fabricating a diffractive optical waveguide is provided, and the flowchart of the method for fabricating the diffractive optical waveguide is shown below. Figure 1 As shown, the method includes:

[0079] S11: Provide a waveguide substrate 101;

[0080] S12: A patterned imprinted adhesive layer is formed on one surface of the waveguide substrate 101; the patterned imprinted adhesive layer includes a first patterned imprinted structure 1031 and a second patterned imprinted structure 1032; the first patterned imprinted structure 1031 is formed in a first region of the surface, and the second patterned imprinted structure 1032 is formed in a second region of the surface; the thickness of the second patterned imprinted structure 1032 is greater than the thickness of the first patterned imprinted structure 1031; the device structure after forming the patterned imprinted adhesive layer is as follows: Figure 3 As shown.

[0081] In one embodiment, step S12, forming a patterned imprinted adhesive layer 103 on one surface of the waveguide substrate 101, specifically includes the following steps S121-S124:

[0082] S121: An impression master 104 is provided; the impression master is provided with a first master graphic structure and a second master graphic structure; wherein, the first master graphic structure corresponds to the coupling-in structure 1011; the second master graphic structure corresponds to the coupling-out structure 1012; the structure of the impression master 104 is as follows: Figure 4 As shown in Figure 104.

[0083] Specifically, the first master graphic structure corresponds to the coupling-in structure 1011, and the second master graphic structure corresponds to the coupling-out structure 1012, including: the graphic of the first master graphic structure corresponds to the graphic of the preset coupling-in structure 1011; the graphic of the second master graphic structure corresponds to the graphic of the preset coupling-out structure 1012. The graphic correspondence can be either consistent or complementary.

[0084] In addition, the first master graphic structure corresponding to the coupling structure 1011 may also include a graphic depth of the first master graphic structure that is consistent with the graphic depth of the coupling structure 1011.

[0085] In one preferred embodiment, the thickness of the first master pattern structure is 100–500 nm, and the thickness of the second master pattern structure is 100–300 nm.

[0086] In one embodiment, the material of the printing master 104 is SiO2, but it can also be SiO2, TiO2, Nb2O5, high-refractive glass, etc.; of course, it can also be other materials, and the present invention is not limited thereto.

[0087] In one embodiment, the cross-section of the first master graphic structure and / or the second master graphic structure is a quadrilateral or a triangle; in other embodiments, other shapes that can achieve the purpose of the present invention may also be used, and the present invention is not limited thereto; any implementation is within the protection scope of the present invention.

[0088] S122: Coat the waveguide substrate 101 with imprinting adhesive 102, such as Figure 2 As shown. Preferably, the imprinting adhesive 102 should have good flowability and photosensitivity, as well as good resistance to dry etching. Considering that the semiconductor etching gases commonly used in dry etching are F-based, Cl-based gases, etc., the imprinting adhesive 102 can be selected based on these etching gases when considering resistance to dry etching.

[0089] In one embodiment, the thickness of the applied imprinting adhesive 102 is adapted to the maximum thickness of the patterns in the first master pattern structure and the second master pattern structure. "Adapted to" means that the thickness of the imprinting adhesive 102 is greater than or equal to the maximum thickness of the patterns in the first master pattern structure and the second master pattern structure, providing a sufficient thickness of imprinting adhesive 102 so that the depth of the finally formed first patterned imprint structure 1031 and second patterned imprint structure 1032 matches the thickness of the first master pattern structure and the second master pattern structure. In practice, the thickness of the imprinting adhesive 102 is typically 100–1000 nm.

[0090] In one embodiment, the method used to coat the waveguide substrate 101 with the imprinting adhesive 102 is spin coating or spray coating; in other embodiments, other implementation methods may also be used, and the present invention is not limited thereto.

[0091] S123: The imprinting master 104 is imprinted onto the imprinting adhesive 102 to form a patterned imprinting adhesive layer 103; wherein the pattern of the patterned imprinting adhesive layer 103 corresponds to the pattern of the first master pattern structure and the pattern of the second master pattern structure; the device structure after the imprinting master 104 is imprinted onto the imprinting adhesive 102 is as follows. Figure 4 As shown.

[0092] In one embodiment, step S123, which involves imprinting the master template 104 onto the imprinting adhesive 102 to form a patterned imprinting adhesive layer 103, specifically includes the following steps S1231-S1232:

[0093] S1231: Imprint the master plate 104 onto the printing adhesive 102.

[0094] In one embodiment, when imprinting the master 104 onto the imprinting adhesive 102, the method used is: integrated nanoimprinting process.

[0095] S1232: Curing the imprinting adhesive 102 to form a patterned imprinting adhesive layer 103.

[0096] In one embodiment, the method used to cure the imprinting adhesive 102 is: ultraviolet light exposure method or thermal curing technology; in other embodiments, other implementation methods may also be used, and the present invention is not limited thereto.

[0097] S124: Separate the imprinting master 104 and the patterned imprinting adhesive layer 103. The device structure after separating the imprinting master 104 and the patterned imprinting adhesive layer 103 is as follows: Figure 3 As shown.

[0098] In one embodiment, the process used to separate the imprint master 104 and the patterned imprint adhesive layer 103 is a demolding process; in other embodiments, other implementation methods may also be used, and the present invention is not limited thereto.

[0099] S13: Using the patterned imprinted adhesive layer 103 as a first mask, a first-stage etching process is performed on the waveguide substrate 101 to form a coupling structure 1011 on the waveguide substrate 101 in the first region. Simultaneously, the remaining patterned imprinted adhesive 102 on the waveguide substrate 101 in the second region maintains the pattern of the second patterned imprinted structure 1032. The device structure after step S13 is as follows: Figure 5 As shown.

[0100] In one embodiment, dry etching is used during the first stage of etching; the etching gas used is a common semiconductor etching gas, such as F-based or Cl-based gases.

[0101] S14: A second mask 107 is formed using the remaining patterned imprinted adhesive layer 105. A second stage of etching is performed on the waveguide substrate 101 based on the second mask 107 to form a coupling structure 1012 or 1013 in the second region. The device after forming the coupling structure 1012 or 1013 is as follows: Figure 8 or Figure 11 As shown (it should be noted that, Figure 8 The device structure shown in the image is a schematic diagram of the device structure before the second mask is removed.

[0102] The second mask 107 covers the coupling structure 1011 to protect the coupling structure 1011 from being etched during the second stage of etching. The coupling structure 1011 and the coupling structures 1012 and 1013 have different structural forms, and the depth of the coupling structures 1012 and 1013 is greater than the depth of the coupling structure 1011.

[0103] In this embodiment, the etching depth of the coupling structure 1012 is equal, while the etching depth of different regions of the coupling structure 1013 is unequal. Based on the etching resistance of hard mask materials compared to photoresist materials, this application uses hard masks in combination with photoresist masks to achieve unequal etching depths in different areas of the coupling structure.

[0104] In one embodiment, the cross-section of the coupling structure 1011 and / or the coupling structures 1012 and 1013 is quadrilateral or triangular; in other embodiments, other shapes that can achieve the purpose of the present invention may also be used, and the present invention is not limited thereto; any implementation is within the protection scope of the present invention.

[0105] The present invention provides a method for fabricating a diffractive optical waveguide, which involves forming a patterned imprinted adhesive layer 103 on a waveguide substrate 101, followed by two sub-steps: Step 1: Forming a coupling structure 1011 in a first region, specifically including: using the patterned imprinted adhesive layer 103 as a first mask, performing a first-stage etching on the first region of the waveguide substrate 101; controlling the etching time to form the coupling structure 1011 while simultaneously forming the remaining patterned imprinted adhesive in a second region; Step 2: Forming a second mask using the remaining patterned imprinted adhesive layer 105, using the second mask as a mask to protect the coupling structure 1011; etching the waveguide substrate 101 in the second region to form a coupling structure 1012 or 1013.

[0106] Because of the technical solution provided by this invention, after forming the coupling structure 1011 and the remaining patterned imprinted adhesive layer 105 in the first step, a second mask is formed using the remaining patterned imprinted adhesive layer 105. The waveguide substrate 101 in the second region is then etched using the second mask as a mask to form the coupling structure 1012 or 1013. It can be seen that, under the protection of the second mask, when there is a difference in etching depth between the coupling structure 1012 or 1013 and the coupling structure 1011, especially when the required depth for forming the coupling structure 1012 or 1013 is greater than that for the coupling structure 1011,… When the etching depth is reached, the etching of deeper grating structures is not limited by the etching depth of shallower grating structures; thus, the etching depths of the coupling structure 1011 and the coupling structure 1012 or 1013 with different depths can be taken into account, achieving the effect of taking into account the performance of the coupling structure 1011 and the coupling structure 1012 or 1013; and at the same time, while the depth of the final coupling structure 1012 or 1013 is different from the depth of the coupling structure 1011, the relative position of the resulting coupling structure 1012 or 1013 and the coupling structure 1011 has no significant deviation from the preset relative position.

[0107] Therefore, the technical solution provided by this invention solves the problem of how to ensure that the coupling structure 1011 and coupling structure 1012 or 1013 of different depths on the waveguide substrate 101 are formed while meeting the requirement that the relative positions of the coupling structure 1011 and coupling structure 1012 or 1013 have no significant deviation, thus achieving the technical effect of improving the overall performance of the diffractive waveguide. It is also suitable for mass production.

[0108] Please refer to Figures 1-11 The following describes, in two specific embodiments, the specific steps of etching the waveguide substrate 101 in the second stage based on the second mask 107 to form coupling structures 1012 and 1013 in the second region:

[0109] In one specific embodiment, step S14, forming a second mask 107 using the remaining patterned imprinted adhesive layer 105, and performing a second stage of etching on the waveguide substrate 101 based on the second mask 107 to form coupling structures 1012 and 1013 in the second region, specifically includes the following steps S141-S143:

[0110] S141: Forming a first hard mask layer 106; the first hard mask layer 106 is formed on the surface of the waveguide substrate 101 and covers the coupling structure 1011 and the remaining patterned imprinted adhesive layer 105.

[0111] Specifically, the material of the first hard mask layer 106 is Cr, Al, SiO2, or Si3N4; of course, it can also be other materials. Any implementation of the first hard mask layer 106 that can achieve the purpose of this invention is within the protection scope of this invention, and this invention is not limited thereto. Preferably, in one embodiment, the first hard mask layer 106 is an Al metal thin film; the Al metal thin film can well cover the surface of the waveguide substrate 101, and avoid deposition on the sidewalls of the remaining patterned imprinted adhesive layer 105 as much as possible; avoid defects in the shape of the etched coupling structures 1012 and 1013, thereby preparing coupling structures 1012 and 1013 with ideal performance, and forming the device structure after the first hard mask layer 106 as follows. Figure 6 As shown;

[0112] Among them, the etching rate of the dry etching of the first hard mask layer 106 is much smaller than the etching rate of the imprinting adhesive 102.

[0113] In one embodiment, when forming the first hard mask layer 106, the semiconductor film formation technology used is PVD coating process, specifically sputtering or evaporation.

[0114] In one embodiment, in order to effectively protect the coupling structure 1011, preferably, the thickness of the first hard mask layer 106 is 50 nm.

[0115] S142: Remove the remaining patterned imprinting adhesive layer 105 and the first hard mask layer 106 covering the remaining patterned imprinting adhesive layer 105 to form a second mask 107. The device structure after forming the second mask 107 is as follows: Figure 7 As shown;

[0116] In one embodiment, the remaining patterned embossing adhesive layer 105 is removed using a solvent extraction process; other implementations are also possible. Any method for removing the remaining patterned embossing adhesive layer 105 that achieves the purpose of this invention is within the scope of protection of this invention, and this invention is not limited thereto.

[0117] The specific process flow of the solvent removal process includes: First, placing the device including the remaining patterned imprint adhesive layer 105 obtained in step S141 into an ultrasonic bath; second, adding a highly polar organic solution to the ultrasonic bath; third, turning on the ultrasonic bath to assist the organic solution in swelling the remaining patterned imprint adhesive layer 105 until the remaining patterned imprint adhesive layer 105 is completely peeled off; finally, using a spin dryer to clean and dry the device including the remaining patterned imprint adhesive layer 105 obtained in step S141, to obtain the device after removing the remaining patterned imprint adhesive layer 105 in step S142.

[0118] The organic solvent must meet the following conditions: it should not have a corrosive or swelling effect on the hard mask material; in one specific embodiment, the organic solvent is generally acetone or dimethyl sulfoxide, etc.

[0119] S143: Using the second mask 107 as a mask, the waveguide substrate 101 is etched in the second stage to form coupling structures 1012 and 1013 in the second region; the device structure after forming coupling structures 1012 and 1013 is as follows. Figure 8 Or as shown in 11.

[0120] In one embodiment, the second-stage etching is performed using a dry etching method. In this second-stage etching, a single etching operation creates coupling structures 1012 with equal etching depths. Multiple etching operations create coupling structures 1013 with varying etching depths in different regions.

[0121] The region within the coupling structure 1013 at each etching depth may include several grating units, all with the same etching depth. The present invention does not limit the number of these grating units.

[0122] In one embodiment, in step S143, the waveguide substrate 101 is etched in a second stage using the second mask 107 as a mask to form a coupling structure 1012 in the second region, including:

[0123] Using the second mask 107 as a mask, the waveguide substrate 101 is etched in the second stage to form a coupling structure 1012 with equal etching depth.

[0124] In one embodiment, in step S143, the waveguide substrate 101 is etched in a second stage using the second mask 107 as a mask to form a coupling structure 1013 in the second region, including:

[0125] The waveguide substrate 101 is etched in the second stage using the second mask 107 as a mask to form a coupling structure 1012 with equal etching depth.

[0126] The photoresist layer 108 is formed in N steps; each photoresist layer 108 formed covers a portion of the coupling structure, where N is an integer greater than or equal to 1.

[0127] After each formation of the photoresist layer 108, the remaining patterned imprinted resist of the photoresist layer 108 and the second mask 107 formed in this step is used as a mask to etch the part of the coupling structure waveguide substrate 101 that was not covered by the photoresist layer 108 in this step, until after the Nth etching, N+1 coupling structures 1013 with different etched regions are formed; then the photoresist and the second mask 107 are removed.

[0128] The material of the second mask 107 is described in reference to the material of the first hard mask layer 106 mentioned above, and will not be repeated here.

[0129] In the aforementioned specific embodiment, after forming the coupling structure 1011 on the waveguide substrate 101 through a first-stage etching process, and simultaneously forming the remaining patterned imprinted adhesive layer 105 on the waveguide substrate 101 in the second region, a first hard mask layer 106 is cleverly formed on the surface of the waveguide substrate 101 and the surface of the remaining patterned imprinted adhesive layer 105. Then, a solvent extraction process is used to remove the remaining patterned imprinted adhesive layer 105. Since the second hard mask layer can protect the coupling structure 1011, the desired coupling junction can be etched out. The structures 1012 and 1013 avoid affecting the coupling structure 1011 in the first region when etching the coupling structure 1012 and 1013 in the second region, thus realizing the etching of the coupling structure 1011 and the coupling structure 1012 and 1013 in steps; ensuring the formation of coupling structures 1011 and 1012 and 1013 with different depths in the diffractive waveguide, while meeting the requirement of no deviation in the relative position of coupling structures 1011 and 1012 and 1013, and is suitable for mass production.

[0130] Please refer to Figure 1-5 12-14, According to another specific embodiment of the present invention, step S14, forming a second mask 107 using the remaining patterned imprinted adhesive layer 105, and performing a second stage of etching on the waveguide substrate 101 based on the second mask 107 to form a coupling structure 1012 in the second region, specifically includes the following steps S141-S142:

[0131] Step S141: Form a coupling protection layer 109 on the surface of the coupling structure 1011; in one specific embodiment, the coupling protection layer 109 is a photoresist layer 108; the device structure after forming the coupling protection layer 109 is as follows Figure 12 As shown;

[0132] In one embodiment, step S141, forming a coupling protective layer 109 on the surface of the coupling structure 1011, specifically includes the following steps S1411-S1413:

[0133] Step S1411: Drop a predetermined amount of photoresist onto the area where the coupling structure 1011 is located;

[0134] Step S1412: Under vacuum and negative pressure conditions, make the photoresist flow uniformly and cover the surface of the coupling structure 1011;

[0135] Step S1413: Curing the photoresist to form a photoresist layer 108.

[0136] In one embodiment, when the coupling protective layer 109 is formed as a photoresist layer 108, the method used to form the coupling protective layer 109 is photoresist vacuum coating.

[0137] Step S141, which involves forming the coupling protective layer 109 using a photoresist vacuum coating method, specifically includes:

[0138] First, drop an appropriate amount of photoresist onto the top of the coupling structure 1011; depending on the size of the coupling structure 1011, the amount of photoresist dropped is generally 0.1 to 10 ml, and then place it horizontally for several minutes.

[0139] The entire device structure is then placed in a dedicated horizontally positioned vacuum dish 110, and a certain negative pressure is applied inside the vacuum dish 110 to ensure that the photoresist flows evenly into the top of the coupling structure 1011 without generating bubbles. Specifically, this process includes: placing the target material substrate with the photoresist applied horizontally in the vacuum dish 110; performing a first vacuum evacuation (vacuum pressure less than 100 Pa), allowing it to remain horizontal for several minutes, and then slowly introducing an inert gas (such as GN2, Ar, etc.) to restore atmospheric pressure; performing a second vacuum evacuation (vacuum pressure less than 100 Pa), allowing it to remain horizontal for several minutes, and then slowly introducing another inert gas (such as GN2, Ar, etc.) to restore atmospheric pressure; performing a third vacuum evacuation (vacuum pressure less than 100 Pa), allowing it to remain horizontal for several minutes, and then slowly introducing another inert gas (such as GN2, Ar, etc.) to restore atmospheric pressure. Generally, after three rounds of vacuum evacuation and devacuation, the protective photoresist in the coupling structure 1011 area will be bubble-free. If bubbles still exist, the vacuum evacuation and devacuation can be repeated until no bubbles remain.

[0140] Finally, remove the device and place it horizontally in an oven or hot plate for photoresist curing.

[0141] The vacuum dish 110 is made of plexiglass and specifically includes: a vacuum dish lid 1102, a vacuum dish base 1101, a sealing ring 11011, and a vacuum extraction / discharge port 11012; the structure of the vacuum dish 110 is as follows: Figure 14 As shown.

[0142] Step S142: Using the coupling protective layer 109 and the remaining patterned imprinted adhesive layer 105 as the second mask 107, the waveguide substrate 101 is etched in the second stage based on the second mask 107 to form the coupling structure 1012 in the second region.

[0143] When the coupling protective layer 109 is a photoresist layer 108, preferably, the thickness of the coupling protective layer 109 is greater than the thickness of the remaining patterned imprinting adhesive layer 105; typically, the thickness difference between the two is controlled between 1 and 2 μm.

[0144] Step S142 is followed by: Step S143: Removing the remaining coupling guard layer 109 to form a diffractive waveguide; the device structure for forming the diffractive waveguide is as follows. Figure 13 As shown.

[0145] In another embodiment, when etching the coupling structure using the hard mask 107 as a mask, a coupling protection layer 109 can also be formed on the surface of the coupling structure 1011, with the specific steps being the same as S1411-S1413.

[0146] Secondly, according to an embodiment of the present invention, a diffractive optical waveguide is also provided, which is fabricated by the method for fabricating a diffractive optical waveguide according to any of the foregoing embodiments of the present invention.

[0147] Furthermore, according to an embodiment of the present invention, an AR device is also provided, including the diffractive waveguide provided in the foregoing embodiments of the present invention.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for fabricating a diffractive optical waveguide, characterized in that, include: Provide a waveguide substrate; A patterned imprinted adhesive layer is formed on one surface of the waveguide substrate; the patterned imprinted adhesive layer includes a first patterned imprinted structure and a second patterned imprinted structure; the first patterned imprinted structure is formed in a first region of the surface, and the second patterned imprinted structure is formed in a second region of the surface; the thickness of the second patterned imprinted structure is greater than the thickness of the first patterned imprinted structure. Using the patterned imprinted adhesive layer as a first mask, the waveguide substrate is etched in the first stage to form a coupling structure on the waveguide substrate in the first region, while the remaining patterned imprinted adhesive layer on the waveguide substrate in the second region maintains the pattern of the second patterned imprinted structure. The remaining patterned imprinted adhesive layer is used to form a second mask, and the waveguide substrate is etched in a second stage based on the second mask to form a coupling structure in the second region; The second mask covers the coupling structure to protect it from etching during the second stage of etching. The coupling structure and the coupling outlet structure have different structural forms, and the depth of the coupling outlet structure is greater than the depth of the coupling structure.

2. The method for fabricating a diffractive optical waveguide according to claim 1, characterized in that, The etching depths of the coupling structures are equal, or the etching depths of different regions of the coupling structures are not equal.

3. The method for fabricating a diffractive optical waveguide according to claim 1, characterized in that, The step of forming a second mask using the remaining patterned imprinted adhesive layer, and then performing a second stage of etching on the waveguide substrate based on the second mask to form a coupling structure in the second region, includes: A first hard mask layer is formed; the first hard mask layer is formed on the surface of the waveguide substrate and covers the coupling structure and the remaining patterned imprinted adhesive layer; Remove the remaining patterned embossing adhesive layer and the first hard mask layer covering the remaining patterned embossing adhesive layer to form the second mask; The waveguide substrate is etched in a second stage using the second mask as a mask to form a coupling structure in the second region.

4. The method for fabricating a diffractive optical waveguide according to claim 3, characterized in that, The second stage of etching the waveguide substrate using the second mask as a mask to form a coupling structure in the second region includes: Using the second mask as a mask, the waveguide substrate is etched in the second stage for the first time to form a coupling structure with equal etching depth; The photoresist layer is formed in N steps; each photoresist layer covers a portion of the coupling structure, where N is an integer greater than or equal to 1. After each photoresist layer is formed, the photoresist layer formed this time and the remaining patterned imprinted resist layer are used as masks to etch the part of the coupling structure that was not covered by the photoresist layer this time, until after the Nth etching, the coupling structure with N+1 different etched regions is formed. Remove the photoresist layer and the second mask.

5. The method for fabricating a diffractive optical waveguide according to claim 3, characterized in that, The material of the first hard mask layer is Cr, Al, SiO2 or Si3N4.

6. The method for fabricating a diffractive optical waveguide according to claim 5, characterized in that, The step of forming a second mask using the remaining patterned imprinted adhesive layer, and then performing a second stage of etching on the waveguide substrate based on the second mask to form a coupling structure in the second region, includes: A coupling protective layer is formed on the surface of the coupling structure; Using the coupling protective layer and the remaining patterned imprinted adhesive layer as a second mask, the waveguide substrate is etched in a second stage based on the second mask to form a coupling structure in the second region.

7. The method for fabricating a diffractive optical waveguide according to claim 6, characterized in that, The coupling protective layer is a photoresist layer.

8. The method for fabricating a diffractive optical waveguide according to claim 7, characterized in that, The process of forming a coupling protective layer on the surface of the coupling structure includes: A predetermined amount of photoresist is applied to the area where the coupling structure is located. Under vacuum and negative pressure conditions, the photoresist is made to flow uniformly and cover the surface of the coupling structure; The photoresist is cured to form the photoresist layer.

9. The method for fabricating a diffractive optical waveguide according to claim 8, characterized in that, The thickness of the coupling protective layer is greater than the thickness of the remaining patterned embossing adhesive layer.

10. The method for fabricating a diffractive optical waveguide according to any one of claims 1-9, characterized in that, The formation of a patterned imprinted adhesive layer on one surface of the waveguide substrate specifically includes: An impression master is provided; the impression master is provided with a first master graphic structure and a second master graphic structure; wherein, the first master graphic structure corresponds to the coupling-in structure; and the second master graphic structure corresponds to the coupling-out structure; An imprinting adhesive is coated onto the waveguide substrate; The printing master is pressed onto the printing adhesive to form the patterned printing adhesive layer; wherein the pattern of the patterned printing adhesive layer corresponds to the pattern of the first master graphic structure and the pattern of the second master graphic structure; Separate the embossing master and the graphic embossing adhesive layer.

11. The method for fabricating a diffractive optical waveguide according to claim 10, characterized in that, The step of imprinting the master printing plate onto the printing adhesive layer to form the patterned printing adhesive layer specifically includes: The embossing master is pressed onto the embossing adhesive layer; The embossing adhesive layer is cured to form the patterned embossing adhesive layer.

12. The method for fabricating a diffractive optical waveguide according to claim 11, characterized in that, The thickness of the embossing adhesive layer is adapted to the maximum depth of the graphics in the first master graphic structure and the second master graphic structure.

13. A diffractive optical waveguide, characterized in that, It is manufactured by the method of fabrication of diffractive optical waveguide according to any one of claims 1-12.

14. An AR device, characterized in that, Including the diffractive waveguide as described in claim 13.

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