CN115236779B - First mold for preparing blazed grating, blazed grating and preparation method - Google Patents

Abstract

The embodiment of the present application provides a first mold for preparing a blazed grating and a preparation method thereof, a blazed grating and a preparation method thereof, and a display device, wherein the first mold includes a first substrate and a plurality of periodically arranged first pattern units disposed on one side of the first substrate. Each periodic first pattern unit includes a first photoresist structure and a first blocking structure arranged along a first direction parallel to the first substrate; the first blocking structure of each first pattern unit, and the first photoresist structure and the first blocking structure of the next first pattern unit are connected in sequence. Along the first direction, there is a first design distance between the first blocking structures of any two adjacent first pattern units, that is, the spacing between adjacent first blocking structures remains unchanged, so that the first photoresist structure located between adjacent first blocking structures always has a first design width, thereby ensuring the design accuracy of the first mold, and further ensuring the design accuracy of the blazed grating prepared based on the first mold.

Description

First mold for preparing blazed grating, blazed grating and preparation method

Technical Field

The present application relates to the field of display technology, and in particular, to a first mold for preparing a blazed grating, a blazed grating, a preparation method, and a display device.

Background Art

With the development of virtual reality (VR) and augmented reality (AR) applications, the use of surface relief grating is a solution that is currently receiving a lot of attention because of its small size, light weight and ease of mass production.

Surface relief gratings mainly include rectangular gratings, tilted gratings and blazed gratings, etc. Among them, the rectangular grating has a simple manufacturing process but low diffraction efficiency, the tilted grating can achieve higher diffraction efficiency, but the preparation cost is high and special equipment is required for manufacturing, the blazed grating can achieve higher diffraction efficiency and the preparation process is relatively simple, so the blazed grating has received more and more attention.

At present, blazed gratings can be prepared by nano-ultraviolet imprinting technology based on some molds, which is a mature and simple technology. Among them, the first mold is mainly prepared by grayscale electron beam lithography technology, specifically, the electron beam photoresist is formed into a first photoresist initial structure by using different exposure amounts, and then the first photoresist initial structure is converted into a first photoresist structure by thermal reflow. The first photoresist structure can obtain the grating structure of the blazed grating by several transfers.

However, electron beam photoresist tends to collapse and flow to both sides during the thermal reflow process, making it difficult for the initial structure of the first photoresist to maintain its original width during the conversion to the first photoresist structure, resulting in an increase in the line width, period, and duty cycle of the final grating structure, and even causing adjacent grating structures to stick together, affecting the diffraction efficiency of the blazed grating.

Summary of the invention

In view of the shortcomings of the existing methods, the present application proposes a first mold for preparing a blazed grating, a blazed grating, a preparation method and a display device for preparing a blazed grating, so as to solve the technical problem in the prior art that electron beam photoresist is prone to collapse and flow to both sides during thermal reflow, thereby making it difficult for the first photoresist initial structure to maintain the original width during the process of conversion into the first photoresist structure, ultimately affecting the diffraction efficiency of the blazed grating prepared based on the first mold.

In a first aspect, an embodiment of the present application provides a first mold for preparing a blazed grating, comprising: a first substrate, and a plurality of periodically arranged first pattern units disposed on one side of the first substrate; each period of the first pattern units comprises a first photoresist structure and a first blocking structure arranged along a first direction parallel to the first substrate;

Between any two adjacent first pattern units, the first blocking structure of the previous first pattern unit, and the first photoresist structure and the first blocking structure of the next first pattern unit are connected in sequence;

Along the first direction, there is a first designed distance between the first blocking structures of any two adjacent first pattern units, so that the first photoresist structure has a first designed width.

Optionally, the thickness of the first blocking structure is 50 nanometers to 150 nanometers;

The thickness of the first photoresist structure is 300-600 nanometers.

Optionally, the first blocking structure comprises: a plurality of columnar hydrophobic structures arranged in an array;

The thickness of each hydrophobic structure is 50 nanometers to 150 nanometers;

In each first blocking structure, the distance between the centers of adjacent hydrophobic structures along the first direction is 40 nanometers to 100 nanometers.

Optionally, the first barrier structure may be made of at least one of molybdenum, aluminum, silver, copper, chromium, gold or silicon dioxide.

Optionally, a period of the first pattern unit is 300 nanometers to 600 nanometers.

In a second aspect, an embodiment of the present application further provides a method for preparing any first mold provided in the first aspect, comprising:

A plurality of periodically arranged first blocking structures are fabricated on one side of the first substrate, wherein a first designed distance exists between any two adjacent first blocking structures;

Forming a first photoresist layer on one side of the first substrate and the first blocking structure;

Performing patterning on the first photoresist layer to obtain a plurality of periodically arranged first photoresist initial structures, each of which is located between two adjacent first blocking structures;

A plurality of first photoresist initial structures are subjected to thermal reflow treatment to obtain a plurality of first photoresist structures, wherein the first photoresist structures have a first design width; and the adjacent first blocking structures and the first photoresist structures form a first pattern unit.

Optionally, a plurality of first blocking structures are formed on one side of the first substrate, including:

forming a first barrier layer on one side of the first substrate;

The first barrier layer is patterned to obtain a plurality of first barrier structures arranged at intervals.

Optionally, a plurality of first blocking structures are formed on one side of the first substrate, including:

Making a plurality of periodically arranged sacrificial structures on one side of the first substrate;

Spin coating a second barrier layer on one side of the first substrate and the sacrificial structure so that the second barrier layer on the first substrate is broken from the second barrier layer on the sacrificial structure;

The sacrificial structure is peeled off, so that the second barrier layer on the sacrificial structure is peeled off, and a plurality of first barrier structures arranged on the first substrate are obtained.

In a third aspect, an embodiment of the present application further provides a blazed grating prepared based on any first mold provided in the first aspect, comprising: a second substrate, and a plurality of periodically arranged grating units disposed on one side of the substrate;

Each periodic grating unit includes a grating structure; the grating structure has the same shape as the first photoresist structure of the first mold;

The grating structure has a first design width in the first direction.

Optionally, the grating unit further includes:

The protruding structure is arranged between the grating structures of any two adjacent grating units.

In a fourth aspect, an embodiment of the present application further provides a display device, comprising: any blazed grating as provided in the first aspect above.

Optionally, the display device further comprises: a stacked functional layer and a waveguide sheet;

The functional layer has an incoupling region and an outcoupling region which expose the waveguide plate and are spaced apart;

The grating structure of the blazed grating is located in the incoupling region.

In a fifth aspect, an embodiment of the present application further provides a method for preparing a blazed grating based on any first mold provided in the first aspect, comprising:

Using any of the first molds provided in the first aspect above, a second mold having a second pattern unit is prepared; the concave shape of the second pattern unit is the same as the convex shape of the first pattern unit of the first mold;

forming a grating material layer on one side of the second substrate;

The side of the second mold having the second pattern unit is used to emboss the grating material layer to obtain a grating structure.

Optionally, using any of the first molds provided in the first aspect to prepare a second mold having a second pattern unit comprises:

Using a second template to imprint one side of any first mold provided in the first aspect having the first pattern unit, to obtain a second mold having a plurality of periodically arranged second pattern units; the second pattern unit comprises: a first grating recess and a first blocking recess;

And, the side of the second mold having the second pattern unit is used to emboss the grating material layer to obtain a grating structure, comprising:

The side of the second mold having the second pattern unit is embossed on the grating material layer so that a part of the grating material layer fills up the first grating recess to form a grating structure, and another part of the grating material layer fills up the first blocking recess to form a convex structure.

Optionally, using any of the first molds provided in the first aspect to prepare a second mold having a second pattern unit comprises:

Removing the first blocking structure of any first mold provided in the first aspect;

Using a second template to emboss one side of the first mold after removing the first blocking structure, to obtain a second mold having a plurality of periodically arranged second pattern units; the second pattern units include: a second grating recess;

And, the side of the second mold having the second pattern unit is used to emboss the grating material layer to obtain a grating structure, comprising:

The side of the second mold having the second grating stamp is used to stamp the grating material layer, so that a part of the grating material layer fills the second grating recess to form a grating structure.

The beneficial technical effects brought about by the technical solution provided by the embodiments of the present application include:

In the embodiment of the present application, the first mold for preparing the blazed grating includes a first substrate and a plurality of periodically arranged first pattern units arranged on one side of the first substrate. Each period of the first pattern unit includes a first photoresist structure and a first blocking structure arranged along a first direction parallel to the first substrate; the first blocking structure of each first pattern unit, and the first photoresist structure and the first blocking structure of the next first pattern unit are connected in sequence, so that the two sides of the first photoresist structure will be blocked by the first blocking structures of two adjacent periods. Along the first direction, there is a first design distance between the first blocking structures of any two adjacent first pattern units, that is, the spacing between the adjacent first blocking structures remains unchanged, so that the first photoresist structure located between the adjacent first blocking structures always has the first design width, ensuring the design accuracy of the first mold, and enabling the parameters such as the line width, period and duty cycle of the first photoresist structure of the first mold to always be consistent with the design parameters in the early stage of preparation, thereby ensuring the design accuracy of the blazed grating prepared based on the first mold, and ensuring that the parameters such as the line width, period and duty cycle of the grating structure of the blazed grating are always consistent with the design parameters in the early stage of preparation.

Additional aspects and advantages of the present application will be partially given in the following description, which will become apparent from the following description, or will be understood through the practice of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

FIG1 is a schematic structural diagram of a first mold provided in an embodiment of the present application;

FIG2 is a schematic structural diagram of another first mold provided in an embodiment of the present application;

FIG3 is a schematic diagram of a process for preparing a first mold according to an embodiment of the present application;

FIG4 is a schematic diagram of a structure in which a plurality of periodically arranged first blocking structures are manufactured on one side of a first substrate in a method for preparing a first mold provided in an embodiment of the present application, and a first designed distance is provided between any two adjacent first blocking structures;

5 is a schematic structural diagram of a method for preparing a first mold provided in an embodiment of the present application, after a first photoresist layer is formed on one side of a first substrate and a first barrier structure;

FIG6 is a schematic structural diagram of a method for preparing a first mold provided in an embodiment of the present application, in which a first photoresist layer is patterned to obtain a plurality of periodically arranged first photoresist initial structures, each of which is located between two adjacent first blocking structures;

FIG7 is a schematic diagram of a structure in which a plurality of periodically arranged first blocking structures are manufactured on one side of a first substrate in another method for preparing a first mold provided in an embodiment of the present application, and a first designed distance is provided between any two adjacent first blocking structures;

8 is a schematic structural diagram of another method for preparing a first mold provided in an embodiment of the present application, after a first photoresist layer is formed on one side of a first substrate and a first barrier structure;

9 is a schematic structural diagram of another method for preparing a first mold provided in an embodiment of the present application, in which a first photoresist layer is patterned to obtain a plurality of periodically arranged first photoresist initial structures, each of which is located between two adjacent first blocking structures;

FIG10 is a schematic diagram of a structure after the second barrier layer is spin-coated on one side of the first substrate and the sacrificial structure in another method for preparing the first mold provided in an embodiment of the present application, so that the second barrier layer on the first substrate and the second barrier layer on the sacrificial structure are broken;

FIG11 is a schematic diagram of the structure of a blazed grating provided in an embodiment of the present application;

FIG12 is a schematic diagram of the structure of another blazed grating provided in an embodiment of the present application;

FIG13 is a schematic diagram of the structure of another blazed grating provided in an embodiment of the present application;

FIG14 is a schematic diagram of the structure of a display device provided in an embodiment of the present application;

FIG15 is a schematic flow chart of a method for preparing a blazed grating provided in an embodiment of the present application;

FIG16 is a schematic structural diagram of using a second template to imprint a side of a first mold having a first pattern unit in a method for preparing a blazed grating provided in an embodiment of the present application;

FIG17 is a schematic structural diagram of a second mold provided in an embodiment of the present application;

FIG18 is a schematic structural diagram of a method for preparing a blazed grating provided in an embodiment of the present application, after a grating material layer is formed on one side of a second substrate;

FIG19 is a schematic diagram of a structure after a grating material layer is embossed on a side of a second mold having a second pattern unit in a method for preparing a blazed grating provided in an embodiment of the present application, so that a portion of the grating material layer fills up the first grating recesses to form a grating structure, and another portion of the grating material layer fills up the first blocking recesses to form a convex structure;

FIG20 is a schematic structural diagram of using a second template to imprint a side of a first mold having a first pattern unit in another method for preparing a blazed grating provided in an embodiment of the present application;

FIG21 is a schematic structural diagram of another second mold provided in an embodiment of the present application;

FIG22 is a schematic diagram of a structure after a side of a second mold having a second pattern unit is embossed on a grating material layer in another method for preparing a blazed grating provided in an embodiment of the present application, so that a portion of the grating material layer fills up the first grating recesses to form a grating structure, and a portion of the grating material layer fills up the first blocking recesses to form a convex structure;

FIG23 is a schematic structural diagram of using a second template to imprint a side of a first mold having a first pattern unit in another method for preparing a blazed grating provided in an embodiment of the present application;

FIG24 is a schematic structural diagram of another second mold provided in an embodiment of the present application;

Figure 25 is a structural schematic diagram of another method for preparing a blazed grating provided in an embodiment of the present application, in which the grating material layer is embossed on one side of the second mold having the second pattern unit so that a portion of the grating material layer fills the second grating recess to form a grating structure.

Reference numerals:

10-first mold; 11-first substrate; 12-first pattern unit; 121-first photoresist structure; 122-first blocking structure; 1221-hydrophobic structure; 123-first photoresist layer; 124-first photoresist initial structure; 125-sacrificial structure; 126-second blocking layer;

20-blazed grating; 21-second substrate; 22-grating unit; 221-grating structure; 222-convex structure; 2221-convex substructure; 23-grating material layer;

30-second mold; 31-second pattern unit; 311-first grating recess; 312-first blocking recess; 313-second grating recess; 32-second template;

40-display device; 41-functional layer; 411-coupling region; 412-coupling region; 42-waveguide plate;

A-first direction; B-first design distance; C-first design width.

DETAILED DESCRIPTION

The embodiments of the present application are described below in conjunction with the drawings in the present application. It should be understood that the implementation methods described below in conjunction with the drawings are exemplary descriptions for explaining the technical solutions of the embodiments of the present application and do not constitute a limitation on the technical solutions of the embodiments of the present application.

Those skilled in the art will appreciate that, unless expressly stated, the singular forms "one", "an", "said" and "the" used herein may also include plural forms. It should be understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, elements and/or components, but does not exclude the implementation of other features, information, data, steps, operations, elements, components and/or combinations thereof supported by the present technical field. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, the element may be directly connected or coupled to the other element, or may refer to the connection relationship between the element and the other element established through an intermediate element. The term "and/or" used herein refers to at least one of the items defined by the term, for example, "A and/or B" may be implemented as "A", or as "B", or as "A and B".

In order to make the objectives, technical solutions and advantages of the present application more clear, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

The grating structure of the blazed grating is generally sawtooth-shaped, and each sawtooth can be regarded as a triangular structure. Conventional blazed gratings are produced by transferring a first mold (also called a master mold) to a second mold (also called a soft mold), and then using the second mold to emboss the blazed grating.

Therefore, the pattern on the first mold directly affects the pattern of the blazed grating, so the pattern accuracy on the first mold is crucial. However, during the process of converting the first photoresist initial structure on the first mold into the first photoresist structure through thermal reflow, the photoresist easily flows, causing the first photoresist structure to collapse to both sides, resulting in the final first photoresist structure not being consistent with the design, and further resulting in the blazed grating prepared using the first mold not being consistent with the design, affecting the diffraction efficiency of the blazed grating.

The first mold for preparing a blazed grating, the blazed grating, the preparation method and the display device provided in the present application are intended to solve the above technical problems in the prior art.

The following is a detailed description of the technical solution of the present application and how the technical solution of the present application solves the above technical problems with specific embodiments. It should be noted that the following implementations can refer to, draw on or combine with each other, and the same terms, similar features and similar implementation steps in different implementations will not be described repeatedly.

The embodiment of the present application provides a first mold 10 for preparing a blazed grating 20, comprising: a first substrate 11, and a plurality of periodically arranged first pattern units 12 disposed on one side of the first substrate 11. Each period of the first pattern unit 12 comprises a first photoresist structure 121 and a first blocking structure 122 arranged along a first direction A parallel to the first substrate 11.

Between any two adjacent first pattern units, the first blocking structure 122 of a first pattern unit 12 , and the first photoresist structure 121 and the first blocking structure 122 of the next first pattern unit 12 are connected in sequence.

Along the first direction A, there is a first designed distance B between the first blocking structures 122 of any two adjacent first pattern units 12 , so that the first photoresist structure 121 has a first designed width C.

In this embodiment, referring to FIG. 1 , a first mold 10 for preparing a blazed grating 20 includes a first substrate 11 and a plurality of periodically arranged first pattern units 12 disposed on one side of the first substrate 11. Each period of the first pattern unit 12 includes a first photoresist structure 121 and a first blocking structure 122 arranged along a first direction A parallel to the first substrate 11. The first blocking structure 122 of each first pattern unit 12, and the first photoresist structure 121 and the first blocking structure 122 of the next first pattern unit 12 are connected in sequence, so that both sides of the first photoresist structure 121 are blocked by the first blocking structures 122 of two adjacent periods. Along the first direction A, there is a first design distance B between the first blocking structures 122 of any two adjacent first pattern units 12, that is, the spacing between adjacent first blocking structures 122 remains unchanged, so that the first photoresist structure 121 located between adjacent first blocking structures 122 always has a first design width C, thereby ensuring the design accuracy of the first mold 10, and enabling the line width, period, duty cycle and other parameters of the first photoresist structure 121 of the first mold 10 to always be consistent with the design parameters in the early stage of preparation, thereby ensuring the design accuracy of the blazed grating 20 prepared based on the first mold 10, and ensuring that the line width, period, duty cycle and other parameters of the grating structure 221 of the blazed grating 20 are always consistent with the design parameters in the early stage of preparation.

It can be understood that the first designed distance B between adjacent first blocking structures 122 is consistent with the first designed width C of the first photoresist structure 121 located between two adjacent first blocking structures 122 .

In the present application, the line width of the first photoresist structure 121 or the line width of the grating structure 221 refers to the width in the first direction A.

In some possible implementations, the thickness of the first blocking structure 122 is 50 nanometers to 150 nanometers.

The thickness of the first photoresist structure 121 is 300-600 nanometers.

The first blocking structure 122 in this embodiment can play a blocking role, so that the first photoresist structure 121 always maintains a certain width. The thickness of the first blocking structure 122 should be at least about one-fourth of the first photoresist structure 121, which can play a good blocking role. For example, the thickest part of the first photoresist structure 121 is 300 nanometers, and the thickness of the first blocking structure 122 can be about 75. The first photoresist structure 121 will be consistent with the shape of the grating structure 221 of the blazed grating 20. Therefore, the thickness of the first photoresist structure 121 is between 300 and 600 nanometers (including 300 nanometers and 600 nanometers), so that the grating structure 221 also has the same thickness and has good diffraction efficiency.

It is understood that the thickness of each structure in the embodiment of the present application is the thickness in the direction perpendicular to each substrate. For example, the cross section of the first photoresist structure 121 can be regarded as a triangle, the thickness is the height of the triangle, and the base is the side where the first photoresist structure 121 contacts the first substrate 11.

In some possible implementations, referring to FIG. 2 , the first blocking structure 122 includes: a plurality of columnar hydrophobic structures 1221 arranged in an array.

The thickness of each hydrophobic structure 1221 is 50 nanometers to 150 nanometers.

In each first blocking structure 122 , the distance between the centers of adjacent hydrophobic structures 1221 along the first direction A is 40 nanometers to 100 nanometers.

In this embodiment, the first blocking structure 122 has a blocking effect as well as a certain hydrophobic effect. When the predecessor of the first photoresist structure 121, the first photoresist initial structure 124 (see the subsequent first mold 10 preparation method) flows during the thermal reflow process, the interface effect of the hydrophobic structure 1221 can prevent the first photoresist initial structure 124 from flowing and maintain its morphology.

In some possible implementations, the first blocking structure 122 may be made of at least one of molybdenum, aluminum, silver, copper, chromium, gold, or silicon dioxide.

The first blocking structure 122 can be made of different materials according to different usage scenarios or preparation processes, and it only needs to ensure its blocking effect or hydrophobic effect during the thermal reflow process.

In some possible implementations, the period of the first pattern unit 12 is 300 nanometers to 600 nanometers.

In this embodiment, the period of the blazed grating 20 is consistent with the period of the first photoresist structure 121. Therefore, the period of the first photoresist structure 121 is between 300 nanometers and 600 nanometers (including 300 nanometers and 600 nanometers), which can ensure good diffraction efficiency when applied to wearable display devices.

Based on the same inventive concept, the embodiment of the present application further provides a method for preparing any first mold 10 provided in the aforementioned embodiment. The flow chart of the method is shown in FIG3 . The method includes steps S101-S104:

S101: A plurality of periodically arranged first blocking structures 122 are fabricated on one side of the first substrate 11, and a first designed distance B is provided between any two adjacent first blocking structures 122. The structural diagram after step S101 can be referred to FIG. 4 or FIG. 7.

Optionally, step S101 may be implemented by the following steps:

A first barrier layer is formed on one side of the first substrate 11 .

The first barrier layer is patterned to obtain a plurality of first barrier structures 122 disposed at intervals.

In this embodiment, a layer of electron beam photoresist may be further deposited on the first barrier layer, and the first barrier structure 122 may be written by electron beam lithography.

Optionally, referring to FIG. 10 , step S101 may also be implemented by the following steps:

A plurality of periodically arranged sacrificial structures 125 are fabricated on one side of the first substrate 11 .

The second barrier layer 126 is spin-coated on one side of the first substrate 11 and the sacrificial structure 125 , so that the second barrier layer 126 on the first substrate 11 is broken from the second barrier layer 126 on the sacrificial structure 125 .

The sacrificial structure 125 is peeled off, so that the second barrier layer 126 on the sacrificial structure 125 is peeled off, and a plurality of first barrier structures 122 disposed on the first substrate 11 are obtained.

In this embodiment, a plurality of periodically arranged sacrificial structures 125 may be first fabricated on one side of the first substrate 11, and then a second barrier layer 126 may be spin coated. The presence of the sacrificial structure 125 causes the second barrier layer 126 on the first substrate 11 to be broken from the second barrier layer 126 on the sacrificial structure 125, and then the sacrificial structure 125 is peeled off to obtain a periodically arranged first barrier structure 122.

Optionally, the periodically arranged sacrificial structures 125 may be written by electron beam lithography. The sacrificial structures 125 are made of photoresist.

Optionally, the first barrier layer is a hydrophobic glue, and after the second barrier layer 126 is spin-coated, it is developed and peeled off to obtain a patterned first barrier structure 122 with multiple periodic arrangements. The height of the second barrier layer 126 (relative to the first substrate 11) should be smaller than the first photoresist structure 121 for easy peeling. The period of the first barrier structure 122 is consistent with the period of the first photoresist structure 121.

S102: forming a first photoresist layer 123 on one side of the first substrate 11 and the first blocking structure 122. The schematic diagram of the structure after step S102 can refer to FIG. 5 or FIG. 8 .

S103 : performing patterning on the first photoresist layer 123 to obtain a plurality of periodically arranged first photoresist initial structures 124 , each of which is located between two adjacent first blocking structures 122 .

Optionally, referring to FIG. 6 or FIG. 9 , the first photoresist initial structure 124 is a step-shaped structure formed on the first photoresist layer 123 by grayscale electron beam lithography technology.

S104 : performing a thermal reflow process on the plurality of first photoresist initial structures 124 to obtain a plurality of first photoresist structures 121 , wherein the first photoresist structures 121 have a first design width C. The adjacent first blocking structures 122 and the first photoresist structures 121 form a first pattern unit 12 .

Optionally, the stepped first photoresist initial structure 124 is subjected to a thermal reflow treatment so that the first photoresist initial structure 124 has a certain fluidity, thereby converting the stepped bending surface into a smooth inclined surface, and finally obtaining a triangular first photoresist structure 121 .

In steps S101-S104 provided in this embodiment, a plurality of periodically arranged first blocking structures 122 are first fabricated on one side of the first substrate 11, so that any two adjacent first blocking structures 122 have a first designed distance B. The first photoresist layer 123 is then fabricated, and the photoresist layer is patterned to obtain a first photoresist initial structure 124, which is then subjected to a thermal reflow treatment. During the thermal reflow treatment, the first blocking structures 122 on both sides of the first photoresist initial structure 124 can limit the width of the first photoresist initial structure 124, so that after the first photoresist initial structure 124 finally becomes the first photoresist structure 121, the first designed width C can also be guaranteed.

Based on the same inventive concept, please refer to Figures 11-13, an embodiment of the present application also provides a blazed grating 20 prepared based on any first mold 10 provided in the aforementioned embodiments, including: a second substrate 21, and a plurality of periodically arranged grating units 22 provided on one side of the substrate.

Each periodic grating unit 22 includes a grating structure 221. The grating structure 221 has the same shape as the first photoresist structure 121 of the first mold 10.

The grating structure 221 has a first design width C in the first direction A.

In the present embodiment, since the first mold 10 for preparing the blazed grating 20 has the first blocking structure 122, the grating structure 221 of the blazed grating 20 finally obtained has a first design width C, which can ensure that the diffraction efficiency of the blazed grating 20 is within the error range and the functional reliability of the blazed grating 20 is ensured.

In some possible implementations, please refer to FIG. 11 and FIG. 12 , the grating unit 22 further includes:

The protruding structure 222 is disposed between the grating structures 221 of any two adjacent grating units 22 .

It can be understood that the protruding structure 222 of the present application is prepared corresponding to the first blocking structure 122 of the first mold 10, but the protruding structure 222 will not be very thick, and the top surface is parallel to the second substrate 21, so it does not affect the diffraction efficiency of the blazed grating 20.

Optionally, the protrusion structure 222 includes protrusion substructures 2221 arranged in an array.

Based on the same inventive concept, an embodiment of the present application further provides a display device 40, comprising: any blazed grating 20 provided in the aforementioned embodiments.

The display device 40 provided in this embodiment includes any blazed grating 20 provided in the above embodiments, and its implementation principle is similar, which will not be repeated here.

Optionally, the display device 40 includes but is not limited to wearable display devices such as AR glasses.

It is understandable that in conventional AR glasses, both the coupling-in area 411 and the coupling-out area 412 of the functional layer 41 use rectangular gratings. Since the rectangular gratings are symmetrical structures, after the light is diffracted by the rectangular gratings, the diffraction efficiency of the negative first-order spectrum (T-1 level) and the positive first-order spectrum (T+1 level) are equal (generally less than 20%), and are much lower than the diffraction efficiency of the zero-order spectrum (generally about 60%), resulting in low optical machine utilization and low brightness of the image entering the human eye. Therefore, the present application also provides the following embodiment, please refer to FIG. 14, the display device 40 also includes: a stacked functional layer 41 and a waveguide plate 42.

The functional layer 41 has an incoupling region 411 and an outcoupling region 412 which expose the waveguide plate 42 and are spaced apart from each other.

The grating structure 221 of the blazed grating 20 is located in the coupling-in region 411 .

In this embodiment, a blazed grating 20 is used to replace the rectangular grating of the coupling-in area 411. The blazed grating 20 can enhance the diffraction efficiency of a specific order. For example, the positive first-order diffraction efficiency required for extracting light in the coupling-in area 411 can be enhanced to 70% to 80%, thereby suppressing the diffraction efficiency of other orders to improve the brightness of the image.

The blazed grating 20 prepared based on the first mold 10 provided in the embodiment of the present application can ensure its designed dimensions (such as designed period, designed line width, designed duty cycle or designed tilt angle, etc.) and improve the grating light extraction efficiency of the coupling region 411.

Optionally, the waveguide plate 42 may form the second substrate 21 of the blazed grating 20 .

Optionally, the blazed grating 20 is transparent, capable of transmitting light and diffracting light.

Based on the same inventive concept, the embodiment of the present application further provides a method for preparing a blazed grating 20 based on any first mold 10 provided in the foregoing embodiments of the present application. The flow chart of the method is shown in FIG. 15 . The method comprises steps S201-S203:

S201: Use the first mold 10 to prepare a second mold 30 having a second pattern unit 31. The concave shape of the second pattern unit 31 is the same as the convex shape of the first pattern unit 12 of the first mold 10. The structural schematic diagram of the second mold can refer to Figure 17, Figure 21 or Figure 24.

The first mold 10 in this step is the first mold 10 provided in the aforementioned embodiment, or is the first mold 10 prepared by the aforementioned method for preparing the first mold 10.

S202 : Referring to FIG. 18 , a grating material layer 23 is formed on one side of the second substrate 21 .

S203: Imprint the grating material layer 23 with the side of the second mold 30 having the second pattern unit 31 to obtain the grating structure 221. The schematic diagram of the structure after step S203 is shown in FIG19 , FIG22 or FIG25 .

In this embodiment, the second mold 30 has a concave pattern, and the grating material layer 23 is embossed with the second mold 30 so that some protruding grating structures 221 can be formed on the grating material layer 23 .

It is understandable that there is no strict sequence between steps S201 and S202.

In some possible implementations, the above step S201 may include:

The second template 32 is used to emboss the side of the first mold 10 having the first pattern unit 12 (the embossing process can refer to Figures 16, 20 or 23), to obtain a second mold 30 having a plurality of periodically arranged second pattern units 31. The second pattern unit 31 includes: a first grating recess 311 and a first blocking recess 312. The structural schematic diagram after this step can refer to Figures 17 or 21.

And, the above step S203 includes:

The side of the second mold 30 having the second pattern unit 31 is embossed on the grating material layer 23, so that a part of the grating material layer 23 fills the first grating recess 311 to form a grating structure 221, and another part of the grating material layer 23 fills the first blocking recess 312 to form a convex structure 222. The structural schematic diagram after this step can refer to Figure 19 or Figure 22.

In this embodiment, since the first mold 10 has the raised first photoresist structure 121 and the first blocking structure 122, the first mold 10 is directly used to emboss the second template 32 to obtain the second mold 30 having the first grating recess 311 and the first blocking recess 312. The second mold 30 is then used to emboss the grating material layer 23 on the second substrate 21, and the grating material layer 23 forms a raised grating structure 221 and a raised structure 222. The shape of the first grating recess 311 is the same as that of the grating structure 221, and the shape of the first blocking recess 312 is the same as that of the raised structure 222.

In some possible implementations, the above step S201 includes:

The first blocking structure 122 of any first mold 10 provided in the first aspect is removed.

The second template 32 is used to emboss one side of the first mold 10 after removing the first blocking structure 122, to obtain a second mold 30 having a plurality of periodically arranged second pattern units 31. The second pattern unit 31 includes: a second grating recess 313. The structural schematic diagram after this step can be referred to in FIG24.

And, the above step S203 includes:

The side of the second mold 30 with the second grating stamp is embossed on the grating material layer 23, so that a part of the grating material layer 23 fills the second grating recess 313 to form the grating structure 221. The structural diagram after this step can be referred to in FIG25 .

In this embodiment, the first blocking structure 122 of the first mold 10 is first removed, which can be removed by etching or other methods. Then, the first mold 10 with the first blocking structure 122 removed is used to emboss the second template 32 to obtain a second mold 30 having only the second grating recess 313. Then, the second mold 30 is used to emboss the grating material layer 23 on the second substrate 21, and the grating material layer 23 forms a raised grating structure 221. The blazed grating 20 obtained in this embodiment has a similar structure to the conventional blazed grating 20, which can ensure the versatility of the blazed grating 20 provided in this application and expand the application scenarios of the blazed grating 20 provided in this application. The shape of the second grating recess 313 is the same as that of the grating structure 221.

Optionally, the imprinting technology provided in the present application includes but is not limited to ultraviolet nanoimprinting technology. The second mold 30 is a soft stamping material, the grating material layer 23 is a nanoimprinting resist, the second substrate 21 can be regarded as a waveguide material, and the grating structure 221 is directly prepared on the waveguide material to obtain the aforementioned display device 40 having the grating structure 221 and the waveguide sheet 42.

By applying the embodiments of the present application, at least the following beneficial effects can be achieved:

1. Both sides of the first photoresist structure 121 will be blocked by the first blocking structures 122 of two adjacent periods. Along the first direction A, there is a first design distance B between the first blocking structures 122 of any two adjacent first pattern units 12, that is, the spacing between the adjacent first blocking structures 122 remains unchanged, so that the first photoresist structure 121 located between the adjacent first blocking structures 122 always has a first design width C, ensuring the design accuracy of the first mold 10, and enabling the parameters such as the line width, period and duty cycle of the first photoresist structure 121 of the first mold 10 to always be consistent with the design parameters in the early stage of preparation, thereby ensuring the design accuracy of the blazed grating 20 prepared based on the first mold 10, and ensuring that the parameters such as the line width, period and duty cycle of the grating structure 221 of the blazed grating 20 are always consistent with the design parameters in the early stage of preparation.

2. The first blocking structure 122 has a blocking effect as well as a certain hydrophobic effect. When the predecessor of the first photoresist structure 121, the first photoresist initial structure 124 (see the subsequent preparation method of the first mold 10) flows during the thermal reflow process, the first photoresist initial structure 124 can be prevented from flowing through the interface effect of the hydrophobic structure 1221 to maintain its morphology.

3. In the method for preparing the first mold 10 provided in the present embodiment, a plurality of periodically arranged first blocking structures 122 are first fabricated on one side of the first substrate 11, so that any two adjacent first blocking structures 122 have a first designed distance B. The first photoresist layer 123 is then fabricated, and the first photoresist initial structure 124 is obtained by patterning the photoresist layer, and then the first photoresist initial structure 124 is subjected to a thermal reflow treatment. During the thermal reflow treatment, the first blocking structures 122 on both sides of the first photoresist initial structure 124 can limit the width of the first photoresist initial structure 124, so that after the first photoresist initial structure 124 finally becomes the first photoresist structure 121, the first designed width C can also be guaranteed.

4. The embodiment of the present application uses a blazed grating 20 to replace the rectangular grating of the coupling-in area 411. The blazed grating 20 can enhance the diffraction efficiency of a specific order. For example, the positive first-order diffraction efficiency required for collecting light in the coupling-in area 411 can be enhanced to 70% to 80%, suppressing the diffraction efficiency of other orders to improve the brightness of the image entering the eye.

5. In a method for preparing a blazed grating 20 provided in an embodiment of the present application, the first blocking structure 122 of the first mold 10 is first removed, which can be removed by etching or other methods. The first mold 10 with the first blocking structure 122 removed is then used to emboss the second template 32 to obtain a second mold 30 having only a second grating recess 313. The second mold 30 is then used to emboss the grating material layer 23 on the second substrate 21, and the grating material layer 23 forms a raised grating structure 221. The blazed grating 20 obtained in this embodiment has a similar structure to a conventional blazed grating 20, which can ensure the versatility of the blazed grating 20 provided in the present application and expand the application scenarios of the blazed grating 20 provided in the present application.

It will be understood by those skilled in the art that the steps, measures, and schemes in the various operations, methods, and processes discussed in this application may be alternated, changed, combined, or deleted. Other steps, measures, and schemes in the various operations, methods, and processes discussed in this application may also be alternated, changed, rearranged, decomposed, combined, or deleted. The steps, measures, and schemes in the prior art that are similar to those disclosed in this application may also be alternated, changed, rearranged, decomposed, combined, or deleted.

In the description of the present application, the directions or positional relationships indicated by words such as "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the exemplary directions or positional relationships shown in the accompanying drawings. They are for the convenience of describing or simplifying the description of the embodiments of the present application, and do not indicate or imply that the referred device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present application.

The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "at least one" means two or more.

In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or at least one embodiment or example.

It should be understood that, although the various steps in the flowchart of the accompanying drawings are displayed in sequence according to the indication of the arrows, the order of implementation of these steps is not limited to the order indicated by the arrows. Unless there is a clear description herein, in some implementation scenarios of the embodiments of the present application, the steps in each process can be executed in other orders according to demand. Moreover, some or all of the steps in each flow chart may include multiple sub-steps or multiple stages based on the actual implementation scenario. Some or all of these sub-steps or stages may be executed at the same time, or may be executed at different times in different scenarios at the execution time, and the execution order of these sub-steps or stages may be flexibly configured according to demand, and the embodiments of the present application do not limit this.

The above is only a partial implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the technical concept of the scheme of the present application, other similar implementation methods based on the technical ideas of the present application also fall within the protection scope of the embodiments of the present application.

Claims (14)

1. A first mold for preparing a blazed grating, characterized in that it comprises: a first substrate, and a plurality of periodically arranged first pattern units disposed on one side of the first substrate; each period of the first pattern unit comprises a first photoresist structure and a first blocking structure arranged along a first direction parallel to the first substrate; Between any two adjacent first pattern units, the first blocking structure of the previous first pattern unit, and the first photoresist structure and the first blocking structure of the next first pattern unit are connected in sequence; Along the first direction, there is a first designed distance between the first blocking structures of any two adjacent first pattern units, so that the first photoresist structure has a first designed width; The first blocking structure comprises: a plurality of columnar hydrophobic structures arranged in an array; The thickness of each of the hydrophobic structures is 50 nanometers to 150 nanometers; In each of the first blocking structures, the distance between the centers of adjacent hydrophobic structures along the first direction is 40 nanometers to 100 nanometers. 2. The first mold according to claim 1, characterized in that the thickness of the first blocking structure is 50 nanometers to 150 nanometers; The thickness of the first photoresist structure is 300-600 nanometers. 3. The first mold according to claim 1 is characterized in that the first blocking structure can be made of at least one of molybdenum, aluminum, silver, copper, chromium, gold or silicon dioxide. 4 . The first mold according to claim 1 , wherein a period of the first pattern unit is 300 nanometers to 600 nanometers. 5. A method for preparing the first mold according to any one of claims 1 to 4, characterized in that it comprises: A plurality of periodically arranged first blocking structures are fabricated on one side of the first substrate, wherein a first designed distance exists between any two adjacent first blocking structures; Forming a first photoresist layer on one side of the first substrate and the first blocking structure; Performing patterning on the first photoresist layer to obtain a plurality of periodically arranged first photoresist initial structures, each of which is located between two adjacent first blocking structures; A plurality of the first photoresist initial structures are subjected to thermal reflow treatment to obtain a plurality of first photoresist structures, wherein the first photoresist structures have a first design width; and the adjacent first blocking structures and the first photoresist structures form a first pattern unit. 6. The method for preparing the first mold according to claim 5, characterized in that the step of manufacturing a plurality of first blocking structures on one side of the first substrate comprises: forming a first barrier layer on one side of the first substrate; The first barrier layer is patterned to obtain a plurality of first barrier structures arranged at intervals. 7. The method for preparing the first mold according to claim 5, characterized in that the step of manufacturing a plurality of first blocking structures on one side of the first substrate comprises: Making a plurality of periodically arranged sacrificial structures on one side of the first substrate; Spin-coating a second barrier layer on one side of the first substrate and the sacrificial structure so that the second barrier layer on the first substrate and the second barrier layer on the sacrificial structure are broken; The sacrificial structure is peeled off, so that the second barrier layer on the sacrificial structure is peeled off, and a plurality of first barrier structures arranged on the first substrate are obtained. 8. A blazed grating prepared based on the first mold according to any one of claims 1 to 4, characterized in that it comprises: a second substrate, and a plurality of periodically arranged grating units disposed on one side of the substrate; Each periodic grating unit includes a grating structure; the grating structure has the same shape as the first photoresist structure of the first mold; The grating structure has a first design width in the first direction. 9. The blazed grating according to claim 8, wherein the grating unit further comprises: The protruding structure is arranged between the grating structures of any two adjacent grating units. 10. A display device, comprising: a blazed grating as claimed in any one of claims 8 to 9. 11. The display device according to claim 10, further comprising: a stacked functional layer and a waveguide sheet; The functional layer has an incoupling region and an outcoupling region which expose the waveguide plate and are spaced apart from each other; The grating structure of the blazed grating is located in the coupling-in region. 12. A method for preparing a blazed grating based on the first mold according to any one of claims 1 to 4, characterized by comprising: A second mold having a second pattern unit is prepared by using the first mold as claimed in any one of claims 1 to 4; the concave shape of the second pattern unit is the same as the convex shape of the first pattern unit of the first mold; forming a grating material layer on one side of the second substrate; The side of the second mold having the second pattern unit is used to emboss the grating material layer to obtain a grating structure. 13. The method for preparing a blazed grating according to claim 12, characterized in that the second mold having the second pattern unit is prepared by using the first mold according to any one of claims 1 to 4, comprising: Using a second template to imprint one side of the first mold having the first pattern unit as claimed in any one of claims 1 to 4, to obtain a second mold having a plurality of periodically arranged second pattern units; the second pattern unit comprises: a first grating recess and a first blocking recess; And, the side of the second mold having the second pattern unit is embossed on the grating material layer to obtain a grating structure, comprising: The side of the second mold having the second pattern unit is used to emboss the grating material layer so that a portion of the grating material layer fills up the first grating recesses to form the grating structure, and another portion of the grating material layer fills up the first blocking recesses to form a convex structure. 14. The method for preparing a blazed grating according to claim 12, characterized in that the second mold having the second pattern unit is prepared by using the first mold according to any one of claims 1 to 4, comprising: Removing the first blocking structure of the first mold as described in any one of claims 1 to 4; Using a second template to emboss one side of the first mold after removing the first blocking structure, to obtain a second mold having a plurality of periodically arranged second pattern units; the second pattern units include: a second grating depression; And, the side of the second mold having the second pattern unit is embossed on the grating material layer to obtain a grating structure, comprising: The side of the second mold having the second grating stamp is used to stamp the grating material layer, so that a portion of the grating material layer fills the second grating recess to form the grating structure.