CN115494568A - A kind of preparation method of microlens array and its microlens array, application - Google Patents

Abstract

The invention provides a preparation method of a micro-lens array, the micro-lens array and application thereof, relating to the technical field of photoelectric devices; the preparation method comprises the following steps: forming a first imprinting adhesive layer on a substrate; transferring the pattern on the nano-imprinting template to a substrate by utilizing imprinting and etching processes to form an array microlens unit; removing the first imprinting adhesive layer to obtain the micro-lens units of the array; forming a dielectric layer on the surfaces of the micro-lens units of the array to obtain a required micro-lens array; the thickness and the material of the dielectric layer are acquired according to the requirements of the focal length and/or the refractive index of a device applied to the micro-lens array; in the etching process, the proportion of hydrogen halide and fluoride in the processing gas adopted in the etching process is adjusted according to the ratio of the diameter D of the bottom surface of the microlens unit to be obtained to the thickness D of the center. The present application also provides a microlens array. The preparation method of the micro-lens array and the micro-lens array thereof have the advantages of high precision and flexible and adjustable parameters.

Description

A kind of preparation method of microlens array and its microlens array, application

technical field

The invention relates to the technical field of photoelectric device preparation methods, in particular to a preparation method of a microlens array and the microlens array and its application.

Background technique

Micro-nanostructures refer to artificially designed functional structures with micron or nanoscale feature sizes and arranged in a specific way. With the development of the third-generation optical imaging technology towards integration, light weight, and ultra-large aperture, the traditional catadioptric optical system faces many bottlenecks, while micro-nano structured optical components have the characteristics of light weight, high degree of design freedom, and flexible structure. Shows significant advantages in the field of imaging.

Microlenses and microlens arrays are very important micro-nano structural optical components. Through precise control of microlens distribution, focal length, duty cycle, numerical aperture and other parameters, effective modulation of beams can be achieved to meet consumer needs. The microlens obtained by effectively controlling the parameters of the microlens can be widely used in the fields of optoelectronics and semiconductor detection, and has good application prospects.

However, the planar process ion exchange method, photosensitive glass method, holographic method, Fresnel zone lens method, and photoresist thermal melting method currently used to prepare microlens arrays have problems such as large errors, difficult control of precision, and complicated procedures. It is difficult to achieve mass production. In order to solve this technical problem, a new preparation method of microlens arrays has been proposed in recent years. This method uses nanoimprinting technology to adjust the size spacing of microlens arrays, and realizes 1:1 in-situ transfer of spherical caps of microlenses. The shape is conducive to improving the consistency of microlens array molding, which provides the possibility for mass production of microlens arrays; but because the parameters of microlens arrays required by different devices or equipment are different, how to realize the parameters of different microlens arrays The adjustment and precise control of microlens arrays are still a major difficulty in the preparation of microlens arrays.

Contents of the invention

The purpose of the present application is to provide a method for preparing a microlens array, which solves the technical problems of difficult adjustment and precise control of the microlens array in the prior art.

Another purpose of the present application is to provide a microlens array.

As another object, the present application also provides an application of a microlens array in the optical field.

In the first aspect, based on the above technical problems, the application provides a method for preparing a microlens array, including:

providing a substrate, a nanoimprint template with a microlens array pattern or a microlens array reverse pattern; forming a first imprint adhesive layer on the substrate;

Transferring the pattern of the microlens array to the first embossing adhesive layer by using an embossing process, or reversely transferring the reverse pattern of the microlens array to the first embossed adhesive layer by using an embossing process;

Transferring the pattern on the first embossed adhesive layer to the substrate by an etching process to form an array of microlens units;

Forming a dielectric layer on the surface of the microlens unit of the array to obtain the required microlens array; wherein, the thickness and material of the dielectric layer are obtained according to the focal length and/or refractive index requirements of the device used in the microlens array;

Wherein, in the etching process, according to the ratio of the bottom surface diameter D and the center thickness d of the microlens unit of the microlens array to be obtained, the ratio of hydrogen halide and fluoride in the processing gas used in the etching process is adjusted to obtain required microlens array.

Further, in some embodiments of the present application, adjusting the ratio of the processing gas used in the etching process includes:

When D/d≥20, the volume ratio of hydrogen halide and fluoride is 1:4.5~8;

When 8≤D/d<20, the volume ratio of hydrogen halide and fluoride is 1:3.5~5;

When 2<D/d<8, the volume ratio of hydrogen halide and fluoride is 1:2~4.

Further, in some embodiments of the present application, the preparation method further includes, in the etching process, adjusting the etching process according to the ratio of the bottom surface diameter D of the microlens unit of the microlens array to the center thickness d and Polarization power of process equipment:

When D/d≥20, the polarization power of the equipment for etching process is 150~300W;

When 8≤D/d<20, the polarization power of the equipment for etching process is 80~150W;

When D/d<8, the polarization power of the equipment performing the etching process is 0~100W.

Further, in some embodiments of the present application, using an embossing process to transfer the microlens array pattern to the first embossed adhesive layer, including:

Provide a transfer plate, the surface of the transfer plate is provided with a second embossing adhesive layer;

Using a nanoimprint template to imprint on the transfer plate, reversely transfer the pattern of the microlens array to the transfer plate to obtain a reverse transfer plate;

embossing on the first embossing adhesive layer by using a reverse transfer plate, and transferring the pattern of the microlens array to the first embossing adhesive layer;

Using an etching process to transfer the pattern on the first embossed adhesive layer to the substrate, including:

Using the reverse transfer plate as a mask, the pattern on the nanoimprint template is transferred to the substrate by etching process.

Further, in some embodiments of the present application, using an embossing process to reversely transfer the reverse pattern of the microlens array to the first embossed adhesive layer, including:

The nano-imprint template with the reverse pattern of the microlens array is used to imprint on the first embossing adhesive layer, and the reverse transfer pattern of the microlens array is reversely transferred to the first embossing adhesive layer to form a pattern of the microlens array.

Further, in some embodiments of the present application, the pressure in the chamber for performing the etching process is 5-50 mTorr; and/or

The source power used by the equipment for etching process is 100~1000w; and/or

The time for performing the etching process is 60-180s; and/or

The flow rate of fluoride is 100~1000SCCM; and/or

The flow rate of hydrogen halide is 20~200SCCM.

Further, in some embodiments of the present application, the fluoride is selected from nitrogen fluoride, carbon tetrafluoride, CHF ₃ , CH ₂ F ₂ , C ₄ F ₈ , C ₄ F ₆ , C ₅ F ₈ , hexafluoro one or more of sulfide; and/or

Hydrogen halide is selected from one or more of hydrogen bromide, hydrogen chloride, hydrogen fluoride; and/or

The material of the dielectric layer is selected from one or more of Si ₃ N ₄ , SiO ₂ , SiON, glass, magnesium fluoride, calcium fluoride, or other high-transparency dielectric layer materials for the target application band. one or more; and/or

The substrate is selected from any one of silicon substrates, silicon dioxide substrates, glass substrates, and sapphire substrates.

Further, in some embodiments of the present application, a dielectric layer is formed on the surface of the microlens unit of the array, including:

According to the requirements of the refractive index of the device used in the microlens array, confirm the material of the dielectric layer;

Selecting the process gas for forming the dielectric layer according to the material of the dielectric layer;

At 200-450°C and 0.5-2.0 Torr, a dielectric layer is formed on the surface of the microlens array by using process gas.

Further, in some embodiments of the present application, the thickness of the dielectric layer is 1/4 of the application wavelength λ or an odd multiple of λ/4; wherein, the application wavelength is 1/4 of the working light wave when the microlens array is applied. wavelength; and/or

The ratio of the thickness of the dielectric layer to the central thickness d is 1:100~2000.

In the second aspect, the present application also provides a microlens array, which is prepared by using the method for preparing the microlens array provided in the first aspect.

In the third aspect, the present application also provides the microlens array prepared by the method for preparing the microlens array provided in the first aspect or the application of the microlens array provided in the second aspect in the optical field.

The present application provides a method for preparing a microlens array, which uses nanoimprinting technology to simplify the process of the pattern transfer process of the microlens array, and reduces the process error in the pattern transfer process of the microlens array; at the same time, for different D/d The microlens array, adjusting the ratio of hydrogen halide and fluoride in the etching process, realizes the flexible adjustment of the parameters of the microlens array, so that it can meet the requirements of devices used in different microlens arrays, and improve the accuracy of the microlens array; in addition, The preparation method of the microlens array provided by the application also forms a dielectric layer on the microlens unit, adjusts the focal length and refractive index of the microlens array, further reduces the error between the actually prepared microlens array and the theoretical value, and improves the microlens array. Accuracy and flexibility of adjustment; at the same time, the dielectric layer can also play a role of water vapor isolation, avoid water vapor damage to the microlens unit, and reduce the impact of water vapor on the microlens array. The preparation method of the microlens array provided by this application has simple process steps, and the parameters of the microlens array can be flexibly adjusted to meet different device requirements. The precision is high, which is conducive to the popularization and use of the microlens array; it can also isolate water vapor, Extend the life of the microlens array.

The present application also provides a microlens array, which uses nanoimprint technology to transfer the pattern of the microlens array, and flexibly fine-tunes the parameters and precision of the microlens array through the etching process and dielectric layer, so as to facilitate its popularization and application.

The present application also provides an application of a microlens array, which uses a high-precision microlens array to be applied in the optical field, and improves the accuracy and application range of devices in the optical field.

Description of drawings

In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the specific embodiments or prior art. Obviously, the accompanying drawings in the following description The drawings are some implementations of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

Fig. 1 is the flowchart of the preparation method of the microlens array that the embodiment 1 of the present application provides;

Fig. 2 is the top view of the semi-finished device before etching obtained through step 3;

Fig. 3 is the A-A cross-sectional schematic view of the semi-finished device before etching obtained in step 3;

Fig. 4 is the A-A cross-sectional schematic view of the etched semi-finished device obtained through step 4;

Fig. 5 is the A-A sectional schematic view of the microlens array obtained through step 5;

Fig. 6 is the A-A cross-sectional schematic view of the microlens array obtained in Example 1 of the present application;

Fig. 7 is the scanning lens picture of the microlens array that the embodiment 1 of the present application obtains;

Fig. 8 is the cross-sectional scanning lens picture of the microlens array obtained in Example 1 of the present application;

Fig. 9 is the A-A cross-sectional schematic view of the microlens array obtained in Example 3 of the present application;

Fig. 10 is the A-A cross-sectional schematic view of the microlens array obtained in Example 4 of the present application;

Fig. 11 is the cross-sectional scanning lens picture of the microlens array that the comparative example of the present application obtains;

Description of main component symbols:

10-glass substrate, 20-microlens unit, 30-dielectric layer.

detailed description

The technical solutions of the present application will be clearly and completely described below in conjunction with the embodiments. Apparently, the described embodiments are part of the embodiments of the present application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The following disclosure provides many different implementations or examples for implementing different structures of the present application. To simplify the disclosure of the present application, components and arrangements of specific examples are described below. Of course, they are examples only and are not intended to limit the application. Furthermore, the present application may repeat reference numerals and/or reference letters in various instances, such repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and/or arrangements discussed. In addition, various examples of specific materials are provided herein, but one of ordinary skill in the art may recognize the application of other processes and/or the use of other materials.

The application provides a preparation method of a microlens array, referring to Fig. 1, comprising:

Step 1: providing a substrate, a nanoimprint template with a microlens array pattern or a microlens array reverse pattern;

Step 2: forming the first embossed adhesive layer on the substrate;

Step 3: transfer the pattern of the microlens array to the first embossed adhesive layer using an embossing process, or transfer the reverse pattern of the microlens array to the first embossed adhesive layer using an embossing process, see Fig. 2, image 3;

Step 4: Utilize the etching process to transfer the pattern of the first embossed adhesive layer to the substrate to form the microlens unit of the array, referring to Fig. 4;

Step 5: form medium layer on the microlens unit surface of array, obtain required microlens array, refer to Fig. 5; Wherein, the thickness of medium layer and the requirement of the focal length and/or refractive index of the device according to microlens array application Obtain;

Wherein, in the etching process, according to the ratio of the bottom surface diameter D and the center thickness d of the microlens unit of the microlens array to be obtained, the ratio of hydrogen halide and fluoride in the processing gas used in the etching process is adjusted to obtain required microlens array.

It should be noted that in the application itself, the parameters of the microlens array required by the device can be simulated by finite element electromagnetic simulation software, and its parameters include the spherical curvature radius R ₀ of the microlens unit of the microlens array, the microlens unit The central thickness d of the microlens unit, the angle θ between the cut surface of the surface of the microlens unit and the bottom surface; referring to Fig. 2, when the microlens is formed, the focal length f of the microlens is determined, because: the size of the focal length f is determined by the microlens unit The radius of curvature of the spherical surface R ₀ is determined by the refractive index n ₀ of the substrate material of the microlens and the refractive index n ₁ of the material of the medium layer covering the microlens, namely:

The size of the radius of curvature R of the spherical surface is determined by the bottom surface diameter D of the microlens unit and the center thickness d of the microlens unit _; that is:

Since D and d are determined when the microlens is formed, the radius of curvature R ₀ of the spherical surface is also determined.

When the microlens is formed, the medium covered on the light-emitting surface of the microlens is usually air, therefore, the refractive index n _of the material of the medium layer covered on the microlens is the refractive index of air; and the refractive index of air is 1, that is: when the light-emitting surface of the micro-lens does not cover other dielectric layers, the focal length of the micro-lens is:

Wherein, D is the diameter of the bottom surface of the microlens unit;

Wherein, L is the distance from the projection of the microlens to the center of the bottom surface of the microlens unit at the junction of the spherical surface of the microlens unit and the surface section of the microlens unit.

It should be noted that, in this application, the diameter of the bottom surface of the microlens unit should be understood as the diameter of a circle formed by the vertical projection of a microlens unit on the substrate; the central thickness of the microlens unit should be understood as the vertex of the microlens unit (each The distance from the farthest point of a microlens unit to the substrate) to the shadow formed by the vertical projection of the microlens unit on the substrate. The microlens array includes several microlens units arrayed on the substrate in the form of spherical protrusions or approximately spherical protrusions. Wherein, the refractive index of the substrate material is determined according to the material of the substrate; the focal length of the microlens unit is determined by the performance required by the device to which the microlens array is to be applied.

Therefore, before providing a nanoimprint template with a microlens array pattern, according to the performance requirements of the device and the material of the substrate, use finite element electromagnetic simulation software to simulate the relevant parameters of the microlens, and prepare a nanoimprint template with a microlens array according to this parameter. Patterned nanoimprint templates.

Wherein, the finite element electromagnetic simulation software is commercially available software that can realize three-dimensional simulation of photoelectric components, such as ANSYS Maxwell finite element electromagnetic field simulation software.

In some embodiments, the material of the first embossing glue layer can be UV photoresist (including UV positive photoresist, UV negative photoresist), deep UV photoresist, X-ray glue, electron beam Any of glue and ion beam glue. Correspondingly, a light source or a radiation source may be used to expose the first embossed adhesive layer.

Since the etching effect of the microlens unit is significantly affected by the etching gas during the etching process, the applicant has found through research that the requirements of different D/d microlens units for the etching gas not only require different etching durations, but also It is also necessary to have different requirements for lateral etching so that the surface of the microlens unit can be approximated to a spherical surface. It can be seen that in this application, not only lateral etching is required but also the extent of lateral etching is required to be limited. In view of such etching According to the etching requirements, please provide the preparation method by adding hydrogen halide to the etching gas to limit the lateral etching of the microlens unit, and on this basis, adjust the ratio of the etching gas according to the D/d value, It achieves the effect of not only limiting lateral etching but also restricting lateral etching, so that the surface of the obtained microlens unit is infinitely close to a spherical surface.

In some embodiments, the substrate may be selected from any one of a silicon substrate, a silicon dioxide substrate, a glass substrate, and a sapphire substrate. According to the application wavelength range, select different substrate materials that can pass through this wavelength band. For example, silicon substrates are suitable for infrared light bands, and silicon dioxide, glass, sapphire and other substrates are suitable for ultraviolet light bands, visible light bands, and infrared light bands.

In some embodiments, adjusting the ratio of processing gases used in the etching process includes:

When D/d≥20, the volume ratio of hydrogen halide and fluoride is 1:4.5~8;

When 8≤D/d<20, the volume ratio of hydrogen halide and fluoride is 1:3.5~5;

When 2<D/d<8, the volume ratio of hydrogen halide and fluoride is 1:2~4.

For microlens arrays with different D/d values, the content of hydrogen halide in the etching gas should not be too low, nor should it be too high. Insufficient sidewall protection, the etched lens cannot achieve a smooth transition state, and even presents an uneven stepped shape on the surface of the microlens, which affects optical performance; and the low hydrogen halide content will cause the overall etching speed to be skewed. Low, affecting process efficiency.

In some embodiments, the preparation method further includes, in the etching process, adjusting the polarization power of the equipment performing the etching process according to the ratio of the bottom surface diameter D and the central thickness d of the microlens unit of the microlens array to be obtained :

When D/d≥20, the polarization power of the equipment for etching process is 150~300W;

When 8≤D/d<20, the polarization power of the equipment for etching process is 80~150W;

When 2<D/d<8, the polarization power of the equipment performing the etching process is 0~100W.

The etching gas accelerates to bombard the sample surface under the action of the polarization voltage. The higher the polarization power is, the faster the etching rate is in the direction of the polarization voltage, and the isotropic etching is suppressed.

In some embodiments, using an embossing process to transfer the pattern of the microlens array to the first embossed adhesive layer includes:

Provide a transfer plate, the surface of the transfer plate is provided with a second embossing adhesive layer;

Using a nanoimprint template to imprint on the transfer plate, reversely transfer the pattern of the microlens array to the transfer plate to obtain a reverse transfer plate;

embossing on the first embossing adhesive layer by using a reverse transfer plate, and transferring the pattern of the microlens array to the first embossing adhesive layer;

Using an etching process to transfer the pattern on the first embossed adhesive layer to the substrate, including:

Using the reverse transfer plate as a mask, the pattern on the nanoimprint template is transferred to the substrate by etching process.

Due to the high cost and long preparation time of the nanoimprint template, and each nanoimprint process will cause slight damage to the nanoimprint template; if a nanoimprint template is used for imprinting each microlens array, Then the nano-imprint template will be easily damaged or have large errors soon, making it difficult to continue to use. In this regard, in some embodiments of the present application, a nanoimprint template is used to prepare a transfer plate, and the transfer plate is used as a template to form a microlens array pattern on the first imprint adhesive layer, reducing the frequency of use of the nanoimprint template, The cost of the transfer plate is much lower than that of the nanoimprint template, thereby reducing the production cost; at the same time, when the accuracy of the transfer plate decreases, a new transfer plate with the required precision can be made through the nanoimprint template to ensure the microlens array Consistency of product performance.

In some embodiments, the transferred version is obtained by the following steps:

provide liners;

forming a second embossed adhesive layer on the liner;

Preheating at 50-70°C for 1-2min, coating an anti-adhesion layer on the second embossing adhesive layer, and then heat-treating at 85-95°C for 0.5-1min to obtain a transfer plate.

In some embodiments, the material of the liner is selected from polyester materials, for example, a polyester liner with high cleanliness and low surface roughness is selected.

In some embodiments, preheat treatment at 50-70°C for 1-2min, and then heat-treat at 85-95°C for 0.5-1min after coating an anti-adhesion layer on the second embossed adhesive layer, including:

Pre-baking at 60°C for 1 min, followed by coating an anti-adhesive layer on the second embossing rubber layer, and then baking at 90°C for 45s to obtain a transfer plate.

In some embodiments, the reverse pattern of the microlens array can be reversely transferred to the first imprint adhesive layer by the imprint process directly on the nanoimprint template, including:

The nano-imprint template with the reverse pattern of the microlens array is used to imprint on the first embossing adhesive layer, and the reverse transfer pattern of the microlens array is reversely transferred to the first embossing adhesive layer to form a pattern of the microlens array.

Because imprinting technology refers to the application of mechanical force to make the template with micro-nano structure closely adhere to the imprinting glue, and the imprinting glue in a viscous or liquid state gradually fills the micro-nano structure on the template, and then the embossed The stamping glue is cured, and the template and the stamping glue are separated, so that the pattern of the template structure can be copied to the stamping glue in equal proportions. The micro-nano structure to be processed in this application is a micro-lens array, which has several convex lenses with a spherical surface arranged in arrays. There are grooves on the spherical arc surface, and these grooves are in one-to-one correspondence with the microlens units of the array, so that the microlens units can be formed on the embossed adhesive layer, and then the microlens units can be copied on the substrate through an etching process. A microlens array is formed.

Therefore, in this application, the "microlens array reverse pattern" is a pattern composed of the cavity of each microlens unit and the area between each cavity; the cavity in the pattern corresponds to the microlens unit one by one, in In the embossing process, it serves as a cavity for the microlens unit and is used for molding the microlens unit. "Reverse transfer" in this application should be understood as using the cavity in the reverse pattern of the microlens array to form a microlens unit on the embossed adhesive layer that is concave-convex to match the inner surface of the cavity.

In some embodiments, the pressure in the chamber for the etching process is 5-50 mTorr; and/or

The source power used by the equipment for etching process is 100~1000w; and/or

The time for performing the etching process is 60-180s; and/or

The flow rate of fluoride is 100~1000SCCM; and/or

The flow rate of hydrogen halide is 20~200SCCM.

Preferably, the pressure in the chamber for the etching process is 5-40mTorr; and/or

The source power used by the equipment for etching process is 100~800w; and/or

The flow rate of fluoride is 100~800SCCM; and/or

The flow rate of hydrogen halide is 50~180SCCM.

It should be noted that "SCCM" is the gas mass flow unit, SCCM (Standard Cubic Centimeterper Minute) is standard milliliters per minute; mTorr is the unit of pressure. mTorr is the pressure in microns of mercury, which is one-thousandth of the pressure in millimeters of mercury. 1mTorr is equal to 0.133Pa.

It should be noted that the etching time can be adjusted according to the central thickness of the microlens unit, and the etching time is longer when the central thickness of the microlens unit is higher.

In some embodiments, after forming the microlens units of the array and before forming the dielectric layer on the surface of the microlens units of the array, it also includes: cleaning the surface of the microlens units of the array with an organic solvent and water, removing the microlens units and Organic impurities and particles on the substrate surface.

Wherein, the organic solvent is selected from commercially available organic solvents, such as acetone and ethanol. Water is selected from any of deionized water, pure water, and ultrapure water.

In some embodiments, the surface of the microlens unit of the array is cleaned with an organic solvent and water, including:

The semi-finished device formed with the microlens unit is cleaned with a mixed solution of acetone and ethanol for 2-5 minutes, and then the semi-finished device formed with the microlens unit is ultrasonically washed with deionized water for 0.5-3 minutes. Wherein, the mass ratio of acetone and ethanol may be 1:100-100:1.

In some embodiments, the fluoride is selected from nitrogen fluoride, carbon tetrafluoride, sulfur hexafluoride, and fluorocarbon gases such as CHF ₃ , CH ₂ F ₂ , C ₄ F ₈ , C ₄ F ₆ , and C ₅ F ₈ . one or more of; and/or

Hydrogen halide is selected from one or more of hydrogen bromide, hydrogen chloride, hydrogen fluoride; and/or

The material of the dielectric layer is selected from one or more of Si ₃ N ₄ , SiO ₂ , SiON, glass, calcium fluoride, magnesium fluoride or other transparent or translucent dielectric layer materials. The material of the dielectric layer can be selected according to the wavelength of the working light wave (hereinafter referred to as: application wavelength) when the microlens array provided by this application is applied, and the material that transmits light within the wavelength range of the light is selected as the material of the dielectric layer; And in order to achieve anti-reflection effect, the material of the medium layer can be selected according to the condition: the refractive index of air n ₀ (≈1)<the refractive index of the medium layer n ₁ <the refractive index of the microlens n ₂ .

Among them, the theoretical reflectance R can be calculated by the following formula:

R=(n ₀ ×n ₂ -n ₁ ^2 )^2/(n ₀ ×n ₂ +n ₁ ^2 )^2

，此时理论反射率可达到0。Ideal AR coating material refractive index n ₁ =

, then the theoretical reflectance can reach 0.

The material of the dielectric layer is preferably a dielectric material with stable chemical properties, high transparency against corrosion and oxidation, and at the same time plays the role of protection and reducing reflection. In addition, the dielectric layer can also be multi-layer composite, and the multi-layer composite dielectric layer can be composited with dielectric layers made of different materials to achieve special anti-reflection effects, such as zero reflection or application in a wide bandwidth range.

In some embodiments, a dielectric layer is formed on the surface of the microlens unit of the array, including:

According to the requirements of the refractive index of the device used in the microlens array, confirm the material of the dielectric layer;

Selecting the process gas for forming the dielectric layer according to the material of the dielectric layer;

At 200-450°C and 0.5-2.0 Torr, a dielectric layer is formed on the surface of the microlens array by using process gas.

Among them, "Torr" is the vacuum pressure unit, which is equivalent to the pressure of 1 mm of mercury column.

It should be noted that the material of the medium layer may be the same as or different from that of the microlens unit.

The material of the dielectric layer is deposited on the microlens unit to form a layer of transparent dielectric film on the surface of the substrate, which can not only change the focal length of the microlens array and the refractive index of the microlens array, but also realize the adjustment of the focal length of the microlens array and the angle of the outgoing light. Precise adjustment improves the precision of the microlens array and the flexible adjustment of the application device; it can also isolate water vapor, avoid the influence of water vapor on the microlens unit, and prolong the service life of the microlens array.

In some embodiments, the deposition process of the dielectric layer is selected from one or more of physical vapor deposition (PVD), chemical vapor deposition (CVD), and atomic layer deposition (ALD).

When the deposition process of the dielectric layer is CVD and/or ALD, the process gas used to form the dielectric layer in this application is adjusted according to the material of the dielectric layer. For example: when the material of the dielectric layer is SiO ₂ , the process gas can include: SiH ₄ , N ₂ O, N ₂ ; when the material of the dielectric layer is Si ₃ N ₄ , the process gas can include: SiH ₄ , NH _3. N ₂ .

In some embodiments, when the deposition process of the dielectric layer is CVD and/or ALD, the electrode plate spacing of the equipment used for deposition is 250~500 mils; wherein mil is the unit of length, mils is the plural form of mils, 10mils = hundredths of an inch.

In some embodiments, when the material of the dielectric layer is _SiO2 , the pressure in the process chamber of the equipment used is 1.0 ~ 2.0 Torr; when the material of the dielectric layer is Si, the pressure in the process chamber of the equipment used is The pressure is 0.5-1.0 Torr; when the material of the dielectric layer is Si ₃ N ₄ , the pressure in the process chamber of the equipment used is 1.0-2.0 Torr.

In some embodiments, when the material of the dielectric layer is SiO ₂ , the distance between the pole plates of the equipment used is 350 ~ 500 mils; when the material of the medium layer is Si ₃ N ₄ , the distance between the pole plates of the equipment used is 350~500mils.

In some embodiments, the ratio of the value of the thickness of the dielectric layer to the value of the center thickness is 1:100~2000, the thickness of the dielectric layer is preferably 30~600nm; more preferably 50~500nm; the specific thickness can also be based on the application The wavelength λ is set, and the thickness of the medium layer can be selected as λ/4 or an odd multiple of λ/4, so as to achieve a λ/2 optical path difference between the reflected beams and achieve the mutual cancellation of the reflected beams to reduce reflection and increase microlens transmission.

It should be noted that the range of the thickness of the dielectric layer means that the thickness of the dielectric layer can be adjusted in this range according to the focal length of the device used by the microlens array. For different devices used in the microlens array, the thickness of the dielectric layer Optimal solutions are not the same.

In some embodiments, the thickness of the first embossed adhesive layer can be adjusted according to the central thickness d, so as to completely display the microlens array pattern; however, the thickness of the first embossed adhesive layer should not be too high to avoid excessive Too much imprinting glue residue will affect the time required for the subsequent etching process.

Similarly, the thickness of the second embossed adhesive layer can also be adjusted according to the central thickness d.

Further, the thickness of the first embossed rubber layer is 1.1 to 1.5 times the central thickness d;

The thickness of the second embossed rubber layer is 1.1 to 2 times of the central thickness d.

The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

This embodiment provides a method for preparing a microlens array, which includes:

S1: The required microlens array parameters are obtained by simulating with finite element electromagnetic simulation software, which includes the spherical curvature radius R ₀ of the microlens unit of the microlens array, the central thickness d of the microlens unit, and the surface of the microlens unit The angle θ between the tangent plane and the bottom surface; the ratio (D/d) of the diameter D of the bottom surface of the microlens unit to the central thickness d of the microlens unit (D/d); in this embodiment, D/d≈15; prepare a nanoimprint template according to the parameters;

Select the glass substrate 10, and use hydrogen fluoride aqueous solution and deionized aqueous solution to clean the glass substrate 10 to remove impurities on its surface;

Prepare a liner, spin-coat the second embossed rubber layer on the liner, heat-treat at 60°C for 1min, and then heat-treat at 90°C for 1min to obtain a transfer plate;

S2: Using imprinting technology to transfer the pattern on the nanoimprint template to the transfer plate to obtain a reverse transfer plate;

S3: Spin-coat the first embossing adhesive layer on the glass substrate 10, heat-treat at 60°C for 1min, then heat-treat at 90°C for 1min, and then use the reverse-transfer plate as a template to transfer The pattern is transferred to the first embossed adhesive layer to obtain a semi-finished device;

S4: By applying ESC voltage and controlling the flow rate of helium, the semi-finished device is electrostatically adsorbed in the process chamber of the etching equipment; the semi-finished device is dry-etched for 100s using inductively coupled plasma etching (ICP) etching technology, among which, The chamber temperature is 60°C, the chamber pressure is 8mTorr, and the volume ratio of HBr/(HBr+SF ₄ ) is 1:5; the etching source power is 500W, and the bias power is 100W;

S5: Use deionized water and an organic solvent to clean the impurities on the surface of the semi-finished device after etching, wherein, first use deionized water to ultrasonically clean for 1 min; then use a mixed solution of acetone and ethanol to clean for 3 min; then use deionized water to ultrasonically clean for 1 min, Get clean semi-finished devices;

S6: According to the optical requirements of the device and parameters such as the focal length and refractive index of the microlens unit 20 on the semi-finished device, calculate the difference between the parameters of the microlens unit 20 on the semi-finished device and the parameters corresponding to the optical requirements of the device, and obtain The material and thickness of the dielectric layer 30;

S7: Use CVD technology to deposit a layer of SiO ₂ on the surface of the microlens unit of the semi-finished device, in the process chamber of the CVD technology equipment; the temperature is 350 ° C, the distance between the plates is 400 mils, and the pressure is 1.2 Torr. The volume ratio: SiH ₄ : N ₂ O:N ₂ is 1:7:30.

S8: After the deposition is completed, the product 1 with a microlens center thickness d of about 37 μm, a microlens bottom diameter D of about 560 μm, a D/d of about 15, and a dielectric layer thickness of about 60 nm is obtained. The product schematic diagram is shown in Figure 6, product scan Lens pictures refer to Figure 7 and Figure 8.

Example 2

Compared with Example 1, in this embodiment, in S7, SiH ₄ , NH ₃ , N ₂ are used as process gases to deposit a layer of silicon nitride film on the surface of the microlens unit of the semi-finished device, wherein SiH ₄ , NH ₃ , N ₂ is a volume ratio of 5:1:90, and the rest of the steps are the same as in Example 1 to obtain product 2 with a microlens center thickness d=41 μm, a microlens bottom diameter D of about 585 μm, and a dielectric layer thickness of 100 nm.

Example 3

Compared with Embodiment 1 in this embodiment, the ratio (D/d) of the bottom surface diameter D of the microlens unit to the central thickness d of the microlens unit in S1: D/d≈25; in S4, the etching time is 120s, wherein the chamber temperature is 60°C, the chamber pressure is 10mTorr, the volume ratio of HBr/(HBr+SF ₄ ) is 1:6; the etching source power is 650W, and the bias power is 200W.

The rest of the steps are the same as in Example 1 to obtain product 3 with a focal length of the microlens center thickness d=24.5 μm, a microlens bottom diameter D of about 600 μm, and a dielectric layer thickness of 80 nm, see FIG. 9 .

Example 4

Compared with Embodiment 1 in this embodiment, the ratio (D/d) of the bottom surface diameter D of the microlens unit to the central thickness d of the microlens unit in S1: D/d≈6; in S4, the etching time is 80s, wherein the chamber temperature is 70°C, the chamber pressure is 8mTorr, the volume ratio of HBr/(HBr+SF ₄ ) is 1:4; the etching source power is 550W, and the bias power is 65W.

The rest of the steps are the same as in Example 1 to obtain product 4 with a focal length of the center thickness of the microlens d=67 μm, a diameter D of the bottom surface of the microlens of about 400 μm, and a thickness of the dielectric layer of 100 nm, see FIG. 10 .

Comparative example 1

Compared with Example 1 in this comparative example, the volume ratio of HBr/(HBr+SF ₄ ) in S4 is 1:7 and the rest of the steps are the same as in Example 1 to obtain a focal length of microlens center thickness d=530 μm, microlens The bottom surface diameter D is about 20 μm, and the comparison product 1 with a dielectric layer thickness of 100 nm, see FIG. 11 .

It can be seen from Figure 11 that under the same etching time, the content of HBr is too low, resulting in insufficient protection of the sidewall of the microlens unit during the etching process, and the etched lens cannot achieve a better smooth transition state, or even The surface of the microlens is uneven and stepped.

Can know from the D/d value of the microlens that embodiment 1～embodiment 4 obtains, the microlens central thickness that adopts this method to obtain, bottom surface diameter and the value of D/d and the central thickness of the microlens unit obtained by simulation, bottom surface The diameter and the value of D/d are almost the same. It can be seen that the microlens unit prepared by the preparation method of the microlens array provided by the present application is consistent with the parameters of the preset microlens unit, and its accuracy is high, and The parameters of the micro-lens unit can be adjusted according to needs, which is beneficial to adjust the parameters of the micro-lens unit for different devices and make it more applicable.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit it; although the application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present application. scope.

Claims (11)

1. a preparation method of microlens array, is characterized in that, comprises: providing a substrate, a nanoimprint template having a microlens array pattern or a microlens array reverse pattern; forming a first embossed adhesive layer on the substrate; Using an embossing process to transfer the pattern of the microlens array to the first embossed adhesive layer, or to use an embossing process to reversely transfer the pattern of the microlens array to the first embossed adhesive layer ; transferring the pattern on the first embossed adhesive layer to the substrate by an etching process to form an array of microlens units; Form a dielectric layer on the surface of the microlens unit of the array to obtain the required microlens array; wherein, the thickness and material of the dielectric layer are obtained according to the focal length and/or refractive index requirements of the device used in the microlens array ; Wherein, in the etching process, according to the ratio of the diameter D of the bottom surface of the microlens unit of the microlens array to the thickness d of the center to be obtained, the hydrogen halide and the hydrogen halide in the processing gas used in the etching process are adjusted. Fluoride ratios to obtain the desired microlens array. 2. the preparation method of microlens array according to claim 1, is characterized in that, adjusting the ratio of the processing gas adopted in described etching process comprises: When D/d≥20, the volume ratio of the hydrogen halide to the fluoride is 1:4.5~8; When 8≤D/d<20, the volume ratio of the hydrogen halide to the fluoride is 1:3.5~5; When 2<D/d<8, the volume ratio of the hydrogen halide to the fluoride is 1:2-4. 3. the preparation method of microlens array according to claim 2, is characterized in that, described preparation method also comprises, in described etching process, according to the bottom surface of the microlens unit of described microlens array to be obtained The ratio of diameter D and center thickness d to adjust the polarization power of the equipment carrying out the etching process: When D/d≥20, the polarization power of the equipment for performing the etching process is 150~300W; When 8≤D/d<20, the polarization power of the equipment for performing the etching process is 80~150W; When D/d<8, the polarization power of the equipment for performing the etching process is 0-100W. 4. The preparation method of the microlens array according to claim 1, characterized in that, utilizing an embossing process to transfer the microlens array pattern to the first embossed adhesive layer, comprising: providing a transfer plate, the surface of the transfer plate is provided with a second embossing rubber layer; Using the nanoimprint template with the microlens array pattern to imprint on the transfer plate, reversely transferring the microlens array pattern onto the transfer plate to obtain a reverse transfer plate; Using the reverse transfer plate to perform embossing on the first embossing adhesive layer, transferring the pattern of the microlens array to the first embossing adhesive layer; Using an etching process to transfer the pattern on the first embossed adhesive layer to the substrate, including: Using the first imprint adhesive layer formed with the microlens array pattern as a mask, the pattern on the nano-imprint template is transferred to the substrate by an etching process. 5. The preparation method of the microlens array according to claim 1, characterized in that, utilizing an embossing process to reversely transfer the reverse pattern of the microlens array to the first embossed adhesive layer, comprising: Imprinting is carried out on the first imprint adhesive layer by using the nanoimprint template having the reverse pattern of the microlens array, and reversely transferring the reverse pattern of the microlens array to the first imprint A microlens array pattern is formed on the adhesive layer. 6. the preparation method of microlens array according to claim 1, is characterized in that, the pressure in the chamber that carries out described etching process is 5～50mTorr; And/or The source power used by the equipment for the etching process is 100-1000w; and/or The time for performing the etching process is 60-180s; and/or The flow rate of the fluoride is 100~1000SCCM; and/or The flow rate of the hydrogen halide is 20-200 SCCM. 7. The preparation method of the microlens array according to claim 1, wherein the fluoride is selected from nitrogen fluoride, carbon tetrafluoride, CHF ₃ , CH ₂ F ₂ , C ₄ F ₈ , C ₄ One or more of F ₆ , C ₅ F ₈ , sulfur hexafluoride; and/or The hydrogen halide is selected from one or more of hydrogen bromide, hydrogen chloride, hydrogen fluoride; and/or The material of the dielectric layer is selected from one or more of Si ₃ N ₄ , SiO ₂ , SiON, glass, magnesium fluoride, and calcium fluoride; and/or The substrate is selected from any one of silicon substrates, silicon dioxide substrates, glass substrates, and sapphire substrates. 8. the preparation method of microlens array according to claim 1, is characterized in that, forms dielectric layer on the microlens unit surface of described array, comprises: Confirming the material of the dielectric layer according to the requirements of the refractive index of the device used by the microlens array; selecting a process gas for forming the dielectric layer according to the material of the dielectric layer; The dielectric layer is formed on the surface of the microlens array by using process gas at 200-450° C. and 0.5-2.0 Torr. 9. the preparation method of microlens array according to claim 1, is characterized in that, the thickness of dielectric layer is the odd multiple of 1/4 or λ/4 of application wavelength λ; Wherein, described application wavelength is described microlens The wavelength of the working light wave when the lens array is applied; and/or The ratio of the thickness of the dielectric layer to the central thickness d is 1:100-2000. 10. A microlens array, characterized in that it is prepared by the method for preparing a microlens array according to any one of claims 1 to 9. 11. The preparation method of the microlens array according to any one of claims 1 to 9 prepares the microlens array or the application of the microlens array according to claim 10 in the optical field.

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