阅读说明：本技术 一种双面微透镜阵列制备方法及紫外led封装装置 (Double-sided micro-lens array preparation method and ultraviolet LED packaging device ) 是由 何苗 高炯健 熊德平 于 2021-08-26 设计创作，主要内容包括：本发明涉及紫外LED制备领域,更具体地,涉及一种双面微透镜阵列制备方法,采用该制备方法在蓝宝石玻璃透镜的上下表面制作均匀、大面积且易于控制的微透镜阵列,基于几何光学的折射原理,光在两种透明介质交界处,将向折射率高的区域弯折。材料的折射率越高,入射光发生折射的能力越强。通过这个原理,将一个完整的激光波前在空间上分成许多微小的部分,每一部分被相应的小透镜聚焦在焦平面上,光斑进行重叠,从而实现在特定区域将光均匀化。将该蓝宝石玻璃透镜应用在紫外LED封装装置上,降低深紫外LED封装光学窗口-空气界面之间的全反射损失,将经过透镜的光聚焦在焦平面上,同时增加发射光的耦合能力,均匀紫外LED的出光强度。(The invention relates to the field of ultraviolet LED (light-emitting diode) preparation, in particular to a method for preparing a double-sided micro-lens array. The higher the refractive index of the material, the greater the ability of incident light to be refracted. By this principle, a complete laser wavefront is spatially divided into a number of tiny portions, each focused by a respective lenslet on the focal plane, and the spots overlap, thereby achieving light homogenization in a particular region. The sapphire glass lens is applied to an ultraviolet LED packaging device, so that the total reflection loss between an optical window and an air interface of deep ultraviolet LED packaging is reduced, light passing through the lens is focused on a focal plane, the coupling capacity of emitted light is increased, and the light-emitting intensity of an ultraviolet LED is uniform.)

1. A method for preparing a double-sided micro-lens array is characterized by comprising the following steps: selecting a sapphire glass lens, and carrying out the following preparation steps:

s1 one side of the sapphire glass lens is polished, and 200nm thick SiO is deposited on the polished surface by plasma chemical vapor deposition₂Membrane, the treatment temperature is 300 ℃;

s2 spin-coating a positive photoresist with the thickness of 700nm, performing projection exposure by adopting a mask, and performing projection exposure by using a stepping photoetching machine, wherein the exposure wavelength is 365nm, and the exposure time is 290 ms;

s3 developing the positive photoresist position for 50 seconds to form nano-holes, and then transferring the pattern to SiO by plasma etching₂On film for 1 minute;

s4 the strong acid mixture was heated to 270 ℃ for 6 minutes to etch sapphire, and then SiO was removed by oxygen plasma etching₂Masking;

s5, repeating the operations S1-S4 on the other surface of the sapphire glass lens to complete double-surface preparation;

s6 cuts the sapphire glass lens having the nano-array into square units using a laser, and encapsulates on the deep ultraviolet LED by using a fluoropolymer encapsulant to form a sealing structure.

2. The double-sided microlens array of claim 1The preparation method is characterized by comprising the following steps: in said S3, the plasma etching is in CF₄And O₂In the mixed atmosphere of (3).

3. The method for manufacturing a lenticular lens array according to claim 2, wherein: the strong acid mixture is a mixture of 98% concentrated sulfuric acid and 84% concentrated phosphoric acid solution, and the volume ratio of the two strong acids is 3: 1.

4. a deep ultraviolet LED packaging hardware which characterized in that: the sapphire glass lens comprises a ceramic base, an ultraviolet LED chip and the sapphire glass lens as claimed in claim 3, wherein the ceramic base is provided with a groove, the ultraviolet LED chip is in flip-chip welding in the groove through gold-tin eutectic, and at least two metal layers are arranged between the positive electrode and the negative electrode of the ultraviolet LED chip and the bottom surface of the groove;

the edge of the groove is provided with a stepped structure, and the sapphire glass lens is arranged on the stepped structure and completely covers the groove.

5. The deep ultraviolet LED package device of claim 4, wherein: and protective gas is filled in a closed space formed by the groove and the sapphire glass lens.

6. The deep ultraviolet LED package device of claim 5, wherein: the curvature radius of the lens of the cubic unit of the sapphire glass lens facing to one surface of the ultraviolet LED chip is 27nm, and the curvature radius of the lens of the opposite surface is 22 nm.

7. The deep ultraviolet LED package apparatus of claim 6, wherein: the light dominant wavelength of the ultraviolet LED chip is 260 nm.

8. The deep ultraviolet LED package apparatus of claim 7, wherein: the cubic cell has a lens thickness of 12 nm.

9. The deep ultraviolet LED package apparatus of claim 8, wherein: the external dimension of the ultraviolet LED chip is 1mm X1 mm, and the bottom of the ultraviolet LED chip is provided with a symmetrical electrode.

10. The deep ultraviolet LED package apparatus of claim 9, wherein: the ceramic base is an aluminum nitride ceramic base.

Technical Field

The invention relates to the field of ultraviolet LED preparation, in particular to a double-sided micro-lens array preparation method and an ultraviolet LED packaging device.

Background

With the development of the technology, the performance of the ultraviolet LED is continuously improved, and compared with the current commonly used gas ultraviolet light source, the ultraviolet LED belongs to a cold light source, has the advantages of long service life, high reliability, uniform irradiation brightness, high efficiency and no toxic substance, and plays an important role in the fields of biomedical treatment, surface sterilization and cleaning, printing and photoetching, photocuring production, communication detection and the like.

However, the development of the deep ultraviolet LED faces many challenges at present, and the conventional LED package structure causes uneven light emission of the ultraviolet LED chip, and cannot meet the requirements of high performance and high uniformity of the ultraviolet LED. Therefore, the improvement of the light extraction rate and the light extraction uniformity of the ultraviolet LED packaging device is a research focus in the field of ultraviolet LED packaging.

Publication No. CN106935695A discloses an ultraviolet LED device, LED chip sets up in the support bottom, and ultraviolet LED chip eutectic face down welds in the ultraviolet LED device in the scheme, covers quartz glass apron again, keeps the closed ring space. However, the light extraction rate and the light uniformity of the quartz glass cover plate are not sufficient to achieve the best effect, and need to be improved.

Disclosure of Invention

The invention provides a double-sided micro-lens array preparation method and a deep ultraviolet LED packaging structure using the double-sided micro-lens array for the light extraction rate and the light extraction uniformity of an ultraviolet LED packaging device.

In order to solve the technical problems, the invention adopts the technical scheme that:

a method for preparing a double-sided micro-lens array selects a sapphire glass lens and comprises the following preparation steps: s1 one side of the sapphire glass lens is polished, and 200nm thick sapphire glass lens is deposited on the polished surface by plasma chemical vapor depositionSiO₂Membrane, the treatment temperature is 300 ℃;

s2 spin-coating a positive photoresist with the thickness of 700nm, performing projection exposure by adopting a mask, and performing projection exposure by using a stepping photoetching machine, wherein the exposure wavelength is 365nm, and the exposure time is 290 ms;

s3 developing the positive photoresist position for 50 seconds to form nano-holes, and then transferring the pattern to SiO by plasma etching₂On film for 1 minute;

s4 the strong acid mixture was heated to 270 ℃ for 6 minutes to etch sapphire, and then SiO was removed by oxygen plasma etching₂Masking;

s5, repeating the operations S1-S4 on the other surface of the sapphire glass lens to complete double-surface preparation;

s6 cuts the sapphire glass lens having the nano-array into square units using a laser, and encapsulates on the deep ultraviolet LED by using a fluoropolymer encapsulant to form a sealing structure.

The deep ultraviolet LED has a better light uniform state by using the micro-nano array double-sided lens, and light bends towards an area with high refractive index at the junction of two transparent media (such as air and glass) based on the refraction principle of geometric optics. The higher the refractive index of the material, the greater the ability of incident light to be refracted. By this principle, a complete laser wavefront is spatially divided into a number of tiny portions, each focused by a respective lenslet on the focal plane, and the spots overlap, thereby achieving light homogenization in a particular region.

Specifically, in S3, the plasma etching is in CF₄And O₂In the mixed atmosphere of (3).

Specifically, the strong acid mixture is a mixture of 98% concentrated sulfuric acid and 84% concentrated phosphoric acid solution, and the volume ratio of the two strong acids is 3: 1.

meanwhile, the deep ultraviolet LED packaging device comprises a ceramic base, an ultraviolet LED chip and the sapphire glass lens which is processed, wherein the ceramic base is provided with a groove, the ultraviolet LED chip is in flip-chip welding in the groove through gold-tin eutectic, and at least two metal layers are arranged between the positive electrode and the negative electrode of the ultraviolet LED chip and the bottom surface of the groove. The ceramic base is an AlN ceramic base, and at least two metal layers with good heat conduction and electric conductivity are arranged between the positive electrode and the negative electrode of the ultraviolet LED chip and the bottom surface of the groove, so that eutectic flip-chip welding of the ultraviolet LED chip is realized.

The sapphire glass lens is adopted to replace commonly used quartz plate glass, and the upper surface and the lower surface of the sapphire glass lens are utilized to manufacture uniform, large-area and easily-controlled nano arrays, so that the total reflection loss between an optical window and an air interface of the deep ultraviolet LED packaging can be reduced, the coupling capacity of emitted light is increased, and the light uniformity of the deep ultraviolet LED is enhanced.

In addition, the edge of the groove is provided with a step-shaped structure, and the sapphire glass lens is arranged on the step-shaped structure and completely covers the groove. The sapphire glass lens is bonded and fixed with the groove stepped structure.

Furthermore, protective gas is filled in a closed space formed by the groove and the sapphire glass lens, and the protective gas is inert gas or nitrogen.

Furthermore, the lens curvature radius of one surface, facing the ultraviolet LED chip, of the cubic unit of the sapphire glass lens is 27nm, and the lens curvature radius of the opposite surface of the cubic unit of the sapphire glass lens is 22 nm. Because the curvature radius is too large, the gradual change of the refractive index of the microlens array layer is not obvious, and the illumination intensity and the light intensity are reduced. Too small a radius of curvature may result in increased microlens array thickness, which is detrimental to light transmission, thereby reducing illuminance and light intensity.

Further, the light dominant wavelength of the ultraviolet LED chip is 260 nm.

Further, the thickness of the lenses of the cubic unit is 12 nm.

Furthermore, the external dimension of the ultraviolet LED chip is 1mm X1 mm, and the bottom of the ultraviolet LED chip is provided with a symmetrical electrode. The symmetrical electrodes are welded with the metal layer.

Further, the ceramic base is an aluminum nitride ceramic base.

Compared with the prior art, the invention has the beneficial effects that: the invention discloses a preparation method of a double-sided micro-lens array, which is used for processing selected sapphire glass lenses to form nano-arrays on the upper surface and the lower surface and improve the refractive index of light.

According to the deep ultraviolet LED packaging structure of the double-sided micro-lens array, the sapphire glass lens of the double-sided micro-lens array is used for replacing quartz plate glass, the uniform, large-area and easily-controlled nano array is manufactured on the upper surface and the lower surface of the sapphire glass lens, the total reflection loss between an optical window and an air interface of the deep ultraviolet LED packaging can be reduced, light passing through the lens is focused on a focal plane, meanwhile, the coupling capacity of emitted light is increased, and the light-emitting intensity of the ultraviolet LED is uniform. The micro-lens array deep ultraviolet LED packaging structure also has the advantages of high luminous intensity, static discharge damage prevention, high efficiency, reliability and the like.

Drawings

FIG. 1 is a schematic diagram of an ultraviolet LED package structure of the embodiment.

Fig. 2 is a schematic view of a sapphire glass lens structure.

Fig. 3 is a side view of a sapphire glass lens.

Fig. 4 is a simulation diagram of the package structure of this example.

FIG. 5 is a graph of peak light intensity data from the simulation experiment of this example.

Fig. 6 is a graph of peak irradiance data for the present example simulation experiment.

Fig. 7 is a simulation diagram of a comparative example package structure.

Fig. 8 is a graph of peak light intensity data for a comparative example simulation experiment.

Fig. 9 is a graph of peak irradiance data for a comparative example simulation experiment.

Wherein, 1 ceramic substrate, 2 ultraviolet LED chips, 3 sapphire glass lens, 4 recesses, 5 metal levels, 6 stairstepping structures.

Detailed Description

The drawings are for illustrative purposes only and are not to be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent.

Examples

As shown in fig. 1 to 3, this embodiment provides a method for manufacturing a double-sided microlens array, which selects a sapphire glass lens 3 with a suitable size, and performs the following steps:

first, one side of the sapphire glass lens 3 was subjected to single-side polishing, and 200nm thick SiO was deposited on the polished surface by plasma chemical vapor deposition₂Membrane, the treatment temperature is 300 ℃; then, spin-coating a positive Photoresist (PR) with the thickness of 700nm, performing projection exposure by adopting a mask, and then performing projection exposure by using a stepping photoetching machine, wherein the exposure wavelength is 365nm, and the exposure time is 290 ms; the PR was then developed for 50 seconds to form nanopores, and the pattern was transferred to SiO by plasma etching₂On film for 1 minute, with plasma etch at CF₄And O₂In a mixed atmosphere of (a); finally, the sapphire is etched after the mixture of 98% concentrated sulfuric acid and 84% concentrated phosphoric acid solution is heated to 270 ℃, and the volume ratio of the two strong acids is 3: 1, etching time 6 minutes, then removing SiO by oxygen plasma etching₂And (5) masking.

Similarly, the above operations are repeated for the other surface of the sapphire glass lens 3, and double-sided processing of the sapphire glass lens 3 is completed. After the completion of the process, the sapphire glass lens 3 having a nano array is cut into a plurality of cube units using a laser, and is encapsulated on a deep ultraviolet LED by using a fluoropolymer sealant to form a sealing structure.

Simultaneously, this embodiment still provides a dark ultraviolet LED packaging hardware, including ceramic base 1, ultraviolet LED chip 2 and two-sided sapphire glass lens 3 that has the nano-array, wherein, ceramic base 1 is aluminium nitride ceramic base 1(AlN), and ceramic base 1 is equipped with recess 4, and recess 4 includes that it is domatic to become the annular of predetermineeing the angle with the horizontal plane, and ultraviolet LED chip 2's overall dimension is 1mm X1 mm, and the bottom is symmetrical electrode. Ultraviolet LED chip 2 is located recess 4 bottom central authorities, and the outside draft expansion of recess 4 lateral wall avoids separation ultraviolet LED chip 2's light path to propagate, and ultraviolet LED chip 2's light dominant wavelength is 260 nm.

In this embodiment, the ultraviolet LED chip 2 is flip-chip bonded in the groove 4 through gold-tin eutectic, generally, there are three metal layers 5 between the positive and negative electrodes of the ultraviolet LED chip 2 and the bottom surface of the groove 4, each metal layer 5 includes a first metal layer 5 plated on the positive and negative electrodes of the ultraviolet LED chip 2, a second metal layer 5 plated on the bottom surface of the groove 4, and a third metal layer 5 located between the first metal layer 5 and the second metal layer 5, the first metal layer 5 and the second metal layer 5 are both gold film layers, the third metal layer 5 is a tin film layer, the thickness of the first metal layer 5 is 7-10um, the thickness of the second metal layer 5 is 3-5um, and the third metal layer 5 is 4-5 um.

In addition, the edge of the groove 4 is provided with a step-shaped structure 6, the sapphire glass lens 3 is arranged on the step-shaped structure 6, the sapphire glass lens 3 completely covers the groove 4, and a closed space is formed between the sapphire glass lens and the groove 4 and filled with protective gas which can be inert gas or nitrogen. Specifically, the stepped structure 6 and the sapphire glass lens 3 with the nano array are bonded by using a fluorine-containing polymer sealant as an inorganic adhesive, so that the groove 4 forms a sealed space.

In this embodiment, the cube unit of sapphire glass lens 3 is 27um towards the lens radius of 2 one sides of ultraviolet LED chip, and the lens radius of relative one side is 22um, and the lens thickness of cube unit is 12 um. The upper surface and the lower surface of the sapphire glass lens 3 are provided with the nano lens arrays, so that the total reflection loss between an optical window and an air interface of the deep ultraviolet LED packaging is reduced, the coupling capacity of emitted light is increased, and the light uniformity of the deep ultraviolet LED is enhanced.

In addition, in this embodiment, the prepared sapphire glass lens 3 and the common sapphire flat glass are respectively used as cover plates of the ultraviolet LED package structure, and other parameters are kept consistent, and a ZMAX simulation comparison experiment is performed.

The sapphire glass lens 3 of the double-sided microlens array is arranged in one of the packaging structures, and the packaging structure is the present example; sapphire flat glass was set in another package structure as a comparative example. The luminescence properties of the two structures were measured at a distance of 10cm from the glass surface and the data are shown in FIGS. 4-9:

	this example is a	Comparative example
			Peak light intensity	19.187W/steradian	11.309W/steradian
Peak irradiance	0.00153W/mm2	0.001135W/mm2

It can thus be concluded that the higher light intensity and illuminance in this example compared to the comparative example, the reason for the better light uniformity is due to:

the microlens array layer refractive index gradient and the pattern array optical coupling characteristics, for a nanostructure, the light transmittance is a function of the geometry and dimensions of the nanostructure and the wavelength of the incident light. Therefore, the nano-array optical coupling enhancement is a combined result of the gradual change two-dimensional nano structure and the continuous spherical form of the surface pattern, the range of the photon escape cone can be effectively expanded, and the total reflection loss at the lens-air interface is reduced.

Based on the principle of refraction in geometric optics, light will bend toward the region with high refractive index at the interface of two transparent media (such as air and glass). The higher the refractive index of the material, the greater the ability of incident light to be refracted. By this principle, a complete laser wavefront is spatially divided into a number of tiny portions, each focused by a respective lenslet on the focal plane, and the spots overlap, thereby achieving light homogenization in a particular region.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.