CN103779489A - Light-emitting diode with light guiding hole structure - Google Patents

Abstract

The invention discloses a light-emitting diode with a light-guiding hole structure. A light-guiding layer is formed on the upper surface of a light-emitting chip of the light-emitting diode, and the light-guiding layer includes a lower film in contact with the light-emitting chip and an upper layer above A film, wherein a plurality of light guide holes are formed through the upper film, and each light guide hole is filled with an optical material having a higher refractive index than the upper film and the lower film. In the light-emitting diode with a light-guide hole structure provided by the present invention, when the light is injected into the light-thinning medium film at a certain angle, the oblique light will undergo multiple total reflections in the structure film of the light-guide layer, and finally pass through the light-guide hole uniformly from the chip The front side sees through, without reducing the light intensity, it solves the problem of low light efficiency on the front side of the LED chip, and improves the brightness of the chip package.

Description

A light-emitting diode with a light guide hole structure

technical field

The invention relates to a light guiding layer, in particular to a light emitting diode with a light guiding hole structure.

Background technique

LED is widely used in lighting and other fields because of its many advantages such as energy saving, environmental protection, high reliability and long life. For front-mounted LED chips, the full-angle light emission characteristics of the epitaxial layer determine that only a very small part of the light is transmitted perpendicular to the front of the chip, while most of the light is transmitted from the chip and has a large angle to the vertical direction of the front, which greatly reduces the front light emission of the chip. Efficiency. Although the later packaging changes the light path by adding side reflective structures, it is often accompanied by a large loss of light efficiency. The disadvantage of low front light efficiency has seriously restricted the development and application of LED lighting chips in downstream sections.

Contents of the invention

The invention provides a light-emitting diode with a light guide hole structure. When the light is injected into the light-thinning medium film at a certain angle, the obliquely incident light will undergo multiple total reflections in the structure film of the light guide layer, and finally pass through the light guide hole uniformly from the The front side of the chip is exposed, and without reducing the light intensity, it solves the problem of low light efficiency on the front side of the LED chip and improves the brightness of the chip package.

The invention provides a light-emitting diode with a light-guiding hole structure. A light-guiding layer is formed on the upper surface of a light-emitting chip of the light-emitting diode, and the light-guiding layer includes a lower film in contact with the light-emitting chip and an upper film on top. A plurality of light guide holes are formed through the upper film, and each light guide hole is filled with an optical material having a higher refractive index than the upper film and the lower film.

The cross-sectional shape of the light guide hole is an isosceles inverted trapezoidal structure.

The material of the lower film is the same as that of the lower film.

The materials of the lower film and the lower film are different, and there is an intermediate film between the upper film and the lower film, and the material of the intermediate film is the same as the light guide material filled in the light guide hole.

The light-guiding layer is prepared through the following process: first, a lower film is prepared on the upper surface of the light-emitting chip of the light-emitting diode, and then a light-guiding hole film layer of the same material as that in the light-guiding hole is prepared on the upper surface of the lower film, and then Etching or etching is carried out intermittently on the light guide hole film layer, the depth of etching or corrosion is the thickness of the light guide hole film layer, and a plurality of light guide holes are formed on the unetched or corroded part, and then Deposit the upper layer of thin film material at the position removed by etching or etching, the deposition thickness is equal to the depth of the light guide hole, and finally form the light guide layer.

The material of the upper film and the lower film of the light guide layer is SiO ₂ , and the material deposited in the light guide hole is ITO.

The light guide layer is prepared through the following process: first, the lower layer film is formed on the surface of the LED light-emitting chip, and then the intermediate layer film is prepared on the surface of the lower layer film, and the cross-section of the intermediate layer film is processed intermittently by etching or etching. Multiple grooves in the waist trapezoidal structure, the etching or corrosion depth is less than the thickness of the middle layer film, and the upper layer film material is filled in the corresponding etched or corroded part to form the upper layer film, corresponding to the discontinuity that has not been etched or corroded The permanent part forms a light guide hole, and finally forms a light guide layer.

The light guiding layer is prepared through the following process: the material of the upper layer film is SiO ₂ ; the material of the middle layer film and the light guide hole is Si ₃ N ₄ ; the material of the lower layer film is ITO.

The incident angle of the light entering the light guide layer is α; the upper base angle of the isosceles inverted trapezoidal structure of the light guide hole is β, the refractive index of the lower film is n ₁ , and the refractive index of the lower film is n ₃ , the refractive index of the light guide hole and the interlayer film is n ₂ , the angle between the light entering the light guide hole and the direction perpendicular to the side wall of the light guide hole is i, where α ≥arc sin(n ₃ /n ₂ ), and α≥arc sin(n ₁ /n ₂ ).

The upper base angle of the isosceles inverted trapezoidal structure of the light guide hole is β, the angle between the light entering the light guide hole and the direction perpendicular to the side wall of the light guide hole is i, and the light emitted from the light guide hole The angle between the outgoing light and the vertical direction is α ₁ , then i≤90°, α≥90°-β, and i≥arc sin(n ₃ /n ₂ ), α≤180°-β-(arc sin( n3/n2)), β+(arc sin(n ₃ /n ₂ ))-90°=arc sin(T/(L+(T/sinβ))), arc sin(T/(L+(T/sinβ) ))=90°-α, where T is the depth of the light guide hole, and L is the width of the bottom of the inverted trapezoidal structure.

The present invention has the advantage that:

The invention provides a light-emitting diode with a light guide hole structure. When the light is injected into the light-thinning medium film at a certain angle, the obliquely incident light will undergo multiple total reflections in the structure film of the light guide layer, and finally pass through the light guide hole uniformly from the The front side of the chip is exposed, and without reducing the light intensity, it solves the problem of low light efficiency on the front side of the LED chip and improves the brightness of the chip package. This new type of LED has a remarkable effect of concentrating light from the front, and has two ways of emitting light from the front at 45° to 135° (that is, α ₁ =0-45°) and vertically at 90°, so it will be used in LED spotlights, LED Widely used in fields such as large searchlights.

Description of drawings

Fig. 1 is a schematic structural view of the first light guide layer in the present invention;

Fig. 2 is a schematic structural diagram of the second light guiding layer in the present invention.

In the figure: 1-lower film; 2-upper film; 3-light guide hole; 4-intermediate film.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the examples given are not intended to limit the present invention.

The invention provides a light-emitting diode with a light-guiding hole structure, which has a light-guiding layer film on the surface of the LED light-emitting chip, the light-guiding layer film is formed on the surface of the light-emitting chip of the light-emitting diode, and the light-guiding layer film It is a combined film layer, and the combined film layer has high transmittance in the visible light wavelength range. As shown in FIG. 1 , the light guide layer includes a lower film 1 in contact with the light-emitting chip, and an upper film 2 above. A plurality of light guide holes 3 are formed through the upper film 2 . The depth is the same as the thickness of the upper film 2 . The plurality of light guide holes 3 are filled with a light guide material with a higher refractive index than the upper film 2 and the lower film 1 . Wherein, the materials of the upper film 2 and the lower film 1 can be the same or different. When the two materials are different, it is required that the refractive index of the two must be smaller than the optical material filled in the light guide hole 3 . The cross-sectional shape of the light guide hole 3 is an inverted trapezoidal structure, and is an isosceles trapezoidal shape. The selection of filling materials in the upper film 2, the lower film 1 and the light guide hole can cover all optical _materials with a refractive index in the range of 1.0 to 2.4, such as _Al2O3 film, ITO film, _SiO2 film, _{Si3N 4} thin films, GaN thin films and other optical films suitable for the light guiding layer of the present invention. The cross-sectional shape of the light guide hole is an isosceles inverted trapezoidal structure.

When the materials of the lower film 1 and the upper film 2 are different, as shown in FIG. The refractive index of the light guiding material is the same, and its specific thickness is not limited.

To sum up, the combination of the light guide layer film in the present invention has the following two methods:

1. The light guide layer is composed of two thin film materials with different refractive indices. The light guide hole 3 is filled with an optical material with a higher refractive index, and the lower film 1 and the upper film 2 are the same film with a lower refractive index. For example, SiO ₂ -ITO-SiO ₂ . A plurality of light guide holes 3 are formed in the upper film 2, and the cross-sectional shape of the light guide holes 3 is an isosceles inverted trapezoidal structure.

2. A light guide layer composed of three film materials with different refractive indices. The lower film 1 and the upper film 2 are two different films with lower refractive index. The upper film 2 has multiple light guide holes 3, and the lower film 1 and the upper film 2 have a middle layer film 4 material with a higher refractive index that is the same as the material filled in the light guide hole 3 . For example, SiO ₂ -GaN-ITO or SiO ₂ -Si ₃ N ₄ -ITO, and the materials of the lower film 1 and the upper film 2 can be interchanged. The cross-sectional shape of the light guide hole 3 is an isosceles inverted trapezoidal structure.

In the present invention, the size of the light guide hole 3 and the depth of the light guide hole 3 meet a certain relationship with the refractive index of the optical material filled in the lower film 1, the upper layer film 2, and the light guide hole 3, so that light can enter from all directions The light in the layer is all reflected, the specific relationship is as follows:

The upper base angle of the isosceles inverted trapezoidal structure of the light guide hole 3 is β, the angle between the incident light and the vertical direction is α, the refractive index of the lower film 1 is n ₁ , and the refractive index of the lower film 1 is n ₃ , the guide The refractive index of the light hole 3 is n ₂ (when the refractive index of the upper film 2 and the lower film 1 are different, the middle film 4 is also included, and its refractive index is also n ₂ ), the light is finally emitted from the light guide hole 3 The included angle between the outgoing light and the vertical direction is α ₁ . For the second structure, it is necessary for the light to enter the light guide hole 3 after multiple total reflections in the middle layer, and all the light is emitted after entering the light guide hole 3 .

To make the incident light with an incident angle α form total reflection between the middle layer film 4 and the upper layer film 2, then α satisfies α≥arc sin(n ₃ /n ₂ ); Total reflection is formed between, then α≥arc sin (n ₁ /n ₂ ).

After entering the light guide hole 3 after total reflection, total reflection needs to occur in the light guide hole 3 , that is, the light entering the light guide hole 3 needs to be totally reflected on the side wall of the light guide hole 3 . The second structure is taken as an example for illustration below. The angle design method of the first structure is the same as that of the second structure, and only the thickness design of the middle layer film 4 is omitted. For the second structure, it is necessary to make the angle i between the light entering the light guide hole 3 and the direction perpendicular to the side wall of the light guide hole 3 (that is, the optical fiber entering the light guide hole 3 relative to the light guide hole 3 The incident angle of the side wall) satisfies i≥arc sin(n ₃ /n ₂ ). It is necessary to make the angle i smaller than the angle of the side wall of the light guide hole 3 when i<β, so that all the light entering the light guide hole 3 can be emitted, and the light guide hole 3 is effective, so i≤90°, α≥90°- beta.

Therefore, according to the above angle relationship, it can be obtained that i-β≤α ₁ ≤β, that is, (arc sin(n ₃ /n ₂ ))-β≤α ₁ ≤β.

If α can still form a total reflection angle on the side wall of the light guide hole 3 after multiple total reflections, it needs to satisfy: α=(90°-β)+(90°-i), i≥arc sin (n ₃ /n ₂ ), that is, α≤180°-β-(arc sin(n3/n2))

The length of the lower bottom of the inverted trapezoidal structure in the light guide hole 3 (the bottom with relatively short length) is L, and the depth of the light guide hole 3 is T.

The angle between the incident light with an incident angle of α and the horizontal plane is γ, γ=β+(arc sin(n3/n2))-90°, then sinγ=T/(L+(T/sinβ)), then β +(arc sin(n ₃ /n ₂ ))-90°=arc sin(T/(L+(T/sinβ))).

And because γ=90°-α, then arc sin (T/(L+(T/sinβ))}=90°-α.

To sum up, arc sin(T/(L+(T/sinβ)))=90°-α. The ranges of α and α ₁ , α and β, L and T are limited, and n ₂ >n ₁ , n ₂ >n ₃ , so that all materials, angles and lengths of the present invention are limited. If it is necessary to emit oblique light from a vertical surface, it is only necessary to make α ₁ =0°; of course, it is also possible to emit light in a non-vertical direction, and α ₁ can be α ₁ =0-45°. If it is necessary to emit as much oblique light as possible from the front, it is only necessary to obtain the α angle range according to the refractive index of the selected material, and then obtain the specific value ranges of β, L and T according to the range of α angle.

For the above light guide holes with different refractive indices, the present invention also provides a method for preparing a light emitting diode with a light guide hole structure. For the first structure, the preparation method is as follows: firstly prepare a light-emitting diode on the upper surface of the light-emitting chip of the light-emitting diode. The lower film 1 is prepared on the upper surface of the lower film 1 with a light guide hole film layer of the same material as that in the light guide hole, and then the excess part is intermittently etched through by etching or etching. Or the depth of corrosion is the thickness of the film layer of the light guide hole, and the part that is not etched or corroded forms a plurality of light guide holes, and then deposits the upper film 2 at the place where the etching or corrosion removes, and its thickness is equal to that of the light guide hole. The depth of the hole, and then form the first structure, such as SiO ₂ -ITO-SiO ₂ structure, the refractive index range of the upper and lower films SiO ₂ is 1.4-1.6, and the refractive index range of the intermediate film 4ITO is 1.7-2.2.

For the second structure, the preparation method is as follows: prepare a lower layer film 1 (such as an ITO film) with an unlimited thickness on the surface of the front-mounted LED light-emitting chip, and then prepare an intermediate layer film 4 with an unlimited thickness on the surface of the lower film 1 as the middle layer. A total reflection layer, such as a Si ₃ N ₄ film, and the underlying film 1 is intermittently processed by etching or etching to produce multiple grooves with a cross-sectional view of a regular isosceles trapezoidal structure, and the etching or etching depth is smaller than that of the intermediate film 4 thickness, that is, to keep a certain depth that has not been etched or corroded. Each trapezoidal structure can be independent or connected in a certain direction. Finally, the corresponding etched or corroded part is filled with an upper layer of thin film material such as SiO ₂ film. The discontinuous part of the upper film 2 that has not been etched or corroded corresponds to a light guide hole. The thickness of the upper film 2 is required to be greater than or equal to the height of the light guide hole during preparation, so as to fill the etched or corroded area completely, but the redundant upper film 2 beyond the light guide hole needs to be disposed of again, and then Form the second structure, such as SiO ₂ -Si ₃ N ₄ -ITO structure, the refractive index range of the upper film 2SiO ₂ is 1.4-1.6, the refractive index range of the middle film Si ₃ N ₄ is 2.0-2.4, and the lower film 1ITO has a refractive index in the range of 1.7-2.2. A light guide layer with high transmittance is formed through the above structure, so that the light incident in the vertical direction directly passes through the front of the light guide layer; the light with a non-vertical incident angle of α can pass through the middle layer film 4 such as Si ₃ N ₄ film After multiple times of total reflection, it converges from the light guide hole and emits in an approximately vertical direction.

The above-mentioned embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention shall be determined by the claims.

Claims (10)

1. one kind has the light-emitting diode of light-conductive hole structure, it is characterized in that, the upper surface of the luminescence chip of described light-emitting diode is formed with optical waveguide layer, described optical waveguide layer comprises the lower film that contacts with luminescence chip and the topmost thin film in top, in described topmost thin film, run through and be formed with multiple light-conductive holes, in each light-conductive hole, be all filled with the optical material filling that refractive index is greater than topmost thin film, lower film.

2. the light-emitting diode with light-conductive hole structure according to claim 1, is characterized in that, the cross sectional shape of described light-conductive hole is isosceles inverted trapezoidal structure.

3. the light-emitting diode with light-conductive hole structure according to claim 2, is characterized in that, the material of described lower film and lower film is identical.

4. the light-emitting diode with light-conductive hole structure according to claim 2, it is characterized in that, the material of described lower film and lower film is not identical, between described topmost thin film and lower film, also comprise one deck intermediate layer film, and the material of intermediate layer film is identical with the optical material of filling in light-conductive hole.

5. the light-emitting diode with light-conductive hole structure according to claim 3, it is characterized in that, described optical waveguide layer is prepared by following process: first prepare lower film at the upper surface of the luminescence chip of light-emitting diode, then prepare at the upper surface of lower film the light-conductive hole thin layer that one deck is identical with material in light-conductive hole, then adopt etching or forms of corrosion discontinuity on light-conductive hole thin layer to run through etching, the degree of depth of etching or corrosion is the thickness of this light-conductive hole thin layer, the part not being etched or corrode forms multiple light-conductive holes, then at the position of etching or erosion removal deposition topmost thin film material, deposit thickness equals the degree of depth of light-conductive hole, and then finally form optical waveguide layer.

6. the light-emitting diode with light-conductive hole structure according to claim 5, is characterized in that, the topmost thin film of described optical waveguide layer and the material of lower film are SiO ₂, the material depositing in light-conductive hole is ITO.

7. the light-emitting diode with light-conductive hole structure according to claim 3, it is characterized in that, described optical waveguide layer is prepared by following process: first prepare lower film on forward LED luminescence chip surface, then prepare intermediate layer film on the surface of lower film, and on intermediate layer film, use etching or caustic solution discontinuity to process multiple grooves that cross section is positive isosceles trapezoidal structure, etching or corrosion depth are less than the thickness of this intermediate layer film, corresponding being partially filled into topmost thin film material of being etched or corroding, form topmost thin film, the corresponding discontinuity part not being etched or corrode forms light-conductive hole, and then finally form optical waveguide layer.

8. the light-emitting diode with light-conductive hole structure according to claim 7, is characterized in that, described optical waveguide layer is prepared by following process: the material of described topmost thin film is SiO ₂; The material of described intermediate layer film and light-conductive hole is Si ₃n ₄; The material of described lower film is ITO.

9. according to the light-emitting diode with light-conductive hole structure described in any one in claim 2,3,5,7,8, it is characterized in that, described in inject the light of optical waveguide layer incidence angle be α; The upper base angle of the isosceles inverted trapezoidal structure of described light-conductive hole is β, and the refractive index of described lower film is n ₁, the refractive index of described lower film is n ₃, the refractive index of described light-conductive hole and intermediate layer film is n ₂, enter the light in light-conductive hole and be i perpendicular to the angle between the sidewall direction of light-conductive hole, described wherein α>=arc sin(n ₃/ n ₂), and α>=arc sin(n ₁/ n ₂).

10. the light-emitting diode with light-conductive hole structure according to claim 9, it is characterized in that, the upper base angle of the isosceles inverted trapezoidal structure of described light-conductive hole is β, enter the light in light-conductive hole and be i perpendicular to the angle between the sidewall direction of light-conductive hole, the emergent ray penetrating from light-conductive hole and the angle of vertical direction are α ₁, i≤90 °, α>=90 °-β, and i>=arc sin(n ₃/ n ₂), α≤180 °-β-(arc sin(n3/n2)), β+(arc sin(n ₃/ n ₂))-90 °=arc sin(T/(L+(T/sin β))), arc sin(T/(L+(T/sin β)))=90 °-α, the degree of depth that wherein T is light-conductive hole, the width of going to the bottom that L is inverted trapezoidal structure.

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