Light emitting diode and method of manufacturing the same

Abstract

The present application provides a light emitting diode and a manufacturing method thereof. The light emitting diode comprises a substrate, a light-proof reflective layer, an inner epitaxial layer, an outer epitaxial layer, a non-conductive layer, an ohmic metal body, a first electrode and a second electrode. The inner epitaxial layer and the outer epitaxial layer are separated by a spacing. From the top of the light emitting diode, the spacing forms a closed path and surrounds a light emitting hole. In a cross section perpendicular to the closed path, the angle between the outer wall of the inner epitaxial layer and the normal of the top surface of the light-proof reflective layer is 2-30 degrees, and the angle between the inner wall of the outer epitaxial layer and the normal of the top surface of the light-proof reflective layer is 2-30 degrees. The spacing has the effect of blocking the current and the light emitting area to the inner epitaxial layer. By guiding the light emitted from the side of the inner epitaxial layer to the top side of the light emitting diode, the light emitting diode has a low side light ratio.

Description

Technical Field

[0001] This invention relates to a light-emitting diode and its manufacturing method, and more particularly to a light-emitting diode and its manufacturing method that utilizes a gap to block the epitaxial layer current to reduce side light emission. Background Technology

[0002] Optical encoders are commonly used sensing devices in electronic and mechanical components to detect the movement and rotation of elements. An optical encoder consists of a code disk, a light signal generator, and a photosensor. The code disk has multiple transparent and opaque areas. Rotation of the code disk causes the photosensor to receive specific light signals, which are then converted into electrical signals to determine the displacement of the element.

[0003] Light-emitting diodes (LEDs) are commonly used as optical signal generators in reflective encoders. For example... Figure 1 As shown, when the light-emitting diode E is used Figure 1 In the reflective encoder RE shown, the light L emitted by the LED E is reflected by the opaque area of ​​the upper code disk ED to the photosensor D. Since the LED E and the photosensor D are located on the same side, the side light SL emitted by the LED E is received by the photosensor, creating noise and affecting measurement accuracy. Therefore, reducing the side light emitted by the LED is a challenge. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the applicant of this invention has researched and designed a light-emitting diode (LED), comprising: a substrate having a top surface and a bottom surface, the top surface and the bottom surface being located opposite to each other; an opaque reflective layer formed on the top surface of the substrate; and an epitaxial layer comprising an inner and outer epitaxial layer and an outer epitaxial layer, the inner and outer epitaxial layers being formed on a portion of the top surface of the opaque reflective layer, the outer epitaxial layer being formed on a portion of the top surface of the opaque reflective layer and surrounding the inner and outer epitaxial layers, the inner and outer epitaxial layers not being in contact with the outer epitaxial layer, and a space between the inner and outer epitaxial layers and the outer epitaxial layer, wherein, viewed from above the LED, the space forms a closed path, and on a cross-section perpendicular to the closed path, the outer wall of the inner and outer epitaxial layers, the inner wall of the outer epitaxial layer, and the top surface of a portion of the opaque reflective layer define an inverted trapezoidal cross-section, the two sides of which are defined by the outer walls of the inner and outer epitaxial layers and the inner walls of the outer epitaxial layer, respectively. The base of the inverted trapezoidal cross-section is defined by a portion of the top surface of the opaque reflective layer. The angle between the outer wall of the inner and outer epitaxial layers and the normal to the top surface of the opaque reflective layer is 2 to 30 degrees, and the angle between the inner wall of the outer epitaxial layer and the normal to the top surface of the opaque reflective layer is 2 to 30 degrees. A non-conductive layer covers the top surface and outer wall of the inner and outer epitaxial layers, the top surface and inner wall of the outer epitaxial layer, and the top surface of the opaque reflective layer between the inner and outer epitaxial layers and the outer epitaxial layer. The material is transparent; an ohmic metal body is disposed in the non-conductive layer and electrically connected to the inner and outer epitaxial layers; a first electrode is electrically connected to the ohmic metal body and is made of a reflective material. A circular light-emitting hole is formed in the first electrode and is located on the top side of the light-emitting diode. When viewed from above the light-emitting diode, the closed path formed by the space is surrounded by the light-emitting hole; and a second electrode is electrically connected to the inner and outer epitaxial layers.

[0005] In one embodiment of the light-emitting diode of the present invention, the first electrode is disposed on the portion of the non-conductive layer covering the top surface and outer wall of the inner and outer epitaxial layers, on the portion of the non-conductive layer covering the top surface and inner wall of the outer epitaxial layer, and on the portion of the non-conductive layer covering the top surface of the opaque reflective layer between the inner and outer epitaxial layers and the outer epitaxial layer.

[0006] In one embodiment of the light-emitting diode of the present invention, the first electrode is disposed on the portion where the non-conductive layer covers the top surface of the inner and outer epitaxial layers without blocking light emitted from the outer walls of the inner and outer epitaxial layers. The non-conductive layer has one or more stacked films and is configured to refract light emitted from the inner walls of the inner and outer epitaxial layers toward the light-emitting diode. The light-emitting diode further includes a side light-reflecting layer disposed on the portion where the non-conductive layer covers the inner wall of the outer epitaxial layer and is configured to reflect light emitted from the outer walls of the inner and outer epitaxial layers toward the light-emitting diode.

[0007] In one embodiment of the light-emitting diode of the present invention, the first electrode is disposed on the portion of the non-conductive layer covering the top surface of the inner and outer epitaxial layers without blocking the light emitted from the outer wall of the inner and outer epitaxial layers. The non-conductive layer has one or more stacked thin films and is configured to refract or reflect the light emitted from the inner wall of the inner and outer epitaxial layers toward the top of the light-emitting diode.

[0008] In one embodiment of the light-emitting diode of the present invention, the non-conductive layer is composed of one or more thin films selected from silicon nitride, silicon oxynitride, silicon dioxide, and titanium dioxide.

[0009] In one embodiment of the light-emitting diode of the present invention, the closed path is circular when viewed from above the light-emitting diode, and the gap space forms a concentric circle with the light-emitting aperture.

[0010] In one embodiment of the light-emitting diode of the present invention, the substrate is a silicon substrate, an aluminum oxide substrate, or an aluminum nitride substrate.

[0011] In one embodiment of the light-emitting diode of the present invention, the epitaxial layer is made of aluminum indium gallium phosphide (AlInGaP) or aluminum gallium arsenide (AlGaAs).

[0012] The present invention also provides a method for manufacturing a light-emitting diode (LED), comprising: providing a substrate having a top surface and a bottom surface, the top surface and the bottom surface being located on opposite sides of each other; forming an opaque reflective layer on the top surface of the substrate; forming an epitaxial layer on the top surface of the opaque reflective layer; removing a portion of the epitaxial layer until the opaque reflective layer is exposed, wherein the removed portion of the epitaxial layer forms a spacer, the spacer dividing the epitaxial layer into an inner and outer epitaxial layer and an outer epitaxial layer, the outer epitaxial layer surrounding the inner and outer epitaxial layers, wherein, viewed from above the LED, the spacer forms a closed path surrounding the light-emitting aperture, and, on a cross-section perpendicular to the closed path, the outer walls of the inner and outer epitaxial layers, the inner wall of the outer epitaxial layer, and a portion of the top surface of the opaque reflective layer define an inverted trapezoidal cross-section, the two sides of the inverted trapezoidal cross-section being defined by the outer walls of the inner and outer epitaxial layers and the inner walls of the outer epitaxial layer, respectively, and the base of the inverted trapezoidal cross-section being defined by a portion of the top surface of the opaque reflective layer. The angle between the outer wall of the inner and outer epitaxial layers and the normal to the top surface of the opaque reflective layer is 2 to 30 degrees, and the angle between the inner wall of the outer epitaxial layer and the normal to the top surface of the opaque reflective layer is 2 to 30 degrees; a non-conductive layer is formed, covering the top surface and outer wall of the inner and outer epitaxial layers, the top surface and inner wall of the outer epitaxial layer, and the top surface of the opaque reflective layer between the inner and outer epitaxial layers, wherein the non-conductive layer is a light-transmitting material; a portion of the material of the non-conductive layer is removed, and [the material is then removed from the non-conductive layer]. An ohmic metal body is formed at the material removal site, and the ohmic metal body is electrically connected to the epitaxial layer; a first electrode is formed, and the first electrode is electrically connected to the ohmic metal body, and a light-emitting aperture is formed through the first electrode, wherein the first electrode is opaque, the light-emitting aperture is located on the top side of the light-emitting diode, wherein, viewed from above the light-emitting diode, the closed path formed by the spacer surrounds the light-emitting aperture; and a second electrode is formed, and the second electrode is electrically connected to the inner and outer epitaxial layers.

[0013] In one embodiment of the light-emitting diode manufacturing method of the present invention, the first electrode is formed on the portion where the non-conductive layer covers the top surface and outer wall of the inner and outer epitaxial layers, on the portion where the non-conductive layer covers the top surface and inner wall of the outer epitaxial layer, and on the portion where the non-conductive layer covers the top surface of the opaque reflective layer between the inner and outer epitaxial layers and the outer epitaxial layer.

[0014] In one embodiment of the light-emitting diode manufacturing method of the present invention, the first electrode is formed on the portion of the non-conductive layer covering the top surface and outer wall of the inner and outer epitaxial layers, and the diode manufacturing method further includes forming a light-reflecting layer on the portion of the non-conductive layer covering the inner wall of the outer epitaxial layer.

[0015] In one embodiment of the light-emitting diode manufacturing method of the present invention, the non-conductive layer is formed by a single film or by stacking multiple films.

[0016] In one embodiment of the LED manufacturing method of the present invention, the closed path is circular when viewed from above the LED, and the space between the light-emitting holes forms concentric circles.

[0017] In one embodiment of the light-emitting diode manufacturing method of the present invention, the method for removing part of the material of the epitaxial layer is to etch the epitaxial layer using a chemical solution.

[0018] In one embodiment of the light-emitting diode manufacturing method of the present invention, the method for removing part of the material of the epitaxial layer is to etch the epitaxial layer using inductively coupled plasma (ICP).

[0019] The light-emitting diode (LED) of this invention utilizes a spacer to confine the current and light-emitting area during energization to the inner and outer epitaxial layers. In some embodiments, the LED is covered by a reflective first electrode on the top surface and outer wall of the inner and outer epitaxial layers, blocking and reflecting light emitted from the inner and outer epitaxial layers, preventing light from emanating from the sides of the inner and outer epitaxial layers, and guiding the light to the light-emitting aperture on the top side of the LED. In some embodiments, the LED uses a single or multiple stacked, tilted, non-conductive, light-transmitting layer and a tilted, reflective side-light-reflecting layer to guide the side-light emitted from the inner and outer epitaxial layers to the top surface of the LED. This invention discloses several techniques for guiding the side-light emitted from the LED during energization to the top surface of the LED, resulting in an LED with a low side-light ratio. When the LED of this invention is applied to a reflective encoder, it can reduce noise in the photosensor and decrease the probability of sensing errors. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a reflective encoder;

[0021] Figure 2A This is a schematic front view of an embodiment of the light-emitting diode of the present invention. Figure 2B Cross-sectional view along the line BB;

[0022] Figure 2B for Figure 2A Top view of the embodiment of the light-emitting diode;

[0023] Figure 2C for Figure 2A The schematic diagram of the light-emitting diode in the present invention omits the non-conductive layer, the ohmic metal body, the first electrode, and the second electrode, and shows the angles of the outer wall of the inner and outer epitaxial layers and the inner wall of the outer epitaxial layer relative to the top surface of the opaque reflective layer. Figure 2C for Figure 2D Cross-sectional view along line CC;

[0024] Figure 2Dfor Figure 2C Top view of the structure in the middle;

[0025] Figure 3 This is a front cross-sectional view of another embodiment of the light-emitting diode of the present invention;

[0026] Figure 4 This is a front cross-sectional view of another embodiment of the light-emitting diode of the present invention;

[0027] Figure 5 This is a flowchart illustrating the steps of the method for manufacturing a light-emitting diode according to the present invention;

[0028] Figures 6A to 6I This is a schematic diagram illustrating the formation process of each component of the light-emitting diode of the present invention, wherein... Figure 6D1 for Figure 6D2 Cross-sectional view along the DD line;

[0029] Figure 7 These are front, back, side, and illuminated appearance photos of the light-emitting diode of the present invention.

[0030] Figure 8A The graph shows the optical power-current results of photoelectric testing of the light-emitting diode chip of the present invention in its unpackaged bare die state.

[0031] Figure 8B This is a voltage-current curve of the light-emitting diode chip of the present invention in the unpackaged bare die state for photoelectric testing.

[0032] Figure 9 This is a polar coordinate diagram of the light power distribution of the LED of the present invention under a forward current of 20mA.

[0033] Explanation of reference numerals in the attached figures:

[0034] 100 - Light Emitting Diode;

[0035] 1-Substrate;

[0036] S1 - Top surface;

[0037] S2 - Bottom surface;

[0038] 2-Opaque reflective layer;

[0039] 21-Top surface;

[0040] 3-Epipolar layer;

[0041] 31 - Inner and outer epitaxial layers;

[0042] 311-Exterior wall;

[0043] 31t - Top surface;

[0044] 32-Outer epitaxial layer;

[0045] 321 - Inner wall;

[0046] 32t - Top surface;

[0047] 4-Non-conductive layer;

[0048] 5-Ohmic metal body;

[0049] 61 - First electrode;

[0050] 62 - Second electrode;

[0051] A-light hole;

[0052] V-space;

[0053] T-groove;

[0054] R - Closed path;

[0055] N-normal;

[0056] θ1 - included angle;

[0057] θ2 - included angle;

[0058] SP1~SP9 - Steps;

[0059] SP8A - Steps;

[0060] 100A - Light Emitting Diode;

[0061] 63-Side light reflective layer;

[0062] 100B - Light Emitting Diode;

[0063] 64 - Stitching section;

[0064] L1 - Light ray;

[0065] L2-side light;

[0066] RE-reflective encoder;

[0067] E-Light Emitting Diode;

[0068] D-photosensor;

[0069] L-ray;

[0070] SL - Side light emission. Detailed Implementation

[0071] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0072] The detailed description and technical content of the present invention are explained below with reference to the accompanying drawings. However, the accompanying drawings are provided for reference and illustration only to help understand the present invention and are not intended to limit the scope of the present invention.

[0073] Please see Figure 2A and Figure 2B In one embodiment of the light-emitting diode of the present invention, the light-emitting diode 100 includes: a substrate 1, an opaque reflective layer 2, an epitaxial layer 3, a non-conductive layer 4, an ohmic metal body 5, a first electrode 61, and a second electrode 62.

[0074] The substrate 1 has a top surface S1 and a bottom surface S2 located opposite each other. The substrate 1 can be a silicon substrate, an alumina (Al2O3) substrate, or an aluminum nitride (AlN) substrate.

[0075] An opaque reflective layer 2 is formed on the top surface S1 of the substrate 1 to reflect upward light emitted by the inner and outer epitaxial layers 31. The opaque reflective layer 2 can be made of metal and can be formed on the top surface S1 of the substrate 1 by appropriate deposition techniques.

[0076] Figure 2C and Figure 2D for Figure 2A and Figure 2B The structure of the light-emitting diode 100 omits the non-conductive layer 4, the ohmic metal body 5, the first electrode 61, and the second electrode 62. The epitaxial layer 3 includes an inner and outer epitaxial layer 31 and an outer epitaxial layer 32. The inner and outer epitaxial layers 31 are formed on a portion of the top surface 21 of the opaque reflective layer 2. The outer epitaxial layer 32 is formed on a portion of the top surface 21 of the opaque reflective layer 2 and surrounds the inner and outer epitaxial layers 31. The inner and outer epitaxial layers 31 and the outer epitaxial layer 32 are not in contact. A space V exists between the inner and outer epitaxial layers 31 and the outer epitaxial layer 32. Figure 6C , Figure 6D1 , Figure 6D2 As shown, after forming the epitaxial layer 3 on the top surface of the opaque reflective layer 2, the spacer V, the inner and outer epitaxial layers 31, and the outer epitaxial layer 32 can be formed by removing part of the material of the epitaxial layer 3. The material of the epitaxial layer 3 can be aluminum indium gallium phosphide (AlInGaP) or aluminum gallium arsenide (AlGaAs), and it is grown on the opaque reflective layer 2 using appropriate epitaxial techniques. The epitaxial layer 3 has p-type doped regions, n-type doped regions, and light-emitting regions (not shown in the figure), which can emit light when current passes through it.

[0077] like Figure 2B and Figure 2D As shown, viewed from above the LED 100, the space V forms a closed path R. Figure 2BIn the presented embodiment, the closed path R is circular. The closed path R can also be square or other closed shapes. Figure 2C As shown, on a cross-section perpendicular to the closed path R, the outer wall 311 of the inner and outer epitaxial layers 31, the inner wall 321 of the outer epitaxial layer 32, and a portion of the top surface 21 of the opaque reflective layer 2 define an inverted trapezoidal cross-section. The two sides of this inverted trapezoidal cross-section are defined by the outer walls 311 of the inner and outer epitaxial layers 31 and the inner walls 321 of the outer epitaxial layer 32, respectively, while the base of the inverted trapezoidal cross-section is defined by a portion of the top surface 21 of the opaque reflective layer 2. The angle θ1 between the outer wall 311 of the inner and outer epitaxial layers 31 and the normal N of the top surface 21 of the opaque reflective layer 2 is 2 to 30 degrees, and the angle θ2 between the inner wall 321 of the outer epitaxial layer 32 and the normal N of the top surface 21 of the opaque reflective layer 2 is also 2 to 30 degrees.

[0078] The non-conductive layer 4 covers the top surface 31t and outer wall 311 of the inner and outer epitaxial layers 31, the top surface 32t and inner wall 321 of the outer epitaxial layer 32, and the top surface 21 of the opaque reflective layer 2 between the inner and outer epitaxial layers 31 and the outer epitaxial layer 32. The non-conductive layer 4 is made of a light-transmitting material and can be formed by stacking single or multiple thin films (not shown). The non-conductive layer 4 can be made of silicon nitride (SiN). y Thin films are formed from one or more of silicon oxynitride (SiON), silicon dioxide (SiO2), and titanium dioxide (TiO2).

[0079] An ohmic metal body 5 is disposed in the non-conductive layer 4, and the ohmic metal body 5 is electrically connected to the inner and outer epitaxial layers 31. The material of the ohmic metal body 5 may be a metal or alloy suitable for forming ohmic contacts and conducting electricity with the inner and outer epitaxial layers 31.

[0080] The first electrode 61 is electrically connected to the ohmic metal body 5. The second electrode 62 is electrically connected to the inner and outer epitaxial layers 31. Depending on the conductivity of the substrate 1 and the opaque reflective layer 2, the second electrode 62 can be disposed on the bottom surface S2 of the substrate 1, directly electrically connected to the inner and outer epitaxial layers 31 through the substrate 1 and the opaque reflective layer 2, or electrically connected to the inner and outer epitaxial layers 31 using appropriate vias and conductor structures (not shown). The light-emitting diode 100 is connected to an external circuit through the first electrode 61 and the second electrode 62 to receive an external voltage. In this embodiment, the first electrode 61 is disposed on the top side of the light-emitting diode 100, and the second electrode 62 is disposed on the bottom side of the light-emitting diode 100 (bottom surface S2 of the substrate 1). The materials of the first electrode 61 and the second electrode 62 can each be metals or alloys suitable for forming ohmic contacts and conducting electricity with the ohmic metal body 5 and the inner and outer epitaxial layers 31.

[0081] The first electrode is made of a reflective material, and a circular light-emitting hole A is formed in the first electrode 61. This light-emitting hole A is used to allow light emitted from the inner and outer epitaxial layers 31 to be emitted. Figure 2B As shown, viewed from above the light-emitting diode 100, the space V forms a closed path R and surrounds the light-emitting aperture A. The space V and the light-emitting aperture A form concentric circles.

[0082] Since the inner and outer epitaxial layers 31 are not in contact with the outer epitaxial layer 32, the current during energization is confined to the inner and outer epitaxial layers 31, thereby increasing the output power of the light-emitting diode 100. In this structure where the sides of the inner and outer epitaxial layers 31 are unobstructed and light can be emitted, the inverted trapezoidal cross-sectional shape defined between the inner and outer epitaxial layers 31 and the outer epitaxial layer 32 can guide the light emitted from the sides (outer wall 311) of the inner and outer epitaxial layers 31 in a direction above the light-emitting diode 100. When the angle between the outer wall 311 of the inner and outer epitaxial layers 31 and the normal N of the top surface 21 of the opaque reflective layer 2 is 2 to 30 degrees, and when the angle between the inner wall 321 of the outer epitaxial layer 32 and the normal N of the top surface 21 of the opaque reflective layer 2 is 2 to 30 degrees, there is lower side light than at other angles.

[0083] exist Figure 2A In the illustrated light-emitting diode 100, the first electrode 61 is disposed on the portion of the non-conductive layer 4 covering the top surface 31t and outer wall 311 of the inner and outer epitaxial layers 31, on the portion of the non-conductive layer 4 covering the top surface 32t and inner wall 321 of the outer epitaxial layer 32, and on the portion of the non-conductive layer 4 covering the top surface 21 of the opaque reflective layer 2 between the inner and outer epitaxial layers 31 and the outer epitaxial layer 32. In the light-emitting diode 100, the first electrode 61 can block light exiting from the top surface 31t of the inner and outer epitaxial layers 31 and most of the light exiting from the outer wall 311, reflecting it back to the inner and outer epitaxial layers 31, allowing most of the light emitted from the inner and outer epitaxial layers 31 to exit the light-emitting diode 100 through the light-emitting aperture A. Furthermore, by not covering the outer side of the outer epitaxial layer 32, the first electrode 61 avoids leakage failure of the device due to excessive proximity to the edge of the light-emitting diode 100.

[0084] Figure 3 The light-emitting diode 100A is an embodiment in which the sides of the inner and outer epitaxial layers 31 are unobstructed and can emit light. In the light-emitting diode 100A, the first electrode 61 is disposed on the portion where the non-conductive layer 4 covers the top surface 31t of the inner and outer epitaxial layers 31 without obstructing the light emitted from the outer wall 311 of the inner and outer epitaxial layers 31. The non-conductive layer 4 is a light-transmitting material and is composed of one or more thin films (not shown in the figure). The non-conductive layer 4 can be made of silicon nitride (SiN). yIt is composed of one or more thin films selected from silicon oxynitride (SiON), silicon dioxide (SiO2), and titanium dioxide (TiO2). The refractive index of one or more thin films of the non-conductive layer 4 can be used to adjust the refraction of light, so as to refract light emitted from the side (outer wall 311) of the inner and outer epitaxial layers 31 toward the top of the light-emitting diode 100, as shown by the arrow in the figure.

[0085] The light-emitting diode 100A further includes a side-light-reflecting layer 63, which is disposed on the portion of the non-conductive layer 4 covering the inner wall 321 of the outer epitaxial layer 32. The side-light-reflecting layer 63 is configured to reflect light emitted from the outer wall 311 of the inner and outer epitaxial layers 31 towards the top of the light-emitting diode 100, and to reflect upwards light L1 that is not completely guided upwards by the non-conductive layer 4 towards the top of the light-emitting diode 100. The first electrode 61 and the side-light-reflecting layer 63 can use the same reflective material and are completed in the same deposition process (e.g., vapor deposition). The preferred material for the side-light-reflecting layer 63 is metal, but it is not limited to metal. The side-light-reflecting layer 63 can extend to the portion of the non-conductive layer 4 covering the top surface 32t of the outer epitaxial layer 32, and can also extend to the portion of the non-conductive layer 4 covering the top surface 21 of the opaque reflective layer 2 between the inner and outer epitaxial layers 31 and the outer epitaxial layer 32. In addition, the side-light reflective layer 63 can be made of a conductive material for wire bonding, and can be electrically connected to the first electrode 61 through a transparent conductive layer (such as indium tin oxide (ITO)) or a line (not shown).

[0086] exist Figure 4 The light-emitting diode 100B is another embodiment in which light can be emitted from the side of the inner and outer epitaxial layers 31. In the light-emitting diode 100B, the first electrode 61 is disposed on the portion of the non-conductive layer 4 covering the top surface 31t of the inner and outer epitaxial layers 31 without blocking the light emitted from the outer wall 311 of the inner and outer epitaxial layers 31. The light-emitting diode 100B and Figure 3 The difference between the LED 100A and the LED 100A is that the side light-reflecting layer 63 is not provided. Instead, the non-conductive layer 4 is used to refract or reflect the light emitted from the outer wall 311 of the inner and outer epitaxial layers 31 towards the top of the LED 100. Figure 4 As shown, this structure of the light-emitting diode 100B produces a small amount of side light L2. In addition, the light-emitting diode 100B may be provided with a conductive bonding portion 64 for bonding as needed, and is electrically connected to the first electrode 61 through a transparent conductive layer (such as indium tin oxide (ITO)) or a line (not shown).

[0087] The steps of the LED manufacturing method of the present invention are summarized in Figure 5 middle. Figures 6A to 6I The diagram illustrates the formation process of each component in the LED manufacturing method of the present invention.

[0088] The method for manufacturing a light-emitting diode according to the present invention includes the following steps:

[0089] Step SP1: Provide a substrate 1. For example... Figure 6A As shown.

[0090] Step SP2: Form an opaque reflective layer 2 on the top surface S1 of the substrate 1. (e.g.) Figure 6B As shown.

[0091] Step SP3: Form an epitaxial layer 3 on the top surface 21 of the opaque reflective layer. For example... Figure 6C As shown.

[0092] Step SP4: Remove a portion of the material from the epitaxial layer 3 until the opaque reflective layer 2 is exposed, thus separating the epitaxial layer 3 into an inner and outer epitaxial layer 31 and an outer epitaxial layer 32. The outer epitaxial layer 32 surrounds the inner and outer epitaxial layers 31, as shown below. Figure 6D1 , Figure 6D2 As shown. The portion of the epitaxial layer 3 that is removed forms a gap space V, which, when viewed from above the epitaxial layer 3, forms a closed path R. On a cross-section perpendicular to this closed path R, the outer wall 311 of the inner and outer epitaxial layers 31, the inner wall 321 of the outer epitaxial layer 32, and a portion of the top surface 21 of the opaque reflective layer 2 define an inverted trapezoidal cross-section. The two sides of this inverted trapezoidal cross-section are defined by the outer wall 311 of the inner and outer epitaxial layers 31 and the inner wall 321 of the outer epitaxial layer 32, respectively, and the base of the inverted trapezoidal cross-section is defined by a portion of the top surface 21 of the opaque reflective layer 2. The angle θ1 between the outer wall 311 of the inner and outer epitaxial layers 31 and the normal N of the top surface 21 of the opaque reflective layer 2 is 2 to 30 degrees, and the angle θ2 between the inner wall 321 of the outer epitaxial layer 32 and the normal N of the top surface 21 of the opaque reflective layer 2 is 2 to 30 degrees. The method for removing part of the material of the epitaxial layer 3 can be by etching the epitaxial layer 3 with a chemical solution or by etching the epitaxial layer 3 with inductively coupled plasma (ICP).

[0093] Step SP5: Form a non-conductive layer 4, such that the non-conductive layer 4 covers the top surface 31t and outer wall 311 of the inner and outer epitaxial layers 31, the top surface 32t and inner wall 321 of the outer epitaxial layer 32, and the top surface 21 of the opaque reflective layer 2 between the inner and outer epitaxial layers 31 and the outer epitaxial layer 32, as shown. Figure 6E As shown. The non-conductive layer 4 is made of a light-transmitting material. In some embodiments, the non-conductive layer 4 may be formed by a single film or by stacking multiple films. The non-conductive layer 4 may be formed by one or more thin films selected from silicon nitride, silicon oxynitride, silicon dioxide, and titanium dioxide.

[0094] Step SP6: Remove a portion of the material from the non-conductive layer 4, such as... Figure 6FAs shown. After the non-conductive layer 4 is formed, part of the material of the non-conductive layer 4 can be removed by photolithography and etching to form a groove T.

[0095] Step SP7: An ohmic metal body 5 is formed at the location where the material has been removed from the non-conductive layer 4 (in the groove T), and the ohmic metal body 5 is electrically connected to the inner and outer epitaxial layers 31, such as... Figure 6G As shown. The ohmic metal body 5 can be formed by vapor deposition. After the ohmic metal body 5 is formed, a lift-off process can be used.

[0096] Step SP8: Form a first electrode 61, electrically connect the first electrode 61 to the ohmic metal body 5, and form a light-emitting aperture A through the first electrode 61, such as... Figure 6H As shown. The first electrode 61 can be formed by deposition using evaporation. The light-emitting aperture A can be formed by removing part of the material from the first electrode 61 using a lift-off process. For example... Figure 2B As shown, viewed from above the light-emitting diode, the light-emitting aperture A is surrounded by the closed path R formed by the space V.

[0097] In step SP8, the deposition area of ​​the first electrode 61 can be adjusted to form, as shown in the figure. Figure 2A LED 100, Figure 3 LED 100A or Figure 4 The light-emitting diode is 100B. In Figure 2A In the light-emitting diode 100, the first electrode 61 is formed on the portion where the non-conductive layer 4 covers the top surface 31t and outer wall 311 of the inner and outer epitaxial layers 31, on the portion where the non-conductive layer 4 covers the top surface 32t and inner wall 321 of the outer epitaxial layer 32, and on the portion where the non-conductive layer 4 covers the top surface 21 of the opaque reflective layer 2 between the inner and outer epitaxial layers 31 and the outer epitaxial layer 32. Figure 3 LED 100A and Figure 4 In the light-emitting diode 100B, the first electrode 61 is formed on the portion where the non-conductive layer 4 covers the top surface 31t of the inner and outer epitaxial layers 31.

[0098] for Figure 3 The light-emitting diode 100A may further include a step SP8A: forming a side-light-reflecting layer 63 on the portion of the non-conductive layer 4 covering the inner wall 321 of the outer epitaxial layer 32. The side-light-reflecting layer 63 may be deposited in the same process as the first electrode 61, or deposited separately. If the side-light-reflecting layer 63 is used as a wire bonding location, a transparent conductive layer (e.g., indium tin oxide (ITO)) or a circuit (not shown) may be additionally formed to electrically connect the side-light-reflecting layer 63 to the first electrode 61.

[0099] for Figure 4 The light-emitting diode 100B may further include a step SP8B as needed: forming a bonding portion 64 on the portion of the non-conductive layer 4 covering the top surface 32t of the outer epitaxial layer 32, and forming a transparent conductive layer (such as indium tin oxide (ITO)) or circuit (not shown) that electrically connects the bonding portion 64 to the first electrode 61.

[0100] Step SP9: Form a second electrode 62, and electrically connect the second electrode 62 to the inner and outer epitaxial layers 31, such as... Figure 6I As shown. The second electrode 62 can be formed by vapor deposition.

[0101] The following are the photoelectric performance test results for the light-emitting diode 100 of the present invention. The effectiveness of the light-emitting diode 100 of the present invention can be demonstrated by the photoelectric performance test results. The photoelectric performance test can be performed using a commercially available die testing machine and integrating sphere system.

[0102] Figure 7 The following photographs are presented: a front view (top view), a rear view (bottom view), a side view, and a photograph showing the illuminated appearance of the light-emitting diode 100 of the present invention. Figure 5 The chip dimensions, thickness, and aperture dimensions listed are measured values.

[0103] The chip specifications of the LED 100 used for photoelectric performance testing are summarized in Table 1 below:

[0104] Table 1

[0105] LED 100 polarity N-up (N-type doped region on top in the epitaxial layer) Chip size (mil) 11.5x7.5 Light exit aperture size (μm) 70 Thickness (μm) 190

[0106] The photoelectric power-forward current and forward voltage-forward current results of photoelectric testing of LED 100 in its unpackaged bare die state are shown in the following figures. Figure 8A and Figure 8B As shown, where Figure 8A The vertical axis represents the optical power (mW), which is the sum of the optical power emitted from the aperture and the side optical power. Figure 8A and Figure 8B The forward voltage, optical power, and saturation current of each chip at a forward current of 20mA are listed in Table 2 below:

[0107] Table 2

[0108]

[0109]

[0110] After packaging the LED 100 into a To-Can form, the forward voltage, optical power, side-light ratio, peak wavelength, and emission angle under a forward current of 20mA are summarized in Table 3 below:

[0111] Table 3

[0112] LED 100 Forward voltage (V) 1.63 Light power emitted from the output port + side light power (mW) 2.07 Side beam power (mW) 0.01 Side light ratio 0.30％ Peak wavelength (nm) 854.5 Light emission angle (°) 119.74

[0113] For the polar plot of the optical power distribution of LED 100 under a forward current of 20mA, please refer to [link / reference needed]. Figure 9 The luminous angle in Table 3 refers to... Figure 9 The power angle at which 50% of the optical power is emitted. The side-light ratio is the ratio of the side-light power to the sum of the light power emitted from the output port and the total side-light power. From the above data, it can be seen that, when packaged in a To-Can configuration, under a forward current of 20mA, the LED 100 has a low side-light ratio, less than 1%.

[0114] The test results above show that the LED of the present invention, by using a spaced structure to block the current in the inner and outer epitaxial layers, can effectively reduce the side light emission of the chip, resulting in a lower side light ratio. Therefore, when the LED of the present invention is applied to a reflective encoder, it can reduce the noise of the photosensor and decrease the probability of sensing errors.

[0115] It should be understood that in this specification and claims, terms such as "above," "top surface," "top side," "top view," "bottom view," "side view," and "outer side" are relative positional terms used to describe the relative positions of the elements as presented in the accompanying drawings, in order to facilitate the description and understanding of the invention, and are not intended to limit the absolute positions of the elements and features of the light-emitting diode of the invention.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. All equivalent structural changes made based on the description and drawings of the present invention are also included within the scope of the present invention.

[0117] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A light-emitting diode, comprising: A substrate having a top surface and a bottom surface, the top surface and the bottom surface being located on opposite sides of each other; An opaque reflective layer is formed on the top surface of the substrate; An epitaxial layer, comprising an inner epitaxial layer and an outer epitaxial layer, The inner and outer epitaxial layers are formed on a portion of the top surface of the opaque reflective layer. The outer epitaxial layer is formed on a portion of the top surface of the opaque reflective layer and surrounds the inner and outer epitaxial layers. The inner and outer epitaxial layers are not in contact with the outer epitaxial layer, and there is a gap between the inner and outer epitaxial layers and the outer epitaxial layer. Viewed from above the light-emitting diode, the gap forms a closed path. On a cross-section perpendicular to the closed path, the outer wall of the inner and outer epitaxial layers, the inner wall of the outer epitaxial layer, and the top surface of a portion of the opaque reflective layer define an inverted trapezoidal cross-section. The two sides of the inverted trapezoidal cross-section are defined by the outer walls of the inner and outer epitaxial layers and the inner walls of the outer epitaxial layers, respectively. The bottom side of the inverted trapezoidal cross-section is defined by the top surface of a portion of the opaque reflective layer. The angle between the outer wall of the inner and outer epitaxial layers and the normal to the top surface of the opaque reflective layer is 2 to 30 degrees, and the angle between the inner wall of the outer epitaxial layer and the normal to the top surface of the opaque reflective layer is 2 to 30 degrees. A non-conductive layer covers the top surface and outer wall of the inner and outer epitaxial layers, the top surface and inner wall of the outer epitaxial layer, and the top surface of the opaque reflective layer between the inner and outer epitaxial layers and the outer epitaxial layer. The non-conductive layer is made of a light-transmitting material. An ohmic metal body is disposed in the non-conductive layer, and the ohmic metal body is electrically connected to the inner and outer epitaxial layers; A first electrode, electrically connected to the ohmic metal body, is made of a reflective material. A circular light-emitting aperture is formed in the first electrode, located on the top side of the light-emitting diode. Viewed from above the light-emitting diode, the space between the electrodes forms a closed path surrounding the light-emitting aperture. A second electrode is electrically connected to the inner and outer epitaxial layers.

2. The light-emitting diode according to claim 1, wherein the first electrode is disposed on the portion of the non-conductive layer covering the top surface and outer wall of the inner and outer epitaxial layers, on the portion of the non-conductive layer covering the top surface and inner wall of the outer epitaxial layer, and on the portion of the non-conductive layer covering the top surface of the opaque reflective layer between the inner and outer epitaxial layers and the outer epitaxial layer.

3. The light-emitting diode according to claim 1, wherein the first electrode is disposed on the portion of the non-conductive layer covering the top surface of the inner and outer epitaxial layers without blocking light emitted from the outer walls of the inner and outer epitaxial layers, the non-conductive layer having one or more stacked films, the non-conductive layer being configured to refract light emitted from the inner walls of the inner and outer epitaxial layers toward the light-emitting diode, the light-emitting diode further comprising a side light-reflecting layer disposed on the portion of the non-conductive layer covering the inner wall of the outer epitaxial layer, the side light-reflecting layer being configured to reflect light emitted from the outer walls of the inner and outer epitaxial layers toward the light-emitting diode.

4. The light-emitting diode according to claim 1, wherein the first electrode is disposed on the portion of the non-conductive layer covering the top surface of the inner and outer epitaxial layers without blocking light emitted from the outer walls of the inner and outer epitaxial layers, the non-conductive layer having one or more stacked thin films, the non-conductive layer being configured to refract or reflect light emitted from the inner walls of the inner and outer epitaxial layers toward the top of the light-emitting diode.

5. The light-emitting diode according to claim 4, wherein the non-conductive layer is composed of one or more thin films selected from silicon nitride, silicon oxynitride, silicon dioxide, and titanium dioxide.

6. The light-emitting diode according to claim 1, wherein, Viewed from above, the closed path is circular, and the gap and the light-emitting aperture form concentric circles.

7. The light-emitting diode according to claim 2, wherein the substrate is a silicon substrate, an aluminum oxide substrate, or an aluminum nitride substrate.

8. The light-emitting diode according to claim 2 or 3, wherein the epitaxial layer is made of aluminum indium gallium phosphide (AlInGaP) or aluminum gallium arsenide (AlGaAs).

9. A method for manufacturing a light-emitting diode, comprising: A substrate is provided having a top surface and a bottom surface, the top surface and the bottom surface being located on opposite sides of each other; An opaque reflective layer is formed on the top surface of the substrate; An epitaxial layer is formed on the top surface of the opaque reflective layer; A portion of the epitaxial layer material is removed until the opaque reflective layer is exposed. The removed portion of the epitaxial layer forms a space that divides the epitaxial layer into an inner and outer epitaxial layer and an outer epitaxial layer. The outer epitaxial layer surrounds the inner and outer epitaxial layers. Viewed from above the light-emitting diode, the space forms a closed path. On a cross-section perpendicular to the closed path, the outer walls of the inner and outer epitaxial layers, the inner wall of the outer epitaxial layer, and a portion of the top surface of the opaque reflective layer define an inverted trapezoidal cross-section. The two sides of the inverted trapezoidal cross-section are defined by the outer walls of the inner and outer epitaxial layers and the inner walls of the outer epitaxial layer, respectively. The bottom side of the inverted trapezoidal cross-section is defined by a portion of the top surface of the opaque reflective layer. The angle between the outer walls of the inner and outer epitaxial layers and the normal to the top surface of the opaque reflective layer is 2 to 30 degrees, and the angle between the inner wall of the outer epitaxial layer and the normal to the top surface of the opaque reflective layer is 2 to 30 degrees. A non-conductive layer is formed, which covers the top surface and outer wall of the inner and outer epitaxial layers, the top surface and inner wall of the outer epitaxial layer, and the top surface of the opaque reflective layer between the inner and outer epitaxial layers and the outer epitaxial layer, wherein the non-conductive layer is a light-transmitting material. A portion of the material in the non-conductive layer is removed, and an ohmic metal body is formed at the location where the material in the non-conductive layer has been removed, so that the ohmic metal body is electrically connected to the epitaxial layer. A first electrode is formed, electrically connected to the ohmic metal body, and a light-emitting aperture is formed through the first electrode, wherein the first electrode is opaque, and the light-emitting aperture is located on the top side of the light-emitting diode, wherein, viewed from above the light-emitting diode, the closed path formed by the spacer surrounds the light-emitting aperture; and A second electrode is formed, and the second electrode is electrically connected to the inner and outer epitaxial layers.

10. The method for manufacturing a light-emitting diode according to claim 9, wherein the first electrode is formed on the portion of the non-conductive layer covering the top surface and outer wall of the inner and outer epitaxial layers, on the portion of the non-conductive layer covering the top surface and inner wall of the outer epitaxial layer, and on the portion of the non-conductive layer covering the top surface of the opaque reflective layer between the inner and outer epitaxial layers and the outer epitaxial layer.

11. The method for manufacturing a light-emitting diode according to claim 9, wherein the first electrode is formed on the portion of the non-conductive layer covering the top surface and outer wall of the inner and outer epitaxial layers, and the method for manufacturing a diode further includes forming a light-reflecting layer on the portion of the non-conductive layer covering the inner wall of the outer epitaxial layer.

12. The method for manufacturing a light-emitting diode according to claim 9 or 11, wherein the non-conductive layer is formed by a single thin film or by stacking multiple thin films.

13. The method for manufacturing a light-emitting diode according to claim 10, wherein, Viewed from above, the closed path is circular, and the gap and the light-emitting aperture form concentric circles.

14. The method for manufacturing a light-emitting diode according to any one of claims 9 to 11, wherein a portion of the material of the epitaxial layer is removed by etching the epitaxial layer with a chemical solution.

15. The method for manufacturing a light-emitting diode according to any one of claims 9 to 11, wherein a portion of the material of the epitaxial layer is removed by etching the epitaxial layer using inductively coupled plasma (ICP).

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