LED device and method for manufacturing an LED device

Abstract

To provide an LED device and a method for manufacturing an LED device that can reduce the technical difficulty when forming LEDs with multiple light-emitting colors. [Solution] The LED device comprises a mounting substrate and a plurality of pixels arranged in a mounting area of ​​the mounting substrate. The pixels consist of a plurality of sub-pixels that emit light in different colors from each other. The sub-pixels include LEDs having a single-layer light-emitting unit layer and LEDs having two layers of light-emitting unit layers. For example, the LED with the single-layer light-emitting unit layer is an LED that emits red light, and the LED with the two layers of light-emitting unit layers is an LED that emits blue light and an LED that emits green light.

Description

Technical Field

[0001] The present disclosure relates to an LED device and a method for manufacturing the LED device.

Background Art

[0002] As small-sized pixels for ultra-high resolution color displays, LED devices are known in which several p-n junction LEDs are grown in the same epitaxial wafer, multi-level mesa etching processing is performed, and independent electrical contacts are formed for each of the p-n junctions. This can significantly reduce the labor required for mounting. Patent Document 1 discloses an LED device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The method of forming LEDs of a plurality of emission colors in the same epitaxial wafer has high technical difficulty. In one aspect of the present disclosure, it is preferable to provide an LED device and a method for manufacturing the LED device that can reduce the technical difficulty when forming LEDs of a plurality of emission colors.

Means for Solving the Problems

[0005] One aspect of the present disclosure is an LED device including a mounting substrate, and a plurality of pixels arranged in a mounting region of the mounting substrate, wherein the pixels are composed of a plurality of sub-pixels having mutually different emission colors, and the sub-pixels include an LED including a single-layer light emitting unit layer and an LED including two-layer light emitting unit layers. The LED device according to one aspect of the present disclosure can reduce the technical difficulty when forming LEDs of a plurality of emission colors.

[0006] Another aspect of the present disclosure is a method for manufacturing an LED device comprising a mounting substrate and a plurality of pixels arranged in a mounting area of ​​the mounting substrate, wherein the pixels consist of a plurality of sub-pixels having different light-emitting colors, and the sub-pixels are LEDs, wherein the method involves mounting a monolithic LED array comprising an element substrate and the LEDs arranged and formed on the element substrate onto the mounting area, and then removing the element substrate multiple times such that the light-emitting colors of the LEDs in the monolithic LED array differ between some of the steps and other steps, thereby forming pixels consisting of a plurality of sub-pixels having different light-emitting colors. The method for manufacturing an LED device, which is another aspect of the present disclosure, can reduce the technical difficulty when forming LEDs with multiple light-emitting colors. [Brief explanation of the drawing]

[0007] [Figure 1] This is a perspective view showing the configuration of the VR goggles and LED device according to the first embodiment. [Figure 2] This is a plan view showing the configuration of the LED device according to the first embodiment. [Figure 3] This is a cross-sectional view taken along the line III-III in Figure 2, according to the first embodiment. [Figure 4] This is a plan view showing the pixel arrangement of the first embodiment. [Figure 5] This is a plan view showing the pixel configuration of the first embodiment. [Figure 6] Figures 6A to 6C are cross-sectional views showing the pixel configuration in the first embodiment, respectively. Figure 6A is a cross-sectional view taken at cross-section AA in Figure 5. Figure 6B is a cross-sectional view taken at cross-section BB in Figure 5. Figure 6C is a cross-sectional view taken at cross-section CC in Figure 5. [Figure 7] This is a plan view showing the configuration of a monolithic LED array according to the first embodiment. [Figure 8] This is an explanatory diagram illustrating the manufacturing method of a monolithic LED array according to the first embodiment. [Figure 9]This is an explanatory diagram illustrating a method for manufacturing an LED device according to the first embodiment. [Figure 10] Figures 10A to 10C are cross-sectional views showing the pixel configuration in the second embodiment, respectively. Figure 10A is a cross-sectional view at cross-section AA in Figure 11. Figure 10B is a cross-sectional view at cross-section BB in Figure 11. Figure 6C is a cross-sectional view at cross-section CC in Figure 11. [Figure 11] This is a plan view showing the pixel configuration of the second embodiment. [Figure 12] This is a plan view showing the configuration of a monolithic LED array according to the second embodiment. [Figure 13] This is an explanatory diagram illustrating the manufacturing method of a monolithic LED array according to the second embodiment. [Figure 14] This is an explanatory diagram illustrating a method for manufacturing an LED device according to a second embodiment. [Figure 15] Figures 15A to 15C are cross-sectional views showing the pixel configuration in the third embodiment, respectively. Figure 15A is a cross-sectional view corresponding to the AA cross-section in Figure 11. Figure 15B is a cross-sectional view corresponding to the BB cross-section in Figure 11. Figure 15C is a cross-sectional view corresponding to the CC cross-section in Figure 11. [Figure 16] In another embodiment, this is a plan view showing multiple mounting compartments provided in the mounting area. [Modes for carrying out the invention]

[0008] Exemplary embodiments of this disclosure will be described with reference to the drawings. <First Embodiment> 1. Basic configuration of VR goggles 200 and LED device 1 LED device 1 is used, for example, in VR goggles 200. The basic configuration of VR goggles 200 and LED device 1 will be explained based on Figures 1 to 3. As shown in Figure 1, VR goggles 200 includes LED device 1 and lens 201. LED device 1 is positioned in front of the viewer's eye 202, as seen from the viewer's eye 202. The distance between LED device 1 and the viewer's eye 202 is approximately 5 cm. Light emitted from LED device 1 passes through lens 201 and reaches the viewer's eye 202.

[0009] The LED device 1 shown in Figure 2 comprises a plurality of pixels 70 and a mounting substrate 90. The LED device 1 is an intermediate structure for LED-equipped display products. The mounting substrate 90 includes a circuit for driving the plurality of pixels 70, which will be described later. The mounting substrate 90 is a CMOS substrate with silicon as the base material. The mounting substrate 90 has a mounting area 90a on which the plurality of pixels 70 are mounted. Although not shown in Figure 2 due to its minute size, the plurality of pixels 70 are arranged in the mounting area 90a.

[0010] Multiple pixels 70 are arranged regularly at equal intervals in both the X and Y directions. The X and Y directions are parallel to the main surface of the mounting substrate 90, respectively. The X direction is perpendicular to the Y direction. The number of multiple pixels 70 arranged in the mounting area 90a is, for example, 320 pixels in the X direction and 240 pixels in the Y direction.

[0011] As shown in Figure 3, each pixel 70 consists of a blue LED 71B, a green LED 71G, and a red LED 71R. A positive electrode 92p, a negative electrode (not shown), and a metal bump (not shown) are formed in the mounting area 90a of the mounting substrate 90, corresponding to the blue LED 71B, green LED 71G, and red LED 71R, respectively. The metal bumps are bonding members used when mounting the blue LED 71B, green LED 71G, and red LED 71R. The metal bumps are made of, for example, gold (Au) or an alloy of gold and sugar (Su). Furthermore, as shown in Figure 2, electrodes 96 for external power supply and signals are formed on the outer edge of the mounting substrate 90.

[0012] 2. Configuration of Pixel 70 In the mounting region 90a, as shown in FIG. 4 and FIG. 5, the plurality of pixels 70 are arranged in a grid pattern along the X direction and the Y direction. In plan view, as indicated by being surrounded by the dashed lines in FIG. 4 and FIG. 5, the shape of the pixel 70 is a square. The plan view refers to viewing from the Z direction orthogonal to the X direction and the Y direction. The Z direction is the direction from the mounting substrate 90 toward the pixels 70.

[0013] As described above, each pixel 70 is composed of a blue LED 71B, a green LED 71G, and a red LED 71R. The blue LED 71B is a sub-pixel that emits blue light. The green LED 71G is a sub-pixel that emits green light. The red LED 71R is a sub-pixel that emits red light. Within each pixel 70, the blue LED 71B, the green LED 71G, and the red LED 71R are arranged along the X direction. The blue LED 71B, the green LED 71G, and the red LED 71R correspond to a plurality of sub-pixels with mutually different emission colors. In addition, the blue LED 71B, the green LED 71G, and the red LED 71R each correspond to the LED 71.

[0014] As shown in FIG. 4, in the mounting region 90a, the blue LEDs 71B are arranged in one line along the Y direction. In the line adjacent to the line of blue LEDs 71B, the green LEDs 71G are arranged in one line along the Y direction. In the line adjacent to the line of green LEDs 71G, the red LEDs 71R are arranged in one line along the Y direction. In the X direction, the line of blue LEDs 71B, the line of green LEDs 71G, and the line of red LEDs 71R are periodically and repeatedly arranged.

[0015] As shown in Figure 5, the blue LED 71B has a light-emitting body 72B and a non-light-emitting part 73B. The light-emitting body 72B and the non-light-emitting part 73B are aligned along the Y direction. The light-emitting body 72B and the non-light-emitting part 73B are separated by a dividing groove 801B. As shown in Figures 6A to 6C, the shapes of the dividing groove 801B, the dividing groove 801G (described later), and the dividing groove 801R (described later) are such that the width of the groove narrows as you approach the bottom of the groove. The sides of the dividing groove 801B, the dividing groove 801G, and the dividing groove 801R are each planes inclined with respect to the Z direction.

[0016] The green LED 71G has a light-emitting body 72G and a non-light-emitting part 73G. The light-emitting body 72G and the non-light-emitting part 73G are aligned along the Y direction. The light-emitting body 72G and the non-light-emitting part 73G are separated by a dividing groove 801G.

[0017] The red LED 71R has a light-emitting body 72R and a non-light-emitting body 73R. The light-emitting body 72R and the non-light-emitting body 73R are aligned along the Y direction. The light-emitting body 72R and the non-light-emitting body 73R are separated by a dividing groove 801R.

[0018] As shown in Figure 6A, the blue LED 71B includes an epitaxial layer 300. The epitaxial layer 300 comprises a buffer layer 301, a light-emitting unit layer 30B, a tunnel junction layer 314, and an n-type layer 315.

[0019] The light-emitting unit layer 30B comprises a first n-type layer 302, a first light-emitting layer 303, and a first p-type layer 304. This configuration of the light-emitting unit layer 30B is the basic configuration of a light-emitting diode. The tunnel junction layer 314 and the n-type layer 315 are protective layers that protect the first p-type layer 304 from exposure and facilitate the injection of current from the n-type layer to the p-type layer, where ohmic electrodes can be easily formed. Note that the tunnel junction layer 314 and the n-type layer 315 may be omitted.

[0020] The buffer layer 301 is made of AlN or GaN grown at low temperature. The buffer layer 301 is located on the side of the epitaxial layer 300 furthest from the electrode 31. The electrode 31 is the positive electrode 31p and the negative electrode 31n, which will be described later. When manufacturing the monolithic LED array 101B, which will be described later, the buffer layer 301 mitigates the degree of lattice mismatch between the element substrate 103 and the first n-type layer 302.

[0021] The first n-type layer 302 is stacked on the buffer layer 301. The thickness of the first n-type layer 302 is, for example, 2000 nm. The first n-type layer 302 is formed of GaN (n-GaN) doped with n-type impurities such as Si.

[0022] The first light-emitting layer 303 is laminated on the first n-type layer 302. The first light-emitting layer 303 is formed, for example, as a multiple quantum well. The thickness of the first light-emitting layer 303 is, for example, 50 nm. The first light-emitting layer 303 is configured to produce light with an emission wavelength corresponding to blue (for example, 450-470 nm) by adjusting the mixed crystal ratio of Ga (gallium), In (indium), and N (nitrogen).

[0023] The first p-type layer 304 is stacked on the first light-emitting layer 303. The thickness of the first p-type layer 304 is, for example, 180 nm. The first p-type layer 304 is formed of GaN (p-GaN) to which p-type impurities such as Mg have been added.

[0024] The tunnel junction layer 314 is laminated on the first p-type layer 304. The thickness of the tunnel junction layer 314 is, for example, 25 nm. The tunnel junction layer 314 is formed by laminating an n++ GaN layer with a high concentration of Si and a p++ GaN layer with a high concentration of Mg. Here, n++ means a state in which n-type impurities are added at a high concentration, and p++ means a state in which p-type impurities are added at a high concentration. The tunnel junction layer 314 enables current to flow from the n-type layer to the p-type layer.

[0025] The n-type layer 315 is stacked on the tunnel junction layer 314. The thickness of the n-type layer 315 is, for example, 400 nm. The n-type layer 315 is formed of GaN (n-GaN) doped with n-type impurities such as Si.

[0026] The dividing groove 801B that separates the light-emitting body portion 72B from the non-light-emitting portion 73B has a depth to the first n-type layer 302 and divides the first light-emitting layer 303 of the light-emitting unit layer 30B.

[0027] A conductive via 33B is formed in the non-luminescent portion 73B. As shown in Figure 5, the conductive via 33B is formed in a slit shape with a longitudinal side and a transverse side in a plan view. The conductive via 33B also has a depth to the first n-type layer 302. The conductive via 33B has a tapered shape, becoming narrower towards the bottom.

[0028] The blue LED 71B comprises a positive electrode 31p and a negative electrode 31n. The positive electrode 31p is formed on the n-type layer 315 in the light-emitting body portion 72B. The negative electrode 31n is formed on the upper surface of the n-type layer 315 in the non-light-emitting portion 73B. The negative electrode 31n is electrically connected to the conductive via 33B.

[0029] This configuration creates an electrical circuit that causes the first light-emitting layer 303 of the light-emitting unit layer 30B to emit light. Specifically, an electrical circuit is formed that runs from the positive electrode 31p through the n-type layer 315, the tunnel junction layer 314, the first p-type layer 304, the first light-emitting layer 303, the first n-type layer 302, and the conductive via 33B to the negative electrode 31n.

[0030] As shown in Figure 6B, the green LED 71G differs from the blue LED 71B in that it lacks the light-emitting unit layer 30B and instead has the light-emitting unit layer 30G. The other components of the green LED 71G are the same as those of the blue LED 71B. The light-emitting unit layer 30G emits green light.

[0031] The light-emitting unit layer 30G differs from the light-emitting unit layer 30B mainly in that it does not have a first light-emitting layer 303, but instead has a second light-emitting layer 307. The second light-emitting layer 307 is laminated on the second n-type layer 306. The second light-emitting layer 307 is formed, for example, as a multiple quantum well. The thickness of the second light-emitting layer 307 is, for example, 50 nm. The second light-emitting layer 307 is configured to produce light with an emission wavelength corresponding to green (for example, 500-570 nm) by adjusting the mixed crystal ratio of Ga (gallium), In (indium), and N (nitrogen). The second n-type layer 306 and the second p-type layer 308 of the light-emitting unit layer 30G have the same configuration as the first n-type layer 302 and the first p-type layer 304, respectively.

[0032] The dividing groove 801G that separates the light-emitting body portion 72G and the non-light-emitting portion 73G has a depth to the second n-type layer 306 and divides the second light-emitting layer 307 of the light-emitting unit layer 30G. A conductive via 33G is formed in the non-light-emitting portion 73G. As shown in Figure 5, the conductive via 33G is formed in a slit shape with a longitudinal side and a transverse side in a plan view. The conductive via 33G also has a depth to the second n-type layer 306.

[0033] The configuration of this light-emitting unit layer 30G constitutes an electrical circuit that causes the second light-emitting layer 307 to emit light. Specifically, an electrical circuit is formed that runs from the positive electrode 31p through the n-type layer 315, the tunnel junction layer 314, the second p-type layer 308, the second light-emitting layer 307, the second n-type layer 306, and the conductive via 33G to the negative electrode 31n.

[0034] As shown in Figure 6C, the red LED 71R differs from the blue LED 71B in that it lacks the light-emitting unit layer 30B and instead has a light-emitting unit layer 30R. The other components of the red LED 71R are the same as those of the blue LED 71B. The light-emitting unit layer 30R emits red light.

[0035] The light-emitting unit layer 30R differs from the light-emitting unit layer 30B mainly in that it does not have a first light-emitting layer 303, but instead has a third light-emitting layer 312 and a third buffer layer 311. The third light-emitting layer 312 is formed, for example, as a multiple quantum well. The thickness of the third light-emitting layer 312 is, for example, 50 nm. The third light-emitting layer 312 is configured to produce light with an emission wavelength corresponding to red (for example, 600-650 nm) by adjusting the mixed crystal ratio of Ga (gallium), In (indium), and N (nitrogen).

[0036] Furthermore, in the light-emitting unit layer 30R, a third buffer layer 311 is laminated between the third n-type layer 310 and the third light-emitting layer 312. The thickness of the third buffer layer 311 is, for example, 600 nm. The third buffer layer 311 mitigates the lattice mismatch between the third light-emitting layer 312 and the third n-type layer 310. The third buffer layer 311 is made of GaInN. The third n-type layer 310 and the third p-type layer 313 in the light-emitting unit layer 30R have the same configuration as the first n-type layer 302 and the first p-type layer 304, respectively.

[0037] The dividing groove 801R that separates the light-emitting body portion 72R and the non-light-emitting portion 73R has a depth to the third n-type layer 310 and divides the third light-emitting layer 312 of the light-emitting unit layer 30R. A conductive via 33R is formed in the non-light-emitting portion 73R. As shown in Figure 5, the conductive via 33R is formed in a slit shape with a longitudinal side and a transverse side in a plan view. The conductive via 33R also has a depth to the third n-type layer 310.

[0038] The configuration of this light-emitting unit layer 30R constitutes an electrical circuit that causes the third light-emitting layer 312 to emit light. Specifically, an electrical circuit is formed that runs from the positive electrode 31p through the n-type layer 315, the tunnel junction layer 314, the third p-type layer 313, the third light-emitting layer 312, the third buffer layer 311, the third n-type layer 310, and the conductive via 33R to the negative electrode 31n. Note that the blue LED 71B, the green LED 71G, and the red LED 71R each correspond to an LED 71 equipped with a single-layer light-emitting unit layer.

[0039] 3. Method for manufacturing LED device 1 (1) Method of manufacturing the mounting board 90 A method for manufacturing the mounting substrate 90 will be described. The mounting substrate 90 is manufactured by a device formation process in which elements such as MOSFETs are formed on a silicon substrate, a wiring process in which wiring is formed to connect the elements, an electrical characteristic inspection of the wafer, and a separation process. These processes can be carried out by known methods such as cleaning, film deposition, photolithography, etching, and ion implantation.

[0040] In the wiring process, wiring is formed to connect the elements, and as shown in Figure 3, a positive electrode 92p and a negative electrode corresponding to each pixel 70 are formed in the mounting area 90a of the mounting substrate 90. Also, as shown in Figure 2, an electrode 96 is formed on the outer edge of the mounting substrate 90. Furthermore, metal bumps are formed on the positive electrode 92p and the negative electrode by electroplating. The positive electrode 92p and the negative electrode are formed to the same height without any special arrangement. The metal bumps are also formed to the same thickness.

[0041] (2) Method for manufacturing multiple pixels 70 First, a monolithic LED array 101 is manufactured, comprising multiple LEDs 71 arranged on an element substrate 103. The LEDs 71 are blue LEDs 71B, green LEDs 71G, or red LEDs 71R. Three monolithic LED arrays 101 are manufactured: a monolithic LED array 101B comprising multiple blue LEDs 71B, a monolithic LED array 101G comprising multiple green LEDs 71G, and a monolithic LED array 101R comprising multiple red LEDs 71R. Figure 7 shows the monolithic LED array 101B.

[0042] A method for manufacturing the monolithic LED array 101B will be described. As shown in S1 of Figure 8, an epitaxial layer 300 is formed on the element substrate 103. The element substrate 103 is, for example, a plate-shaped sapphire substrate with both sides polished to a flat surface. The thickness of the element substrate 103 is, for example, 300 μm. On the element substrate 103, a buffer layer 301 is formed, for example, with a thickness of 2000 nm, and the epitaxial layer 300 of the blue LED 71B is formed.

[0043] Next, as shown in S2 of Figure 8, by forming partition grooves 80, the regularly arranged blue LEDs 71B are separated, excluding the epitaxial layer 300 other than the positions of the multiple blue LEDs 71B. The number of blue LEDs 71B in the monolithic LED array 101B is the same as the number of sub-pixels blue LEDs 71B arranged in the mounting area 90a of the mounting substrate 90. The arrangement of the multiple blue LEDs 71B on the element substrate 103 is the same as the arrangement on the mounting substrate 90 shown in Figure 4. The blue LEDs 71B are arranged in a single row along the Y direction. The row of blue LEDs 71B is arranged periodically and repeatedly with intervals in the X direction. The spacing between the blue LEDs 71B in the X and Y directions is the same as the spacing on the mounting substrate 90.

[0044] Next, in S3 of Figure 8, the divided grooves 801B and conductive vias 33B shown in Figure 6A are formed in each of the blue LEDs 71B.

[0045] Next, in S4 of Figure 8, a negative electrode 31n and a positive electrode 31p are formed on each blue LED 71B.

[0046] For example, the steps of separating multiple blue LEDs 71B, forming dividing grooves 801B, and forming conductive vias 33B include the steps of forming a laminated mask and etching. The steps of forming the positive electrode 31p and the negative electrode 31n include, for example, sputtering, vapor deposition, and plating.

[0047] By following the above steps, the monolithic LED array 101B shown in Figure 7 can be manufactured. Furthermore, monolithic LED arrays 101G and 101R can be manufactured using essentially the same method. However, when manufacturing the monolithic LED array 101G, an epitaxial layer 320 of green LEDs 71G is formed on the element substrate 103, and multiple green LEDs 71G are formed from the epitaxial layer 320. Similarly, when manufacturing the monolithic LED array 101R, an epitaxial layer 340 of red LEDs 71R is formed on the element substrate 103, and multiple red LEDs 71R are formed from the epitaxial layer 340.

[0048] (3) Implementation of monolithic LED arrays 101B, 101G, and 101R (i) Measure the electrical and optical characteristics of the monolithic LED array 101B to confirm that the monolithic LED array 101B is a good product.

[0049] (ii) Next, as shown in S11 of Figure 9, the monolithic LED array 101B that has been confirmed to be good is placed on the mounting area 90a of the mounting substrate 90. The multiple blue LEDs 71B of the monolithic LED array 101B are arranged in a manner that allows them to be aligned on the mounting substrate 90. Furthermore, these multiple blue LEDs 71B are placed at the positions of the positive electrode 92p, negative electrode, and metal bump on the mounting substrate 90, corresponding to each of the blue LEDs 71B.

[0050] (iii) Next, the positioned monolithic LED array 101B is pressurized and heated. This connects the positive electrode 31p and negative electrode 31n of each blue LED 71B to the positive electrode 92p and negative electrode of the mounting substrate 90 via the metal bumps. In this way, the monolithic LED array 101B is mounted on the mounting substrate 90.

[0051] (iv) Next, as shown in S12 of Figure 9, the element substrate 103 is removed from the monolithic LED array 101B that was mounted in (iii) above. Methods for removing the element substrate 103 include laser lift-off and immersion of the monolithic LED array 101B in water. When the monolithic LED array 101B is immersed in water, the buffer layer 301 dissolves, separating the element substrate 103 from the blue LED 71B. When the element substrate 103 is removed, part or all of the buffer layer 301 is also separated from the blue LED 71B. Figure 6A shows the case where part of the buffer layer 301 remains.

[0052] (v) Next, the same process as in (i) to (iv) above is performed on the monolithic LED array 101G to mount the green LED 71G onto the mounting substrate 90. The position where the green LED 71G is mounted on the mounting substrate 90 is shifted in the X direction compared to the blue LED 71B that was mounted earlier.

[0053] (vi) Next, the same process as in (i) to (iv) above is performed on the monolithic LED array 101R to mount the red LED 71R onto the mounting substrate 90. The position where the red LED 71R is mounted on the mounting substrate 90 is shifted in the X direction compared to the blue LED 71B and green LED 71G that were mounted earlier. Through the above process, as shown in S13 of Figure 9, the blue LED 71B, green LED 71G, and red LED 71R are mounted on the mounting substrate 90, and the LED device 1 is completed.

[0054] The manufacturing method for the LED device 1 described above involves mounting a monolithic LED array 101, which includes one of the following: a blue LED 71B, a green LED 71G, and a red LED 71R, onto a mounting area 90a, and then removing the element substrate 103. This process is repeated multiple times until the blue LED 71B, green LED 71G, and red LED 71R are mounted on the mounting substrate 90. The light-emitting color of the LED 71 in the monolithic LED array 101 used will differ at each stage of the process.

[0055] 4. Effects of LED device 1 and the method for manufacturing LED device 1 (1A) When light-emitting unit layers with different emission colors are stacked, stress effects due to differences in grid spacing may occur. In particular, the difference in grid spacing between the blue light-emitting unit layer 30B and the red light-emitting unit layer 30R is large, so when the blue light-emitting unit layer 30B and the red light-emitting unit layer 30R are stacked, stress effects due to differences in grid spacing are more likely to occur.

[0056] In the LED device 1 of this disclosure, each of the multiple subpixels with different emission colors is an LED 71 formed from a single-layer light-emitting unit layer. Therefore, since light-emitting unit layers with different emission colors are not stacked, the effects of differences in grid spacing can be suppressed.

[0057] When light-emitting unit layers with different emission colors are stacked, the light-emitting unit layer formed earlier may be affected by heat during the formation of the light-emitting unit layer formed later. In particular, the blue light-emitting unit layer 30B and the green light-emitting unit layer 30G are affected more by heat because their formation temperatures are almost the same.

[0058] In the LED device 1 of this disclosure, each of the multiple subpixels with different light-emitting colors is an LED 71 formed from a single-layer light-emitting unit layer. Therefore, since light-emitting unit layers with different light-emitting colors are not stacked, thermal effects can be suppressed.

[0059] These features enable the LED device 1 to maintain good electrical and optical properties. Therefore, the LED device 1 of this disclosure can reduce the technical difficulty when forming LEDs 71 with multiple light-emitting colors.

[0060] Furthermore, according to the manufacturing method of the LED device 1 of this disclosure, by mounting a monolithic LED array 101 on a mounting substrate 90 in which a plurality of LEDs 71 are formed, many pixels 70 can be formed and mounted all at once, enabling efficient manufacturing. Therefore, the manufacturing method of the LED device 1 of this disclosure can reduce the technical difficulty when forming LEDs 71 of multiple light-emitting colors.

[0061] <Second Embodiment> 1. Differences from the first embodiment The second embodiment has the same basic configuration as the first embodiment, so the differences will be explained below. In the first embodiment, all of the subpixels with different emission colors were LEDs 71 formed from a single-layer light-emitting unit layer. In contrast, the second embodiment differs in that the multiple subpixels with different emission colors are composed of LEDs 71 formed from a single-layer light-emitting unit layer and LEDs 71 formed from a double-layer light-emitting unit layer.

[0062] 2. Configuration of subpixels (2-1) Configuration of the blue LED 71B As shown in Figure 10A, the blue LED 71B includes an epitaxial layer 400. The epitaxial layer 400 comprises a buffer layer 301, a light-emitting unit layer 30B, a tunnel junction layer 305, a light-emitting unit layer 30G, a tunnel junction layer 314, and an n-type layer 315.

[0063] The light-emitting unit layer 30B comprises a first n-type layer 302, a first light-emitting layer 303, and a first p-type layer 304. The light-emitting unit layer 30G comprises a second n-type layer 306, a second light-emitting layer 307, and a second p-type layer 308. In the first embodiment, the thickness of the second n-type layer 306 was 2000 nm, the same as the thickness of the first n-type layer 302, but in the second embodiment, the thickness of the second n-type layer 306 is 400 nm.

[0064] The dividing groove 801B that separates the light-emitting body portion 72B from the non-light-emitting portion 73B has a depth to the first n-type layer 302 of the light-emitting unit layer 30B and divides the first light-emitting layer 303 of the light-emitting unit layer 30B. The conductive via 33B of the non-light-emitting portion 73B has a depth to the first n-type layer 302.

[0065] Furthermore, conductive vias 34B are also formed in the light-emitting body portion 72B. As shown in Figure 11, in a plan view, the conductive vias 34B of the light-emitting body portion 72B are formed in a slit shape having a longitudinal side and a transverse side. The conductive vias 34B of the light-emitting body portion 72B have a depth to the second n-type layer 306. The conductive vias 34B have a tapered shape, becoming narrower as they approach the bottom of the conductive vias 33B.

[0066] This configuration of the blue LED 71B creates an electrical circuit that causes the first light-emitting layer 303 of the light-emitting unit layer 30B to emit light. Specifically, an electrical circuit is formed that runs from the positive electrode 31p through the conductive via 34B, the second n-type layer 306, the tunnel junction layer 305, the first p-type layer 304, the first light-emitting layer 303, the first n-type layer 302, and the conductive via 33B to the negative electrode 31n. Note that the blue LED 71B corresponds to the LED 71 which has two light-emitting unit layers.

[0067] (2-2) Configuration of the Green LED 71G As shown in Figure 10B, the green LED 71G has an epitaxial layer 400 with the same configuration as the blue LED 71B. The dividing groove 801G that separates the light-emitting body 72G and the non-light-emitting part 73G has a depth to the second n-type layer 306 of the light-emitting unit layer 30G and divides the second light-emitting layer 307 of the light-emitting unit layer 30G. The conductive via 33G of the non-light-emitting part 73G has a depth to the second n-type layer 306.

[0068] This configuration of the green LED 71G creates an electrical circuit that causes the second light-emitting layer 307 of the light-emitting unit layer 30G to emit light. Specifically, an electrical circuit is formed that runs from the positive electrode 31p through the n-type layer 315, the tunnel junction layer 314, the second p-type layer 308, the second light-emitting layer 307, the second n-type layer 306, and the conductive via 33G to the negative electrode 31n. The green LED 71G corresponds to the LED 71 which has two light-emitting unit layers.

[0069] (2-3) Configuration of the red LED 71R As shown in Figure 10C, the red LED 71R has the same structure as in the first embodiment.

[0070] 3. Method for manufacturing LED device 1 (1) Differences from the first embodiment The basic manufacturing method of the second embodiment is the same as that of the first embodiment, so the differences will be explained below. In the first embodiment, all of the subpixels with different light-emitting colors were LEDs 71 formed from a single-layer light-emitting unit layer. In contrast, the second embodiment differs in that it uses a manufacturing method in which LEDs 71 formed from two layers of light-emitting unit layers are used as the blue LED 71B and the green LED 71G.

[0071] (2) Configuration of monolithic LED arrays 101BG and 101R As shown in Figure 12, the monolithic LED array 101BG comprises an element substrate 103, a plurality of blue LEDs 71B, and a plurality of green LEDs 71G. The plurality of blue LEDs 71B and the plurality of green LEDs 71G are arranged on one surface of the element substrate 103. The orientation of the blue LEDs 71B and green LEDs 71G relative to the element substrate 103 is such that the buffer layer 301 is in contact with the element substrate 103. The arrangement of the plurality of blue LEDs 71B and the plurality of green LEDs 71G on the element substrate 103 is the same as the arrangement on the mounting substrate 90.

[0072] In the monolithic LED array 101BG, the blue LEDs 71B are arranged in a single row along the Y direction. The row of blue LEDs 71B is arranged in a periodically repeating pattern with intervals in the X direction. The spacing between the blue LEDs 71B in the X and Y directions is the same as the spacing on the mounting substrate 90.

[0073] In the monolithic LED array 101BG, the green LEDs 71G are arranged in a single row along the Y direction. The row of green LEDs 71G is arranged periodically in the X direction with intervals between them. The spacing between the green LEDs 71G in the X and Y directions is the same as the spacing on the mounting substrate 90.

[0074] In the monolithic LED array 101BG, the relative position of the green LED 71G to the blue LED 71B is the same as the position in LED device 1. The configuration of the monolithic LED array 101R is the same as in the first embodiment.

[0075] (3) Manufacturing method of monolithic LED arrays 101BG and 101R A method for manufacturing the monolithic LED array 101BG will be described. As shown in S21 of Figure 13, an epitaxial layer 400 is formed on the element substrate 103. Next, as shown in S22 of Figure 13, a plurality of regularly arranged blue LEDs 71B and a plurality of green LEDs 71G are separated from the epitaxial layer 400 by forming partition grooves 80.

[0076] Next, in step S23 of Figure 13, the division groove 801B, conductive via 33B, conductive via 34B, etc., shown in Figure 10A, are formed on each blue LED 71B. Similarly, the division groove 801G, conductive via 33G, etc., shown in Figure 10B, are formed on each green LED 71G.

[0077] Next, in step S24 of Figure 13, a negative electrode 31n and a positive electrode 31p are formed on the blue LED 71B and the green LED 71G, respectively. Through these steps, the monolithic LED array 101BG can be manufactured.

[0078] Next, the monolithic LED array 101R is manufactured in the same manner as in the first embodiment.

[0079] (4) Implementation of monolithic LED arrays 101BG and 101R (i) Electrical and optical characteristics of monolithic LED arrays 101BG and 101R are measured to confirm that the monolithic LED arrays 101BG and 101R are of good quality.

[0080] (ii) As shown in S31 of Figure 14, the monolithic LED array 101R that has been confirmed to be good is placed in the mounting area 90a of the mounting substrate 90. The method of placing the monolithic LED array 101R is the same as in the first embodiment. The reason for mounting the monolithic LED array 101R first is that the thickness of the epitaxial layer 340 of the monolithic LED array 101R is thinner than the thickness of the epitaxial layer 400 of the monolithic LED array 101BG.

[0081] (iii) Next, the positioned monolithic LED array 101R is heated under pressure. This connects the positive electrode 31p and negative electrode 31n of each red LED 71R to the positive electrode 92p and negative electrode of the mounting substrate 90 via the metal bumps. In this way, the monolithic LED array 101R is mounted on the mounting substrate 90.

[0082] (iv) Next, as shown in S32 of Figure 14, the element substrate 103 is removed from the monolithic LED array 101R that was mounted in (iii) above. The method for removing the element substrate 103 is the same as in the first embodiment.

[0083] (v) Next, as shown in S33 of Figure 14, the monolithic LED array 101BG that has been confirmed to be good is placed in the mounting area 90a of the mounting substrate 90. At this time, the positions in which the blue LED 71B and green LED 71G are mounted are shifted in the X direction compared to the red LED 71R that was mounted earlier.

[0084] Since the heights of the blue LED 71B and the green LED 71G are greater than the height of the red LED 71R, the element substrate 103 of the monolithic LED array 101BG is less likely to come into contact with the red LED 71R.

[0085] (vi) Next, the positioned monolithic LED array 101BG is heated under pressure. This connects the positive electrode 31p and negative electrode 31n of each blue LED 71B and each green LED 71G to the positive electrode 92p and negative electrode of the mounting substrate 90 via the metal bumps. In this way, the monolithic LED array 101BG is mounted on the mounting substrate 90.

[0086] (vii) Next, as shown in S34 of Figure 14, the element substrate 103 is removed from the monolithic LED array 101BG that was mounted in (vi). The method for removing the element substrate 103 is the same as in the first embodiment. Through the above steps, the red LED 71R, blue LED 71B, and green LED 71G are mounted on the mounting substrate 90, and the LED device 1 is completed.

[0087] The manufacturing method for the LED device 1 described above involves mounting a monolithic LED array 101, which includes one or two of the blue LED 71B, green LED 71G, and red LED 71R, onto a mounting area 90a, and then removing the element substrate 103. This process is repeated multiple times until the blue LED 71B, green LED 71G, and red LED 71R are mounted on the mounting substrate 90. The light-emitting color of the LEDs 71 in the monolithic LED array 101 used will differ at each stage of the process.

[0088] 4. Effects of LED device 1 and the method for manufacturing LED device 1 (2A) According to the LED device 1 of this disclosure, the multiple subpixels with different light-emitting colors are LEDs 71 formed with a single-layer light-emitting unit layer and LEDs 71 formed with two layers of light-emitting unit layers. The LEDs 71 formed with two layers of light-emitting unit layers are a combination of a blue light-emitting unit layer 30B and a green light-emitting unit layer 30G. Therefore, the blue light-emitting unit layer 30B and the red light-emitting unit layer 30R, which have a large difference in the grid spacing of their light-emitting layers, are not stacked. As a result, the difference in grid spacing between the blue light-emitting unit layer 30B and the red light-emitting unit layer 30R does not affect the device. This makes it possible to maintain good electrical and optical characteristics.

[0089] (2B) According to the manufacturing method of the LED device 1 of this disclosure, the monolithic LED array 101 is mounted only twice. Therefore, the number of steps can be reduced compared to the first embodiment.

[0090] <Third Embodiment> 1. Differences from the second embodiment The third embodiment has the same basic configuration as the second embodiment, so the differences will be explained below. In the second embodiment, the LED 71 formed with a single-layer light-emitting unit was a red LED 71R, and the LED 71 formed with two layers of light-emitting unit was a blue LED 71B and a green LED 71G. In contrast, in the third embodiment, the LED 71 formed with a single-layer light-emitting unit is a blue LED 71B, and the LED 71 formed with two layers of light-emitting unit is a green LED 71G and a red LED 71R. These will be explained in detail below.

[0091] 2. Configuration of subpixels (2-1) Configuration of the blue LED 71B As shown in Figure 15A, the configuration of the blue LED 71B is the same as in the first embodiment. (2-2) Configuration of green LED 71G and red LED 71R As shown in Figures 15B and 15C, the green LED 71G and the red LED 71R are equipped with an epitaxial layer 500. The epitaxial layer 500 comprises a buffer layer 301, an emitting unit layer 30G, a tunnel junction layer 305, an emitting unit layer 30R, a tunnel junction layer 314, and an n-type layer 315.

[0092] The configurations of the light-emitting unit layer 30G and the light-emitting unit layer 30R are basically the same as in the first and second embodiments. The light-emitting unit layer 30G comprises a second n-type layer 306, a second light-emitting layer 307, and a second p-type layer 308. The light-emitting unit layer 30R comprises a third n-type layer 310, a third buffer layer 311, a third light-emitting layer 312, and a third p-type layer 313. However, the thickness of the second n-type layer 306 is, for example, 2000 nm, and the thickness of the third n-type layer 310 is, for example, 400 nm.

[0093] Furthermore, the green LED 71G is configured with an electrical circuit that causes the second light-emitting layer 307 of the light-emitting unit layer 30G to light up. Similarly, the red LED 71R is configured with an electrical circuit that causes the third light-emitting layer 312 of the light-emitting unit layer 30R to light up.

[0094] The manufacturing method for LED device 1 uses a monolithic LED array 101GR and a monolithic LED array 101B. In this embodiment, the monolithic LED array 101B is mounted first, and then the monolithic LED array 101GR is mounted.

[0095] 3. Effects of the manufacturing method of LED device 1 (3A) According to the manufacturing method of the LED device 1 of this disclosure, the multiple subpixels having different light-emitting colors are LEDs 71 formed with a single-layer light-emitting unit layer and LEDs 71 formed with two layers of light-emitting unit layers. The LEDs 71 formed with two layers of light-emitting unit layers include a combination of a green light-emitting unit layer 30G and a red light-emitting unit layer 30R. Therefore, the blue light-emitting unit layer 30B and the green light-emitting unit layer 30G, which are formed at approximately the same temperature, are formed in separate subpixels. This makes it possible to maintain good electrical and optical characteristics.

[0096] (3B) According to the manufacturing method of the LED device 1 of this disclosure, the monolithic LED array 101 is mounted only twice. Therefore, the number of steps can be reduced compared to the first embodiment.

[0097] <Other Embodiments> Although embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above and can be implemented in various modified forms.

[0098] (1) In the first to third embodiments, each monolithic LED array 101 had a size approximately equal to the mounting area 90a. For example, as shown in Figure 16, the mounting area 90a can be divided into a plurality of mounting sections 91. A red LED 71R, a blue LED 71B, or a green LED 71G can be mounted in each mounting section 91 using the monolithic LED array 101.

[0099] For example, the red LED 71R can be implemented as follows. (i) Each monolithic LED array 101R is formed to have a size corresponding to one mounting section 91 and to have a number of red sub-pixels corresponding to the mounting section 91. Then, the monolithic LED array 101R is subjected to measurements of its electrical and optical characteristics, and monolithic LED arrays 101R with a high yield rate are selected.

[0100] (ii) One selected monolithic LED array 101R is mounted in one of the mounting sections 91. Next, the element substrate 103 is removed from the mounted monolithic LED array 101R. (iii) Next, another selected monolithic LED array 101R is newly mounted in an adjacent mounting section 91. The method for mounting the other monolithic LED array 101R is the same as the method used to mount the monolithic LED array 101R in (ii) above.

[0101] (iv) Next, the element substrate 103 is removed from the monolithic LED array 101R that was implemented in (iii) above. (v) Similarly, the process of mounting a new monolithic LED array 101R in another mounting section 91 adjacent to a mounting section 91 on which a monolithic LED array 101R has already been mounted, and then removing the element substrate 103 from that monolithic LED array 101R is repeated. Finally, red LEDs 71R are mounted in all mounting sections 91. Blue LEDs 71B and green LEDs 71G can also be mounted in the same manner in each mounting section 91.

[0102] This makes it possible to increase the yield rate of good pixels in LED device 1. In other words, it is not easy to consistently produce good pixels 70 in a single monolithic LED array 101 that covers the entire mounting area 90a, and defective pixels 70 often occur in some areas. In contrast, by using multiple selected monolithic LED arrays 101 with a high yield rate, the entire mounting area 90a can be composed of pixels 70 with a high yield rate.

[0103] The number of pixels in LED device 1, the number of divisions of the pixels in LED device 1, and the number of pixels in monolithic LED array 101 are arbitrary. However, for production efficiency, it is preferable for the monolithic LED array 101 used after characteristic verification to have excellent compatibility. For this reason, it is desirable that the pixels 70 of LED device 1 are evenly divided among multiple monolithic LED arrays 101, and that each monolithic LED array 101 has the same number of pixels. In this case, the multiple mounting sections 91 will have the same shape. Furthermore, while the mounting process can be made more efficient even if the monolithic LED array 101 has 4 or 16 pixels, it is desirable to have 64 or more pixels.

[0104] (2) In the first and second embodiments, the material of the light-emitting unit layer 30R may be a material other than GaN, such as AlInGaP or GaAlAs. In this case, for example, GaP can be used as the element substrate 103, and after mounting the red LED 71R onto the mounting substrate 90, the element substrate 103 can be removed by polishing.

[0105] (3) In the second and third embodiments, the subpixels formed by stacking two light-emitting unit layers may be integrated. With this configuration, the two subpixels are continuous, making color mixing easier. Also, when these subpixels are mounted using a pick-and-place method, the two subpixels can be mounted at once, thus reducing the mounting process.

[0106] To achieve this configuration, for example, in S22 of Figure 13, the adjacent blue LED 71B and green LED 71G, which constitute the same pixel 70, are not separated. Instead, in S23 of Figure 13, a partition groove 80 is formed that is the same depth as the dividing groove 801B and does not reach the sapphire element substrate 103. Subsequently, the monolithic LED array 101BG is mounted on the mounting substrate 90, and the element substrate 103 is removed from the monolithic LED array 101BG. As a result, the two subpixels (i.e., the adjacent blue LED 71B and green LED 71G) are connected by a buffer layer 301 or a first n-type layer 302.

[0107] (4) The pixels 70 only need to be arranged regularly enough that they do not cause any problems as a display when a viewer sees the LED device 1. Not all of the pixels 70 in the mounting area 90a need to be equally spaced. For example, the spacing of the pixels 70 in the boundary areas of multiple mounting sections 91 in the mounting area 90a may be slightly larger than in the central part of the mounting section 91.

[0108] (5) The function of one component in each of the above embodiments may be divided among multiple components, or the function of multiple components may be performed by one component. Also, some of the configurations of each of the above embodiments may be omitted. Also, at least some of the configurations of each of the above embodiments may be added to, replaced with, etc., the configurations of other embodiments.

[0109] (6) In addition to the manufacturing method of the LED device 1 described above, this disclosure can also be realized in various forms, such as the LED device 1, a system using the LED device 1 as a component, etc. [Explanation of Symbols]

[0110] 1…LED device, 30B, 30G, 30R…light-emitting unit layer, 31n…negative electrode, 31p…positive electrode, 33B, 33G, 33R, 34B, 34G…conductive via, 70…pixel, 71B…blue LED, 71G…green LED, 71R…red LED, 72B, 72G, 72R…light-emitting body, 73B, 73G, 73R…non-light-emitting part, 80…partition groove, 90…mounting substrate, 90a…mounting area, 91…mounting area, 92p…positive electrode, 96…electrode, 101B, 101BG, 101BR, 101G, 101GR, 101R…monolithic LED array 103...Element substrate, 200...Goggles, 201...Lens, 202...Eye, 300, 320, 340, 400, 500...Epitaxial layer, 301...Buffer layer, 302...First n-type layer, 303...First light-emitting layer, 304...First p-type layer, 305...Tunnel junction layer, 306...Second n-type layer, 307...Second light-emitting layer, 308...Second p-type layer, 310...Third n-type layer, 311...Third buffer layer, 312...Third light-emitting layer, 313...Third p-type layer, 314...Tunnel junction layer, 315...n-type layer, 801B, 801G, 801R...Divided groove

Claims

1. Implemented circuit board and The mounting substrate comprises a plurality of pixels arranged in the mounting area, The aforementioned pixel consists of a plurality of subpixels whose emitted colors are different from each other. The sub-pixels include an LED having a single-layer light-emitting unit layer and an LED having two-layer light-emitting unit layers. LED device.

2. The LED device according to claim 1, The LED comprising the aforementioned single-layer light-emitting unit is an LED that emits red light, The LED comprising the two light-emitting unit layers includes an LED that emits blue light and an LED that emits green light. LED device.

3. The LED device according to claim 1, The LED comprising the aforementioned single-layer light-emitting unit is an LED that emits either blue or green light, The LED comprising the two light-emitting unit layers includes an LED that emits light other than the other of green and blue, and an LED that emits red light. LED device.

4. Implemented circuit board and The mounting substrate comprises a plurality of pixels arranged in the mounting area, The aforementioned pixel consists of a plurality of subpixels whose emitted colors are different from each other. The method for manufacturing an LED device in which the sub-pixel is an LED, A method for manufacturing an LED device, comprising mounting a monolithic LED array, which includes an element substrate and the LEDs arranged and formed on the element substrate, onto a mounting area, and then removing the element substrate multiple times such that the light-emitting color of the LEDs in the monolithic LED array differs between some of the steps and other steps, thereby forming pixels consisting of a plurality of sub-pixels with different light-emitting colors.

5. A method for manufacturing an LED device according to claim 4, The process using the monolithic LED array comprising the LED having a single-layer light-emitting unit layer, The process involves using the monolithic LED array, which includes the LED having two light-emitting unit layers, A method for manufacturing LED devices.

6. A method for manufacturing an LED device according to claim 4 or 5, The monolithic LED array is mounted in each of the multiple mounting sections included in the aforementioned mounting area. A method for manufacturing LED devices.

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