JP3874971B2 - Manufacturing method of light emitting diode chip - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is to reduce the loss of the output light inside the LED chips for the production method of the light-emitting diodes chips Ru improve brightness.
[0002]
[Prior art]
Conventionally, a light emitting diode (LED) chip as shown in a vertical side view of FIG. 6 is known. In FIG. 6, the LED chip 1 has a substantially rectangular cross-sectional shape, in which a light emitting layer 2 is formed, a front surface electrode 3 is provided on the front surface side, and a back surface electrode 4 is provided on the back surface side. ing.
[0003]
The output light Ra emitted from the light emitting layer 2 toward the lower side surface is reflected by the side surface X of the LED chip 1 and travels toward the bottom surface as reflected light Rb, and reflects from the bottom surface Z and travels upward as reflected light Rc. The reflected light Rc is reflected from the side surface Y of the LED chip 1 and emitted from the surface of the LED chip 1 as reflected light Rd. Reference numeral 10 denotes such a locus of light.
[0004]
FIG. 7 is a longitudinal sectional side view showing another conventional LED chip 1a. The LED chip 1a has a substantially trapezoidal cross-sectional shape and is formed with inclined surfaces X and Y. Also in this case, the output light Ra emitted from the light emitting layer 2 toward the lower side surface is sequentially reflected on one side surface X, the bottom surface Z, and the other side surface Y to become Rb, Rc, Rd, and the reflected light Rd is converted into the LED chip. Fired from the surface of la.
[0005]
FIG. 8 is a schematic configuration diagram of an example in which a large number of LED chips 1 having the shape shown in FIG. 6 are manufactured. In FIG. 8, 7 is a stage and 8 is a sticking tape. A light emitting layer is formed inside the wafer as a base material, and the front surface electrode 3 and the back surface electrode 4 are formed at predetermined intervals. An affixing tape 8 is affixed to the surface of the back electrode 4 and carried onto the stage 7.
[0006]
Next, the straight blade 5 having a substantially rectangular cross-section is moved in the direction of arrow A to perform dicing, and the hatched portion 9 is removed, and the individual LED chips 1 are separated from the substrate wafer. Form. FIG. 9 is a schematic configuration diagram of an example in which a large number of LED chips 1a having the shape shown in FIG. 7 are manufactured. In this case, the tape blade 6 having a substantially inverted trapezoidal cross section is moved in the direction of arrow B. Then, a dicing process is performed, and the hatched portion is removed from the base wafer to form individual LED chips 1a.
[0007]
[Problems to be solved by the invention]
As shown in FIG. 6 and FIG. 7, in the conventional LED chip, the output light emitted from the light emitting layer toward the lower side surface is one side, the bottom, the other side of the LED chip and the inside of the LED chip three times. It is fired outside after being reflected by. For this reason, there is a problem that the loss of output light increases inside the LED chip, the output light emitted to the outside decreases, and the luminance decreases.
[0008]
The present invention has been made in view of such problems, and an object of the present invention is to provide a light emitting diode chip capable of reducing the loss of output light inside the LED chip and improving the luminance, and a method for manufacturing the same.
[0010]
[Means for solving the problems]
The above object of the present invention is to provide a method of manufacturing a light emitting diode chip by forming a plurality of front and back electrodes respectively corresponding to individual light emitting diode chips on the front side and the back side of a wafer having a light emitting layer formed therein. And a step of applying an adhesive tape to each surface electrode, carrying the surface electrode side down and the back electrode side upward, and setting the focal length of the infrared light source at the position of the surface electrode. Receiving the reflected light from the surface, aligning the tapered blade having a substantially inverted trapezoidal cross section with respect to the position of the surface electrode, and dicing the wafer at a predetermined position by the tapered blade. This is achieved by separating the individual light-emitting diode chips.
[0011]
According to the above feature of the present invention , the light-emitting diode chip is formed in a substantially inverted trapezoidal shape with the front side being the long side and the back side being the short side. Therefore, the output light emitted toward the lower side surface of the light emitting layer, one side surface of the LED chip, emitted from the reflected inside of the other side and twice LED chip to the outside, than construction of traditional number of reflections LED chip inside is reduced, less loss of output light, the light emitting diode chip can be obtained with improved Brightness.
[0012]
In this case, the length of the long side is L, the depth from the surface side to the position where the light emitting layer is formed is d, and the angle formed by the perpendicular drawn from the long side and the line connecting the long side and the short side When θ is selected as (L−d · tan θ) · tan 2θ ≧ d, the output light emitted from the position T of the light emitting layer at a minute distance from one end face of the LED chip is of the side surface upper end can reach the inside, the ratio of the output light emitted from the surface of the LED chip is increased, thereby improving the luminous efficiency.
[0013]
In the present invention, since infrared rays are used as the light source, the output light is partially incident on the wafer and reflected at the position of the surface electrode, and the reflected light travels inside the wafer and is emitted to the outside. Therefore, the accurate alignment of the tapered blade during dicing process.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is a vertical side view showing the LED chip 1x, and FIG. 4 is a schematic configuration diagram of an example of manufacturing a large number of LED chips 1x. Parts that are the same as or correspond to those in the conventional example are given the same reference numerals, and detailed descriptions thereof are omitted.
[0015]
In FIG. 3, the LED chip 1 x has a long side on the front side, a short side on the back side, an inclined surface that is inclined at an elevation angle from the back side to the front side, and has a substantially inverted trapezoidal cross-sectional shape. The output light Rp emitted from the light emitting layer 2 toward the lower side surface is reflected at one side surface X at a reflection angle symmetric to the incident angle with respect to the normal line 14a to become reflected light Rq.
[0016]
The reflected light Rq is reflected from the other side surface Y of the LED chip 1x at a reflection angle symmetric to the incident angle with respect to the normal line 14b to be reflected light Rs, and is emitted to the outside from the surface of the LED chip 1x.
[0017]
Thus, in the configuration of FIG. 3, the output light emitted from the light emitting layer toward the lower side surface is reflected inside the LED chip twice on the one side surface and the other side surface of the LED chip and then emitted to the outside. ing. For this reason, there is no reflected light reflected from the bottom surface, and the number of times of reflection inside the LED chip is smaller than in the conventional configuration, so that the loss of output light is reduced and the luminance can be improved.
[0018]
In FIG. 4, a wafer serving as a base material is carried onto a stage 7 with a tape 8 attached to the surface electrode 3 with the back electrode 4 on the top and the surface electrode 3 on the bottom. . Next, the taper blade 6 having an inverted trapezoidal cross section is moved in the direction of arrow B to perform dicing, and the hatched portion 9 is excised to form individual LED chips 1y. By removing the sticking tape 8 and inverting the individual LED chips 1y, the LED chip 1x having the configuration shown in FIG. 3 is obtained.
[0019]
By the way, when forming individual LED chips by dicing the wafer serving as the base material, the position of the surface electrode is recognized by irradiating visible light and reflected light, and the position of the surface electrode is used as a reference. -Position alignment. However, when the dicing process is performed with the surface electrode on the lower side as shown in FIG. 4, the position of the surface electrode cannot be recognized using the reflected light by irradiation with visible light as in the prior art.
[0020]
FIG. 5 is a schematic configuration diagram illustrating a configuration for recognizing the position of the surface electrode in the present invention. In FIG. 5, reference numeral 11 denotes an LED that emits infrared rays as a light source. The focal length of the light source 11 is adjusted to the position of the surface electrode 3. An infrared camera 12 recognizes the position of the surface electrode 3 when the reflected light Rx from the surface electrode 3 is incident.
[0021]
As described above, since the infrared ray is used as the light source in the configuration of FIG. 5, the output light enters the wafer and is reflected at the position of the surface electrode 3, and the reflected light Rx travels through the wafer and is emitted to the outside. Is done. For this reason, the taper blade is accurately aligned when the dicing process is performed.
[0022]
FIG. 1 shows that θ is selected when the cutting angle θ with respect to the LED chip 1x during the dicing process, that is, the angle formed by the perpendicular drawn from the long side and the line connecting the long side and the short side is θ. FIG. 2 is an explanatory diagram showing an enlarged view of part B in FIG. 1. As shown in FIG. 1, the length of the long side of the LED chip 1x (the length from the upper end of one side surface X to the upper end of the other side surface Y) is L, and from the surface side to the position where the light emitting layer 2 is formed. Depth (junction depth) is d.
[0023]
The cutting angle θ with respect to the LED chip 1x is set so that the output light emitted from the position T of the light emitting layer 2 that is a minute distance ΔL away from the one end face X of the LED chip 1x reaches the inner side of the upper end A of the other side face Y. If selected, the output light leaking from the side surface decreases, the ratio of the output light emitted from the surface of the LED chip 1x increases, and the light emission efficiency of the LED chip 1x improves.
[0024]
In FIG. 2, the incident light with respect to the one side surface X of the output light emitted from the position T of the light emitting layer is P, and the reflected light reflected by the incident light P at the reflection angle equal to the incident angle with respect to the normal line 14a. Q. At this time, the incident angle and the reflection angle are both equal to the cutting angle θ.
[0025]
Here, since E = d · tan θ, La = LE−L−d · tan θ. Also, from tan2θ = (d / La), La · tan2θ = d is obtained, and the cutting angle θ is selected so as to satisfy the condition of (Ld · tanθ) · tan2θ ≧ d.
[0026]
For example, when L = 270 μm and d = 20 μm, θ is about 4.23 degrees. Therefore, the luminous efficiency of the LED chip 1x can be improved by selecting a cutting angle θ larger than this.
[0027]
【The invention's effect】
According to the above feature of the present invention, since infrared rays are used as the light source, the output light is incident on the wafer and reflected at the position of the surface electrode, and the reflected light travels inside the wafer and is emitted to the outside. The For this reason, the alignment of the taper blade in performing the dicing process becomes accurate, and a light emitting diode chip with improved output brightness with little loss of output light can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an example of selecting a cutting angle θ in a dicing process for an LED chip according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram enlarging a portion B in FIG. 1;
FIG. 3 is a longitudinal side view showing an LED chip according to an embodiment of the present invention.
FIG. 4 is a schematic configuration diagram of an example of manufacturing a large number of LED chips.
FIG. 5 is a schematic configuration diagram illustrating a configuration for recognizing the position of a surface electrode in the embodiment of the present invention.
FIG. 6 is a vertical sectional side view showing a conventional LED chip.
FIG. 7 is a vertical side view showing a conventional LED chip.
8 is a schematic configuration diagram of an example in which a large number of LED chips of FIG. 6 are manufactured.
9 is a schematic configuration diagram of an example in which a large number of LED chips of FIG. 7 are manufactured.
[Explanation of symbols]
1x LED chip 2 Light emitting layer 3 Front electrode 4 Back electrode 6 Tape blade 7 Stage 8 Adhesive tape 11 Infrared light source 12 Infrared light receiving camera

Claims (1)

A process of forming a plurality of front and back electrodes corresponding to individual light-emitting diode chips on the front side and the back side of the wafer on which the light emitting layer is formed, and a sticking tape on each front electrode, On the back with the back electrode side facing up, the step of setting the focal length of the infrared light source to the position of the surface electrode and receiving the reflected light from the surface electrode, and the position of the surface electrode as a reference And a step of aligning a tapered blade having a substantially inverted trapezoidal cross-sectional shape, and a step of dicing the wafer at a predetermined position of the wafer by the tapered blade to separate individual light emitting diode chips. A method for manufacturing a light emitting diode chip.

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