KR101181415B1 - Light emitting diode and manufacturing method thereof - Google Patents

Abstract

A light emitting diode emitting white light and a method of manufacturing the same are disclosed. The disclosed light emitting diode manufacturing method includes measuring the light emitting diode; And performing a conformal coating on the light emitting diode having a compounding ratio of phosphors based on the measurement result so that the light output from the light emitting diode is converted into white light.

Description

LIGHT EMITTING DIODE AND MANUFACTURING METHOD THEREOF

The present invention relates to a light emitting diode and a method of manufacturing the same, and more particularly, to a light emitting diode emitting a white light and a method of manufacturing the same.

Light Emitting Diodes (LEDs) are energy-efficient products, and their use is increasing, and research and development on them are continuing. In this respect, white light output from the light emitting diode is not only required but also difficult to implement. In the past, various new methods have been attempted to realize white light.

Many of these approaches, however, have done so at the chip level instead of at the wafer level. Such an approach leads to chip waste.

Moreover, none of the existing approaches have altered the proportion of phosphors (phosphorescent materials) based on fundamental measurement results, such as the wavelength of light being output.

Accordingly, there is a need for a light emitting diode and a method of manufacturing the same according to a new approach.

An object of the present invention is to provide a light emitting diode emitting a high yield of white light and a method of manufacturing the same.

Another object of the present invention is to provide a light emitting diode emitting white light and a method of manufacturing the same, which can reduce manufacturing costs.

Another object of the present invention is to provide a light emitting diode capable of outputting the same target white light on a color coordinate and a manufacturing method thereof.

The object is, according to the present invention, a method of manufacturing a light emitting diode, comprising the steps of: measuring a light emitting diode at the wafer level; And performing a conformal coating on the light emitting diode having a compounding ratio of phosphors based on the measurement result so that the light output from the light emitting diode is converted into white light at a wafer level. It can be achieved by the method.

Here, the measuring step may include measuring a wavelength of light output by the light emitting diodes.

In addition, the light emitting diode may include at least one of a blue light emitting diode and an ultraviolet light emitting diode.

The method may further include separating a region of the light emitting diode to which the conformal coating is applied.

The region can also be separated using at least one of paraffin wax, silkscreen and photoresist.

Here, the conformal coating may be provided to have a compounding ratio of the phosphor including at least one of yellow, green or red color.

The light emitting diode may be disposed on a wafer together with a plurality of other light emitting diodes, and the conformal coating may be provided to be applied to the wafer.

In addition, according to the present invention, there is provided a light emitting diode manufacturing method comprising the steps of: measuring the wavelength of light output by the light emitting diode at the wafer level; And performing a conformal coating on the light emitting diode having a compounding ratio of phosphors based on the measurement result such that light output from the light emitting diode is converted to white light at a wafer level, wherein the compounding ratio is yellow, It can also be achieved by a light emitting diode manufacturing method characterized in that it comprises at least one of green or red.

The light emitting diode may include at least one of a blue light emitting diode and an ultraviolet light emitting diode.

The method may further include separating a region of the light emitting diode to which the conformal coating is applied.

Here, the region can be separated using at least one of paraffin wax, silkscreen and photoresist.

The object is, according to the present invention, a light emitting diode comprising: a light emitting unit; Also achieved by a light emitting diode having a phosphor compounding ratio based on the wavelength of the light output from the light emitting unit so that the light output from the light emitting unit is converted into white light, and comprises a conformal coating applied to the upper portion of the light emitting unit Can be.

Here, the phosphor compounding ratio may include at least one color of yellow, green, red.

In the present invention, unlike the chip unit packaging method, the white light emitting diode manufacturing method performs a white light emitting diode manufacturing process at a wafer level and corresponds to each unit chip by measuring wavelength data in advance for each unit chip at the wafer level. Phosphors are dispensed for each chip on the wafer by precisely controlling the mixing ratio of the phosphors (yellow (Y), green (G), and red (R)) for each wavelength.

The conformal coating method having a constant coating thickness on the chip surface has the following effects.

First, since a phosphor + Si material for converting each unit chip into the same target white light in color coordinates is determined and applied to each chip at the wafer level, the color deviation of the white light output for each chip is reduced. As a result, the white light diode process yield is increased.

Second, the design margin is increased when designing the optical lens using the light emitting diode chip of each white light by minimizing the color deviation.

Third, since the phosphor coating process is performed for each chip on a wafer basis, a sorting process for classifying LEDs having a similar range of wavelengths for each chip is unnecessary in the packaging step. In addition, since the WHITE color coordinate is already obtained in the wafer LEVEL rather than in the packaging step, no additional packaging process and material costs are incurred.

Fourth, since white light chips are manufactured at the wafer level, production equipment investment and white light diode chip management costs are reduced. In particular, equipment for carrying out a packaging process such as sorting equipment for sorting is not required.

Fifth, since the white photodiode chip is completed for each chip at the wafer level, when using a chip on module (COM) or a chip on board (COB) using a flip chip method, a separate die attach, wiring, Existing processes such as phosphor coating can be omitted, thereby reducing process costs and material costs.

1 is a graph of chip wavelength distribution in a light emitting diode wafer;
FIG. 2 is a table showing chip wavelengths measured for chip types 1, 2, and 3 corresponding to the color coordinate system and white light having the same color coordinate, and corresponding phosphor + Si mixing ratios;
3 is a diagram schematically showing a method of applying a phosphor at a packaging level;
4 is a view schematically showing a conformal coating method performed for each chip at the wafer level of the light emitting diode manufacturing method of the present invention;
5 is a diagram schematically showing a conformal coating step of the light emitting diode manufacturing method according to the first embodiment of the present invention;
6 is a diagram schematically illustrating a conformal coating step of a light emitting diode manufacturing method according to a second embodiment of the present invention;
7 is a diagram schematically showing a conformal coating step of the light emitting diode manufacturing method according to the second embodiment of the present invention;
8 is a flowchart schematically showing a method of manufacturing a light emitting diode according to a fourth embodiment of the present invention.

As described above, the present invention relates to a light emitting diode capable of outputting white light and a method of manufacturing the same. More specifically, the wavelength of light emitted from light emitting diodes (eg, blue LEDs, ultra-violet LEDs) is measured, for example, at the wafer level. Based on the wavelength measurement results, a conformal coating is applied to the LED. The conformal coating has a phosphor compounding ratio based on the wavelength. In addition, the phosphor blending ratio includes at least one of yellow, green, or red color. Thereby, the light output from the LED is converted to white light using a conformal coating. In embodiments of the present invention, these steps may be performed at the wafer level to obtain better uniformity and consistency.

On the other hand, wavelength dispersion exists between each chip in the LED wafer due to process and equipment deviation in the metal organic chemical vapor deposition (MOCVD) process of the LED chip EPI process. In FIG. 1, the wavelength of the blue light of the chips 10 in the arbitrary LED wafer 12 is measured. The chips 10 in the wafer 12 do not have one and the same single wavelength but have a wavelength dispersion between the chips 10. In general, when the difference between the wavelength between the chip 10 is 5nm or more, a human can recognize it.

2 shows an RGB color coordinate system. When the same phosphor is collectively applied at the wafer level in order to convert the chips 10 on the same wafer 12 into white light in a state where the wavelength distribution between the chips 10 exists in the same wafer 12 as shown in FIG. 1. WHITE color coordinates vary from chip to chip. Therefore, the combination of different phosphors according to the wavelength of each individual chip 10 may be applied to implement white light having the same WHITE color coordinate.

In the color coordinate system of FIG. 2, number 1 of the BLUE portion is a wavelength of a. In this case, in order to form the WHITE TARGET color coordinate, the combination ratio of yellow, green, and red (Y, R, G) phosphors should be A applied. In addition, when the wavelength of the chip is b and c, as in Nos. 2 and 3, respectively, in this case, in order to form the same WHITE TARGET color coordinate as No. 1, the compounding ratio of phosphors B and C different from A should be applied. Here, the phosphor of the compounding ratio may be combined with silicon (Si).

If the same compounding ratio phosphors and silicon (Si) A phosphor layers are applied to chips having different wavelengths a, b, and c, the three chips have different WHITE TARGET color coordinates. If the WHITE color coordinates are different, there is difficulty in product composition due to color scattering when using LEDs for BLU (back light unit), lighting, etc. used in LCD (Liquid Crystal Display) display devices. Due to this problem, the phosphor coating process is performed at the individual chip level during the LED PKG (package) process rather than at the wafer level. SORTING (RANKING) the individual chips by the wavelength of the blue light output from each chip prior to the COATING process of the phosphor. The process takes place first.

However, when the phosphor is applied to each chip in the packaging process, in addition to the above-described sorting process, the phosphors must be maintained for each sorted individual chip, and the process order increases and becomes complicated, which is a major factor in increasing the product cost.

3 schematically shows a process in which phosphor is applied at each individual chip level. First, the LED chip 10 is attached to the center of the CUP 18 in the lead frame 16 in which the CUP 18 exists, and the metal pad 20 of the LED chip 10 and the electrode of the lead frame 16 are attached. Lines 22 are bonded to each other by wires 24. In order to form a WHITE TARGET color coordinate, a coating layer 24 (phosphor + Si material) designed according to the wavelength of the chip is dispensed on the surface of the LED chip 10.

The above-described phosphor coating technique (coating technique) at the chip level has some problems.

First, since the thickness of the phosphor + Si (at least 300um or more) is thick, the average optical path varies depending on the position of the LED chip, resulting in color deviation (LED BINNING phenomenon). The occurrence of color deviation introduces many limitations in optical design.

Second, since the phosphor coating process is performed at the chip level, not at the wafer level, additional package materials and process costs are generated in addition to the chip cost when defects occur due to the deviation of the WHITE color coordinates after the package.

Third, in order to apply chip level coating, the SORTING process is involved for the same wavelength bands for the wavelength dispersion of the chips in the wafer. If the phosphor coating process is performed for each unit chip at the wafer level, no separate sorting process is required and WHITE color coordinates are already obtained at the wafer level instead of the package level. It does not occur.

As described above, the white light emitting diode manufacturing method according to the present invention allows the white light emitting diode manufacturing process to be performed at the wafer level, unlike the chip level packaging method. Particularly, in order to measure the wavelength data in advance for each unit chip at the wafer level, which is the relatively lower stage described above, and convert the target data into the same target white light for each wavelength in each unit chip, a phosphor (yellow: Y), green (G), red (R)) accurately determine the compounding ratio and distribute the phosphor of the compounding ratio for each of the unit chips at the wafer level by a predetermined thickness on the surface of each unit chip The coating layer which has is formed. In this way, the phosphor conformal coating is relatively thin in thickness compared to that at the chip level.

Figure 4 schematically shows a fluorescent material coating process of the light emitting diode manufacturing method commonly applied to the present invention. Based on the measurement results of the wavelengths of all the chips 30 in order to realize the same WHITE color coordinates for all the chips 30 in the wafer 32, a suitable phosphor compounding ratio to be applied to each unit chip 30 is determined. do. For example, the compounding ratio of A for wavelength a, the compounding ratio of B for wavelength b, and the compounding ratio of C for c. The same three dispensers 34A, 34B, 34C are prepared for the above three or more types of compounding ratios, and each dispenser contains phosphors having different compounding ratios. As shown in FIG. 4, the plurality of dispensers 34A-34C perform phosphorescent silicon on a chip top by dispensing a phosphor + silicon (Si) material (hereinafter, referred to as a phosphor) corresponding to each unit chip at a wafer level. Forming a conformal coating. Through this, a white LED (wihte LED) for outputting white light through the phosphor coating at the wafer level may be implemented.

Here, the LED chip 30 before the fluorescent material on the wafer 32 is applied may be referred to as a light emitting unit. The light emitting unit is composed of an N layer, a P layer, and an active layer. Such a configuration is already known, and thus a detailed description thereof will be omitted.

Here, the wafer level means a wafer step before cutting and separating each unit individual LED chip 30 formed on the wafer.

Here, as the number of dispensers increases, more accurate compounding ratios of fluorescent materials may be coated on individual unit chips having various wavelength dispersions formed at the wafer level.

In some cases, the above-described plurality of dispensers 34A-34C may be used to apply a fluorescent compound of any compounding ratio for each unit chip at the wafer level. In more detail, by using at least two or more dispensers of different compounding ratios among the plurality of dispensers 34A-34C, the fluorescent substance of any desired compounding ratio is applied to a single unit chip a plurality of times by applying a different amount of fluorescent substance. The material may also be coated. That is, the fluorescent substance applied a plurality of times is finally a fluorescent layer of any desired compounding ratio.

Meanwhile, the present invention provides three embodiments in which the phosphor + silicon (Si) (phosphorescent material) is independently coated for each unit chip 30 at the wafer level.

The first embodiment is shown in FIG.

In this case, a scribe line between the chip 30 and the chip 30 in the wafer 32 is printed with a material containing paraffin 36 (other may be contained). As a result, the fluorescent material may be prevented from being coated on the scribe line. Next, the metal pad portion is also printed with a material containing paraffin 36 or the like along the pad line so that the phosphor of the phosphor + silicon (Si) to be dispensed by the dispenser does not penetrate the metal pad 35 portion. Done. In this case, when a material such as paraffin is printed, the thickness of the fluorescent material coating layer is approximately 100 μm. The main function of the paraffin material is to act as a guide dam 38 to allow the fluorescent material to be present therein without flowing the fluorescent material to be coated on the chip 30.

The light emitting diode manufacturing method according to the present embodiment is as follows.

(1) measure the wavelength of each diode chip 30 at the wafer level;

(2) determine the compounding ratio of phosphors (Y, G, B) and Si against the WHITE TARGET color coordinate for each of the measured wavelength groups;

(3) As shown in FIG. 5, a material such as paraffin 36 is printed on a scribe line and a metal pad 35 in each chip 30 in the wafer 32 to guide the dam 38. );

(4) In order to implement WHITE TARGET color coordinates, a phosphor having a compounding ratio corresponding to the wavelength of each chip 30 in the wafer 32 and the phosphor may be attached to the top of the chip 30 well. Coating a fluorescent material composed of a silicon (Si) material;

Here, the phosphor of the specific compounding ratio and the phosphor containing the silicon material may be distributed through the plurality of dispensers (34A-34C of FIG. 4) described above.

(5) hard curing the phosphor + silicon (Si) material in an oven;

(6) Next, the chip 30 coated with a fluorescent material is cut out on the wafer 32 along the scribe line.

In FIG. 5, a scribe line is formed for each individual chip 30. However, as in the case where the wavelength distribution exists within an error range and the fluorescent material may be applied with the same dispenser, two chips 30 may be simultaneously used. If the fluorescent material can be coated with a dispenser, the daughter scribe line may also be formed in a shape that surrounds the two chips 30 accordingly.

If necessary, if the plurality of chips 3 adjacent to each other have a wavelength dispersion within an error range and the fluorescent material can be coated with one dispenser, the scribe line may be surrounded to surround the three or more chips 3. It may be formed.

In addition, between the above-described steps (3) and (4), from which measured wavelength data of the individual chips 30 on the wafer 32, the individual chip 30 should be applied by which dispenser the fluorescent material is applied. The determining may further include. That is, since the wavelength dispersion of the individual chips 30 may appear in various ways, in order to apply the fluorescent material with a limited dispenser, a range of wavelength dispersion that can be compensated with each dispenser may be determined. For example, the A dispenser may have a wavelength of 10 nm as a range of wavelengths to apply the fluorescent material.

Here, if a predetermined phosphor compounding ratio has already been determined for each of the plurality of dispensers, step (2) described above may be performed from the measured wavelength data of the individual chips 30 on the wafer 32 through step (1). The chip 30 may be replaced by determining which of the plurality of dispensers is suitable.

A second embodiment of the present invention will be described with reference to FIG. 6 as follows.

In this case, the scribe line between the chip 30 and the chip 30 and the portion of the metal pad 35 may be formed of a silk screen 40 or a metal mask to prevent penetration of the phosphor of the phosphor + silicon (Si) to be dispensed. metal mask, 40), etc. After the blocking is performed, the phosphor + silicon (Si) material is dispensed according to the wavelength of each unit chip at the wafer level by the dispensing method. The manufacturing method of the light emitting diode is as follows.

(1) measure the wavelength of each configured diode chip at the wafer level;

(2) determine the compounding ratio of phosphors (Y, G, B) and silicon (Si) corresponding to the WHITE TARGET color coordinate for each of the measured wavelength groups;

(3) As shown in FIG. 6, the scribe line 37 and the metal pad 35 portion of each chip in the wafer are blocked using the silk screen 40;

(4) in order to implement WHITE TARGET color coordinates, each chip is coated with a phosphor composed of a phosphor and a silicon (Si) material having a corresponding compounding ratio for each chip wavelength;

(5) simple curing phosphor + Si material;

(6) removing the silk screen and / or metal mask block;

(7) Phosphor + silicon (Si) fluorescent material is HARD CURING in the oven.

In this case, the simple curing step of (5) described above may be omitted in some cases.

A third embodiment of the present invention will be described with reference to FIG.

In this case, the portions of the scribe line 37 and the metal pad 35 between the chip 30 and the chip 30 are prevented from penetrating the photoresist to prevent the phosphors of the dispensed phosphor + silicon (Si) from penetrating. masked by the sacrificial layer 42 and / or organic material of the photoresist (PR). After the masking process, the phosphors of the phosphor + silicon (Si) are dispensed according to the wavelength of each chip in the wafer unit by the dispensing method. Hereinafter, a light emitting diode manufacturing method according to the present embodiment will be described in detail.

(1) measuring the wavelength of each configured diode chip on a wafer basis;

(2) Determine the compounding ratio of the phosphors (Y, G, R) and Si according to the WHITE TARGET color coordinate for each of the measured wavelength groups;

(3) As shown in Fig. 7, masking the scribe line and the metal pad portion of each chip in the wafer using the sacrificial layer or the like;

(4) in order to implement WHITE TARGET color coordinates, a fluorescent material of phosphor + silicon (Si) having a compounding ratio corresponding to the wavelength of each chip is coated in the wafer;

(5) HARD CURING the phosphor + silicon (Si) phosphor in OVEN;

(6) The scribe line and the sacrificial layer PR of the metal pad portion are removed.

Hereinafter, a light emitting diode manufacturing method according to a fourth embodiment of the present invention will be described in detail with reference to FIG. 8.

First, a plurality of LED chips are formed on the wafer (S10). Here, the LED may be a blue LED or an ultraviolet (ultra-violet) LED that outputs blue or ultraviolet rays.

Next, a unique wavelength value output by each LED chip on the wafer is measured (S20).

Next, in order to compensate for the wavelength dispersion of the LED chip, a phosphor compounding ratio corresponding to the wavelength value of each LED chip is determined on the wafer (S30). Here, each of the LEDs formed by the semiconductor process in step S10 outputs the white light in the same color coordinates in order to convert to output the white light in the same color coordinates because the wavelength is scattered with an error rather than outputting the same wavelength. The phosphor compounding ratio corresponding to the measured wavelength of the individual LED chips is determined so as to convert light.

Next, as shown in FIG. 4, a matching map representing a phosphor compounding ratio that accurately corresponds to the measured wavelength value of each LED chip on the wafer is obtained (S40).

According to the blending ratio of the matching map, a plurality of phosphors and silicon are mixed and defoamed for each blending ratio type (S50).

The phosphors mixed according to the matching map (phosphor + silicon (Si) in an appropriate blending ratio) are applied to each LED chip on the wafer (S60).

The fluorescent material is cured in the wafer state (S70).

The individual LED chips are cut along the scribe line on the wafer and separated from the wafer (S80).

Here, the coating of the fluorescent material after masking the scribe line and the metal pad of the LED chip is omitted in the first to third embodiments.

32: wafer 30: chip
34A, 34B, 34C: Dispenser 35: Metal Pad
37: scribe line

Claims (12)

In the light emitting diode manufacturing method,
Measuring light emitting diodes for each unit chip at a wafer level; And
And performing a conformal coating on the light emitting diode having a compounding ratio of phosphors based on the measurement result so that the light output from the light emitting diode is converted into white light for each unit chip at a wafer level.
The measuring step,
And measuring the wavelength of light output by the light emitting diodes. delete The method of claim 1,
The light emitting diode is a light emitting diode manufacturing method comprising at least one of a blue light emitting diode and an ultraviolet light emitting diode. The method of claim 1,
And separating a region of the light emitting diode to which the conformal coating is applied. The method of claim 4, wherein
Wherein said region is separated using at least one of paraffin wax, silkscreen and photoresist. The method of claim 1,
The conformal coating is a light emitting diode manufacturing method characterized in that it has a blending ratio of the phosphor including at least one of the yellow, green or red color. In the light emitting diode manufacturing method,
Measuring light emitting diodes for each unit chip at a wafer level; And
And performing a conformal coating on the light emitting diode having a compounding ratio of phosphors based on the measurement result so that the light output from the light emitting diode is converted into white light for each unit chip at a wafer level.
The blending ratio includes at least one color of yellow, green or red,
The light emitting diode manufacturing method of the light emitting diode, characterized in that it comprises at least one of a blue light emitting diode and an ultraviolet light emitting diode. delete The method of claim 7, wherein
And separating a region of the light emitting diode to which the conformal coating is applied. 10. The method of claim 9,
Wherein said region is separated using at least one of paraffin wax, silkscreen and photoresist. In the light emitting diode,
Light emitting unit;
It has a phosphor compounding ratio based on the wavelength of the light output from the light emitting portion so that the light output from the light emitting portion is converted to white light, and includes a conformal coating portion applied on the light emitting portion,
The phosphor compounding ratio is light emitting diode, characterized in that it comprises at least one color of yellow, green, red. delete

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