Method for manufacturing light emitting diode with improved brightness uniformity
By detecting and adjusting the light-emitting area of the LED chip with brightness higher than the benchmark, the problem of inconsistent LED brightness is solved, and the uniformity of the LED brightness is improved.
Patent Information
- Application Number
- CN202211153536.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-21
- Publication Date
- 2025-10-10
- Estimated Expiration
- 2042-09-21
AI Technical Summary
In the prior art, the light emitting brightness of light emitting diodes produced on the same wafer is inconsistent, resulting in large differences in brightness.
By detecting the brightness of the light-emitting diode chip, the light-emitting area of the chip with brightness higher than the reference brightness is reduced. The specific method includes determining the brightness ratio and the original area, calculating the area to be reduced, and removing part of the area by etching to reduce the brightness.
The brightness consistency of light-emitting diodes produced on the same wafer is improved, ensuring that the brightness is closer to the reference brightness.
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Figure CN115692554B_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a method for preparing a light-emitting diode (LED) with improved brightness consistency. Background Art
[0002] As an extremely influential new product in the optoelectronics industry, light-emitting diodes (Micro LEDs) have the characteristics of small size, long service life, rich colors, and low energy consumption. They are widely used in display devices.
[0003] LEDs are typically obtained by slicing wafers. Before slicing, each wafer contains multiple LED chips. Ideally, LEDs produced from the same wafer should emit the same brightness under the same normal operating conditions, resulting in high brightness consistency. However, in actual production, LEDs produced from the same wafer can have varying brightness under the same conditions due to various reasons, resulting in poor brightness consistency. Summary of the Invention
[0004] The present disclosure provides a method for manufacturing light-emitting diodes with improved brightness consistency, which can improve the consistency of the brightness of light-emitting diodes manufactured from the same wafer. The technical solution is as follows:
[0005] The present disclosure provides a method for manufacturing a light emitting diode, the method comprising:
[0006] Providing a wafer, wherein the wafer includes a plurality of light-emitting diode chips;
[0007] Detect the luminous brightness of the light-emitting diode chip;
[0008] The area of the light-emitting region of the first light-emitting diode chip is reduced, wherein the first light-emitting diode chip is a light-emitting diode chip having a light-emitting brightness higher than a reference brightness.
[0009] Optionally, reducing the area of the light-emitting region of the first light-emitting diode chip includes:
[0010] Determining a brightness ratio between the reference brightness and the light emitting brightness of the first light emitting diode chip;
[0011] determining an area to be reduced based on the brightness ratio and an original area of the light-emitting region of the first light-emitting diode chip;
[0012] Based on the area to be reduced, a portion of the light-emitting region of the first light-emitting diode chip is removed.
[0013] Optionally, determining the area to be reduced based on the brightness ratio and the original area of the light-emitting region of the first light-emitting diode chip includes:
[0014] determining a target area based on a product of the brightness ratio and the original area;
[0015] The difference between the original area and the target area is determined as the area that needs to be reduced.
[0016] Optionally, detecting the light emitting brightness of the light emitting diode chip includes:
[0017] The light emitting brightness of a preset number or a preset proportion of the light emitting diode chips is randomly inspected from the plurality of light emitting diode chips.
[0018] Optionally, the step of detecting the light emitting brightness of the light emitting diode chip further includes:
[0019] Dividing the wafer into a plurality of non-overlapping distribution areas;
[0020] Determining the degree of deviation between the luminance of the light-emitting diode chips whose luminance is higher than the reference brightness and the reference brightness in each distribution area;
[0021] Based on the degree of deviation, a supplementary sampling is performed on at least part of the distribution area. The supplementary sampling is to select light-emitting diode chips that have not been inspected to detect the luminous brightness. The number of selected chips is positively correlated with the degree of deviation.
[0022] Optionally, the method further includes:
[0023] The area of the light-emitting region of the second light-emitting diode chip is reduced. The second light-emitting diode chip is adjacent to the first light-emitting diode chip and is not subjected to light-emitting brightness detection.
[0024] Optionally, the reduced area of the light-emitting region of the second light-emitting diode chip is less than or equal to the reduced area of the light-emitting region of the first light-emitting diode chip adjacent thereto; or, the ratio of the reduced area of the light-emitting region of the second light-emitting diode chip is less than or equal to the ratio of the reduced area of the light-emitting region of the first light-emitting diode chip adjacent thereto.
[0025] Optionally, the first electrode of the light-emitting diode chip is located in the light-emitting area, and the minimum distance from the edge of the light-emitting area after the area is reduced to the first electrode is not less than a safety distance.
[0026] Optionally, after reducing the area of the light-emitting region of the first light-emitting diode chip, the method further includes:
[0027] The light emitting brightness of the light emitting diode chip is tested again.
[0028] Optionally, after reducing the area of the light-emitting region of the first light-emitting diode chip, the method further includes:
[0029] A passivation layer is formed on the plurality of light emitting diode chips.
[0030] The beneficial effects of the technical solutions provided by the embodiments of the present disclosure include at least:
[0031] By detecting the luminous brightness of the LED chips in the wafer, the relationship between the actual luminous brightness of the LED chips and the reference brightness can be obtained. For LED chips with luminous brightness higher than the reference brightness, the luminous brightness is reduced by reducing the area of their luminous regions, so that the luminous brightness of the LED chips is closer to the reference brightness, thereby improving the consistency of the luminous brightness of LEDs produced from the same wafer. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.
[0033] Figure 1 is a top view of a wafer provided by an embodiment of the present disclosure;
[0034] Figure 2 yes Figure 1 A partial enlarged schematic diagram;
[0035] Figure 3 This is a flow chart of a method for preparing a light-emitting diode with improved brightness consistency provided by an embodiment of the present disclosure;
[0036] Figure 4 This is a flow chart of another method for preparing a light-emitting diode with improved brightness consistency provided by an embodiment of the present disclosure;
[0037] Figure 5 This is a schematic diagram of a manufacturing process of a light emitting diode provided by an embodiment of the present disclosure;
[0038] Figure 6 This is a schematic diagram of reducing the area of the light-emitting region provided by an embodiment of the present disclosure. DETAILED DESCRIPTION
[0039] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.
[0040] Figure 1 FIG. 1 is a top view of a wafer provided by an embodiment of the present disclosure. Figure 1 As shown, the wafer includes a plurality of light emitting diode chips 20. After the wafer is split, a plurality of light emitting diodes can be produced.
[0041] Figure 2 yes Figure 1 A partial enlarged schematic diagram of Figure 2 As shown, the LED chip 20 includes a first semiconductor layer 201, a second semiconductor layer 202, a first electrode 203, and a second electrode 204. For example, the first semiconductor layer 201 can be a P-type layer, and the second semiconductor layer 202 can be an N-type layer. The first semiconductor layer 201 is stacked on the second semiconductor layer 202. The surface of the first semiconductor layer 201 away from the second semiconductor layer 202 is the light-emitting region 201a. The first electrode 203 is located in the light-emitting region 201a, and the second electrode 204 is located on the second semiconductor layer 202.
[0042] The above only provides a general structure of the light-emitting diode chip 20 . In practice, the light-emitting diode chip 20 may also include other structures, which are not limited in the embodiments of the present disclosure.
[0043] Figure 3 This is a flow chart of a method for preparing a light-emitting diode with improved brightness consistency provided by an embodiment of the present disclosure. Figure 3 As shown, the preparation method comprises:
[0044] In step S11 , a wafer is provided.
[0045] The wafer includes a plurality of light emitting diode chips 20 .
[0046] In step S12 , the light emitting brightness of the LED chip 20 is detected.
[0047] In step S13 , the area of the light emitting region 201 a of the first LED chip 210 is reduced.
[0048] The first LED chip 210 is a LED chip 20 having a light emitting brightness higher than a reference brightness.
[0049] By detecting the luminous brightness of the LED chip 20 in the wafer, the relationship between the actual luminous brightness of the LED chip 20 and the reference brightness can be obtained. For the LED chip 20 whose luminous brightness is higher than the reference brightness, the luminous brightness is reduced by reducing the area of its light-emitting region 201a, so that the luminous brightness of the LED chip 20 is closer to the reference brightness, thereby improving the consistency of the luminous brightness of the LEDs produced on the same wafer.
[0050] Figure 4 FIG. 1 is a flow chart of another method for preparing a light-emitting diode with improved brightness consistency provided by an embodiment of the present disclosure. Figure 4 As shown, the preparation method comprises:
[0051] In step S21 , a wafer is provided.
[0052] The wafer includes multiple LED chips 20. For detailed wafer preparation methods, please refer to relevant technologies. During the wafer preparation process, after the first electrodes 203 and second electrodes 204 of the LED chips 20 are fabricated, a passivation layer is typically formed on the surfaces of the LED chips 20. The wafer provided in step S21 may be a wafer on which the first electrodes 203 and second electrodes 204 have already been fabricated, but on which the passivation layer has not yet been fabricated.
[0053] In step S22 , a random inspection is performed on the plurality of LED chips 20 .
[0054] In some examples, the light emitting brightness of a preset number of LED chips 20 is randomly checked from the plurality of LED chips 20 .
[0055] That is, the wafer includes n LED chips 20 , and m LED chips 20 can be sampled from the n LED chips 20 , where m≤n, and both m and n are positive integers.
[0056] The preset number can be pre-set according to the level of the requirement for the consistency of the luminous brightness. The higher the requirement, the larger the preset number.
[0057] In other examples, the light emitting brightness of a preset proportion of the LED chips 20 is randomly inspected from the plurality of LED chips 20 .
[0058] That is, a wafer includes n LED chips 20. A percentage of the n LED chips 20 can be sampled for inspection, where a is a positive number and is ≤ 100. Since the number of LED chips 20 can only be an integer, if the number of LED chips 20 to be sampled is not an integer during sampling, the number of LED chips 20 to be sampled can be rounded up or down, and must not be less than 1.
[0059] The preset ratio can be pre-set according to the level of the requirement for the consistency of the luminous brightness. The higher the requirement, the larger the preset ratio.
[0060] Generally, only a part of the light-emitting diode chips 20 is selected for testing in order to reduce the cost of testing and improve production efficiency. In the case of extremely strict requirements for the consistency of luminous intensity, the luminous intensity of each of the n light-emitting diode chips 20 can be tested.
[0061] In the case of sampling inspection, the selection of the light-emitting diode chips 20 can be random. For the same light-emitting diode chip 20, the luminous intensity can be different under different driving conditions, such as different voltages or currents. In the embodiments of the present disclosure, the testing of the luminous intensity of the light-emitting diode chip 20 is performed under the same driving condition in the case of normal operation of the light-emitting diode chip 20.
[0062] In some examples, the following optional steps can be performed when testing the luminous intensity of the light-emitting diode chip 20.
[0063] In step S23, the wafer is divided into a plurality of distribution regions 10a that do not overlap.
[0064] For example, the distribution regions 10a can be fan-shaped, circular, annular, or the like. The areas of the distribution regions 10a can be equal or unequal, and the number of light-emitting diode chips 20 distributed in each distribution region 10a can be equal or unequal.
[0065] For example, as shown in FIG. 2, the wafer is divided into four distribution regions 10a that are equal in area and fan-shaped, and the number of light-emitting diode chips 20 in each distribution region 10a is equal. Figure 5
[0066] In some examples, step S23 can also be performed before step S22. In the case of sampling inspection, at least one light-emitting diode chip 20 in each distribution region 10a is selected for testing.
[0067] In step S24, the deviation of the luminous intensity of each light-emitting diode chip 20 in each distribution region 10a from the reference luminous intensity is determined.
[0068] The reference luminous intensity can be the desired luminous intensity in the ideal case during the preparation of the wafer, or the luminous intensity of a selected light-emitting diode chip 20 or the average luminous intensity of a plurality of selected light-emitting diode chips 20.
[0069] The degree of deviation can be the difference or ratio between the average luminous brightness of the LED chips 20 sampled in the same distribution area 10a and having a luminous brightness higher than the reference brightness and the reference brightness, or it can be other quantities that can reflect the difference between the luminous brightness of the LED chips 20 sampled in the same distribution area 10a and having a luminous brightness higher than the reference brightness and the reference brightness.
[0070] In step S25, based on the degree of deviation, additional sampling is performed on at least part of the distribution area 10a.
[0071] The supplementary sampling is to select the LED chips 20 that have not been sampled for testing the luminous brightness, and the number of selected chips is positively correlated with the degree of deviation.
[0072] By performing additional random inspections, the number of inspected LED chips 20 is increased, which is beneficial for further improving the consistency of the luminance of the multiple LED chips 20 .
[0073] Ideally, the luminous brightness of the LED chips 20 distributed on the same wafer is the same. In actual production, factors such as temperature and the uniformity of the distribution of raw materials in the reaction chamber will cause differences in the luminous brightness of different LED chips 20. However, the LED chips 20 in the same distribution area 10a are relatively close to each other, and the differences in various factors are relatively small. Therefore, the luminous brightness of the LED chips 20 in the same distribution area 10a is often relatively close. For distribution areas 10a with a large degree of deviation, the number of LED chips 20 with a luminous brightness higher than the reference brightness is likely to be greater. By performing supplementary inspections, the number of LED chips 20 tested is increased. During supplementary inspections, the number selected is positively correlated with the degree of deviation, that is, the greater the degree of deviation, the more LED chips 20 are selected during the supplementary inspection. This is conducive to further improving the consistency of the luminous brightness of the LED chips 20 in the same wafer.
[0074] In step S26 , a brightness ratio between the reference brightness and the light emitting brightness of the first LED chip 210 is determined.
[0075] Figure 5 FIG2 schematically illustrates five first LED chips 210 in a distribution area 10a. The first LED chips 210 are the LED chips 20 whose luminance is determined to be higher than the reference brightness in steps S22 to S25. These first LED chips 210 include the LED chips 20 whose luminance is higher than the reference brightness detected in the random inspection and the LED chips 20 whose luminance is higher than the reference brightness detected in the supplementary random inspection.
[0076] In step S27 , the area to be reduced is determined based on the brightness ratio and the original area of the light emitting region 201 a of the first LED chip 210 .
[0077] The original area of the light-emitting area 201a refers to the area of the light-emitting area 201a before the area of the light-emitting area 201a is reduced. The area to be reduced is determined based on the brightness ratio and the original area so that the brightness of the LED chip 20 can be closer to the reference brightness after the light-emitting area 201a is reduced.
[0078] For example, the following method can be used to determine
[0079] The target area is determined based on the product of the brightness ratio and the original area.
[0080] The target area is the area after the light emitting area 201a is reduced.
[0081] The difference between the original area and the target area is determined as the area that needs to be reduced.
[0082] That is, subtract the target area from the original area to get the area that needs to be reduced.
[0083] For example, the brightness ratio is 80% and the original area is 4mm 2 , the area that needs to be reduced is 0.8mm 2 .
[0084] In step S28 , based on the area to be reduced, a portion of the light-emitting region 201 a of the first LED chip 210 is removed.
[0085] Illustratively, the light emitting region 201 a of the first light emitting diode chip 210 is etched through a patterning process, and a portion of the light emitting region 201 a is removed to reduce the area of the light emitting region 201 a.
[0086] Optionally, the minimum distance between the edge of the light-emitting region 201 a after the area reduction and the first electrode 203 is not less than the safety distance.
[0087] like Figure 6 As shown, the light-emitting area 201a includes a first rectangular area a and a second rectangular area b. The area of the first rectangular area a is larger than the area of the second rectangular area b. The second rectangular area b is located on a side of the first rectangular area a close to the second electrode 204. The first electrode 203 is located in the first rectangular area a.
[0088] The distances from different positions on the edge of the light-emitting area 201a to the first electrode 203 are different. For example, in this example, the first electrode 203 is closer to the corner of the first rectangular area a and farther from the second electrode 204. The minimum distance from the edge of the light-emitting area 201a to the first electrode 203 refers to the distance from the position of the edge of the light-emitting area 201a closest to the first electrode 203 to the first electrode 203.
[0089] When reducing the area of the light-emitting region 201a, the etched area is located at the edge of the light-emitting region 201a. For example, if etching is performed on the side of the second rectangular region b away from the first rectangular region a, the distance from the side of the second rectangular region b away from the first rectangular region a to the first electrode 203 will be reduced after etching compared to before etching. Similarly, etching at any position on the edge of the light-emitting region 201a will result in a reduction in distance. The smaller the distance from the first electrode 203 to the edge of the light-emitting region 201a, the higher the possibility of leakage from the light-emitting diode chip 20, which may cause the light-emitting diode chip 20 to fail. The safety distance here is the minimum distance between the edge of the light-emitting region 201a and the first electrode 203 when the possibility of leakage from the light-emitting diode chip 20 does not exceed the design requirements.
[0090] That is, when etching the light emitting region 201a to reduce the area of the light emitting region 201a, etching can be performed preferentially at the edge of the light emitting region 201a that is farther from the first electrode 203, for example. Figure 6 Of course, in some cases, such as when a large area needs to be removed, etching can also be performed at a position closer to the edge of the light-emitting area 201a and the first electrode 203, but at least the minimum distance must be no less than a safe distance to ensure the reliability of the light-emitting diode chip 20.
[0091] In step S29 , the area of the light emitting region 201 a of the second LED chip 220 is reduced.
[0092] The second LED chip 220 is an LED chip 20 adjacent to the first LED chip 210 and is not subjected to the light emitting brightness detection. Figure 5 Schematically shows three second light emitting diode chips 220 .
[0093] As previously mentioned, in actual production, different LED chips 20 exhibit varying brightness, while LED chips 20 that are relatively close together often exhibit similar brightness. If the brightness of a first LED chip 210 is higher than a reference brightness, the brightness of adjacent LED chips 20 is likely higher than the reference brightness. By reducing the area of the light-emitting region 201a of the second LED chip 220, thereby lowering the brightness of the second LED chip 220, the brightness consistency of the LED chips 20 on the same wafer can be further improved.
[0094] In step S29 , the areas of the light-emitting regions 201 a of all the second LED chips 220 may be reduced, or the areas of the light-emitting regions 201 a of only a portion of the second LED chips 220 may be reduced.
[0095] For example, for a first LED chip 210 whose difference or ratio of luminance to a reference brightness does not exceed a preset value, the luminous area 201a of the second LED chip 220 adjacent thereto may not be processed, i.e., the area of the luminous area 201a of this type of LED chip 20 will not be reduced; for a first LED chip 210 whose difference or ratio of luminance to a reference brightness exceeds a preset value, the luminous area 201a of the second LED chip 220 adjacent thereto may be processed, i.e., the area of the luminous area 201a of this type of LED chip 20 will be reduced.
[0096] The preset value here can be set according to specific needs. If the difference or ratio exceeds the preset value, it means that the actual production environment of the first LED chip 210 may be significantly different from the ideal production environment, and the adjacent LED chip 20 is more likely to also have a higher brightness than the reference brightness.
[0097] During the preparation process, step S29 can be performed simultaneously with step S28, that is, the light-emitting region 201a of the second LED chip 220 can be etched together with the light-emitting region 201a of the first LED chip 210 to reduce the area of the light-emitting region 201a.
[0098] In some examples, the reduced area of the light-emitting region 201 a of the second LED chip 220 is smaller than or equal to the reduced area of the light-emitting region 201 a of the adjacent first LED chip 210 .
[0099] Because the second LED chip 220 does not undergo luminous brightness detection, the relationship between the luminous brightness of the second LED chip 220 and the reference brightness, as well as the specific difference, cannot be fully determined. By setting the reduced area of the light-emitting region 201a of the second LED chip 220 to not exceed the reduced area of the light-emitting region 201a of the adjacent first LED chip 210, this more conservative approach can prevent excessive reduction of the light-emitting region 201a of the second LED chip 220, which could result in excessively low luminous brightness of the second LED chip 220.
[0100] In some other examples, the ratio of the area reduction of the light emitting region 201 a of the second LED chip 220 is less than or equal to the ratio of the area reduction of the light emitting region 201 a of the adjacent first LED chip 210 .
[0101] This is also to adopt a more conservative approach to avoid excessive removal of the light-emitting area 201 a of the second LED chip 220 , which would result in excessively low brightness of the second LED chip 220 .
[0102] In step S30 , the light emitting brightness of the LED chip 20 is detected again.
[0103] After reducing the light-emitting area 201a of the first LED chip 210 and the light-emitting area 201a of the second LED chip 220, the difference between the light-emitting brightness of the LED chip 20 and the reference brightness is determined by re-detecting the light-emitting brightness to ensure that the consistency of the light-emitting brightness of the LED chips 20 in the same wafer meets the design requirements.
[0104] When the luminous brightness of the LED chip 20 is re-tested, only the luminous brightness of the LED chip 20 with the area of the light-emitting region 201a reduced, that is, the first LED chip 210 and the second LED chip 220, can be tested, or the LED chip 20 can be spot-checked again.
[0105] After the luminous brightness is detected again in step S30, if the consistency of the luminous brightness of the LED chip 20 meets the design requirements, the subsequent preparation process can be carried out; if the consistency of the luminous brightness of the LED chip 20 does not meet the design requirements, it can return to step S22 and repeat the above process until the consistency of the luminous brightness of the LED chip 20 meets the design requirements.
[0106] In step S31 , a passivation layer is formed on the plurality of light emitting diode chips 20 .
[0107] The passivation layer can provide protection for the light emitting diode chip 20, and the specific forming process of the passivation layer can be the same as in the related art.
[0108] After the passivation layer is formed, the wafer can be subjected to processes such as dicing and splitting to obtain a plurality of light emitting diodes.
[0109] The above merely provides optional embodiments of the present disclosure, but is not intended to limit the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.
Claims
1. A method for preparing a light emitting diode, characterized in that: include: Providing a wafer, the wafer comprising a plurality of light-emitting diode chips (20); sampling a preset number or a preset proportion of light-emitting diode chips (20) from the plurality of light-emitting diode chips (20) to determine their luminous brightness; Dividing the wafer into a plurality of non-overlapping distribution areas (10a); Determining the degree of deviation between the luminous brightness of the light-emitting diode chips (20) whose luminous brightness is higher than the reference brightness and the reference brightness in each distribution area (10a), respectively, wherein the degree of deviation is the difference between the average luminous brightness of the light-emitting diode chips (20) whose luminous brightness is higher than the reference brightness and the reference brightness in the same distribution area (10a), and the ratio of the average luminous brightness of the light-emitting diode chips (20) whose luminous brightness is higher than the reference brightness to the reference brightness; Based on the degree of deviation, performing supplementary sampling on at least part of the distribution area (10a), wherein the supplementary sampling is to select light-emitting diode chips (20) that have not been sampled for detection of luminous brightness, and the number of selected chips is positively correlated with the degree of deviation; The area of the light-emitting region (201a) of the first light-emitting diode chip (210) is reduced, wherein the first light-emitting diode chip (210) is a light-emitting diode chip (20) having a light-emitting brightness higher than a reference brightness.
2. The preparation method according to claim 1, characterized in that The reducing the area of the light-emitting region (201a) of the first light-emitting diode chip (210) comprises: Determining a brightness ratio between the reference brightness and the light emitting brightness of the first light emitting diode chip (210); Determining an area that needs to be reduced based on the brightness ratio and the original area of the light-emitting region (201a) of the first light-emitting diode chip (210); Based on the area that needs to be reduced, a portion of the light-emitting region (201a) of the first light-emitting diode chip (210) is removed.
3. The preparation method according to claim 2, characterized in that Determining the area to be reduced based on the brightness ratio and the original area of the light-emitting region (201a) of the first light-emitting diode chip (210) comprises: determining a target area based on a product of the brightness ratio and the original area; The difference between the original area and the target area is determined as the area that needs to be reduced.
4. The preparation method according to any one of claims 1 to 3, characterized in that The method further comprises: The area of the light-emitting region (201a) of the second light-emitting diode chip (220) is reduced. The second light-emitting diode chip (220) is a light-emitting diode chip (20) adjacent to the first light-emitting diode chip (210) and not subjected to light-emitting brightness detection.
5. The preparation method according to claim 4, characterized in that The reduced area of the light-emitting region (201a) of the second light-emitting diode chip (220) is smaller than or equal to the reduced area of the light-emitting region (201a) of the first light-emitting diode chip (210) adjacent thereto; or, the ratio of the reduced area of the light-emitting region (201a) of the second light-emitting diode chip (220) is smaller than or equal to the ratio of the reduced area of the light-emitting region (201a) of the first light-emitting diode chip (210) adjacent thereto.
6. The preparation method according to any one of claims 1 to 3, characterized in that The first electrode (203) of the light-emitting diode chip (20) is located in the light-emitting area (201a), and the minimum distance from the edge of the light-emitting area (201a) after the area is reduced to the first electrode (203) is not less than a safety distance.
7. The preparation method according to any one of claims 1 to 3, characterized in that After reducing the area of the light-emitting region (201a) of the first light-emitting diode chip (210), the method further comprises: The light emitting brightness of the light emitting diode chip (20) is detected again.
8. The preparation method according to any one of claims 1 to 3, characterized in that After reducing the area of the light-emitting region (201a) of the first light-emitting diode chip (210), the method further comprises: A passivation layer is formed on the plurality of light emitting diode chips (20).
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