Aging method of GaAs-based LED epitaxial wafer

Abstract

The application relates to a GaAs-based LED epitaxial wafer aging method, which comprises the following steps: making a square cutting pattern which is not completely separated on a GaAs-based light-emitting diode epitaxial wafer, placing the P face on a conductive metal plate and the N face on a conductive copper plate in a mode, and forming current aging. The aging test process is selected before the chip preparation process, and the long aging feedback cycle caused by the GaAs-based LED chip manufacturing is fundamentally solved. The aging method is simple in operation, the aging feedback cycle can be shortened by more than 80%, the aging of the GaAs-based LED epitaxial wafer can be effectively completed, and unnecessary manufacturing waste is reduced.

Description

Technical Field

[0001] This invention relates to an aging method for GaAs-based LED epitaxial wafers, belonging to the field of optoelectronic technology. Background Technology

[0002] As a new lighting source for the 21st century, LEDs consume only 1 / 10 the power of ordinary incandescent lamps for the same brightness, while extending their lifespan by 100 times. LED devices are cold light sources with high luminous efficacy, low operating voltage, low power consumption, small size, and can be planar packaged, making it easy to develop thin and lightweight products. They are robust in structure and have a long lifespan. The light source itself does not contain harmful substances such as mercury or lead, and there is no infrared or ultraviolet pollution, so it will not cause pollution to the outside world during production and use. Therefore, semiconductor lamps have the characteristics of energy saving, environmental protection, and long lifespan. Just as transistors replaced vacuum tubes, semiconductor lamps replacing traditional incandescent and fluorescent lamps will be an inevitable trend. Whether from the perspective of saving energy, reducing greenhouse gas emissions, or reducing environmental pollution, LEDs, as a new type of lighting source, have great potential to replace traditional lighting sources.

[0003] In the 1950s, thanks to the efforts of numerous renowned research institutions, including the IBM Thomas J. Watson Research Center, III-V semiconductors, represented by GaAs, rapidly rose to prominence in the field of semiconductor light emission. Subsequently, the advent of metal-organic chemical vapor deposition (MOCVD) technology enabled the growth of high-quality III-V semiconductors to overcome technological barriers, leading to the emergence of semiconductor light-emitting diode (LED) devices of various wavelengths on the market. Due to their superior efficiency, long lifespan, and resistance to strong mechanical shocks compared to current light-emitting devices, semiconductor LEDs are considered the next generation of lighting devices worldwide.

[0004] Due to the growth characteristics of GaAs-based LED epitaxial wafers, these wafers require aging tests to confirm their performance parameters. Conventional methods involve sampling verification, and GaAs-based LED chips must be manufactured before aging can begin. Although the growth process for each batch of GaAs-based LED epitaxial wafers is essentially the same, individual wafers may exhibit performance fluctuations. Current sampling verification methods cannot guarantee effective feedback on the performance parameters of every wafer, leading to customer complaints due to performance parameter fluctuations and impacting the use of GaAs-based LED chips.

[0005] Currently, to avoid customer complaints caused by aging degradation, chip manufacturers can only increase the aging ratio of chips, resulting in a long epitaxial wafer aging screening process. The unqualified chips selected have to be scrapped, which increases the manufacturing cost of the chip segment and wastes manufacturing resources. How to quickly and effectively provide comprehensive feedback on the aging degradation of GaAs-based LED epitaxial wafers has become the main factor affecting the quality and cost of GaAs-based LED chips. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an aging method for GaAs-based LED epitaxial wafers. This aging method fundamentally solves the problem of long aging feedback cycles caused by the manufacturing of GaAs-based LED chips. This method is simple to operate, and the aging feedback cycle can be shortened by more than 80%. It can effectively complete the aging of GaAs-based LED epitaxial wafers and reduce unnecessary manufacturing waste.

[0007] The technical solution of this invention is as follows:

[0008] An aging method for GaAs-based LED epitaxial wafers, comprising the following steps:

[0009] 1) A GaAs-based LED epitaxial layer is grown on a GaAs substrate to obtain a GaAs-based LED epitaxial wafer. Then, the GaAs-based LED epitaxial layer is cut from the GaAs-based LED epitaxial layer to the GaAs substrate on the P-side of the GaAs-based LED epitaxial wafer to perform incomplete cutting, thereby forming a square cutting pattern on the P-side.

[0010] 2) A conductive metal sheet is placed on the square cut pattern obtained in step 1), and conductive silver paste is applied between the conductive metal sheet and the square pattern on the P side, and then the conductive silver paste is cured; the conductive metal sheet is located on the upper part of the square pattern.

[0011] 3) Place the GaAs substrate obtained in step 2) onto a conductive metal plate;

[0012] 4) The negative terminal of the test power supply is connected to the conductive metal plate, and the positive terminal of the test power supply is connected to the conductive metal plate through the conductive test probe, forming an electric current, which makes the square cut pattern on the P side of the GaAs-based LED epitaxial wafer light up, and then the test results before aging are obtained.

[0013] 5) Keep the GaAs-based LED epitaxial wafer obtained in step 4) lit and place it in an oven. After the set lighting time is reached, test it to obtain the test results after aging.

[0014] 6) Compare the test results after aging with the test results before aging to determine whether the aging parameter fluctuation of the GaAs-based LED epitaxial wafer is acceptable; if the parameter fluctuation is acceptable, the test results of the GaAs-based LED epitaxial wafer are fed back to the growth stage of the GaAs-based LED epitaxial wafer and the manufacturing stage of the GaAs-based LED chip.

[0015] If the parameter fluctuations are within acceptable limits, it proves that the products grown in the LED epitaxial wafer production stage are qualified, and the parameters and conditions in the LED epitaxial wafer production stage do not need to be adjusted. The GaAs-based LED chip manufacturing stage can proceed normally with subsequent operations, and no further chip aging screening is required after the chips are manufactured. After removing the conductive silver paste from the GaAs-based LED epitaxial wafers used in the test, GaAs-based LED chips can be prepared.

[0016] The acceptable standards for parameter fluctuations are: brightness fluctuation ≤ 5%, voltage fluctuation ≤ 0.05V, and wavelength fluctuation ≤ 1nm.

[0017] If the parameters fluctuate and fail to meet the requirements, the chip will be scrapped directly to avoid waste in LED chip manufacturing.

[0018] According to a preferred embodiment of the present invention, in step 1), a certain area is randomly selected on the P-side of the GaAs-based LED epitaxial wafer and cut to form a single square cut pattern.

[0019] According to a preferred embodiment of the present invention, in step 1), the depth of the cutting channel is 1 / 6 to 1 / 5 of the total thickness of the epitaxial wafer, the width of the cutting channel is 15 to 25 μm, and the length of the square cutting pattern is 190 to 210 μm.

[0020] According to a preferred embodiment of the present invention, in step 2), the conductive silver paste is cured by baking in an oven at a temperature of 140-180°C for 30-40 minutes. Choosing this oven temperature and baking time will not affect subsequent testing and also facilitates the removal of the conductive silver paste.

[0021] According to a preferred embodiment of the present invention, in step 2), the conductive metal sheet is circular, with a diameter of 70-90 μm and a thickness of 15-30 μm.

[0022] According to a preferred embodiment of the present invention, in step 3), the conductive metal plate is a conductive copper plate.

[0023] According to a preferred embodiment of the present invention, in step 5), the temperature of the oven is 75-85°C, and the lighting time is set to 17-24 hours.

[0024] The beneficial effects of this invention are as follows:

[0025] This invention involves fabricating an incompletely segmented square pattern on a GaAs-based LED epitaxial wafer, then placing the P-side on a conductive metal plate and the N-side on a conductive copper plate to induce an electrical aging process. By prioritizing the aging test before chip fabrication, this method fundamentally solves the problem of long aging feedback cycles caused by the need to manufacture GaAs-based LED chips. This aging method is simple to operate, reduces the aging feedback cycle by over 80%, and effectively completes the aging of GaAs-based LED epitaxial wafers, reducing unnecessary manufacturing waste. Existing aging methods for GaAs-based LED epitaxial wafers all require the fabrication of GaAs-based LED chips before aging, resulting in longer processing times, poor efficiency, and long feedback cycles, leading to unnecessary waste. Attached Figure Description

[0026] Figure 1 This is a cross-sectional view of the GaAs-based LED epitaxial wafer provided by the present invention.

[0027] Figure 2 This is a top view of the P-side of the GaAs-based LED epitaxial wafer obtained after step 1).

[0028] 1. GaAs substrate, 2. GaAs-based LED epitaxial layer, 3. Conductive silver paste, 4. Conductive circular metal sheet, 5. Conductive copper plate, 6. Square cut pattern. Detailed Implementation

[0029] The present invention will be further described below with reference to the embodiments and accompanying drawings, but is not limited thereto.

[0030] Example 1

[0031] An aging method for GaAs-based LED epitaxial wafers, such as Figure 1 and Figure 2 As shown, it includes the following steps:

[0032] (1) A GaAs-based LED epitaxial layer 2 is grown on a GaAs substrate 1 to obtain a GaAs-based LED epitaxial wafer. Then, the P-side of the GaAs-based LED epitaxial wafer is cut to form a square cutting pattern 6 with a side length of 190-210μm on the P-side. The depth of the cutting channel is 1 / 6 of the epitaxial wafer thickness - 1 / 5 of the epitaxial wafer thickness, and the width of the cutting channel is 15-25μm.

[0033] Among them, such as Figure 2 As shown, a single square cut pattern 6 is formed by randomly selecting a region on the P-side of the GaAs-based LED epitaxial wafer and cutting it.

[0034] (2) Place a conductive circular metal sheet 4 with a thickness of 15-30μm and a diameter of 70-90μm on the square P-side pattern obtained in step 1). Coat the bottom of the conductive circular metal sheet 4 with conductive silver paste 3 and bake it in an oven at 180-220℃ for 40-60 minutes to cure the conductive silver paste 3.

[0035] (3) Place the GaAs-based LED epitaxial wafer substrate from step 2) on the conductive copper plate 5. The conductive copper plate 5 is connected to the negative terminal of the test power supply, and the positive terminal of the test power supply is connected to the conductive test needle. The test needle is connected to the conductive circular metal sheet 4 on the P-side of the GaAs-based LED epitaxial wafer, thus forming an electrical connection. The square pattern on the P-side of the GaAs-based LED epitaxial wafer is lit up, and the test results before aging are obtained.

[0036] (4) Place the GaAs-based LED epitaxial wafer (already connected to the test power supply) obtained in step 3) in an oven at 75-85℃ and keep it lit for 17-24 hours. After the continuous lighting time is completed, perform the test to obtain the aging test results. Compare the aging test results with the aging test results before aging to determine the fluctuation of the aging parameters of the GaAs-based LED epitaxial wafer.

[0037] If the parameter fluctuations are within acceptable limits, the test results of the GaAs-based LED epitaxial wafer will be fed back to the growth stage of the GaAs-based LED epitaxial wafer and the manufacturing stage of the GaAs-based LED chip. The acceptable standards for parameter fluctuations are: brightness fluctuation ≤ 5%, voltage fluctuation ≤ 0.05V, and wavelength fluctuation ≤ 1nm.

[0038] If the parameter fluctuations are within acceptable limits, it proves that the products grown in the LED epitaxial wafer production stage are qualified, and the parameters and conditions in the LED epitaxial wafer production stage do not need to be adjusted. The GaAs-based LED chip manufacturing stage can proceed normally with subsequent operations, and no further chip aging screening is required after the chips are manufactured. After removing the conductive silver paste 3 from the GaAs-based LED epitaxial wafers used in the test, GaAs-based LED chips can be prepared.

[0039] If the parameters fluctuate and fail to meet the requirements, the chip will be scrapped directly to avoid waste in LED chip manufacturing.

[0040] Comparative Example 1

[0041] A conventional aging method for GaAs-based LED epitaxial wafers includes the following steps:

[0042] 1) GaAs-based LED epitaxial layer is grown on GaAs substrate to obtain GaAs-based LED epitaxial wafer, and P-electrode and N-electrode of GaAs-based LED epitaxial wafer are prepared by conventional P-side metal deposition, photolithography P-electrode, thinning, and N-side metal deposition.

[0043] 2) The GaAs-based LED epitaxial wafer obtained in step 1) is half-cut on the P-side, and a rectangular dicing channel cut to the substrate is uniformly formed between the two P electrodes. The chip separated by the dicing channel is tested to obtain the photoelectric parameters of the chip before aging.

[0044] 3) The GaAs-based LED epitaxial layer obtained in step 2) is completely cut along the dicing path to obtain a GaAs-based LED chip;

[0045] 4) Take the N-side of the GaAs-based LED chip obtained in step 3) and attach it to the aging substrate with conductive silver paste (equivalent to connecting to the negative electrode of the aging substrate). Then, use gold or aluminum wire to connect the P electrode (positive electrode) of a single GaAs-based LED chip to the positive electrode of the aging substrate. Then, use a dedicated testing device to test the photoelectric parameters of the GaAs-based LED chip before aging through the aging substrate. Then, apply power to age it for 17-24 hours. After aging, test the photoelectric parameters of the GaAs-based LED chip after aging. Compare the parameter fluctuations before and after aging. If the chip is qualified, it will be sent to the warehouse for sale. If the chip is unqualified, it will be scrapped and fed back to the GaAs-based LED epitaxial wafer growth stage. However, at this time, multiple batches of risky epitaxial wafers have already been grown.

[0046] As can be seen from the comparison between Example 1 and Comparative Example 1, the aging method provided in this application fundamentally solves the problem of long aging feedback cycle caused by the need to manufacture GaAs-based LED chips. The aging method is simple to operate, and the aging feedback cycle can be shortened by more than 80%. It can effectively complete the aging of GaAs-based LED epitaxial wafers and reduce unnecessary manufacturing waste.

Claims

1. An aging method for GaAs-based LED epitaxial wafers, characterized in that, Including the following steps: 1) A GaAs-based LED epitaxial layer is grown on a GaAs substrate to obtain a GaAs-based LED epitaxial wafer. Then, the GaAs-based LED epitaxial layer is cut from the GaAs-based LED epitaxial layer to the GaAs substrate on the P-side of the GaAs-based LED epitaxial wafer to perform incomplete cutting, thereby forming a square cutting pattern on the P-side. 2) A conductive metal sheet is placed on the square cut pattern obtained in step 1), and conductive silver paste is applied between the conductive metal sheet and the square pattern on the P side, and then the conductive silver paste is cured; the conductive metal sheet is located on the upper part of the square pattern. 3) Place the GaAs substrate obtained in step 2) onto a conductive metal plate; 4) The negative terminal of the test power supply is connected to the conductive metal plate, and the positive terminal of the test power supply is connected to the conductive metal plate through the conductive test probe, forming an electric current, which makes the square cut pattern on the P side of the GaAs-based LED epitaxial wafer light up, and then the test results before aging are obtained. 5) Keep the GaAs-based LED epitaxial wafer obtained in step 4) lit and place it in an oven. After the set lighting time is reached, test it to obtain the test results after aging. 6) Compare the test results after aging with the test results before aging to determine whether the aging parameter fluctuation of the GaAs-based LED epitaxial wafer is acceptable; if the parameter fluctuation is acceptable, the test results of the GaAs-based LED epitaxial wafer are fed back to the growth stage of the GaAs-based LED epitaxial wafer and the manufacturing stage of the GaAs-based LED chip. If the parameters fluctuate and fail to meet the requirements, the chip will be scrapped directly to avoid waste in LED chip manufacturing.

2. The aging method for a GaAs-based LED epitaxial wafer according to claim 1, characterized in that, In step 1), a region is randomly selected on the P-side of the GaAs-based LED epitaxial wafer and cut to form a single square cut pattern.

3. The aging method for a GaAs-based LED epitaxial wafer according to claim 1, characterized in that, In step 1), the depth of the slit is 1 / 6 to 1 / 5 of the total thickness of the epitaxial wafer, the width of the slit is 15 to 25 μm, and the length of the square slit pattern is 190 to 210 μm.

4. The aging method for a GaAs-based LED epitaxial wafer according to claim 1, characterized in that, In step 2), the conductive silver paste is cured by baking in an oven at a temperature of 140-180℃ for 30-40 minutes.

5. The aging method for a GaAs-based LED epitaxial wafer according to claim 1, characterized in that, In step 2), the conductive metal sheet is circular with a diameter of 70-90 μm and a thickness of 15-30 μm.

6. The aging method for a GaAs-based LED epitaxial wafer according to claim 1, characterized in that, In step 3), the conductive metal plate is a conductive copper plate.

Images