LED resistor chip preparation method

Abstract

The application relates to an LED resistance chip preparation method and belongs to the technical field of semiconductors. The LED resistance chip preparation method is characterized in that after N-type phosphorus source diffusion is carried out on the surface of a silicon wafer, nickel plating treatment is carried out, three times of photoetching operation are carried out after sintering, and electrode evaporation, etching, glue removal and other operations are added between the three times of photoetching operation, and finally, the LED resistance chip is obtained. The LED resistance chip prepared by the application can replace ordinary resistance, can be directly bound in the interior of an LED lamp bead, and is designed for directly limiting current and connecting high voltage. The resistance chip can achieve more accurate resistance value, can optimize the heat dissipation effect during operation, and can be used for adjusting the brightness of LED lamp beads with different voltages.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to a method for fabricating an LED resistor chip. Background Technology

[0002] In today's lighting field and many other scenarios involving light-emitting displays, LED chips have been widely used due to their numerous advantages such as energy saving, long lifespan, and high brightness.

[0003] Existing LED chips typically have a relatively fixed internal structure and connection method. Specifically, the LED chip is first placed and fixed within a specially designed LED bracket, and then electrical connection channels are established using metal wires. The P-terminal of the LED chip is connected to one metal plate of the bracket, while the N-terminal of the LED chip is connected to the other metal plate of the bracket. Through this connection method, the LED chip can achieve normal light emission when powered on, and its normal operating voltage is close to the voltage characteristics inherent to the LED chip itself.

[0004] However, in practical applications, especially when using a constant DC voltage to light up LED chips, a rather tricky problem arises. Because LED chips have strict requirements regarding the current flowing through them, excessive current can easily cause irreversible damage. Therefore, an external resistor is often needed to regulate the current and protect the LED chip.

[0005] However, the introduction of external resistors also brings a series of significant impacts. During the product circuit design phase, the placement of the external resistors must be carefully considered to ensure accurate connection to the appropriate circuit loop for effective current regulation. Furthermore, the continuity of the circuit must be fully considered to guarantee stable and reliable operation of the entire circuit.

[0006] Furthermore, external resistors are electronic components with a certain size, occupying internal space, which is undoubtedly a disadvantage for applications with strict size constraints. Simultaneously, because their connection alters the overall circuit layout and electrical characteristics, they affect the circuit's design width, causing additional voltage drops during power transmission. This increased voltage drop further impacts overall product performance, most notably reducing the number of LEDs that can be cascaded at normal brightness, limiting application flexibility and luminous effect in scenarios requiring multiple LEDs connected in series.

[0007] In summary, while the conventional method of using external resistors to regulate current and protect chips ensures the basic safety of existing LED chips, it also brings many issues that need to be optimized in terms of product circuit design, space utilization, and overall performance. Summary of the Invention

[0008] To address the problems of existing external resistors requiring consideration of placement and connectivity during circuit design, occupying product space, and affecting circuit width, thereby increasing voltage drop and reducing the number of cascaded resistors at normal brightness, this invention provides a method for fabricating an LED resistor chip to solve these issues. The LED resistor chip fabricated by this invention can replace ordinary resistors, can be directly bonded inside LED chips, and is designed for direct current limiting and high-voltage connection. The resistor chip of this invention achieves more precise resistance values, optimizes heat dissipation during operation, and can be used to adjust the brightness of LED chips at different voltages.

[0009] The technical solution of this invention is as follows: A method for fabricating an LED resistor chip includes the following steps: (1) Cleaning impurities on the surface of silicon wafers: Clean the silicon wafers with solution #1 and solution #2, and then dry them; (2) N-type doped phosphorus source diffusion: The silicon wafer is placed on a silicon carbide flat boat fixture and placed in a diffusion furnace for source diffusion; (3) Deoxidized layer cleaning; (4) Nickel plating on silicon wafers: Place the cleaned silicon wafers from step (3) into a nickel plating tank for nickel plating. (5) Silicon wafer sintering: The silicon wafer after nickel plating in step (4) is placed in a quartz boat and nickel sintered in a nickel furnace. After sintering, it is cooled to room temperature. (6) The silicon wafer sintered in step (5) is placed into the cartridge. The heating plate is turned on in advance to heat the nitric acid solution to a temperature of 95±5℃. The nitric acid solution is made by mixing 65% concentrated nitric acid with water at a volume ratio of 1:1. The cartridge is then immersed in the hot nitric acid solution for 3 minutes, overflowed and rinsed for 5 minutes, and then transferred to the hot HAEMO-SOL® solution for ultrasonication for 10~15 minutes. The cartridge is then overflowed and ultrasonicated for 10~15 minutes. During the ultrasonic rinsing process, the cartridge should be shaken up and down 20 times. The main components of the HAEMO-SOL® solution include organic solvents (such as ethanol, isopropanol, acetone, etc.), surfactants, corrosion inhibitors, stabilizers and deionized water. (7) Cleaning; (8) Perform a photolithography process to form a pattern that meets the process requirements on the silicon wafer surface using exposure and development methods, thereby achieving local protection and localized processing. (9) Electrode deposition was performed using an electron beam evaporation stage, wherein CrTiAl was deposited on the photolithographic surface and NiAuGeNiAu was deposited on the back side; (10) Perform secondary photolithography, using exposure and development to form patterns on the silicon wafer surface that meet the process requirements, to achieve local protection and local processing. (11) Use ICP equipment for etching, with etching depth > doping depth; (12) Remove the adhesive from the silicon wafer and grow a silicon dioxide thin film using PECVD (plasma-enhanced chemical vapor deposition) equipment; (13) Perform three photolithography steps and use exposure and development to form patterns that meet the process requirements on the silicon wafer surface to achieve local protection and local processing. (14) The silicon wafer is etched with silicon dioxide and then the silicon wafer is de-adhesive treated; (15) Alloying is performed on the silicon wafer after the adhesive removal process, and the alloying temperature is 500℃~600℃; (16) Test the silicon wafer; (17) Cut silicon wafers by using an ultraviolet laser scribing machine to make grooves and then using a dicing machine to split them into individual chips.

[0010] Furthermore, in step (1), the 1# solution is hydrogen peroxide: ammonia: deionized water = 1:1:6 (volume ratio); the 2# solution is hydrogen peroxide: hydrochloric acid: deionized water = 1:1:6 (volume ratio), wherein the concentration of hydrogen peroxide is 20%~35%, the concentration of ammonia is 25%~28%, and the concentration of hydrochloric acid is 36%~38%.

[0011] Furthermore, in step (2), the phosphorus source diffusion temperature is 1200℃~1300℃ and the time is 3~5h.

[0012] Furthermore, in step (3), the solution used for cleaning the oxide layer is hydrofluoric acid: 40 wt% ammonium fluoride aqueous solution: water = 1 ml: 2 g: 3 ml.

[0013] Furthermore, in step (4), the nickel plating process is as follows: 2000ml of nickel solution and 4000ml of hot deionized water are poured into the nickel plating tank and heated to 95±5℃, then ammonia water is added to control the pH value of the nickel solution to 8.5; then the metal is plated with nickel. During the nickel plating process, the basket is shaken up and down continuously for 60~120 seconds, overflow rinsing water for 5~15 minutes, spin-drying at 100~200rpm, and drying in an oven at 100~200℃ for 30~60 minutes.

[0014] Furthermore, in step (4), the nickel solution is citric acid: gold chloride: nickel chloride: sodium hyponitrite: water = 2.6 kg: 2 kg: 1.2 kg: 0.4 kg: 20 L.

[0015] Furthermore, in step (5), the nickel sintering furnace is set to a temperature of 575±5℃. The heating is turned on in advance, and the nitrogen gas is turned on with a flow rate of 10L / minute. The silicon wafer after nickel plating in step (4) is placed into the quartz boat. The quartz boat containing the silicon wafer is slowly pushed into the constant temperature zone. The furnace cap is closed and nickel sintering begins. The sintering time is set to 60 minutes. Once the time is up, the wafer is taken out of the furnace and cooled to room temperature.

[0016] Further, in step (6), the cleaning steps are as follows: the ultrasonically treated silicon wafer is immersed in a 5% hydrofluoric acid aqueous solution for 10 seconds, then transferred to activation solution #1 for 15 seconds, then transferred to activation solution #2 for 15 seconds, taken out and rinsed with water for 1 second and immediately transferred to nickel plating solution. During the nickel plating process, the basket is continuously shaken up and down for 60~120 seconds; the composition of activation solution #1 is AuCl3:H2O=1g:2500mL; the composition of activation solution #2 is AuCl3:H2O=1g:1000mL.

[0017] Furthermore, in step (11), the mixed acid used for etching is nitric acid: hydrofluoric acid: glacial acetic acid = 5:3:1 (volume ratio), the etching time is 6~15 minutes, the etching depth is 60~80 micrometers, and the trench width is 100~150 micrometers.

[0018] Furthermore, in step (17), the laser ultraviolet scribing speed is 200~300mm / s and the power is 2~5W, while the back infrared cutting speed is 200~400mm / s and the power is 1~3W.

[0019] The beneficial effects of this invention are as follows: The LED resistor chip prepared by this invention can replace ordinary resistors and can be directly bonded inside LED beads. It is designed for direct current limiting and high voltage connection. The LED resistor chip preparation method provided by this invention can produce resistor chips with more precise resistance values, optimize heat dissipation during operation, and can be used to adjust the brightness of LED beads at different voltages. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1This is a schematic cross-sectional view of the LED resistor chip prepared according to the present invention.

[0022] In the figure, 1-back electrode, 2-front electrode, 3-passivation layer, 4-doped region, 5-base region. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0024] The compositions of the various solutions used in the examples are as follows: Solution #1 is hydrogen peroxide (concentration 20%~35%): ammonia: deionized water = 1:1:6 (volume ratio); Solution #2 is hydrogen peroxide (concentration 20%~35%): hydrochloric acid: deionized water = 1:1:6 (volume ratio); The composition of activating solution #1 is AuCl3:H2O = 1g:2500mL; The composition of the activating solution #2 is AuCl3:H2O = 1g:1000mL.

[0025] Example 1 A preparation such as Figure 1 The method for fabricating the LED resistor chip shown includes the following steps: (1) Clean the impurities on the surface of the silicon wafer. Heat solution 1 and solution 2 to 75±5℃, soak the silicon wafer for 8 minutes, and rinse with overflow water for 8 minutes. After cleaning, the silicon wafer is dried. (2) N-type doped phosphorus source diffusion: The silicon wafer is placed upright on a silicon carbide flat boat and pushed into a diffusion furnace for source diffusion. The diffusion temperature is 1200℃, the time is 3h, and the doping depth is 7μm. (3) Oxide layer removal cleaning: The silicon wafer after doping in step (2) is cleaned and dried in a solution of hydrofluoric acid: ammonium fluoride: water = 1:2:3; (4) Nickel plating on silicon wafers: Pour 2000ml of nickel solution and 4000ml of hot deionized water into the nickel plating tank and heat to 95±5℃. Then add 600ml of ammonia water and test the pH value of the nickel solution with pH test paper to 8.5. Then plate the silicon wafers with the oxide layer removed in step (3) with metal nickel. During the nickel plating process, shake the basket up and down continuously for 60 seconds, overflow and rinse for 5 minutes, spin dry at 100rpm, and dry in an oven at 100℃ for 30 minutes. (5) Silicon wafer sintering: The nickel furnace is set to a temperature of 575±5℃. The heating is turned on in advance, and the nitrogen gas is turned on at a flow rate of 10L / min. The nickel-plated silicon wafers obtained in step (4) are placed into the quartz boat in sequence. The quartz boat containing the silicon wafers is slowly pushed into the constant temperature zone. The furnace cap is closed and nickel sintering begins. The sintering time is set to 60 minutes. Once the time is up, the wafers are taken out of the furnace and cooled to room temperature. (6) The sintered silicon wafers are sequentially loaded into the cassette. The heating plate is turned on in advance to heat the nitric acid solution to a temperature of 95±5℃. The cassette is immersed in the hot nitric acid solution for 3 minutes, then overflowed and rinsed for 5 minutes. It is then transferred to a hot HAEMO-SOL® electronic cleaning agent solution and sonicated for 15 minutes. Then overflowed and sonicated for 15 minutes. During the ultrasonic rinsing process, the cassette should be shaken up and down 20 times continuously. (7) After ultrasonication, the silicon wafer is immersed in a hydrofluoric acid aqueous solution with a volume ratio of 1:20 for 10 seconds, then transferred to Activation Solution 1 for 15 seconds, then transferred to Activation Solution 2 for 15 seconds, taken out and rinsed with water for 1 second, and immediately transferred to the nickel plating solution. During the nickel plating process, the basket is continuously shaken up and down for 100 seconds. (8) Perform photolithography on the silicon wafer obtained in step (7) and use exposure and development to form a pattern that meets the process requirements on the surface of the silicon wafer to achieve local protection and achieve the purpose of local processing. (9) Electrode deposition was performed on the silicon wafer after one photolithography using an electron beam evaporation stage. The photolithographic surface was deposited with aluminum electrode CrTiAl with a thickness of 3.5 μm; the unlithographic surface was deposited with gold electrode NiAuGeNiAu with a thickness of 2 μm. (10) Perform secondary photolithography on the silicon wafer after evaporation in step (9), and use exposure and development to form a pattern that meets the process requirements on the surface of the silicon wafer to achieve local protection and achieve the purpose of local processing. (11) The silicon wafer obtained after the second photolithography in step (10) is etched using an ICP device to a depth of 10 μm; (12) Remove the adhesive from the silicon wafer after etching in step (11) and grow a silicon dioxide film on the surface of the silicon wafer using a PECVD device. The film thickness is 5000 angstroms. (13) Perform three photolithography steps on the silicon wafer obtained in step (12), and use exposure and development to form a pattern that meets the process requirements on the surface of the silicon wafer to achieve local protection and achieve the purpose of local processing. (14) After three photolithography steps, the silicon wafer is etched with silicon dioxide and then the silicon wafer is de-etched. (15) The silicon wafer after removing the adhesive is alloyed at a temperature of 600°C for 15 minutes. (16) Test the silicon wafer; (17) Silicon wafers are cut. The passivated glass surface is grooved using an ultraviolet laser scribing machine with a scribing speed of 200 mm / s, a power of 4 W, a line width of 8 μm, and a groove depth of 40 μm. The back side is grooved using an infrared scribing machine with a cutting speed of 400 mm / s, a power of 5 W, a groove depth of 45 μm, and a line width of 20 μm. The wafers are then split using a dicing machine to form individual chips.

[0026] Using this embodiment, 200 pieces were processed, with resistance accuracy within ±3%, leakage current pass rate of 99.8%, and wire bonding pass rate of 99.8%.

[0027] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A method for fabricating an LED resistor chip, characterized in that, Includes the following steps: (1) Cleaning impurities on the surface of silicon wafers: Clean the silicon wafers with solution #1 and solution #2, and then dry them; (2) N-type doped phosphorus source diffusion: The silicon wafer is placed on a silicon carbide flat boat fixture and placed in a diffusion furnace for source diffusion; (3) Deoxidized layer cleaning; (4) Nickel plating on silicon wafers: Place the cleaned silicon wafers from step (3) into a nickel plating tank for nickel plating. (5) Silicon wafer sintering: The silicon wafer after nickel plating in step (4) is placed in a quartz boat and nickel sintering is carried out in a nickel furnace. After sintering, it is cooled to room temperature. (6) The silicon wafer sintered in step (5) is placed into the cassette. The heating plate is turned on in advance to heat the nitric acid solution to a temperature of 95±5℃. Then the cassette is immersed in the hot nitric acid solution for 3 minutes, overflow and rinse for 5 minutes, and then transferred to the hot Hamo powder electronic cleaning agent solution for ultrasonication for 10~15 minutes. Then overflow and ultrasonicate for 10~15 minutes. During the ultrasonic rinsing process, the cassette should be shaken up and down 20 times continuously. (7) Cleaning; (8) Perform a photolithography process to form a pattern that meets the process requirements on the silicon wafer surface using exposure and development methods, thereby achieving local protection and localized processing. (9) Electrode deposition was performed using an electron beam evaporation stage, wherein CrTiAl was deposited on the photolithographic surface and NiAuGeNiAu was deposited on the back side; (10) Perform secondary photolithography, using exposure and development to form patterns on the silicon wafer surface that meet the process requirements, to achieve local protection and local processing. (11) Use ICP equipment for etching, with etching depth > doping depth; (12) Remove the adhesive from the silicon wafer and grow a silicon dioxide thin film using a PECVD device; (13) Perform three photolithography steps and use exposure and development to form patterns that meet the process requirements on the silicon wafer surface to achieve local protection and local processing. (14) The silicon wafer is etched with silicon dioxide and then the silicon wafer is de-adhesive treated; (15) Alloying is performed on the silicon wafer after the adhesive removal process, and the alloying temperature is 500℃~600℃; (16) Test the silicon wafer; (17) Cut silicon wafers by using an ultraviolet laser scribing machine to make grooves and then using a dicing machine to split them into individual chips.

2. The method for fabricating an LED resistor chip as described in claim 1, characterized in that, In step (1), solution #1 is hydrogen peroxide: ammonia: deionized water = 1:1:6; solution #2 is hydrogen peroxide: hydrochloric acid: deionized water = 1:1:

6.

3. The method for fabricating an LED resistor chip as described in claim 1, characterized in that, In step (2), the phosphorus source diffusion temperature is 1200℃~1300℃ and the time is 3~5h.

4. The method for fabricating an LED resistor chip as described in claim 1, characterized in that, In step (3), the solution used for cleaning the oxide layer is hydrofluoric acid: ammonium fluoride: water = 1:2:

3.

5. The method for fabricating an LED resistor chip as described in claim 1, characterized in that, In step (4), the nickel plating process is as follows: pour 2000ml of nickel solution and 4000ml of hot deionized water into the nickel plating tank and heat it to 95±5℃, then add ammonia water and control the pH value of the nickel solution to 8.5; then perform metal nickel plating, and continuously shake the basket up and down during the nickel plating process for 60~120 seconds, overflow and rinse for 5~15 minutes, spin dry at 100~200rpm, and dry in an oven at 100~200℃ for 30~60 minutes.

6. The method for fabricating an LED resistor chip as described in claim 5, characterized in that, In step (4), the nickel solution is citric acid: gold chloride: nickel chloride: sodium hyponitrite: water = 2.6kg: 2kg: 1.2kg: 0.4kg: 20L.

7. The method for fabricating an LED resistor chip as described in claim 1, characterized in that, In step (5), the nickel sintering furnace is set to a temperature of 575±5℃. The heating is turned on in advance, and the nitrogen gas is turned on with a flow rate of 10L / minute. The silicon wafers after nickel plating in step (4) are placed into the quartz boat. The quartz boat containing the silicon wafers is slowly pushed into the constant temperature zone. The furnace cap is closed and nickel sintering begins. The sintering time is set to 60 minutes. Once the time is up, the wafers are taken out of the furnace and cooled to room temperature.

8. The method for fabricating an LED resistor chip as described in claim 1, characterized in that, In step (6), the cleaning steps are as follows: the ultrasonically cleaned silicon wafer is immersed in a 5% hydrofluoric acid aqueous solution for 10 seconds, then transferred to Activation Solution 1 for 15 seconds, then transferred to Activation Solution 2 for 15 seconds, taken out and rinsed with water for 1 second and immediately transferred to nickel plating solution. During the nickel plating process, the basket is continuously shaken up and down for 60~120 seconds.

9. The method for fabricating an LED resistor chip as described in claim 1, characterized in that, In step (11), the mixed acid used for etching is nitric acid: hydrofluoric acid: glacial acetic acid = 5:3:1, the etching time is 6~15 minutes, the etching depth is 60~80 micrometers, and the trench width is 100~150 micrometers.

10. The method for fabricating an LED resistor chip as described in claim 1, characterized in that, In step (17), the laser ultraviolet scribing speed is 200~300mm / s and the power is 2~5W, while the back infrared cutting speed is 200~400mm / s and the power is 1~3W.

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