A method for manufacturing a zener diode chip

Abstract

The present application relates to a kind of zener diode chip manufacturing method, belong to electronic accessories field.In the present application, the method that metal is plated nickel and silver, increase the adhesion between each layer of metal, not easy to fall off, improve the weldability, uniformity.The method of using diffusion silicon chip, only use photolithography once, greatly reduce the cost.In addition, the glass powder of the present application is used for glass passivation, the glass powder of this formula is more easily melted quickly after high temperature, avoid melting uneven and cause thickness inconsistency, lead to glass layer appear crack, improve the uniformity of glass passivation, while the area of PN junction increases better protect PN junction, avoid leakage bad rate, improve the working current.The present application uses front ultraviolet laser to remove groove glass to groove and back infrared to groove, then carries out the way of splitting, greatly reduce the loss of cutting process and the damage to glass passivation layer, effectively improve product output rate and yield.

Description

TECHNICAL FIELD

[0001] The application relates to a method for manufacturing a zener diode chip and belongs to the technical field of electronic accessories. BACKGROUND

[0002] A zener diode, also called a Zener diode, is a diode that is used as a voltage stabilizer and is made by using the phenomenon that the current of a pn junction can vary in a large range while the voltage is basically unchanged. The diode is a semiconductor device with a very high resistance until the critical reverse breakdown voltage. At the critical breakdown point, the reverse resistance is reduced to a very small value, and the current increases while the voltage remains constant in the low resistance region. The zener diode is graded according to the breakdown voltage. Due to this characteristic, the zener diode is mainly used as a voltage stabilizer or voltage reference element.

[0003] The core structure of the zener diode is a PN junction, and the reverse breakdown voltage of the zener diode is usually equal to the reverse breakdown voltage of the PN junction. In the prior art, a heavily doped N region (or P region) is usually provided, and a lightly doped P region (or N region) is provided. By adjusting the doping concentration of the lightly doped region, the desired reverse breakdown voltage is achieved. This method is relatively simple, but the stable voltage of the zener diode mainly depends on the doping concentration of the lightly doped P region (or N region), and it is found in practical processes that the doping concentration of the lightly doped P region (or N region) is converted into an ion implantation dose of 3E13-3E14. The ion implantation process of this order of magnitude cannot be integrated with other ion implantation process steps in integrated circuits, so a photolithography and doping (ion implantation) process step must be specially set up for the zener diode. The process steps are increased, and the manufacturing cost is relatively high. The working current of the zener diode is used to enhance its voltage stabilizing performance. The common method to increase the working current of the zener diode is to increase the area of the PN junction. However, the increase of the PN junction area will also cause the increase of the leakage current of the zener diode, which limits the increase of the working current. Solving the PN junction leakage is a technical problem. SUMMARY

[0004] In view of the deficiencies of the prior art, the application provides a method for manufacturing a zener diode chip, which can solve the problem of high manufacturing cost caused by the need to specially set up a photolithography and doping process for the lightly doped region of the zener diode in the prior art. The glass powder configuration coating method in the application can better protect the PN junction, reduce the leakage failure rate of the zener diode, improve the yield of the chip through the non-destructive cutting method, and improve the uniformity and solderability of the plated layer of the die through the silver plating technology of the method, thereby improving the wire bonding yield.

[0005] The technical scheme of the application is as follows:

[0006] A method for manufacturing a zener diode chip, comprising the following steps:

[0007] (1) cleaning the surface of the silicon wafer, drying the silicon wafer after two cleaning processes;

[0008] (2) high temperature oxidation, generating a SiO2 film on the surface of the silicon wafer;

[0009] (3) single side spin coating photoresist, single side removing the oxide layer, removing the photoresist, and cleaning;

[0010] (4) N-type doping phosphorus source diffusion: the wafer and phosphorus paper (P95A) are placed alternately, and are pressed tightly, and are placed on a silicon carbide flat boat, and are pushed into a diffusion furnace for source diffusion;

[0011] (5) wafer segmentation after diffusion: through an acid etching process, borosilicate glass or phosphosilicate glass formed at high temperature is dissolved, the wafer is separated, the glass crystal on the surface of the wafer is removed, and the surface of the silicon wafer is clean and free of foreign matter;

[0012] (6) removing the oxide layer and cleaning: the wafer is soaked in an oxide layer etching liquid, and the oxide layer in the photoetching line is observed under a microscope to be clean;

[0013] (7) high pressure sand blasting (0.4-0.6 MPa), adjusting the thickness of the silicon wafer, through high pressure diamond blasting on the surface of the wafer, the purpose of adjusting the thickness is achieved, and the oxide layer, surface particles and other foreign matter pollution on the surface of the wafer are removed;

[0014] (8) P-type doping boron source diffusion: the wafer phosphorus surface is opposite to the phosphorus surface, and a boron paper (B20) is clamped between the two (the N-type doping phosphorus source diffusion side is called the phosphorus surface, and the other side is called the empty surface), and is arranged alternately and pressed tightly, and is placed on a silicon carbide flat boat, and a silicon blind piece is placed below, and an ultra-thick silicon pressing piece is pressed on the surface, and is pushed into a diffusion furnace for source diffusion;

[0015] (9) wafer segmentation, double side sand blasting, and removing the oxide layer and cleaning;

[0016] (10) performing photoetching, exposing and developing to form a pattern on the surface of the wafer, realizing local protection, and achieving the purpose of localized processing;

[0017] (11) slotting: opening a slotting machine (the slotting machine is a device commonly used in the art to etch with acid), and placing the wafer into a mixed acid tank to start slotting on the diffusion phosphorus side according to the rocker key, and slotting in the X and Y directions to form a "+" shaped groove, and forming a PN junction;

[0018] (12) Glass powder coating for glass passivation: the cleaned wafer trench side up, put into the suction cup, suction cup suction wafer bottom; with a powder spoon to 1 mL glass powder on the wafer with a groove on one side, with a scraper evenly, do not follow the trench scraping, along the chip arrangement angle 45 degrees glass paste into the wafer trench, wafer into the quartz boat, push into the glass sintering furnace for glass passivation;

[0019] (13) the wafer has been completed passivation in turn into the basket (basket is a tool used to load the wafer in the art), put into 5: 1 hydrofluoric acid solution immersion 5 seconds or so, overflow water 4 minutes, again into the mixed acid immersion 1 second, the mixed acid with step (11) the same composition of mixed acid, take out overflow water 4 minutes, put into hot cleaning solution (hamo powder solution) ultrasonic cleaning 10-15 minutes, up and down shake basket no less than 10 times; put into pure water overflow ultrasonic cleaning 10-15 minutes, up and down shake basket no less than 10 times;

[0020] (14) the 2000 ml nickel liquid and 4000 ml of 50-70 DEG hot deionized water into the nickel plating cylinder and heated to 95 DEG C + 5, then add 600 ml of ammonia, test the nickel liquid PH value 8.5 or so, put the basket into the nickel plating cylinder for metal nickel plating, constantly up and down shake the basket during the process of nickel plating, time 60-120 seconds, overflow water 5-15 minutes, 100-200 rpm / s dry, oven 100-200 DEG C / 30-60 minutes drying.

[0021] (15) wafer cutting, using ultraviolet laser dicing machine for glass passivation groove, using infrared dicing machine for back groove, with the help of the splitting machine for splitting, into a chip;

[0022] (16) die silver plating: according to the silver plating solution formula, the surface of the electrode is plated with a silver layer, the thickness of the electrode is increased, and the solderability of the electrode is improved.

[0023] Preferably, in step (1), the two times of cleaning respectively use 1# and 2# solution, the volume ratio of 1# solution is: hydrogen peroxide (hydrogen peroxide): ammonia: deionized water = 1:1:6; the volume ratio of 2# solution is hydrogen peroxide (hydrogen peroxide): hydrochloric acid: deionized water = 1:1:6.

[0024] Preferably, in step (2), the silicon dioxide growth conditions are: oxidation furnace temperature 600-800 DEG C, wet oxygen 2-3 L / min, time 8-10 h; dry oxygen 2-3 L / min, time 1-2 h.

[0025] Preferably, in step (4), the phosphorus source diffusion temperature is 1200-1300 DEG C, and the time is 30-50 h;

[0026] Preferably, in step (5), the solution used in the acid etching process is hydrofluoric acid solution, and the soaking time is 12-48h.

[0027] Preferably, in step (6), the volume ratio of the solution used in the oxide layer removal process is hydrofluoric acid:ammonium fluoride:water = 1:2:3.

[0028] In step (7), sandblasting removes 3-15um.

[0029] Preferably, in step (8), the boron source diffusion temperature is 1100-1300℃, and the diffusion time is 10-20h.

[0030] Preferably, in step (11), the volume ratio of the mixed acid in the mixed acid tank is nitric acid:hydrofluoric acid:glacial acetic acid = 5:3:1, the etching time is 6-15 minutes, the etching depth is 60-80 microns, and the groove width is 100-150 microns.

[0031] Preferably, in step (12), the preparation method of the glass powder is:

[0032] a. Take 1000g of glass powder GP-230S, 6g of ethyl nitrate cellulose, and 460g of ethyl butyl carbitol, and put them into a 125℃ oven respectively, and bake for 10 minutes;

[0033] b. Mix the ethyl nitrate cellulose and ethyl butyl carbitol thoroughly, then put them into the oven again and bake for 30 minutes, and stir them evenly with a glass rod to obtain mixture one;

[0034] c. Take out the glass powder and mixture one obtained in step b, mix them while stirring, then fully stir them with a stirrer for 60 minutes to obtain mixture two;

[0035] d. Ultrasonic oscillation for 90 minutes to fully mix and evenly distribute mixture two, and then pour mixture two into a special bottle and roll it on a powder rolling machine for more than 60 minutes before use.

[0036] Preferably, in step (14), the nickel solution is citric acid:gold chloride:nickel chloride:sodium nitrite:water = 2.6kg:2kg:1.2kg:0.4kg:20L;

[0037] Preferably, in step (15), glass passivation is performed in the "+" shaped groove, and then laser is used to groove at the glass passivation position; the speed of the ultraviolet laser scribe machine is 200-300mm / s, and the power is 2-5W; the cutting speed of the infrared scribe machine is 200-400mm / s, and the power is 1-3W.

[0038] Preferably, in step (16), the preparation method of the silver plating solution is:

[0039] Put 900g of disodium EDTA and 225g of imidazole into a barrel, add 12 liters of water, and then add 750ml of ammonia water, and stir to dissolve; pour 45g of silver nitrate into a 5L beaker, add 3L of water and stir to dissolve, to obtain a silver nitrate solution; pour the silver nitrate solution into the barrel while stirring, and pour in 120ml of formaldehyde while stirring, and stir until uniform.

[0040] The above technical solutions that are not described in detail and limited are referred to the prior art.

[0041] The beneficial effects of the present application are:

[0042] The metal adopts a nickel and silver plating method, which increases the adhesion between the metal layers and is not easy to fall off, and improves the solderability and uniformity. The diffusion silicon wafer method only uses one-time photolithography, which greatly reduces the cost. In addition, the glass powder configuration method is used for glass passivation. The glass powder of this formula is more likely to melt quickly after being subjected to high temperature, avoiding uneven melting, causing inconsistent thickness, leading to cracks in the glass layer, improving the uniformity of glass passivation, better protecting the PN junction while increasing the PN junction area, avoiding the leakage of poor rate, and improving the working current. The present application adopts the method of front ultraviolet laser removal groove glass for grooving and back infrared for grooving, and then performs the method of cracking, which greatly reduces the loss in the cutting process and the damage to the glass passivation layer, effectively improving the product output rate and yield. DETAILED DESCRIPTION

[0043] In order to make the person in the technical field better understand the technical solutions in the specification, the technical solutions in the embodiments of the present application are described clearly and completely, but not limited to this, the present application is not described in detail, which is according to the conventional technology in the art.

[0044] Example 1

[0045] A method for manufacturing a zener diode chip, comprising the following steps:

[0046] (1) cleaning the surface impurities of the silicon wafer, drying the silicon wafer after two times of cleaning; the two times of cleaning respectively uses 1# and 2# solutions, 1# and 2# solutions are heated to 75±5℃, and the wafer is soaked for 8 minutes and overflowed for 8 minutes;

[0047] The volume ratio in the 1# solution is: hydrogen peroxide (hydrogen peroxide): ammonia water: deionized water = 1:1:6; the volume ratio in the 2# solution is: hydrogen peroxide (hydrogen peroxide): hydrochloric acid: deionized water = 1:1:6.

[0048] (2) high temperature oxidation, oxidation furnace temperature 600°C, wet oxygen 2L / min, time 8h; dry oxygen 2L / min, time 1h, a layer of SiO2 film is formed on the surface of the silicon wafer, the thickness of the SiO2 film is 8000-10000 angstroms;

[0049] (3) single side spin photoresist, single side deoxidation layer (step 2), dephotoresist, cleaning;

[0050] (4) N-type doped phosphorus source diffusion: the wafer and phosphorus paper (P95A) are placed alternately, arranged and compressed, placed on a silicon carbide flat boat, and then pushed into a diffusion furnace for source diffusion, the diffusion temperature is 1200°C, and the time is 30h;

[0051] (5) wafer segmentation after diffusion: through hydrofluoric acid solution corrosion, the soaking time is 12-48h, the borosilicate glass or phosphosilicate glass formed at high temperature is dissolved, the wafer is separated, the glass crystal on the surface of the wafer is removed, and the surface of the silicon wafer is clean and free of foreign matter;

[0052] (6) deoxidation layer cleaning: the wafer is soaked in an oxidation layer etching solution, hydrofluoric acid: ammonium fluoride: water = 1:2:3, and the oxidation layer in the photoetching line is observed to be clean under a microscope;

[0053] (7) high pressure sand blasting (0.4-0.6MPa), adjusting the thickness of the silicon wafer, through high pressure diamond blasting on the surface of the wafer, the purpose of adjusting the thickness is achieved, 3-15um is removed by sand blasting, and the oxidation layer, surface particles and other foreign matter pollution on the surface of the wafer are removed;

[0054] (8) P-type doped boron source diffusion: the wafer phosphorus side is opposite to the phosphorus side, and one boron paper (B20) is clamped between the two sides (the side of N-type doped phosphorus source diffusion is called the phosphorus side, and the other side is called the empty side), arranged and compressed alternately, placed on a silicon carbide flat boat, and then pushed into a diffusion furnace for source diffusion; the boron source diffusion temperature is 1100°C, and the diffusion time is 10h.

[0055] (9) wafer segmentation, double side sand blasting, and deoxidation layer cleaning;

[0056] (10) one-time photoetching, exposure and development are used to form a pattern on the surface of the wafer, local protection is realized, and the purpose of local processing is achieved;

[0057] (11) slotting: the slotting machine is opened (the slotting machine is a device commonly used in the art for etching with acid), the wafer is placed in the mixed acid tank, the slotting machine is started by pressing the rocker key, a sub-line slot is opened on the diffused phosphorus side, and slotting is performed in the X and Y directions to form a "+" shaped groove and form a PN junction;

[0058] The mixed acid volume ratio of the mixed acid tank is nitric acid:hydrofluoric acid:glacial acetic acid = 5:3:1, the etching time is 6 minutes, the etching depth is 60 microns, and the groove width is 100 microns.

[0059] (12) Glass powder is coated for glass passivation: the wafer with the etched groove is placed on a suction disc with the etched groove facing upward, the suction disc sucks the bottom of the wafer; 1 mL of glass powder is taken on the wafer with the etched groove by a powder coating spoon, and is evenly spread by a scraper, the glass paste is scraped at an angle of 45 degrees along the arrangement angle of the chip without following the groove, the wafer is loaded into a quartz boat, and is pushed into a glass sintering furnace for glass passivation, and the glass passivation thickness is 35 um;

[0060] The preparation method of the glass powder is as follows:

[0061] a. 1000 g of glass powder GP-230S, 6 g of ethyl nitrate cellulose, and 460 g of ethyl butyl carbitol are respectively placed in a 125 °C oven and baked for 10 minutes;

[0062] b. The ethyl nitrate cellulose and the ethyl butyl carbitol are fully mixed, and then are again placed in an oven and baked for 30 minutes, and are uniformly stirred by a glass rod to obtain a mixture one;

[0063] c. The glass powder and the mixture one obtained in step b are mixed while stirring, and then are fully stirred by a stirrer for 60 minutes to obtain a mixture two;

[0064] d. The mixture two is ultrasonically oscillated for 90 minutes to fully mix and uniformly mix the mixture two, and the mixed liquid two is loaded into a special bottle and rolled on a powder rolling machine for more than 60 minutes before use.

[0065] (13) The wafer with completed passivation is sequentially placed into a flower basket (the flower basket is a tool used in the art to load wafers), is soaked in 5:1 hydrofluoric acid solution for about 5 seconds, is overflowed and washed for 4 minutes, is again soaked in 11:1 mixed acid for 1 second, the mixed acid is nitric acid:hydrofluoric acid:glacial acetic acid = 5:3:1, is taken out, is overflowed and washed for 4 minutes, is loaded into hot cleaning solution (Hamar powder solution) and ultrasonically cleaned for 10-15 minutes, the flower basket is shaken up and down for not less than 10 times; is loaded into pure water and overflowed and ultrasonically cleaned for 10-15 minutes, the flower basket is shaken up and down for not less than 10 times;

[0066] (14) 2000 ml of nickel liquid and 4000 ml of 50-70 ° hot deionized water are poured into a nickel plating tank and heated to 95 °C ± 5, 600 ml of ammonia water is added, the PH value of the nickel liquid is tested by a PH test paper to be about 8.5, the flower basket is placed into the nickel plating tank for metal nickel plating, the flower basket is constantly shaken up and down during the nickel plating process, the time is 60 seconds, the overflow is washed for 5 minutes, 100 rpm / s is spun dry, and the oven is dried at 100 °C / 30 minutes.

[0067] The nickel liquid is citric acid: gold chloride: nickel chloride: sodium nitrite: water = 2.6 kg: 2 kg: 1.2 kg: 0.4 kg: 20 L;

[0068] (15) wafer cutting, using ultraviolet laser dicing machine to groove on the glass passivation surface, using infrared dicing machine to groove on the back surface, and using a cleaving machine to split and divide into individual chips;

[0069] Specifically, glass passivation is performed in the "+" shaped groove, and then laser is used to groove at the glass passivation position; the dicing speed of the ultraviolet laser dicing machine is 200 mm / s, the power is 4 W, the line width is 8 um, and the groove depth is 40 um; the cutting speed of the infrared dicing machine is 200 mm / s, the power is 3 W, the groove depth is 45 um, the line width is 20 um, and the cleaving machine is used for splitting and dividing into individual chips.

[0070] (16) silver plating of the die: according to the silver plating liquid formula, a silver layer is plated on the surface of the electrode to increase the thickness of the electrode and improve the solderability of the electrode, and the specific process is as follows:

[0071] A, the die is poured into a conical flask, anhydrous ethanol is added, and ultrasonic is performed at room temperature for 10 minutes; B, the ethanol is poured out, pure water is washed once, nitric acid solution (1:10) is added, and the flask is shaken for 3 minutes, and then pure water is washed for 3 times; C, the silver plating liquid is added into the conical flask, heated for 8 minutes (80℃) and shaken; D, pure water is washed for 4 times, and anhydrous ethanol is used for dehydration; E, the die is poured into a sieve, and heated on a hot plate for 10 minutes (80℃).

[0072] The preparation method of the silver plating liquid is as follows:

[0073] Put 900 g of disodium EDTA and 225 g of imidazole into a barrel, add 12 liters of water, then add 750 mL of ammonia water, and stir to dissolve; pour 45 g of silver nitrate into a 5L beaker, add 3L water, stir to dissolve, and obtain a silver nitrate solution; while stirring, pour the silver nitrate solution into the barrel, and while stirring, pour in 120 ml of formaldehyde, and stir until uniform.

[0074] The above dried die is a stable voltage diode chip.

[0075] The above is a preferred embodiment of the present application. It should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method of fabricating a zener diode chip, comprising: It comprises the following steps: (1) cleaning the surface of the silicon wafer, drying the silicon wafer after two times of cleaning; (2) high temperature oxidation, generating a layer of SiO2 film on the surface of the silicon wafer; (3) single side spinning photoresist, single side removing the oxidation layer, removing the photoresist, and cleaning; (4) N-type doping phosphorus source diffusion: the wafer and the phosphorus paper are placed alternately, arranged and compressed, placed on the silicon carbide flat boat, and then pushed into the diffusion furnace for source diffusion; (5) wafer segmentation after diffusion: through the acid etching process, the borosilicate glass or phosphosilicate glass formed at high temperature is dissolved, the wafer is separated, the glass crystallization on the surface of the wafer is eliminated, and the surface of the silicon wafer is clean and free of foreign matter; (6) removing the oxidation layer and cleaning: the wafer is soaked in the oxidation layer etching liquid, and the oxidation layer in the photoetching line is observed under a microscope to ensure that it is clean; (7) high pressure sand blasting, adjusting the thickness of the silicon wafer, and removing the oxidation layer and surface particles on the surface of the wafer; (8) P-type doping boron source diffusion: the wafer is placed with the phosphorus side against the phosphorus side, and a boron paper is clamped between the two wafers, which are arranged and compressed alternately, placed on the silicon carbide flat boat, and then pushed into the diffusion furnace for source diffusion; (9) wafer segmentation, double side sand blasting, and oxidation layer cleaning; (10) performing photoetching, exposing and developing to form patterns on the surface of the wafer, realizing local protection, and achieving the purpose of localized processing; (11) slotting: opening the slotting machine, placing the wafer into the mixed acid tank, starting the slotting on the diffused phosphorus side according to the rocker key, and slotting in the X and Y directions to form "+"-shaped grooves and form PN junctions; (12) glass passivation by coating glass powder: the cleaned wafer is placed on the suction disc with the slotted side facing up, the wafer is sucked at the bottom by the suction disc; 1 mL of glass powder is taken with a powder coating spoon and applied to the wafer with the slotted side, and the glass paste is scraped into the wafer groove at an angle of 45 degrees along the arrangement angle of the chip; the wafer is loaded into a quartz boat and pushed into a glass sintering furnace for glass passivation; (13) the wafer with completed passivation is placed into a flower basket in sequence, soaked in 5:1 hydrofluoric acid solution for 5 seconds, overflowed and washed for 4 minutes, soaked in mixed acid again for 1 second, taken out, overflowed and washed for 4 minutes, ultrasonic cleaned in hot cleaning liquid for 10-15 minutes, the flower basket is shaken up and down for not less than 10 times; ultrasonic cleaned in pure water overflow for 10-15 minutes, the flower basket is shaken up and down for not less than 10 times; (14) 2000 ml of nickel liquid and 4000 ml of 50-70° hot deionized water are poured into a nickel plating tank and heated to 95℃±5℃, then ammonia water is added, and the PH value of the nickel liquid is tested with a PH test paper to be 8.5; the flower basket is placed into the nickel plating tank for metal nickel plating, the flower basket is constantly shaken up and down during the nickel plating process, the time is 60-120 seconds, overflowed and washed for 5-15 minutes, 100-200 rpm / s is spun dry, and the oven is dried at 100-200℃ / 30-60 minutes; (15) wafer cutting: the glass passivation side is slotted by using an ultraviolet laser dicing machine, the back side is slotted by using an infrared dicing machine, and the chips are separated by using a wafer splitting machine. (16) Tube core silver plating: according to the silver plating liquid formula, silver layer is plated on the surface of the electrode, the thickness of the electrode is increased, and the solderability of the electrode is improved.

2. The method for manufacturing a Zener diode chip according to claim 1, characterized in that, In step (1), the two cleaning processes use 1# and 2# solutions respectively, the volume ratio of 1# solution is: hydrogen peroxide: ammonia: deionized water = 1:1:6; the volume ratio of 2# solution is hydrogen peroxide: hydrochloric acid: deionized water = 1:1:

6.

3. The method of claim 2, wherein the step of forming the first and second electrodes comprises the steps of: forming a first electrode on the first surface of the substrate; and forming a second electrode on the second surface of the substrate. In step (2), the growth conditions of silicon dioxide are: the temperature of the oxidation furnace is 600-800℃, the wet oxygen flow is 2-3L / min, the time is 8-10h; the dry oxygen flow is 2-3L / min, the time is 1-2h.

4. The method for manufacturing a Zener diode chip according to claim 3, characterized in that, In step (4), the phosphorus source diffusion temperature is 1200-1300℃, the time is 30-50h; In step (5), the solution used in the acid etching process is hydrofluoric acid solution, and the soaking time is 12-48h.

5. The method according to claim 4, wherein In step (6), the volume ratio of the solution used for removing the oxidation layer is hydrofluoric acid: ammonium fluoride: water = 1:2:3; In step (7), the sand blasting removes 3-15um.

6. The method of claim 5, wherein the step of forming the first and second electrodes comprises the steps of: forming a first electrode layer on the substrate; forming a second electrode layer on the first electrode layer; and forming a third electrode layer on the second electrode layer. In step (8), the boron source diffusion temperature is 1100-1300℃, and the diffusion time is 10-20h.

7. The method according to claim 6, wherein In step (11), the volume ratio of the mixed acid in the mixed acid tank is nitric acid: hydrofluoric acid: glacial acetic acid = 5:3:1, the etching time is 6-15 minutes, the etching depth is 60-80 microns, and the groove width is 100-150 microns.

8. The method according to claim 7, wherein In step (12), the preparation method of glass powder is: a. Take 1000g of glass powder GP-230S, 6g of ethyl nitrate cellulose, and 460g of ethyl butyl carbitol, and put them into a 125℃ oven, and bake for 10 minutes; b. Mix the ethyl nitrate cellulose and ethyl butyl carbitol thoroughly, then put them into the oven again and bake for 30 minutes, and stir evenly with a glass rod to obtain mixture one; c. Take out the glass powder and mix it with the mixture obtained in step b while stirring, then fully stir for 60 minutes with a stirrer to obtain mixture two; d. Ultrasonic oscillation for 90 minutes to fully mix and uniform the mixture two, and then pour the mixture two into a special bottle and roll on a powder rolling machine for more than 60 minutes.

9. The method according to claim 8, wherein In step (14), the nickel liquid is citric acid: gold chloride: nickel chloride: sodium nitrite: water = 2.6kg:2kg:1.2kg:0.4kg:20L; In step (15), glass passivation is carried out in the "+" shaped groove, and then laser is used to groove at the position of glass passivation; the speed of the ultraviolet laser scribing machine is 200-300mm / s, the power is 2-5W, the cutting speed of the infrared scribing machine is 200-400mm / s, and the power is 1-3W.

10. The method according to claim 9, wherein In step (16), the preparation method of the silver plating solution is: Put 900g of EDTA disodium and 225g of imidazole into a barrel, add 12 liters of water, then add 750ml of ammonia water, and stir to dissolve; pour 45g of silver nitrate into a 5L beaker, add 3L of water and stir to dissolve, to obtain a silver nitrate solution; while stirring, pour the silver nitrate solution into the barrel, and while stirring, pour 120ml of formaldehyde into the barrel, and stir until uniform.