CN113223959B - Method for manufacturing compression joint type diode core - Google Patents

Abstract

The invention discloses a compression joint type diode core and a manufacturing method thereof, comprising the following steps: 1) preparing a diode diffusion sheet, 2) corroding a voltage tank, 3) depositing a polycrystalline silicon film or a silicon nitride film by the voltage tank, 4) passivating voltage tank glass, 5) etching to remove a passivation film of most of cathode surface and anode surface areas which do not need protection of the polycrystalline silicon film or the silicon nitride, 6) welding a chip and a molybdenum sheet, 7) evaporating aluminum on a cathode surface, 8) selectively corroding an aluminum layer on the cathode surface, and 9) microalloy on an aluminum layer. Further 10) single-side multilayer metallization of the molybdenum sheet on the anode surface of the tube core, and 11) coating of a third protective layer on the voltage slot. The chip is tested before welding, unqualified chips are removed, waste of molybdenum sheets and the like is avoided, and the unqualified chips are reused after being processed. The voltage slot adopts three-layer protection, so that the leakage current of the tube core tested under high-temperature dynamic conditions is reduced; the molybdenum sheet is protected by titanium-nickel-silver multilayer metal to prevent oxidation, so that the thermal resistance and the resistance are reduced, and the power consumption is reduced.

Description

A method of manufacturing a crimped diode die

technical field

The invention relates to a diode die and a manufacturing method, in particular to a method for manufacturing a crimping diode die. It belongs to the technical field of semiconductor devices.

Background technique

At present, the existing technology is: the preparation of the pressure-connected two-layer structure diode tube diffusion sheet: 1) according to the requirements of the electrical parameters, select the resistivity and the sheet thickness of the N-type silicon wafer, and expand N+ on both sides of the silicon single wafer, and keep One side is used as the cathode, and then the N+ layer on the other side is removed, and then the P layer is expanded to form the anode. 2) Then weld the aluminum foil and the molybdenum sheet. 3) The cathode is steamed aluminum and aluminum microalloy. 4) Grinding the positive bevel, corroding the positive bevel, coating silicone rubber or polyimide to protect the table. There are four deficiencies in the existing technology and flow process: 1. The discarded tube core molybdenum sheets cannot be reused. Die cores with unqualified electrical parameters in the test are waste products. However, because the molybdenum sheet and the chip are welded together through aluminum foil, the edge of the molybdenum sheet has been deformed after grinding and corroding the positive bevel angle, and the geometric size does not match the original molybdenum sheet. The molybdenum sheet is scrapped together, resulting in an increase in production costs. high. 2. The efficiency of the angle grinding process is low. After the chip and the molybdenum sheet are welded to form a tube core, the bevel needs to be ground one by one, and the production efficiency is low. The bevel grinding occupies a large area of the cathode surface of the chip, causing a large on-state voltage drop. 3. Low pressure chemical vapor deposition (CVD) cannot be used to deposit semi-insulating polysilicon film or silicon nitride film on the mesa of the die. After the core is welded, the positive and negative bevels are corroded and cleaned, and the low-pressure chemical vapor deposition process (CVD) cannot be used at a high temperature of 700-800°C to make a semi-insulating polysilicon film or a silicon nitride film to passivate the positive bevel. The reason is that the melting point of silicon-aluminum alloy is 577°C, the brazing temperature of the chip and the molybdenum sheet is about 650°C, and the temperature of the passivation positive angle of the subsequent film formation needs to be carried out at 700-800°C, and the film passivation temperature If the temperature is higher than the welding temperature, the cathode aluminum layer and the alloy layer of the anode P layer will burn too deeply at this high temperature, causing the reverse withstand voltage to decrease and be scrapped. Therefore, the positive bevel can only be used for general passivation film protection, such as polyimide and silicone rubber. This type of insulating protection material is difficult to prevent most ionic impurities from staining and eroding the positive and negative beveled mesa. Therefore, under the high temperature test, the reverse leakage current is too large, the high temperature reverse bias characteristic is unstable, and the qualified rate is low. 4. The molybdenum sheet on the anode side of the tube core is easy to oxidize. Since the molybdenum sheet on the anode surface of the tube core has no anti-oxidation metal layer, an oxide layer will form on the surface of the molybdenum sheet after long-term storage. This oxide layer has a certain thermal resistance and electrical resistance, which increases power consumption.

Chinese patent application 201710649775.5 discloses a rectifier diode chip structure and its preparation method. The rectifier diode chip structure includes a long base region N, an N+ layer disposed on the upper surface of the long base region N, P and a layer disposed on the lower surface of the long base region N. The P+ layer, the N+ layer extends downwards to the P layer with a voltage groove, the voltage groove is located on the periphery of the chip, and is a single-sided groove structure; a P-type boss is arranged on the P-layer plane, and the P-type boss The platform is located below the voltage groove; the width of the P-type boss is greater than the width of the bottom of the voltage groove. The length of the hypotenuse of the voltage groove is greater than the thickness of the N-type base region, so as to facilitate the widening of the depletion layer. Because the cathode and anode are nickel-plated with gold. This chip can only be used for soft soldering (below 400°C), and cannot be used for press-fit devices. Because the crimp-type die is welded with aluminum foil and molybdenum sheet at 600-700°C, the nickel-gold electrode layer will penetrate into the N+ cathode and P layer, resulting in a serious decline in chip performance or even damage.

Contents of the invention

The object of the present invention is to provide a crimped diode die and a manufacturing method to improve the electrical parameters of the product, reduce the production cost, and improve the qualified rate of the product, aiming at the above shortcomings of the prior art.

The technical solution adopted by the present invention to achieve the above purpose is: a method for manufacturing a crimped diode die, firstly making a chip with a P-shaped boss, capable of withstanding reverse pressure and without metallization on the surface, and then passing the aluminum foil Brazing with molybdenum sheet; includes the following steps:

1) Prepare a two-layer structure diode diffusion sheet: According to the requirements of electrical parameters, select the resistivity and thickness of the N-type silicon wafer, and expand N+ on both sides; one side is set as the cathode, and the voltage groove area is reserved on the cathode side; then remove the other On one side of N+, use a laser to drill a blind hole under the voltage groove, and then expand the P layer anode and P-type boss; remove boron and phosphosilicate glass; clean and set aside.

2) Apply photoresist on the cathode surface, expose according to the voltage groove pattern, develop, corrode the voltage groove, rinse and remove the photoresist after etching, and dry for later use.

3) The semi-insulating polysilicon film or silicon nitride film is deposited on the voltage tank, and the etched sheet with the voltage tank structure is placed in the chemical vapor deposition equipment, and the semi-insulating polysilicon film or silicon nitride film is deposited, according to the conventional Film making process operation, film thickness

4) Glass passivation of the voltage tank: the semi-insulating polysilicon or silicon nitride passivation film area of the voltage tank on the cathode surface is coated with glass powder and then passivated to form a glass passivation film. The passivation temperature is 690-750°C. Passivation time 30-60min;

5) Etching and removing the passivation film on most of the cathode and anode areas that do not need semi-insulating polysilicon film or silicon nitride protection: after passivating the voltage tank, apply photoresist, according to the cathode surface Design the pattern for exposure and development, and keep the photoresist on the voltage slot; after development, use dilute hydrofluoric acid to remove the residual glass powder on the cathode surface; then use mixed acid etching solution to etch the unnecessary semi-insulating polysilicon film, or use plasma The equipment is etched to remove most of the cathode surface protected by the silicon nitride film and the passivation film on the entire area of the anode surface, and then placed in sulfuric acid to remove the photoresist on the voltage slot.

6) Welding of chip and molybdenum sheet: before welding the chip and molybdenum sheet, test the chip and reject unqualified chips. Stack chips, aluminum foil, and molybdenum sheets together and weld them in a high vacuum sintering furnace at 620-700°C and constant temperature for 10-20 minutes, then cool down and leave the furnace.

7) Aluminum steaming on the cathode surface: place the welded tube core in a high-vacuum coating or magnetron sputtering equipment, and steam the cathode surface, and the thickness of the aluminum layer is not less than

8) Selective corrosion of the aluminum layer on the cathode surface: apply photoresist on the surface of the cathode with an existing aluminum layer, expose and develop to remove the photoresist on the voltage groove, and then perform aluminum etching with an aluminum corrosion solution to remove the photoresist on the cathode surface. The resist retains the aluminum layer on the cathode side;

9) Micro-alloying of the aluminum layer: Place the tube core that has been selectively corroded on the aluminum layer on the cathode surface in an alloy furnace protected by nitrogen gas for aluminum micro-alloying at a temperature of 500-550°C and an alloying time of 10-50 minutes.

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并在温度400-450℃、时间为20-60min的下进行微合金。因为银层不易氧化，起到抗氧化作用。Further, it also includes step 10) single-sided multilayer metallization of the molybdenum sheet on the anode side of the tube core: placing the molybdenum sheet on the anode side of the tube core upwards in a vacuum magnetron sputtering device or in a vacuum coating machine for titanium-nickel-silver multilayer metallization oxidized sputtering, thicknesses were Ti

Nickel />

Silver />

And carry out microalloying at a temperature of 400-450° C. and a time of 20-60 minutes. Because the silver layer is not easy to oxidize, it acts as an anti-oxidant.

Further, it also includes step 11) coating the voltage groove with a third protective layer: coating the voltage groove with polyimide or silicone rubber for further passivation protection to prevent damage caused by collision.

The positive effect of the present invention is: (1) adopt earlier to form two-layer structure and have P-type boss diode diffuser sheet on the silicon single chip, then make the chip that can bear reverse withstand voltage, before welding, chip can be Test piece by piece (in the prior art, the chip does not have the test conditions before welding), first remove the chip that cannot withstand the reverse withstand voltage, and then weld the chip that can withstand the reverse withstand voltage with the molybdenum sheet to avoid the molybdenum sheet , chemical reagents, artificial waste, greatly reducing production costs. (2) Diode chips use the process of corroding the voltage groove instead of the grinding process. In the acid etching machine, the number of chips etched at one time reaches 100-300 pieces (Φ30-60mm), which is dozens of times more efficient than the traditional piece-by-piece grinding process. , greatly improving production efficiency. (3) Since the chip and the molybdenum sheet are welded to form a tube core, a small number of unqualified tube cores after various electrical parameter tests have not undergone grinding and corrosion after welding, and the geometric dimensions of the molybdenum sheet have not changed. After that, it can be reused completely, which further reduces the production cost. (4) The chip voltage tank is protected by the first semi-insulating polysilicon film or silicon nitride film passivation and the second protection of the glass passivation film on the sensitive voltage tank area by using a low-pressure chemical vapor deposition (CVD) process. It effectively prevents the pollution and erosion of most ionic impurities, and then uses polyimide and elastic silicone rubber for the third protection to prevent collisions, significantly reducing the leakage current of the die under high temperature and dynamic testing, and improving the The stability and pass rate of the test under high temperature reverse bias. (5) The molybdenum sheet on the anode surface of the diode core is protected by sputtering or evaporating titanium-nickel-silver multi-layer metal to prevent oxidation, reduce thermal resistance and electrical resistance, and reduce power consumption.

The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

Description of drawings

FIG. 1 is a schematic diagram of a cross-sectional structure of a crimping die according to the present invention.

In the figure: 1. Anode, 2. N-type base area, 3. Cathode, 4. Aluminum layer, 5. Voltage tank, 6. Semi-insulating polysilicon film, 7. Glass passivation film, 8. Silicone rubber, 9. P Type boss, 10. Laser blind hole, 11. Molybdenum sheet, 12. Multi-metallization layer, 13. Aluminum foil.

Detailed ways

Embodiment 1. As shown in Figure 1, a kind of method of making crimping type diode tube core, first make the chip that has P-type boss (9), can bear reverse withstand voltage and the surface is not carried out metallization, then pass Hard welding of aluminum foil (13) and molybdenum sheet (11); comprises the following steps:

1) Prepare a two-layer structure diode diffusion sheet: According to the requirements of electrical parameters, select the resistivity and thickness of the N-type silicon wafer, and expand the N+ diffusion layer on both sides; one side is set as the cathode (3), and the cathode side is reserved for voltage slots area; then remove the N+ on the other side, drill a blind hole (10) with a laser below the voltage groove, and then expand the P layer anode (1) and P-type boss (9); remove boron and phosphosilicate glass; clean and set aside.

2) Coating photoresist on the cathode surface, exposing according to the voltage groove pattern, developing, and corroding the voltage groove (5), rinsing and removing the photoresist after etching, and drying for later use. Specifically, the diffusion sheet with a two-layer structure of the diode is coated with photoresist, exposed, and developed to obtain the corroded area of the voltage groove (5), and then placed in a mixed acid etching solution for etching. The temperature of the acid solution is -10°C to 12°C. ℃, time 5-20min, the mixed acid etching solution, the mixed acid volume ratio is 5 parts of hydrofluoric acid, 4 parts of glacial acetic acid, 2 parts of fuming nitric acid, and 1 part of nitric acid.

半绝缘多晶硅膜制作工艺参数:气体为硅烷、一氧化二氮、氯化氢；氯化氢清洁工艺参数：温度炉口575℃、炉中575℃、炉尾575℃，清洁时间40min，清洁压力200-300毫托，清洁流量100-200ml/min；SIPOS沉积工艺参数：温度炉口640-660℃、炉中640-660℃、炉尾640-660℃；SIPOS先通硅烷淀积40S后，再SIPOS沉积30-45min；SIPOS沉积压力：300毫托，气体流量：N2O为50-80ml/min，SiH4为260-320m l/min；MTO温度为炉口600-670℃、炉中600-670℃、炉尾600-670℃；时间20-30min；致密化炉口700-800℃、炉中700-800℃、炉尾700-800℃，时间20-30min。3) Deposit a semi-insulating polysilicon film (6) or a silicon nitride film on the voltage tank, place the corroded sheet with a voltage tank structure in a chemical vapor deposition device, and deposit a semi-insulating polysilicon film or a silicon nitride film, According to the conventional film making process, the film thickness

Semi-insulating polysilicon film production process parameters: gas is silane, nitrous oxide, hydrogen chloride; hydrogen chloride cleaning process parameters: temperature furnace mouth 575 ℃, furnace 575 ℃, furnace tail 575 ℃, cleaning time 40min, cleaning pressure 200-300 mm Torr, cleaning flow rate 100-200ml/min; SIPOS deposition process parameters: temperature furnace mouth 640-660°C, furnace temperature 640-660°C, furnace tail 640-660°C; -45min; SIPOS deposition pressure: 300mTorr, gas flow: 50-80ml/min for N2O, 260-320ml/min for SiH4; MTO temperature is 600-670℃ at the furnace mouth, 600-670℃ in the furnace, 600-670°C; time 20-30min; densification furnace mouth 700-800°C, furnace 700-800°C, furnace tail 700-800°C, time 20-30min.

4) Glass passivation of the voltage tank: the semi-insulating polysilicon or silicon nitride passivation film area of the voltage tank on the cathode surface is then coated with glass powder and passivated to form a glass passivation film (7). The passivation temperature is 690- 750℃, passivation time 30-60min;

5) Etching and removing the passivation film on most of the cathode and anode areas that do not need semi-insulating polysilicon film or silicon nitride protection: after passivating the voltage tank, apply photoresist, according to the cathode surface Design the pattern for exposure and development, and keep the photoresist on the voltage slot; after development, use dilute hydrofluoric acid to remove the residual glass powder on the cathode surface; then use mixed acid etching solution to etch the unnecessary semi-insulating polysilicon film, or use plasma The device etches to remove most of the passivation film on the cathode surface and the entire area of the anode surface protected by the silicon nitride film, and then places it in sulfuric acid to remove the photoresist on the voltage slot; the volume ratio of the mixed acid etching solution is hydrogen fluorine 5 parts of acid, 4 parts of glacial acetic acid, 2 parts of fuming nitric acid, and 1 part of nitric acid.

6) Welding of chip and molybdenum sheet: before welding the chip and molybdenum sheet, test the chip and reject unqualified chips. Stack chips, aluminum foil, and molybdenum sheets together and weld them in a high vacuum sintering furnace at 620-700°C and constant temperature for 10-20 minutes, then cool down and leave the furnace.

7) Aluminum steaming on the cathode surface: place the welded tube core in a high-vacuum coating or magnetron sputtering equipment, and steam aluminum on the cathode surface. The thickness of the aluminum layer (4) is not less than

8) Selective corrosion of the aluminum layer on the cathode surface: apply photoresist on the surface of the cathode with an existing aluminum layer, expose and develop to remove the photoresist on the voltage groove, and then perform aluminum etching with an aluminum corrosion solution to remove the photoresist on the cathode surface. The resist retains the aluminum layer on the cathode surface; the aluminum corrosion solution volume ratio, phosphoric acid: glacial acetic acid: nitric acid: water = 76.58%: 14.64%: 3.94%: 4.84%; temperature 60-70 ℃, corrosion 9-20min .

9) Micro-alloying of the aluminum layer: Place the tube core that has been selectively corroded on the aluminum layer on the cathode surface in an alloy furnace protected by nitrogen gas for aluminum micro-alloying at a temperature of 500-550°C and an alloying time of 10-50 minutes.

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并在温度400-450℃、时间为20-60min的下进行微合金，形成多金属化层(12)。Further, it also includes step 10) single-sided multilayer metallization of the molybdenum sheet on the anode side of the tube core: placing the molybdenum sheet on the anode side of the tube core upwards in a vacuum magnetron sputtering device or in a vacuum coating machine for titanium-nickel-silver multilayer metallization oxidized sputtering, thicknesses were Ti

Nickel />

Silver />

And carry out microalloying at a temperature of 400-450° C. for 20-60 minutes to form a multi-metallization layer (12).

Further, it also includes step 11) coating the voltage groove with a third protective layer: coating the voltage groove with polyimide or silicone rubber (8).

12) Die test storage.

The specific operation details in this specific embodiment are processes known to those in the industry and will not be repeated here. But it does not affect the main content of the implementation plan.

Claims (9)

1. A method for making a press-fit diode tube core, first making a chip with a P-type boss (9), which can withstand reverse voltage resistance and without metallization on the surface, and then pass aluminum foil (13) and molybdenum sheet ( 11) Brazing; including the following steps: 1) Prepare a two-layer structure diode diffusion sheet: According to the requirements of electrical parameters, select the resistivity and thickness of the N-type silicon wafer, and expand the N+ diffusion layer on both sides; one side is set as the cathode (3), and the cathode side is reserved for voltage slots area; then remove the N+ on the other side, drill a blind hole (10) with a laser below the voltage groove, and then expand the P layer anode (1) and P-type boss (9); remove boron and phosphosilicate glass; clean and set aside; 2) Coating photoresist on the cathode surface, exposing according to the voltage groove pattern, developing, and corroding the voltage groove (5), rinsing and removing the photoresist after etching, and drying for later use; 3) Deposit a semi-insulating polysilicon film (6) or a silicon nitride film on the voltage tank, place the corroded sheet with a voltage tank structure in a chemical vapor deposition device, and deposit a semi-insulating polysilicon film or a silicon nitride film, According to the conventional film making process, the film thickness

4) Glass passivation of the voltage tank: the semi-insulating polysilicon or silicon nitride passivation film area of the voltage tank on the cathode surface is then coated with glass powder and passivated to form a glass passivation film (7). The passivation temperature is 690- 750℃, passivation time 30-60min; 5) Etching and removing the passivation film on most of the cathode and anode areas that do not need semi-insulating polysilicon film or silicon nitride protection: after passivating the voltage tank, apply photoresist, according to the cathode surface Design the pattern for exposure and development, and keep the photoresist on the voltage slot; after development, use dilute hydrofluoric acid to remove the residual glass powder on the cathode surface; then use mixed acid etching solution to etch the unnecessary semi-insulating polysilicon film, or use plasma The equipment is etched to remove most of the passivation film on the cathode side and the entire area of the anode side protected by the silicon nitride film, and then placed in sulfuric acid to remove the photoresist on the voltage slot; 6) Welding of chip and molybdenum sheet: stack the chip, aluminum foil, and molybdenum sheet together in a high-vacuum sintering furnace at 620-700°C and constant temperature for 10-20 minutes for welding, then cool down and leave the furnace; 7) Aluminum steaming on the cathode surface: place the welded tube core in a high-vacuum coating or magnetron sputtering equipment, and steam aluminum on the cathode surface. The thickness of the aluminum layer (4) is not less than

8) Selective corrosion of the aluminum layer on the cathode surface: apply photoresist on the surface of the cathode with an existing aluminum layer, expose and develop to remove the photoresist on the voltage groove, and then perform aluminum etching with an aluminum corrosion solution to remove the photoresist on the cathode surface. The resist retains the aluminum layer on the cathode side; 9) Micro-alloying of the aluminum layer: Place the tube core that has been selectively corroded on the aluminum layer on the cathode surface in an alloy furnace protected by nitrogen gas for aluminum micro-alloying at a temperature of 500-550°C and an alloying time of 10-50 minutes. 2. The manufacturing method of crimping type diode tube core as claimed in claim 1, it is characterized in that: also comprise step 10) tube core anode surface molybdenum sheet is provided with multi-metallization layer (12): the tube core anode surface molybdenum sheet faces Put it in the vacuum magnetron sputtering equipment or in the vacuum coating machine for sputtering of titanium-nickel-silver multi-layer metallization, the thickness is respectively titanium

nickel

Silver />

And carry out microalloying at a temperature of 400-450° C. and a time of 20-60 minutes. 3. The manufacturing method of the crimping type diode tube core as claimed in claim 1 or 2, characterized in that: it also includes step 11) the voltage groove is coated with a third protective layer: the voltage groove is coated with polyimide or coated with silicon Rubber (8). 4. The method for manufacturing a pressure-bonded diode die as claimed in claim 1 or 2, wherein in step 2) the diffusion sheet of the two-layer structure of the diode is coated with photoresist, exposed, and developed to produce a voltage The area to be corroded in the tank (5) is then placed in a mixed acid etching solution for corrosion, the temperature of the acid solution is -10°C-10°C, and the time is 5-20min. In the mixed acid etching solution, the volume ratio of the mixed acid is hydrogen 5 parts of hydrofluoric acid, 4 parts of glacial acetic acid, 2 parts of fuming nitric acid, and 1 part of nitric acid. 5. as claimed in claim 1 or 2 described method for making crimping type diode tube core, it is characterized in that: described step 3), semi-insulating polysilicon film manufacturing process parameter: gas is silane, nitrous oxide, hydrogen chloride; Hydrogen chloride cleaning process parameters: temperature furnace mouth 575°C, furnace 575°C, furnace tail 575°C, cleaning time 40min, cleaning pressure 200-300 millitorr, cleaning flow rate 100-200ml/min; SIPOS deposition process parameters: temperature furnace mouth 640 -660°C, 640-660°C in the furnace, 640-660°C at the end of the furnace; SIPOS is first passed through silane deposition for 40S, and then SIPOS is deposited for 30-45min; SIPOS deposition pressure: 300 millitorr, gas flow: N2O is 50-80ml /min, SiH4 is 260-320ml/min; MTO temperature is furnace mouth 600-670℃, furnace 600-670℃, furnace tail 600-670℃; time 20-30min; densification furnace mouth 700-800℃, furnace Middle 700-800°C, furnace tail 700-800°C, time 20-30min. 6. The method for making a crimping diode tube core as claimed in claim 1 or 2, characterized in that: the volume ratio of the mixed acid etching solution described in the step 5) is 5 parts of hydrofluoric acid, 4 parts of glacial acetic acid 1 part, 2 parts of fuming nitric acid, 1 part of nitric acid. 7. The manufacturing method of press-fit diode tube core as claimed in claim 1 or 2, characterized in that: in the described step 8), the volume ratio of the aluminum corrosion solution is phosphoric acid: glacial acetic acid: nitric acid: water = 76.58%: 14.64%: 3.94%: 4.84%; temperature 60-70 ℃, corrosion 9-20min. 8. The manufacturing method of press-fit diode tube core as claimed in claim 1 or 2, characterized in that: in the described step 6), before the described chip is welded with the molybdenum sheet, the chip is tested to remove unqualified chip. 9 . The crimping diode die according to claim 1 , characterized in that it is formed by the method for preparing the crimping diode die according to any one of claims 1-8. 10 .

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