Manufacturing method of fast recovery diode, fast recovery diode and electronic equipment

Abstract

The invention provides a manufacturing method of a fast recovery diode, the fast recovery diode and electronic equipment, and relates to the technical field of semiconductor chips. The manufacturing method of the fast recovery diode comprises the steps that a device structure is provided, wherein the device structure comprises a substrate, an oxide layer located on one side of the substrate and a first metal layer located on the side, away from the substrate, of the oxide layer; forming a protection layer on one side, far away from the substrate, of the first metal layer; sequentially carrying out thinning treatment and corrosion treatment on one side, far away from the first metal layer, of the substrate; removing the protective layer; and metal evaporation is performed on the side, away from the first metal layer, of the substrate to form the second metal layer, so that friction between the fast recovery diode and the thinning equipment can be reduced in the thinning process, static electricity is reduced, the sparking phenomenon in the testing process is avoided, and the production efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more particularly, to a method for manufacturing a fast recovery diode, a fast recovery diode, and an electronic device. Background Art

[0002] A fast recovery diode (FRD) is a special diode that can change from the forward conduction state to the reverse cut-off state in a relatively short time. Compared with ordinary diodes, the fast recovery diode has a faster recovery speed and a lower reverse recovery time, and can better meet the working requirements in environments such as high frequency, high voltage, and high temperature.

[0003] Fast recovery diodes are mainly used in high-efficiency, high-precision, and high-reliability electronic circuits such as power switches, inverters, frequency converters, and AC motor drives. The fast recovery diode can effectively reduce the switching loss and stray noise of the circuit, and improve the efficiency and stability of the system.

[0004] Currently, the fast recovery diodes in the prior art usually adopt a structure design of a field ring terminal plus a metal field plate. However, during the wafer (Chip Probing, CP) test process, the fast recovery diode is prone to arcing, which may cause damage to the wafer and the test equipment. Summary of the Invention

[0005] In order to at least overcome the above deficiencies in the prior art, an object of this application is to provide a method for manufacturing a fast recovery diode, a fast recovery diode, and an electronic device.

[0006] In a first aspect, an embodiment of this application provides a method for manufacturing a fast recovery diode, and the method for manufacturing the fast recovery diode includes:

[0007] Providing a device structure, where the device structure includes a substrate, an oxide layer on one side of the substrate, and a first metal layer on the side of the oxide layer away from the substrate;

[0008] Forming a protective layer on the side of the first metal layer away from the substrate;

[0009] Performing a thinning process and an etching process on the side of the substrate away from the first metal layer in sequence;

[0010] Removing the protective layer;

[0011] Performing metal evaporation on the side of the substrate away from the first metal layer to form a second metal layer.

[0012] In a possible implementation manner, the material of the protective layer includes an insulating material;

[0013] The protective layer is a SPV-214RT protective film.

[0014] In a possible implementation, the step of thinning the side of the substrate away from the first metal layer includes:

[0015] Rough grinding and thinning the side of the substrate away from the first metal layer to thin the device structure to 330 to 320 microns;

[0016] Fine grinding and thinning the side of the substrate away from the first metal layer to thin the device structure to 270 to 290 microns.

[0017] In a possible implementation, the step of etching the side of the substrate away from the first metal layer includes:

[0018] Set the etching time to 5 min, and use an etching solution with a ratio of nitric acid, hydrofluoric acid, glacial acetic acid, and water of 40:1:2:20 to etch the side of the substrate away from the first metal layer on the second surface.

[0019] In a possible implementation, the step of removing the protective layer includes:

[0020] Use a film peeling machine to remove the protective layer under heating conditions.

[0021] In a possible implementation, the step of providing a device structure includes:

[0022] Provide a substrate;

[0023] Successively perform oxidation, implantation, diffusion, drive-in, photolithography, etching, sputtering, and evaporation on the substrate to obtain the device structure.

[0024] In a possible implementation, the second metal layer includes a first sub-metal layer, a second sub-metal layer, and a third sub-metal layer arranged in sequence;

[0025] The material of the first sub-metal layer includes titanium; the material of the second sub-metal layer includes nickel; the material of the third sub-metal layer includes silver.

[0026] In a possible implementation, the thickness of the first sub-metal layer is 0.1 micron; the thickness of the second sub-metal layer is 0.4 micron; the thickness of the third sub-metal layer is 1.2 microns.

[0027] In a second aspect, an embodiment of the present application further provides a fast recovery diode, and the fast recovery diode is made by the manufacturing method of the fast recovery diode described in any of the above aspects.

[0028] In a third aspect, an embodiment of the present application further provides an electronic device, and the electronic device includes the fast recovery diode described in any of the above aspects.

[0029] Based on any of the above aspects, for the manufacturing method of the fast recovery diode, the fast recovery diode and the electronic device provided by the embodiments of the present application, by setting a protective layer before the thinning process and removing the protective layer after the thinning process, the friction between the fast recovery diode and the thinning device can be reduced during the thinning process, thereby reducing the generation of static electricity, avoiding the occurrence of arcing during the testing process, and improving the production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be referred to in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 It is a schematic flowchart of the manufacturing method of the fast recovery diode provided in this embodiment;

[0032] Figure 2 It is a schematic structural diagram of the device structure provided in this embodiment;

[0033] Figure 3 It is one of the schematic diagrams of the manufacturing process of the manufacturing method of the fast recovery diode provided in this embodiment;

[0034] Figure 4 It is a schematic diagram of the sub-steps of step S300 provided in this embodiment;

[0035] Figure 5 It is the second of the schematic diagrams of the manufacturing process of the manufacturing method of the fast recovery diode provided in this embodiment;

[0036] Figure 6 It is a schematic diagram of the sub-steps of step S100 provided in this embodiment;

[0037] Figure 7 It is a schematic structural diagram of the fast recovery diode provided in this embodiment.

[0038] Icons: 100 - device structure; 110 - substrate; 120 - oxide layer; 130 - first metal layer; 141 - channel cutoff ring; 142 - voltage dividing ring; 143 - active region; 150 - passivation layer; 200 - protective layer; 300 - second metal layer; 310 - first sub - metal layer; 320 - second sub - metal layer; 330 - third sub - metal layer; 400 - heating plate; 500 - heating device. Detailed implementation manners

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. Components of the embodiments of this application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts belong to the scope of protection of this application.

[0041] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0042] In the description of this application, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of this application. In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0043] In addition, terms such as "horizontal", "vertical", "overhanging", etc. do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0044] In the description of the present application, it should also be noted that unless otherwise clearly specified and defined, the terms "arrangement", "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0045] It should be noted that, without conflict, different features in the embodiments of the present application can be combined with each other.

[0046] After research by the inventor, it is found that in order to reduce the product cost, for existing fast recovery diodes with a voltage of more than 1200V, the aluminum-under-silicon-nitride process is usually adopted in the manufacturing process, which will cause the surface of the fast recovery diode to lack the protection of a passivation layer. During the thinning process, friction will occur between the fast recovery diode and the thinning equipment, resulting in the generation of static electricity. When performing wafer (Chip Probing, CP) testing, a high voltage or high power signal will be applied to the fast recovery diode, resulting in arc discharge and possibly sparking, which will affect the product qualification rate. In addition, during the testing process, a fluorination solution needs to be coated on the surface of the fast recovery diode, and the step of coating the fluorination solution needs to be manually operated, which will reduce the production efficiency of the product, easily cause damage to the surface of the fast recovery diode, and in addition, the amount of the fluorination solution coated cannot be accurately controlled, which will affect the production progress.

[0047] In view of this, this embodiment provides a solution that can reduce the risks of the above problems. The solution provided in this embodiment will be elaborated in detail below.

[0048] Please refer to Figure 1 , Figure 1 FIG. is a schematic flow chart of the manufacturing method of the fast recovery diode provided in this embodiment. The manufacturing method of the fast recovery diode may include the following steps.

[0049] Step S100: Provide a device structure 100, where the device structure 100 includes a substrate 110, an oxide layer 120 on one side of the substrate 110, and a first metal layer 130 on the side of the oxide layer 120 away from the substrate 110.

[0050] In this embodiment, please refer to Figure 2, the device structure 100 may include a substrate 110, an oxide layer 120, and a first metal layer 130 that are stacked in sequence. Among them, the substrate 110 may be an N-type substrate 110, which is composed of an N-type semiconductor layer, an N-type buffer layer, and an N+-type semiconductor layer stacked. By oxidizing the silicon wafer, an oxide layer 120 on one side of the substrate 110 can be obtained. The oxide layer 120 can be used to prevent impurities from entering the substrate and can also serve as a mask layer in subsequent processes for precisely controlling the implantation and diffusion of impurities. The material of the oxide layer 120 can be silicon dioxide. The first metal layer 130 can be an anode layer, and the first metal layer can be used to connect the fast recovery diode to other external circuits and improve the current transmission efficiency. The material of the first metal layer 130 can be aluminum.

[0051] In addition, the thickness range of the device structure 100 can be from 510 micrometers (μm) to 540 micrometers (μm).

[0052] Step S200, forming a protective layer 200 on the side of the first metal layer 130 away from the substrate 110.

[0053] In this embodiment, please refer to Figure 3 , an automatic film sticking machine can be used to form a protective layer 200 on the side of the first metal layer 130 away from the substrate 110. The orthographic projection of the protective layer 200 on the substrate 110 can completely cover the orthographic projection of the first metal layer 130 on the substrate 110.

[0054] In some examples, a DR-8500II automatic film sticking machine can be used to paste the protective layer 200 on one side of the first metal layer 130.

[0055] In the above design, by setting the protective layer 200, the device structure 100 can be protected from damage caused by contact with chemical or mechanical tools during the thinning process. At the same time, the protective layer 200 can also play a buffering role, reducing the impact of stress on the device structure 100 and avoiding damage to the device structure 100 due to excessive stress.

[0056] Step S300, sequentially performing a thinning process and an etching process on the side of the substrate 110 away from the first metal layer 130.

[0057] In this embodiment, please refer to again Figure 3 , a grinding device (such as a thinning machine, a thinning grinding wheel, etc.) can be used to perform a thinning process on the side of the substrate 110 away from the first metal layer 130. Specifically, multiple thinning processes can be performed on the side of the substrate 110 away from the first metal layer 130, and the grinding speed and grinding tools for the multiple thinning processes can be different.

[0058] After the thinning process, an etching solution can be used to etch the side of the substrate 110 away from the first metal layer 130 to remove the damaged layer caused by the thinning process, making the substrate surface smoother and flatter. Specifically, an etching solution mixed with multiple chemical substances can be used for the etching process, or multiple different chemical substances can be used for the etching process separately in sequence. In this way, the mechanical strength of the back of the fast recovery diode can be improved, damage caused by external stress can be reduced, and the durability and reliability of the fast recovery diode can be enhanced. At the same time, after the etching process, the electrical performance of the fast recovery diode can also be optimized, reducing parasitic capacitance and resistance, thereby improving the signal transmission speed and reducing power consumption.

[0059] Step S400, remove the protective layer 200.

[0060] In this embodiment, please refer again to Figure 3 , the protective layer 200 can be removed after the thinning process and the etching process.

[0061] Step S500, perform metal evaporation on the side of the substrate 110 away from the first metal layer 130 to form a second metal layer 300.

[0062] In this embodiment, please refer again to Figure 3 , metal evaporation can be performed on the side of the substrate 110 away from the first metal layer 130 to form a second metal layer 300. Among them, the second metal layer 300 can be a cathode.

[0063] By setting the second metal layer 300, the internal resistance of the fast recovery diode can be reduced, thereby reducing power loss.

[0064] After forming the second metal layer 300, chip testing and dicing can also be performed. Specifically, an automatic test bench can be used for chip testing, and there is no need to coat the fluorination solution. Therefore, testing can be performed automatically to improve production capacity and production efficiency, and the generation of waste chips can also be reduced, avoiding damage to the chip surface, thereby effectively ensuring the surface quality and reliability of the product.

[0065] In the above design, by setting the protective layer 200 before the thinning process and removing the protective layer 200 after the thinning process, the friction between the fast recovery diode and the thinning equipment can be reduced during the thinning process, thereby reducing the generation of static electricity, avoiding the occurrence of arcing during the testing process, and improving production efficiency.

[0066] In a possible implementation, the material of the protective layer 200 may include an insulating material. Exemplarily, the protective layer 200 may be an SPV-214RT protective film. The material of the SPV-214RT protective film may include polyolefin or polyester, and the polyolefin or polyester has high flexibility and low thermal shrinkage rate, which can be used to reduce the influence of stress on the fast recovery diode.

[0067] In this embodiment, the material of the protective layer 200 is an insulating material, which can prevent static electricity. During the thinning process, the protective layer 200 can play a buffering role to reduce the friction between the fast recovery diode and the thinning equipment, thereby reducing the generation of static electricity and avoiding the occurrence of arcing.

[0068] In a possible implementation, when thinning the side of the substrate 110 away from the first metal layer 130, please refer to Figure 4 , step S300 may include the following sub-steps.

[0069] Step S310, perform rough grinding and thinning on the side of the substrate 110 away from the first metal layer 130 to thin the device structure 100 to 330 microns to 320 microns.

[0070] In this embodiment, the fast recovery diode with the protective layer 200 already set can be placed in a thinning machine, and the device structure 100 is subjected to rough grinding and thinning using a diamond grinding wheel to thin the device structure 100 to 300 microns (μm) to 320 microns (μm). Preferably, the device structure 100 can be thinned to 310 microns (μm) through rough grinding and thinning.

[0071] In the above design, by performing rough grinding and thinning on the device structure 100, materials can be quickly removed to avoid thermal damage.

[0072] Step S320, perform fine grinding and thinning on the side of the substrate 110 away from the first metal layer 130 to thin the device structure 100 to 270 microns to 290 microns.

[0073] In this embodiment, a finer grinding wheel (such as a resin grinding wheel) can be used to perform fine grinding and thinning on the device structure 100 to thin the device structure 100 to 270 (μm) microns to 290 microns (μm). Preferably, the device structure 100 can be thinned to 310 microns (μm) through rough grinding and thinning.

[0074] In the above design, by performing fine grinding and thinning on the device structure 100, the damaged layer caused by rough grinding and thinning can be eliminated.

[0075] In a possible implementation, when etching the side of the substrate 110 away from the first metal layer 130, the etching time can be set to 5 minutes, and an etching solution with a ratio of nitric acid, hydrofluoric acid, glacial acetic acid, and water of 40:1:2:20 is used to etch the side of the substrate 110 away from the first metal layer 130 on the second surface.

[0076] In this embodiment, after the thinning process, the back surface of the fast recovery diode can be etched using an etching solution, and the etching time can be 5 minutes. Among them, the etching solution can be composed of nitric acid (HNO3), hydrofluoric acid (HF), glacial acetic acid (CH3COOH), and water (H2O), and nitric acid (HNO3):hydrofluoric acid (HF):glacial acetic acid (CH3COOH):water (H2O) = 40:1:2:20.

[0077] After the etching process, it is also necessary to flush and spin dry to avoid damage to the fast recovery diode caused by residual etching solution.

[0078] In the above design, by etching the back surface of the fast recovery diode, surface defects caused by the thinning process can be eliminated, the mechanical strength can be improved, and the back surface of the fast recovery diode can be made smoother, thereby reducing the parasitic capacitance.

[0079] In a possible implementation, when removing the protective layer 200, a film peeling machine can be used to remove the protective layer 200 under heating conditions.

[0080] In this embodiment, please refer to Figure 5 ., the fast recovery diode can be placed above the heating plate 400, and the fast recovery diode can be heated by the heating device 500. When the temperature is between 60°C and 80°C, the protective layer 200 can be removed using an automatic film peeling machine. Since the viscosity of the protective layer 200 changes little with temperature, residual glue can be avoided during high-temperature film peeling. If there is residual glue, it will form microelectrodes, resulting in arcing during testing. Therefore, after removing the protective layer 200, the front surface of the fast recovery diode can also be detected by Automated Optical Inspection (AOI) to ensure that there is no residual glue.

[0081] In a possible implementation, please refer to Figure 6 ., step S100 can include the following sub-steps.

[0082] Step S110, provide a substrate 110.

[0083] Step S120, sequentially perform oxidation, implantation, diffusion, drive-in, lithography, etching, sputtering, and evaporation processes on the substrate 110 to obtain the device structure 100.

[0084] In this embodiment, please refer to again Figure 2 , the substrate 110 can be first oxidized to form an oxide layer 120, and then implantation, diffusion, and drive-in processes are performed to form a channel stop ring 141, a voltage dividing ring 142, and an active region 143. Finally, photolithography, etching, sputtering, and evaporation processes are performed to form a passivation layer 150 and a first metal layer 130. Among them, the material of the passivation layer 150 is silicon nitride (Si3N4), and the passivation layer 150 and the first metal layer 130 can be made by the silicon nitride under aluminum process.

[0085] Specifically, when forming the channel stop ring 141, the voltage dividing ring 142, and the active region 143, boron ions and / or phosphorus ions can be first implanted, and then diffusion treatment is performed in a diffusion furnace, and drive-in treatment is performed after the diffusion treatment, so as to form the channel stop ring 141, the voltage dividing ring 142, and the active region 143.

[0086] In a possible implementation manner, please refer to Figure 7 , the second metal layer 300 can include a first sub-metal layer 310, a second sub-metal layer 320, and a third sub-metal layer 330 that are sequentially arranged. Among them, the material of the first sub-metal layer 310 can include titanium (Ti), the material of the second sub-metal layer 320 can include nickel (Ni), and the material of the third sub-metal layer 330 can include silver (Ag).

[0087] In this embodiment, titanium, nickel, and silver can be sequentially deposited on the back of the fast recovery diode to form the second metal layer 300.

[0088] Among them, the second metal layer 300 can be the cathode. The second metal layer 300 made of a titanium-nickel-silver multi-layer metal has good conductivity and high service life, can reduce the contact resistance, improve the heat dissipation ability, and further enhance the device stability.

[0089] It should be noted that the second metal layer can also include more sub-metal layers, which can be designed according to actual needs and are not specifically limited here.

[0090] In a possible implementation manner, please refer to again Figure 7 , the thickness H1 of the first sub-metal layer 310 can include 0.1 micrometers (μm). The thickness H2 of the second sub-metal layer 320 can include 0.4 micrometers (μm). The thickness H3 of the third sub-metal layer 330 can include 1.2 micrometers (μm).

[0091] The embodiment of the present application also provides a fast recovery diode, and the fast recovery diode can be made by the manufacturing method of the fast recovery diode provided in this embodiment.

[0092] An embodiment of the present application further provides an electronic device, and the electronic device may include the fast recovery diode provided in this embodiment.

[0093] In summary, this embodiment provides a method for manufacturing a fast recovery diode, a fast recovery diode, and an electronic device. By setting a protective layer before the thinning process and removing the protective layer after the thinning process, the friction between the fast recovery diode and the thinning device can be reduced during the thinning process, thereby reducing the generation of static electricity, avoiding the occurrence of arcing during the testing process, and improving production efficiency.

[0094] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0095] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A manufacturing method of a fast recovery diode, characterized in that, The method includes: providing a device structure, which includes a substrate, an oxide layer on one side of the substrate, and a first metal layer on the side of the oxide layer away from the substrate; forming a protective layer on the side of the first metal layer away from the substrate; performing a thinning process and an etching process on the side of the substrate away from the first metal layer in sequence; removing the protective layer; performing metal evaporation on the side of the substrate away from the first metal layer to form a second metal layer.

2. The manufacturing method of the fast recovery diode according to claim 1, characterized in that, The material of the protective layer includes an insulating material; The protective layer is an SPV-214RT protective film.

3. The manufacturing method of the fast recovery diode according to claim 1, characterized in that, The step of performing a thinning process on the side of the substrate away from the first metal layer includes: performing a rough grinding and thinning process on the side of the substrate away from the first metal layer to thin the device structure to 330 to 320 microns; performing a fine grinding and thinning process on the side of the substrate away from the first metal layer to thin the device structure to 270 to 290 microns.

4. The manufacturing method of the fast recovery diode according to claim 1, wherein, The step of performing an etching process on the side of the substrate away from the first metal layer includes: setting the etching time to 5 min, and using an etching solution with a ratio of nitric acid, hydrofluoric acid, glacial acetic acid, and water of 40:1:2:20 to perform an etching process on the side of the substrate away from the first metal layer on the second surface.

5. The manufacturing method of the fast recovery diode according to claim 1, characterized in that, The step of removing the protective layer includes: using a film peeling machine to remove the protective layer under heating conditions.

6. The manufacturing method of the fast recovery diode according to claim 1, wherein, The step of providing a device structure includes: providing a substrate; performing oxidation, implantation, diffusion, drive-in, photolithography, etching, sputtering, and evaporation processes on the substrate in sequence to obtain the device structure.

7. The manufacturing method of the fast recovery diode according to claim 1, characterized in that The second metal layer includes a first sub-metal layer, a second sub-metal layer, and a third sub-metal layer arranged in sequence; The material of the first sub-metal layer includes titanium; the material of the second sub-metal layer includes nickel; the material of the third sub-metal layer includes silver.

8. The manufacturing method of the fast recovery diode according to claim 7, characterized in that, The thickness of the first sub-metal layer is 0.1 micron; the thickness of the second sub-metal layer is 0.4 micron; the thickness of the third sub-metal layer is 1.2 microns.

9. A fast recovery diode, characterized in that, The fast recovery diode is made by using the manufacturing method of the fast recovery diode according to any one of claims 1-8.

10. An electronic device, characterized in that, including the fast recovery diode according to any one of claim 9.

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