Power semiconductor discrete device and wafer metallization method thereof

Abstract

The invention discloses a power semiconductor discrete device and a wafer metallization method thereof. The wafer metallization method is applied to metallization of a wafer in a power semiconductor discrete device. The wafer metallization method comprises the following steps: providing a wafer; the surface of the wafer is provided with windows to be metalized which are arranged in an array; forming at least one metal raw material layer in each to-be-metallized window through a printing process by adopting at least one metal raw material with a preset ratio; after the at least one metal raw material layer is formed through printing, the metal raw material layer is sintered layer by layer so as to form at least one metal layer on the surface of the wafer; wherein each metal layer has a preset thickness. According to the technical scheme provided by the embodiment of the invention, the process for selectively metallizing the wafer in the related technology can be effectively simplified, the metal layer with a relatively thick thickness is relatively easy to prepare, and the heat dissipation and through-current capability of the discrete power semiconductor device can be improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a power semiconductor discrete device and a wafer metallization method thereof. Background Art

[0002] Traditional metallization methods for power semiconductor devices include chemical plating, evaporation and sputtering. Among them, the chemical plating process can only use a single material, and requires 2 to 3 repeated operations of chemical plating and sintering to increase the thickness and bonding strength of the metal layer. The evaporation and sputtering processes are not selective and can only be used for full-surface coating and then selective etching through photolithography. The process flow is complicated and the cost is high. In addition, due to stress problems, the thickness of the metal layer formed is generally thin. The metal layer thickness of the above metallization schemes generally does not exceed 5μm, and it is difficult to further increase the thickness of the metal layer. Summary of the invention

[0003] The present invention provides a power semiconductor discrete device and a wafer metallization method thereof, so as to solve the problem that the metallization process of the power semiconductor device is complicated and the thickness of the formed metal layer is relatively thin.

[0004] According to one aspect of the present invention, a method for metallizing a wafer of a power semiconductor discrete device is provided, which is applied to metallize a wafer in a power semiconductor discrete device;

[0005] The wafer metallization method of the power semiconductor discrete device comprises:

[0006] A wafer is provided; a surface of the wafer is provided with windows to be metallized arranged in an array;

[0007] Using at least one metal raw material with a preset ratio, forming at least one metal raw material layer in each of the windows to be metallized by a printing process;

[0008] The metal raw material layer is sintered layer by layer to form at least one metal layer on the surface of the wafer; wherein each metal layer has a preset thickness.

[0009] Optionally, the preset thickness of each metal layer is in the range of 5 to 50 μm.

[0010] Optionally, the printing process includes a screen printing process and an inkjet printing process; the metal raw material with the preset ratio includes a metal slurry with a first preset ratio and a metal ink with a second preset ratio;

[0011] The screen printing process uses the metal paste having the first preset ratio, and the inkjet printing process uses the metal ink having the second preset ratio.

[0012] Optionally, the metal slurry comprises metal powder, a binder and an organic solvent;

[0013] The first preset ratio includes: the weight percentage range of the metal powder includes 80% to 95%, the weight percentage range of the binder includes 1% to 5%, and the weight percentage range of the organic solvent includes 5% to 15%.

[0014] Optionally, the metal ink comprises metal particles, a binder and an organic solvent;

[0015] The second preset ratio includes: the weight percentage of the metal particles ranges from 60% to 80%, the weight percentage of the binder ranges from 0.3% to 5%, and the weight percentage of the organic solvent ranges from 20% to 40%.

[0016] Optionally, the metal material in the metal paste and the metal ink includes any one of silver, nickel, aluminum, copper, titanium, gold and alloys.

[0017] Optionally, sintering the metal raw material layer layer by layer to form at least one metal layer on the surface of the wafer includes:

[0018] Printing a first metal raw material layer on the surface of the wafer;

[0019] sintering the first metal raw material layer to form a first metal layer;

[0020] Printing a second metal raw material layer on a side of the first metal layer away from the wafer;

[0021] sintering the second metal raw material layer to form a second metal layer;

[0022] The materials of the first metal layer and the second metal layer include a combination of two metal materials.

[0023] Optionally, the bonding property of the first metal layer is better than the bonding property of the second metal layer;

[0024] And / or, the packaging welding performance of the second metal layer is better than the packaging welding performance of the first metal layer.

[0025] Optionally, the sintering temperature range of the metal raw material layer for sintering layer by layer includes 680-820°C.

[0026] According to another aspect of the present invention, a power semiconductor discrete device is provided, wherein a wafer is metallized using the wafer metallization method for a power semiconductor discrete device as described in any embodiment of the first aspect, and the wafer is cut and packaged to obtain the power semiconductor discrete device.

[0027] The wafer metallization method for power semiconductor discrete devices provided in an embodiment of the present invention uses at least one metal raw material with a preset ratio, and selectively prints at least one metal raw material layer on each window to be metallized on the surface of the wafer through a printing process, and after each metal raw material layer is formed in sequence, the corresponding metal raw material layer is sintered layer by layer to form at least one metal layer. In this way, the printing process is applied to the metallization of the wafer in the power semiconductor discrete device, which can effectively simplify the process of selective metallization of the wafer in the related technology, and by using the metal raw material with a preset ratio, the formed metal layer can have good bonding with the wafer. And the preset thickness of the metal layer formed by the printing process is greater than the thickness of the metal layer formed by the traditional metallization process, so that the heat dissipation and flow capacity of the power semiconductor discrete device can be effectively improved, and the performance of the power semiconductor discrete device can be improved.

[0028] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a schematic flow chart of a wafer metallization method for a power semiconductor device provided in accordance with an embodiment of the present invention;

[0031] Figure 2 is a cross-sectional scanning electron microscope image of a metal layer formed by printing according to an embodiment of the present invention;

[0032] Figure 3 yes Figure 1 Specific flow chart of step S130;

[0033] Figure 4 is a schematic diagram of metallization of a power semiconductor device structure provided in an embodiment of the present invention;

[0034] Figure 5is a schematic diagram of metallization of another power semiconductor device structure provided in an embodiment of the present invention;

[0035] Figure 6 is a schematic diagram of metallization of another power semiconductor device structure provided in an embodiment of the present invention;

[0036] Figure 7 It is a schematic diagram of metallization of another power semiconductor device structure provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0039] As described in the background technology, the traditional methods for metallizing power semiconductor devices include chemical plating, evaporation and sputtering. Among them, the chemical plating process is to form a metal layer on the surface of the semiconductor wafer by chemical plating, then form an alloy layer with the substrate by sintering, and then remove the surface oxide layer by rinsing. Repeat the above chemical plating process 2 to 3 times to complete the metallization of the semiconductor wafer. However, the applicable materials of the chemical plating process are relatively single. The more mature process application is chemical nickel plating. There are still many problems in the application of other metal materials in the chemical plating process. The thickness of the metal coating formed by the chemical plating process is thin, and the method of increasing the thickness of the metal coating by increasing the chemical plating time is prone to the fall of the metal layer. In addition, the chemical plating process has high requirements on the cleanliness of the wafer surface, and needs to cooperate with the previous cleaning and activation processes, and the process window and process conditions of chemical plating are relatively complex, and it is easy to have problems such as uneven color difference. The evaporation process is to cover the entire surface of the wafer with a metal layer by evaporation. It can be seen that the use of evaporation process to metallize the wafer is not selective, and it is necessary to cooperate with photolithography and corrosion processes to etch away the metal layer in the area where the metal layer does not need to be covered, which makes the process flow long and the process cost high. In addition, the evaporation process generally needs to be carried out under low pressure, and the evaporation equipment needs to be evacuated before the evaporation operation. Therefore, the entire evaporation process takes a long time, and the production capacity of a single device is low, and the equipment cost is high. The sputtering process is to cover the entire surface of the wafer with a metal layer by magnetron sputtering. Similar to the evaporation process, the use of sputtering process to metallize the wafer is not selective, which makes the process flow long and the process cost high. In addition, the sputtering process also needs to be carried out under low pressure, and the magnetron sputtering equipment needs to be evacuated before the sputtering operation. The entire process takes a long time, and the production capacity of a single device is low.

[0040] Based on the above technical problems, the embodiments of the present invention propose the following technical solutions:

[0041] An embodiment of the present invention provides a wafer metallization method for a power semiconductor discrete device. Figure 1 A schematic flow chart of a wafer metallization method for power semiconductor discrete devices provided in an embodiment of the present invention. The wafer metallization method is applied to metallize wafers in power semiconductor discrete devices, thereby solving the problem of complex process and thin metal layer thickness when metallizing power semiconductor discrete devices using traditional metallization methods. Figure 1 As shown, the wafer metallization method of the power semiconductor discrete device specifically includes the following steps:

[0042] S110, providing a wafer; the surface of the wafer is provided with windows to be metallized arranged in an array.

[0043] Specifically, in power semiconductor discrete devices, silicon-based wafers are used as substrates. Before metallization, the wafer is pre-doped to form functional areas of power semiconductor discrete devices. And the surface of the wafer is cleaned to ensure the surface is clean. Since the surface of a wafer includes multiple power semiconductor discrete devices, a metal layer needs to be selectively set on the surface of the wafer. Therefore, multiple windows to be metallized are formed on the surface of the wafer through photolithography and etching processes, that is, areas where a metal layer needs to be set, and multiple windows to be metallized are arranged in an array so that the wafer can be cut later to form multiple power semiconductor discrete devices.

[0044] S120, using at least one metal raw material with a preset ratio, and forming at least one metal raw material layer in each window to be metallized through a printing process.

[0045] Specifically, the printing process is to form a material layer with a corresponding specific pattern on the surface of an object through one printing according to the designed specific pattern. The printing process is applied to form a metal layer on the surface of a silicon-based wafer, and a metal raw material with a preset ratio is selected, and the metal raw material layer is directly selectively printed at the position corresponding to each window to be metallized on the wafer. Among them, the use of a metal raw material with a preset ratio can make the metal raw material have good bonding with the silicon-based surface, thereby making the power semiconductor discrete device have good ohmic contact.

[0046] S130, sintering the metal raw material layer layer by layer to form at least one metal layer on the surface of the wafer; wherein each metal layer has a preset thickness.

[0047] Specifically, the metal raw material layer formed by printing on the surface of the wafer is solidified and sintered at high temperature, so that the metal raw material layer forms a metal layer and is firmly bonded to the surface of the wafer. In this way, the printing process is used to selectively form a metal layer in the window to be metallized on the surface of the wafer at one time, which can effectively simplify the process of selective metallization of the wafer, and the use of metal raw materials with a preset ratio can ensure that the formed metal layer has good bonding with the surface of the wafer. In addition, compared with the metal layer formed by related traditional technologies, it is easy to form a metal layer with a preset thickness by using a printing process. Exemplarily, the preset thickness of each metal layer ranges from 5 to 50μm. The thickness of the metal layer formed on the surface of the wafer using traditional technology is only about 0.5 to 5μm, Figure 2 is a cross-sectional scanning electron microscope image of a metal layer formed by printing provided by an embodiment of the present invention. Figure 2, the preset thickness of the metal layer formed by printing can reach 21.94μm. It can be seen that the printing process can be used to prepare a metal layer with a preset thickness on the surface of the wafer, which is beneficial to improve the heat dissipation and flow capacity of power semiconductor discrete devices and improve the performance of power semiconductor discrete devices. It should be noted that a layer of metal raw material layer can be printed on the surface of the wafer, and a metal layer can be formed after sintering; or more than one layer of metal raw material layer can be printed layer by layer on the surface of the wafer, so as to form more than one metal layer after sintering layer by layer, which is not limited here.

[0048] The wafer metallization method for power semiconductor discrete devices provided in an embodiment of the present invention uses at least one metal raw material with a preset ratio, and selectively prints at least one metal raw material layer on each window to be metallized on the surface of the wafer through a printing process, and after each metal raw material layer is formed in sequence, the corresponding metal raw material layer is sintered layer by layer to form at least one metal layer. In this way, the printing process is applied to the metallization of the wafer in the power semiconductor discrete device, which can effectively simplify the process of selective metallization of the wafer in the related technology, and by using the metal raw material with a preset ratio, the formed metal layer can have good bonding with the wafer. And the preset thickness of the metal layer formed by the printing process is greater than the thickness of the metal layer formed by the traditional metallization process, so that the heat dissipation and flow capacity of the power semiconductor discrete device can be effectively improved, and the performance of the power semiconductor discrete device can be improved.

[0049] Optionally, based on the above embodiment, the printing process includes a screen printing process and an inkjet printing process; the metal raw material with a preset ratio includes a metal slurry with a first preset ratio and a metal ink with a second preset ratio.

[0050] The screen printing process uses a metal paste having a first preset ratio, and the inkjet printing process uses a metal ink having a second preset ratio.

[0051] Specifically, the printing process may include screen printing and inkjet printing. The screen printing process uses a screen as a base, and uses a photosensitive platemaking method to make a screen printing plate with images, and uses a scraper to push the slurry poured into the screen printing plate, so that the slurry is squeezed from the mesh of the image part to the surface of the object by the scraper. The inkjet printing process is a contactless, pressure-free and plate-free printing method.

[0052] The metal raw material used in screen printing includes a metal paste with a first preset ratio, and the metal paste includes metal powder, a binder and an organic solvent. Exemplarily, the binder can be selected from glass powder as a special binder added to the metal paste, which can effectively reduce the contact resistance between the metal layer formed by metal paste printing and the wafer surface, which is beneficial to improve the electrical performance of power semiconductor discrete devices. Exemplarily, the first preset ratio of the metal paste includes: the weight percentage range of the metal powder includes 80% to 95%, the weight percentage range of the binder includes 1% to 5%, and the weight percentage range of the organic solvent includes 5% to 15%. It can be seen that compared with the metal paste used in the existing screen printing process for metallization of photovoltaic modules, the metal paste provided in this embodiment increases the weight proportion of metal powder in the entire metal paste, that is, increases the purity of the metal paste, so that when the metal paste is applied to the metallization of the wafer by screen printing, it can ensure that the metal layer has good bonding with the wafer surface, and can ensure the performance requirements of power semiconductor discrete devices.

[0053] The metal raw material used in inkjet printing includes a metal ink having a second preset ratio, and the metal ink includes metal particles, a binder and an organic solvent. Exemplarily, the second preset ratio of the metal ink includes: the weight percentage range of the metal particles includes 60% to 80%, the weight percentage range of the binder includes 0.3% to 5%, and the weight percentage range of the organic solvent includes 20% to 40%. The binder can be glass particles. By increasing the purity of the metal particles in the metal ink, the bonding between the formed metal layer and the wafer surface is improved, and the performance of the power semiconductor discrete device is guaranteed.

[0054] Optionally, based on the above embodiments, the metal material in the metal paste and the metal ink includes any one of silver, nickel, aluminum, copper, titanium, gold and alloys.

[0055] Specifically, when using the screen printing process, the metal paste used may include any one of silver paste, nickel paste, aluminum paste, copper paste and alloy paste; when using the inkjet printing process, the metal ink used may include any one of silver ink, nickel ink, aluminum ink, copper ink and alloy ink.

[0056] Optionally, Figure 3 yes Figure 1 Based on the above embodiments, a metal layer can be printed on the surface of the wafer, or more than one metal layer can be printed on the surface of the wafer according to the performance requirements of the power semiconductor discrete device, which is not limited here. Figure 3As shown, after printing and forming at least one metal raw material layer in step S130, the metal raw material layer is sintered layer by layer to form at least one metal layer on the surface of the wafer, which may specifically include the following steps:

[0057] S131 , printing and forming a first metal raw material layer on the surface of the wafer.

[0058] Specifically, in the case of printing more than one metal layer on the wafer surface, a first metal raw material layer needs to be uniformly printed on the wafer surface first.

[0059] S132, sintering the first metal raw material layer to form a first metal layer.

[0060] Specifically, the first metal raw material layer is solidified and sintered at a high temperature, so as to form a first metal layer on the surface of the wafer.

[0061] S133 , forming a second metal raw material layer by printing on a side of the first metal layer away from the wafer.

[0062] Specifically, a second metal raw material layer is evenly printed on the surface of the first metal layer.

[0063] S134, sintering the second metal raw material layer to form a second metal layer; wherein the materials of the first metal layer and the second metal layer include a combination of two metal materials.

[0064] Specifically, the second metal raw material layer is solidified and sintered at a high temperature, so as to form a second metal layer stacked on the surface of the first metal layer.

[0065] Optionally, based on the above embodiments, the bonding property of the first metal layer is better than that of the second metal layer; and / or, the packaging welding performance of the second metal layer is better than that of the first metal layer.

[0066] Specifically, for more than one metal layer formed, the metal materials used in each metal layer can be combined, and there is no restriction here. It should be noted that the basis for combining different metal materials may include that the bonding property of the first metal layer is better than the bonding property of the second metal layer, and the packaging welding performance of the second metal layer is better than the packaging welding performance of the first metal layer. Since the first metal layer is directly bonded to the surface of the wafer, it is necessary to select a metal material with good bonding property to the surface of the wafer for preparing the first metal layer. Since the second metal layer is a metal layer located on the surface of the power semiconductor discrete device, it is necessary to complete the subsequent packaging bonding process, therefore, it is necessary to select a metal material that is easy to perform packaging bonding for preparing the second metal layer. In addition, a metal material that is not prone to ion migration can be selected for preparing the first metal layer, and the second metal layer can be prepared using a metal material that is prone to ion migration, thereby ensuring the performance of the power semiconductor discrete device. Exemplarily, the first metal layer can be made of aluminum and the second metal layer can be made of nickel; or the first metal layer can be made of nickel and the second metal layer can be made of silver, and there is no restriction here. For example, if three metal layers are printed on the surface of the wafer, the metal material combination used in the direction from close to the wafer to far away from the wafer can be aluminum, nickel, silver, or aluminum, nickel, copper, etc., without limitation.

[0067] Optionally, based on the above embodiments, the sintering temperature range for sintering the metal raw material layer layer by layer includes 680-820°C.

[0068] Specifically, the sintering temperature range for sintering the metal raw material layer can be divided into two cases. Figure 4 is a schematic diagram of metallization of a power semiconductor device structure provided by an embodiment of the present invention, Figure 5 is a schematic diagram of metallization of another power semiconductor device structure provided by an embodiment of the present invention, Figure 6 is a schematic diagram of metallization of another power semiconductor device structure provided by an embodiment of the present invention, Figure 7 Schematic diagram of metallization of another power semiconductor device structure provided by an embodiment of the present invention. Figure 4 and Figure 5 , which shows the cross-sectional structure of a planar power semiconductor device; see Figure 6 and Figure 7 , which shows the cross-sectional structure of a mesa-type power semiconductor device. Since the glass component in the metal raw material used for printing the metal layer on the surface of a planar device is different from the glass component in the metal raw material used for printing the metal layer on the surface of a mesa-type device, the temperature range for sintering the metal raw material printed on the surface of a planar device can be 700-820°C; while the temperature range for sintering the metal raw material printed on the surface of a mesa-type device can be 680-700°C. Figures 4 to 7, the preset thickness of the metal layer 10 formed by the printing process is relatively thick, and at least two layers of metal layers 10 with a preset thickness can be stacked, and the orthographic projection of the metal layer 10 on the side close to the wafer on the wafer completely covers the orthographic projection of the metal layer 10 on the side away from the wafer on the wafer, which is beneficial to improving the heat dissipation and flow capacity of the power semiconductor device. It should be noted that the printing process can be used to form a metal layer 10 with a preset thickness on a wafer of a single-sided power semiconductor discrete device, and can also be used to form a metal layer 10 with a preset thickness on a wafer of a double-sided power semiconductor discrete device, and there is no limitation here.

[0069] The embodiment of the present invention also provides a power semiconductor discrete device. The power semiconductor discrete device uses the wafer metallization method of the power semiconductor discrete device provided in any of the above embodiments to complete the metallization of the wafer, and cuts and packages the wafer to obtain a power semiconductor discrete device. Specifically, the power semiconductor discrete device uses a printing process to form a metal layer on the surface of the wafer, which can effectively simplify the process of selective metallization on the surface of the wafer, and uses a preset ratio of metal raw materials so that the formed metal layer has good bonding with the wafer. And the metal layer formed by the printing method has a preset thickness greater than the thickness of the metal layer formed by the traditional metallization process, that is, the printing method can more easily form a metal layer with a preset thickness, thereby effectively improving the heat dissipation and flow capacity of the power semiconductor discrete device, and improving the performance of the power semiconductor discrete device.

[0070] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for wafer metallization of power semiconductor discrete devices, characterized in that: Used for metallization of wafers in power semiconductor discrete devices; The wafer metallization method of the power semiconductor discrete device comprises: A wafer is provided; a surface of the wafer is provided with windows to be metallized arranged in an array; Using at least one metal raw material with a preset ratio, forming at least one metal raw material layer in each of the windows to be metallized by a printing process; The metal raw material layer is sintered layer by layer to form at least one metal layer on the surface of the wafer; wherein each metal layer has a preset thickness.

2. The wafer metallization method for power semiconductor discrete devices according to claim 1, characterized in that: The preset thickness of each metal layer ranges from 5 to 50 μm.

3. The wafer metallization method for power semiconductor discrete devices according to claim 1, characterized in that: The printing process includes screen printing process and inkjet printing process; The metal raw material with the preset ratio includes a metal slurry with a first preset ratio and a metal ink with a second preset ratio; The screen printing process uses the metal paste having the first preset ratio, and the inkjet printing process uses the metal ink having the second preset ratio.

4. The wafer metallization method for power semiconductor discrete devices according to claim 3, characterized in that: The metal slurry comprises metal powder, a binder and an organic solvent; The first preset ratio includes: the weight percentage range of the metal powder includes 80% to 95%, the weight percentage range of the binder includes 1% to 5%, and the weight percentage range of the organic solvent includes 5% to 15%.

5. The wafer metallization method for power semiconductor discrete devices according to claim 3, characterized in that: The metal ink comprises metal particles, a binder and an organic solvent; The second preset ratio includes: the weight percentage of the metal particles ranges from 60% to 80%, the weight percentage of the binder ranges from 0.3% to 5%, and the weight percentage of the organic solvent ranges from 20% to 40%.

6. The wafer metallization method for power semiconductor discrete devices according to claim 3, characterized in that: The metal material in the metal paste and the metal ink includes any one of silver, nickel, aluminum, copper, titanium, gold and alloys.

7. The wafer metallization method for power semiconductor discrete devices according to claim 6, characterized in that: The step of sintering the metal raw material layer layer by layer to form at least one metal layer on the surface of the wafer includes: Printing a first metal raw material layer on the surface of the wafer; sintering the first metal raw material layer to form a first metal layer; Printing a second metal raw material layer on a side of the first metal layer away from the wafer; sintering the second metal raw material layer to form a second metal layer; The materials of the first metal layer and the second metal layer include a combination of two metal materials.

8. The wafer metallization method for power semiconductor discrete devices according to claim 7, characterized in that: The bonding property of the first metal layer is better than the bonding property of the second metal layer; And / or, the packaging welding performance of the second metal layer is better than the packaging welding performance of the first metal layer.

9. The wafer metallization method for power semiconductor discrete devices according to claim 1, characterized in that: The sintering temperature range of the metal raw material layer for sintering layer by layer includes 680-820°C.

10. A power semiconductor discrete device, characterized in that: The wafer is metallized using the wafer metallization method for power semiconductor discrete devices as described in any one of claims 1 to 9, and the wafer is cut and packaged to obtain the power semiconductor discrete devices.

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