Monitoring method in silicon carbide wafer processing process

Abstract

The invention relates to a monitoring method in a silicon carbide wafer treatment process. The monitoring method in the silicon carbide wafer processing process comprises the following steps: providing a silicon carbide wafer; forming a metal seed layer covering the back surface of the silicon carbide wafer; processing the silicon carbide wafer and the metal seed layer by adopting a laser annealing process to form an ohmic contact layer; forming a back metal layer on the surface, deviating from the silicon carbide wafer, of the ohmic contact layer to form a silicon carbide power device; obtaining the roughness of the surface of the back metal layer as first roughness; mounting a silicon carbide power device on the packaging substrate through an adhesive to form a silicon carbide packaging device; and judging the size of the porosity in the adhesive between the silicon carbide power device and the packaging substrate according to the first roughness. According to the method, the roughness is adopted to represent the size of the porosity, online monitoring in the silicon carbide wafer treatment process is achieved, and influences such as damage to the silicon carbide wafer are avoided.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a monitoring method in a silicon carbide wafer processing process. Background Art

[0002] The back process of silicon carbide power devices in the manufacturing process usually includes substrate back thinning process, metal seed layer deposition process, laser annealing process, back metal layer deposition process and cleaning process. Among them, the laser annealing process is to focus the laser on the metal seed layer on the back of the substrate to generate instantaneous high temperature to activate the metal seed layer and combine with the substrate to form silicide, so as to achieve the purpose of ohmic contact with the substrate. Since the laser annealing process has an important influence on the electrical performance parameters of semiconductor devices, the current method of measuring impedance is mainly used to characterize the effect of the laser annealing process for silicon-based devices. The impedance inflection point method can effectively capture the inflection point energy required for metal activation energy. However, the impedance measurement method can only characterize the electrical properties of silicon-based semiconductor devices, and cannot effectively characterize the performance of silicon carbide power devices (because the impedance of silicon carbide wafers cannot be accurately measured). Moreover, the impedance measurement method cannot monitor the product online and is prone to damage to semiconductor products.

[0003] Therefore, how to achieve online monitoring during the processing of silicon carbide wafers, reduce damage to silicon carbide wafers during the monitoring process, and expand the monitoring range to better characterize the performance of silicon carbide products is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present invention provides a monitoring method during silicon carbide wafer processing, which is used to realize online monitoring during the processing of silicon carbide wafers, reduce damage to the silicon carbide wafers during the monitoring process, and expand the monitoring range to better characterize the performance of silicon carbide products.

[0005] According to some embodiments, the present invention provides a method for monitoring a silicon carbide wafer during processing, comprising the following steps:

[0006] Providing a silicon carbide wafer, the silicon carbide wafer comprising a front side and a back side that are relatively distributed along a first direction;

[0007] forming a metal seed layer covering the back side of the silicon carbide wafer;

[0008] Processing the silicon carbide wafer and the metal seed layer by a laser annealing process to form an ohmic contact layer covering the back side of the silicon carbide wafer;

[0009] forming a back metal layer on a surface of the ohmic contact layer facing away from the silicon carbide wafer to form a silicon carbide power device;

[0010] Acquire the roughness of a surface of the back metal layer facing away from the silicon carbide wafer as a first roughness;

[0011] Mounting the silicon carbide power device on a packaging substrate by means of an adhesive to form a silicon carbide packaging device;

[0012] The porosity of the adhesive between the silicon carbide power device and the packaging substrate is determined according to the first roughness.

[0013] In some embodiments, before forming the metal seed layer covering the back side of the silicon carbide wafer, the following steps are further included:

[0014] The back side of the silicon carbide wafer is ground by a grinding process to thin the silicon carbide wafer.

[0015] In some embodiments, before forming the metal seed layer covering the back side of the silicon carbide wafer, the following steps are further included:

[0016] Acquiring the roughness of the back side of the thinned silicon carbide wafer as the initial roughness;

[0017] It is determined whether the initial roughness is within a first threshold range; if not, grinding the back side of the silicon carbide wafer again.

[0018] In some embodiments, before forming a back metal layer on the surface of the ohmic contact layer away from the silicon carbide wafer, the following steps are also included:

[0019] Acquire the roughness of a surface of the ohmic contact layer facing away from the silicon carbide wafer as a second roughness;

[0020] The laser energy in the laser annealing process is judged according to the second roughness.

[0021] In some embodiments, the following steps are also included:

[0022] It is determined whether the second roughness is lower than a second threshold range, and if so, it is determined that the laser energy in the laser annealing process is attenuated.

[0023] In some embodiments, there are multiple silicon carbide wafers, and multiple different laser energies are used to perform laser annealing process on the multiple silicon carbide wafers respectively, so as to form the ohmic contact layer on the back side of each silicon carbide wafer respectively; after obtaining the roughness of the surface of the ohmic contact layer away from the silicon carbide wafer as the second roughness, the following steps are also included:

[0024] The laser energy inflection point of the laser annealing process is obtained according to a plurality of different laser energies and a plurality of second roughnesses respectively corresponding to a plurality of laser energies.

[0025] In some embodiments, the specific steps of obtaining the laser energy inflection point of the laser annealing process according to the plurality of different laser energies and the plurality of second roughnesses respectively corresponding to the plurality of laser energies include:

[0026] Separating the second roughness within a third threshold range from the plurality of second roughnesses as a target roughness;

[0027] A lowest laser energy is selected from the plurality of laser energies corresponding to the plurality of target roughnesses as a laser energy inflection point of the laser annealing process.

[0028] In some embodiments, the specific step of determining the porosity of the adhesive between the silicon carbide power device and the packaging substrate according to the first roughness includes:

[0029] It is determined whether the first roughness is lower than a fourth threshold range, and if so, it is determined that the porosity in the silicon carbide packaging device is greater than a threshold porosity.

[0030] In some embodiments, the following steps are also included:

[0031] Acquiring roughness of a plurality of back metal regions on a surface of the back metal layer facing away from the silicon carbide wafer to form a roughness distribution map;

[0032] The electrical parameter distribution of the silicon carbide power device is obtained according to the roughness distribution map.

[0033] In some embodiments, the specific steps of obtaining the electrical parameter distribution of the silicon carbide power device according to the roughness distribution map include:

[0034] The roughness distribution abnormal roughness region is obtained from the roughness distribution map, and the roughness distribution abnormal roughness region is used as the electrical parameter distribution abnormal roughness region.

[0035] In some embodiments, the electrical parameter includes a diode forward voltage.

[0036] The monitoring method in the silicon carbide wafer processing process provided by the present invention comprises: after a silicon carbide wafer and a metal seed layer located on the back side of the silicon carbide wafer are processed by a laser annealing process to form an ohmic contact layer, a back metal layer is formed on the surface of the ohmic contact layer away from the silicon carbide wafer, and a silicon carbide power device is formed, the roughness of the surface of the back metal layer away from the silicon carbide wafer is obtained as the first roughness, and the porosity in the adhesive between the silicon carbide power device and the packaging substrate is judged according to the first roughness, that is, the roughness of the surface of the back metal layer away from the silicon carbide wafer is used to characterize the porosity between the silicon carbide power device and the packaging substrate after packaging, which can not only realize online monitoring in the silicon carbide wafer processing process, but also will not cause damage to the silicon carbide wafer, and can realize the monitoring of various types of silicon carbide products, expand the monitoring range, and realize the synchronous monitoring of various aspects of the performance of silicon carbide products. Moreover, since the present invention only needs to monitor the roughness of the silicon carbide wafer surface and does not need to measure electrical parameters such as impedance, it can simplify the operation of monitoring the silicon carbide wafer processing process and improve the efficiency of silicon carbide wafer monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a flow chart of a monitoring method in a silicon carbide wafer processing process according to a specific embodiment of the present invention;

[0038] Figure 2 It is a structural schematic diagram of a roughness test of a silicon carbide wafer in a specific embodiment of the present invention;

[0039] Figure 3 It is a graph showing the correlation between the surface roughness of the back metal layer and the porosity in the silicon carbide packaging device in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0040] The specific implementation of the monitoring method during the silicon carbide wafer processing provided by the present invention is described in detail below with reference to the accompanying drawings.

[0041] This specific embodiment provides a monitoring method during the processing of silicon carbide wafers. Figure 1 FIG. 1 is a flow chart of a monitoring method in a silicon carbide wafer processing process according to a specific embodiment of the present invention. Figure 1 As shown, the monitoring method during the silicon carbide wafer processing process includes the following steps:

[0042] Step S11, providing a silicon carbide wafer, wherein the silicon carbide wafer includes a front side and a back side that are relatively distributed along a first direction;

[0043] Step S12, forming a metal seed layer covering the back side of the silicon carbide wafer;

[0044] Step S13, treating the silicon carbide wafer and the metal seed layer with a laser annealing process to form an ohmic contact layer covering the back side of the silicon carbide wafer;

[0045] Step S14, forming a back metal layer on a surface of the ohmic contact layer away from the silicon carbide wafer to form a silicon carbide power device;

[0046] Step S15, obtaining the roughness of the surface of the back metal layer away from the silicon carbide wafer as the first roughness;

[0047] Step S16, mounting the silicon carbide power device on a packaging substrate by means of an adhesive to form a silicon carbide packaging device;

[0048] Step S17: determining the porosity of the adhesive between the silicon carbide power device and the packaging substrate according to the first roughness.

[0049] Figure 2 2 is a schematic diagram of the structure of the roughness test of the silicon carbide wafer in a specific embodiment of the present invention. In some embodiments, before forming the metal seed layer covering the back side 201 of the silicon carbide wafer 20, the following steps are also included:

[0050] The back side 201 of the silicon carbide wafer 20 is ground by a grinding process to thin the silicon carbide wafer 20 .

[0051] In some embodiments, before forming the metal seed layer covering the back side 201 of the silicon carbide wafer 20, the following steps are further included:

[0052] Obtaining the roughness of the back side 201 of the thinned silicon carbide wafer 20 as the initial roughness;

[0053] It is determined whether the initial roughness is within a first threshold range. If not, the back side 201 of the silicon carbide wafer 20 is ground again.

[0054] For example, after the device structure is formed on the front side of the silicon carbide wafer 20, a protective film can be attached to the front side of the silicon carbide wafer 20 to avoid damage to the device structure during the processing of the back side 201 of the silicon carbide wafer 20. The silicon carbide wafer 20 is thinned from the back side 201 of the silicon carbide wafer 20 using a grinding process, and the thickness after thinning depends on the voltage resistance requirements of the silicon carbide power device finally formed. In one example, a probe profiler is used to perform a roughness test on the back side 201 of the silicon carbide wafer 20. For example, after the thinning process, the silicon carbide wafer 20 is placed on a vacuum adsorption table in a probe profiler with the back side 201 of the silicon carbide wafer 20 facing upward, and the flat edge at the edge of the silicon carbide wafer 20 is aligned with the limit pin on the vacuum adsorption table to limit the position of the silicon carbide wafer 20 on the vacuum adsorption table. After the vacuum adsorption table adsorbs the silicon carbide wafer 20 by vacuum adsorption force, the probe profiler uses a probe pressure of 2mg to 3mg and scans 500μm to perform a roughness test on the back side of the silicon carbide wafer 20. In one example, a plurality of test points 202 ( Figure 2 13 test points are used as an example for explanation), and the average roughness obtained by testing the plurality of test points 202 is used as the initial roughness of the back side 201 of the silicon carbide wafer 20. In this specific embodiment, the term "multiple" refers to more than two.

[0055] In this specific embodiment, the initial roughness of the back side 201 of the silicon carbide wafer 20 is adjusted to within the first threshold range through a grinding process, thereby avoiding the first roughness measured later being affected by the change of the initial roughness, so as to further ensure the reliability and accuracy of the porosity size in the silicon carbide packaging device characterized by the first roughness later. In one example, the first threshold range can be 10nm to 25nm.

[0056] In some embodiments, before forming a back metal layer on the surface of the ohmic contact layer away from the silicon carbide wafer, the following steps are also included:

[0057] Acquire the roughness of a surface of the ohmic contact layer facing away from the silicon carbide wafer 20 as a second roughness;

[0058] The laser energy in the laser annealing process is judged according to the second roughness.

[0059] In some embodiments, the specific steps of obtaining the roughness of the surface of the ohmic contact layer facing away from the silicon carbide wafer 20 as the second roughness include:

[0060] The roughness of a plurality of ohmic contact regions on the surface of the ohmic contact layer facing away from the silicon carbide wafer 20 is detected in situ, and an average value of the roughness of the plurality of points is taken as the second roughness.

[0061] For example, the probe profilometer is used to in-situ detect the roughness of multiple ohmic contact areas on the surface of the ohmic contact layer away from the silicon carbide wafer 20, and the average roughness of the multiple ohmic contact areas is used as the second roughness. In order to further improve the accuracy of the roughness characterization of the porosity, the multiple ohmic contact areas used to obtain the second roughness correspond one-to-one with the multiple test points used to obtain the initial roughness, that is, the projections of the multiple ohmic contact areas used to obtain the second roughness on the back side 201 of the silicon carbide wafer 20 overlap one-to-one with the multiple test points used to obtain the initial roughness.

[0062] In some embodiments, the monitoring method during the silicon carbide wafer processing further includes the following steps:

[0063] It is determined whether the second roughness is lower than a second threshold range, and if so, it is determined that the laser energy in the laser annealing process is attenuated.

[0064] Specifically, after the ohmic contact layer is formed by the laser annealing process, the roughness of the surface of the ohmic contact layer away from the silicon carbide wafer 20 will be greater than the initial roughness of the back side 201 of the silicon carbide wafer 20. When the laser energy of the laser annealing process decreases, the second roughness will also decrease accordingly, so the second roughness can reflect the laser energy of the laser annealing process. When the laser energy in the laser annealing process is attenuated, the second roughness of the surface of the ohmic contact layer away from the silicon carbide wafer 20 will be affected by the doping ion concentration in the silicon carbide wafer 20, resulting in a low second roughness. Therefore, by judging whether the second roughness is lower than the second threshold range, it can be determined whether the laser energy of the laser annealing process is attenuated. In one example, the second threshold range is 100nm to 140nm.

[0065] In some embodiments, there are multiple silicon carbide wafers 20, and multiple different laser energies are used to perform laser annealing process on the multiple silicon carbide wafers 20, respectively, to form the ohmic contact layer on the back side 201 of each silicon carbide wafer 20; after obtaining the roughness of the surface of the ohmic contact layer away from the silicon carbide wafer 20 as the second roughness, the following steps are also included:

[0066] The laser energy inflection point of the laser annealing process is obtained according to a plurality of different laser energies and a plurality of second roughnesses respectively corresponding to a plurality of laser energies.

[0067] In some embodiments, the specific steps of obtaining the laser energy inflection point of the laser annealing process according to the plurality of different laser energies and the plurality of second roughnesses respectively corresponding to the plurality of laser energies include:

[0068] Separating the second roughness within a third threshold range from the plurality of second roughnesses as a target roughness;

[0069] A lowest laser energy is selected from the plurality of laser energies corresponding to the plurality of target roughnesses as a laser energy inflection point of the laser annealing process.

[0070] The laser energy inflection point in this specific embodiment refers to the minimum energy for activating the metal atoms in the metal seed layer so that the metal seed layer can react with the silicon carbide wafer 20 to generate the ohmic contact layer. The third threshold range is the roughness range of the ohmic contact layer away from the surface of the silicon carbide wafer 20 after the metal seed layer reacts with the silicon carbide wafer 20 to generate the ohmic contact layer. In one example, the third threshold range is 100nm to 140nm. By using a plurality of different sizes of laser energy to perform laser annealing treatment on a plurality of silicon carbide wafers 20 formed with the metal seed layer, and respectively obtaining the second roughness of the plurality of ohmic contact layers, the lowest laser energy is selected from the plurality of laser energies corresponding to the plurality of target roughnesses, thereby monitoring the laser energy inflection point of the laser annealing process, so as to further expand the monitoring range during the silicon carbide wafer processing.

[0071] Figure 3 is a graph of the correlation between the surface roughness of the back metal layer and the porosity in the silicon carbide package device in a specific embodiment of the present invention. In some embodiments, the specific steps of determining the porosity of the adhesive between the silicon carbide power device and the package substrate according to the first roughness include:

[0072] It is determined whether the first roughness is lower than a fourth threshold range, and if so, it is determined that the porosity in the silicon carbide packaging device is greater than a threshold porosity.

[0073] In one example, the probe profiler can be used to in-situ detect the roughness of multiple back metal regions on the surface of the back metal layer away from the silicon carbide wafer 20, and the average roughness of the multiple back metal regions is used as the first roughness. In order to further improve the accuracy of the roughness characterization of the porosity, the multiple back metal regions used to obtain the first roughness correspond one-to-one with the multiple test points used to obtain the initial roughness, that is, the projections of the multiple back metal regions used to obtain the first roughness on the back side 201 of the silicon carbide wafer 20 overlap one-to-one with the multiple test points used to obtain the initial roughness.

[0074] After forming the silicon carbide power device, the silicon carbide power device is attached to the packaging substrate by an adhesive with the back metal layer 30 facing the packaging substrate. When the silicon carbide packaging device is formed, the roughness of the surface of the back metal layer 30 away from the silicon carbide wafer 20 (i.e., the first roughness) will affect the filling of the adhesive, thereby affecting the size of the porosity in the adhesive between the silicon carbide power device and the substrate. When the roughness of the surface of the back metal layer 30 away from the silicon carbide wafer 20 is large (i.e., the first roughness is greater than the fourth threshold range), the filling effect of the adhesive is better, so that after the adhesive is filled and cured, the porosity in the adhesive between the silicon carbide power device and the packaging substrate is small; when the roughness of the surface of the back metal layer 30 away from the silicon carbide wafer 20 is small (i.e., the first roughness is less than the fourth threshold range), the filling effect of the adhesive is poor, so that after the adhesive is filled and cured, the porosity in the adhesive between the silicon carbide power device and the packaging substrate is large. Therefore, the porosity in the adhesive between the silicon carbide power device and the packaging substrate can be characterized by the first roughness without physically destroying the formed silicon carbide packaging device, which not only simplifies the detection operation of the silicon carbide packaging device, but also further expands the monitoring range during the silicon carbide wafer processing.

[0075] This specific implementation method establishes a correspondence between the first roughness and the porosity in the adhesive between the silicon carbide power device and the packaging substrate as a first correspondence by statistically analyzing historical data, thereby achieving quantitative characterization of the specific size of the porosity in the adhesive between the silicon carbide power device and the packaging substrate through the specific value of the first roughness, thereby contributing to the improvement of the silicon carbide wafer processing process and the performance of silicon carbide packaging devices. In one example, the fourth threshold range is 90nm to 135nm, and the threshold porosity is 3%.

[0076] In one example, the probe profiler can be used to in-situ detect the roughness of multiple back metal regions on the surface of the back metal layer 30 away from the silicon carbide wafer 20, thereby obtaining multiple back roughnesses corresponding to the multiple back metal regions one by one, for example Figure 3 (a) shows 13 back roughnesses corresponding to 13 back metal regions (i.e., the first back roughness R1, the second back roughness R2, the third back roughness R3, the fourth back roughness R4, the fifth back roughness R5, the sixth back roughness R6, the seventh back roughness R7, the eighth back roughness R8, the ninth back roughness R9, the tenth back roughness R10, the eleventh back roughness R11, the twelfth back roughness R12, and the thirteenth back roughness R13) to construct a roughness distribution diagram of the surface of the back metal layer 30 away from the silicon carbide wafer 20. By statistically analyzing historical data, the corresponding relationship between the roughness of the surface of the back metal layer away from the silicon carbide wafer and the porosity in the adhesive between the silicon carbide power device and the packaging substrate can also be constructed as a second corresponding relationship. Through the second corresponding relationship and the roughness distribution map of the surface of the back metal layer 30 away from the silicon carbide wafer 20, the distribution of holes in the adhesive between the silicon carbide power device and the packaging substrate can be obtained, thereby further accurately characterizing the performance of the silicon carbide packaging device. Figure 3 (b) shows thirteen porosities corresponding to the 13 back side roughnesses (i.e., the first porosity P1, the second porosity P2, the third porosity P3, the fourth porosity P4, the fifth porosity P5, the sixth porosity P6, the seventh porosity P7, the eighth porosity P8, the ninth porosity P9, the tenth porosity P10, the eleventh porosity P11, the twelfth porosity P12 and the thirteenth porosity P13).

[0077] In some embodiments, the monitoring method during the silicon carbide wafer processing process further includes the following steps:

[0078] Acquiring roughness of a plurality of back metal regions on a surface of the back metal layer facing away from the silicon carbide wafer to form a roughness distribution map;

[0079] The electrical parameter distribution of the silicon carbide power device is obtained according to the roughness distribution map.

[0080] In some embodiments, the specific steps of obtaining the electrical parameter distribution of the silicon carbide power device according to the roughness distribution map include:

[0081] The roughness distribution abnormal roughness region is obtained from the roughness distribution map, and the roughness distribution abnormal roughness region is used as the electrical parameter distribution abnormal electrical parameter region.

[0082] In some embodiments, the electrical parameter includes a diode forward voltage.

[0083] For example, the roughness of the surface of the back metal layer away from the silicon carbide wafer affects the electrical performance of the silicon carbide power device (such as the forward voltage of the diode). Therefore, by constructing the roughness distribution map, the electrical parameter distribution of the silicon carbide power device can be characterized, and there is no need to conduct electrical testing on the silicon carbide power device, and it will not cause damage to the silicon carbide wafer, thereby further expanding the monitoring range during the silicon carbide wafer processing. In one example, the area with a roughness lower than the fourth threshold range can be obtained from the roughness distribution map as the abnormal roughness area, and the roughness distribution abnormal roughness area is used as the abnormal distribution area of ​​electrical parameters such as the diode forward voltage (i.e., the abnormal electrical parameter area).

[0084] The monitoring method during the silicon carbide wafer processing process provided in this specific embodiment uses a laser annealing process to process a silicon carbide wafer and a metal seed layer located on the back side of the silicon carbide wafer to form an ohmic contact layer, and forms a back metal layer on the surface of the ohmic contact layer away from the silicon carbide wafer to form a silicon carbide power device. Then, the roughness of the surface of the back metal layer away from the silicon carbide wafer is obtained as the first roughness, and the porosity in the adhesive between the silicon carbide power device and the packaging substrate is judged according to the first roughness. That is, the roughness of the surface of the back metal layer away from the silicon carbide wafer is used in this specific embodiment to characterize the porosity between the silicon carbide power device and the packaging substrate after packaging. This method can not only realize online monitoring during the silicon carbide wafer processing process, but also will not cause damage to the silicon carbide wafer, and can realize the monitoring of various types of silicon carbide products, expand the monitoring range, and realize the synchronous monitoring of various aspects of the performance of silicon carbide products. Moreover, since the present specific implementation only needs to monitor the roughness of the silicon carbide wafer surface and does not need to measure electrical parameters such as impedance, it is possible to simplify the operation of monitoring the silicon carbide wafer processing process and improve the efficiency of silicon carbide wafer monitoring.

[0085] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A monitoring method during silicon carbide wafer processing, characterized in that: The steps include: Providing a silicon carbide wafer, the silicon carbide wafer comprising a front side and a back side that are relatively distributed along a first direction; forming a metal seed layer covering the back side of the silicon carbide wafer; Processing the silicon carbide wafer and the metal seed layer by a laser annealing process to form an ohmic contact layer covering the back side of the silicon carbide wafer; forming a back metal layer on a surface of the ohmic contact layer facing away from the silicon carbide wafer to form a silicon carbide power device; Acquire the roughness of a surface of the back metal layer facing away from the silicon carbide wafer as a first roughness; The silicon carbide power device is mounted on a packaging substrate by an adhesive to form a silicon carbide packaging device; and the porosity of the adhesive between the silicon carbide power device and the packaging substrate is determined according to the first roughness.

2. The monitoring method during silicon carbide wafer processing according to claim 1, characterized in that: Before forming the metal seed layer covering the back side of the silicon carbide wafer, the following steps are also included: The back side of the silicon carbide wafer is ground by a grinding process to thin the silicon carbide wafer.

3. The monitoring method during silicon carbide wafer processing according to claim 2, characterized in that: Before forming the metal seed layer covering the back side of the silicon carbide wafer, the following steps are also included: Acquiring the roughness of the back side of the thinned silicon carbide wafer as the initial roughness; It is determined whether the initial roughness is within a first threshold range; if not, grinding the back side of the silicon carbide wafer again.

4. The method for monitoring silicon carbide wafer processing according to claim 2, characterized in that: Before forming a back metal layer on the surface of the ohmic contact layer away from the silicon carbide wafer, the method further includes the following steps: Acquire the roughness of a surface of the ohmic contact layer facing away from the silicon carbide wafer as a second roughness; The laser energy in the laser annealing process is judged according to the second roughness.

5. The method for monitoring silicon carbide wafer processing according to claim 4, characterized in that: The following steps are also included: It is determined whether the second roughness is lower than a second threshold range, and if so, it is determined that the laser energy in the laser annealing process is attenuated.

6. The method for monitoring silicon carbide wafer processing according to claim 4, characterized in that: There are multiple silicon carbide wafers, and multiple different laser energies are used to perform laser annealing process on the multiple silicon carbide wafers respectively, so as to form the ohmic contact layer on the back side of each silicon carbide wafer respectively; after obtaining the roughness of the surface of the ohmic contact layer away from the silicon carbide wafer as the second roughness, the following steps are also included: The laser energy inflection point of the laser annealing process is obtained according to a plurality of different laser energies and a plurality of second roughnesses respectively corresponding to a plurality of laser energies.

7. The method for monitoring silicon carbide wafer processing according to claim 6, characterized in that: The specific steps of obtaining the laser energy inflection point of the laser annealing process according to the plurality of different laser energies and the plurality of second roughnesses respectively corresponding to the plurality of laser energies include: Separating the second roughness within a third threshold range from the plurality of second roughnesses as a target roughness; A lowest laser energy is selected from the plurality of laser energies corresponding to the plurality of target roughnesses as a laser energy inflection point of the laser annealing process.

8. The method for monitoring silicon carbide wafer processing according to claim 1, characterized in that: The specific step of judging the porosity of the adhesive between the silicon carbide power device and the packaging substrate according to the first roughness comprises: It is determined whether the first roughness is lower than a fourth threshold range, and if so, it is determined that the porosity in the silicon carbide packaging device is greater than a threshold porosity.

9. The method for monitoring silicon carbide wafer processing according to claim 1, characterized in that: The following steps are also included: Acquiring roughness of a plurality of back metal regions on a surface of the back metal layer facing away from the silicon carbide wafer to form a roughness distribution map; The electrical parameter distribution of the silicon carbide power device is obtained according to the roughness distribution map.

10. The method for monitoring silicon carbide wafer processing according to claim 9, characterized in that: The specific steps of obtaining the electrical parameter distribution of the silicon carbide power device according to the roughness distribution map include: The roughness distribution abnormal roughness region is obtained from the roughness distribution map, and the roughness distribution abnormal roughness region is used as the electrical parameter distribution abnormal roughness region.

11. The method for monitoring silicon carbide wafer processing according to claim 10, characterized in that: The electrical parameters include the diode forward voltage.

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