Preparation method of n-type SiC high-temperature resistant ohmic contact electrode structure

Abstract

The present invention provides a preparation method for an n-type SiC high-temperature-resistant ohmic contact electrode structure, comprising the following steps: cleaning a silicon carbide structure, wherein the silicon carbide structure includes a silicon carbide substrate, a buffer layer, and an epitaxial layer stacked; oxidizing the cleaned silicon carbide structure to form a silicon oxide layer on the epitaxial layer; removing the silicon oxide layer based on wet etching, and performing hydrogen plasma treatment on the epitaxial layer after the removal of the silicon oxide layer; patterning one side of the epitaxial layer away from the buffer layer to form a transmission line model on the epitaxial layer; depositing metal on the transmission line model to form a metal layer on the transmission line model, wherein the metal layer includes a titanium metal layer, a titanium carbide metal layer, and a platinum metal layer stacked; annealing the metal layer to form an ohmic contact electrode structure. The present invention at least improves chemical and mechanical stability.

Description

Technical Field

[0001] The present invention relates to data processing technologies, and in particular to a method for preparing an n-type SiC high-temperature resistant ohmic contact electrode structure. Background Art

[0002] With the development of technologies such as intelligent control, information and communication, pressure sensors applicable to high-temperature environments have extensive application requirements in fields involving engines, space exploration, rotating parts, etc. For example, in systems involving fuel combustion, such as aerospace and automotive systems, the monitoring of the internal pressure of the engine combustion chamber can provide necessary parameters for improving engine performance and combustion efficiency. For large equipment operating in harsh environments (such as high temperature, high frequency, high pressure, high power, etc.), it is necessary to monitor its temperature, pressure and other parameters in real time to ensure stable operation and accurate fault prediction. The relevant sensor elements and signal processing circuits must be able to withstand harsh environments. Devices based on the first-generation semiconductor Si have stable performance and wide applications in the fields of integrated circuits and microelectromechanical system (MEMS) devices. However, due to the effects of intrinsic plastic deformation and heterojunction leakage current at high temperatures, it cannot directly operate in harsh environments and at temperatures exceeding 250°C.

[0003] SiC is a third-generation wide-bandgap semiconductor material with characteristics such as a wide bandgap, high breakdown voltage, and chemical inertness, and has the potential for applications in high-temperature harsh environments. A large number of experimental results show that the main reason for the failure of sensors during long-term operation at high temperatures is the deterioration of the metal-semiconductor ohmic contact performance. In fact, whether it is microelectronic devices such as metal-oxide-semiconductor field-effect transistors (MOSFETs) and junction field-effect transistors (JFETs), or microelectromechanical system (MEMS) devices including pressure sensors, radiation sensors, and acceleration sensors, the research of SiC devices is inseparable from the preparation of SiC ohmic contact electrodes. Ohmic contact, as a key process step in device manufacturing, directly affects the gain, noise, efficiency, and reliability of the device. For example, even if the sensitive element of a MEMS sensor is intact, if the ohmic contact fails, the output of the sensor will be lost. Therefore, the high-temperature resistance ability of the ohmic contact directly affects the performance of the resistor.

[0004] To solve this problem, this patent proposes an ohmic contact electrode structure applied to high-temperature environments, aiming to improve the high-temperature stability of sensors. The ohmic contact process flow is simple, which can effectively reduce the contact resistance and improve the overall performance of the device, and is of great significance for the development of high-performance SiC power devices and MEMS sensors. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a method for preparing an n-type SiC high-temperature-resistant ohmic contact electrode structure that overcomes or at least partially solves the above problems.

[0006] According to one aspect of the present invention, there is provided a method for preparing an n-type SiC high-temperature-resistant ohmic contact electrode structure, including the following steps:

[0007] Clean the silicon carbide structure, wherein the silicon carbide structure includes a silicon carbide substrate, a buffer layer, and an epitaxial layer stacked;

[0008] Oxidize the silicon carbide structure after the cleaning to form a silicon oxide layer on the epitaxial layer;

[0009] Remove the silicon oxide layer based on wet etching, and perform hydrogen plasma treatment on the epitaxial layer after removing the silicon oxide layer;

[0010] Form a photoresist layer on the side of the epitaxial layer away from the buffer layer, and perform patterning on the photoresist layer to form a shielding layer;

[0011] Use the shielding layer as a mask to etch the epitaxial layer to form a transmission line model on the epitaxial layer, wherein the transmission line model includes a rectangular transmission model and a circular ring transmission model;

[0012] Deposit metal on the transmission line model to form a metal layer on the transmission line model, wherein the metal layer includes a titanium metal layer, a titanium carbide metal layer, and a platinum metal layer stacked;

[0013] Perform an annealing operation on the metal layer to form an ohmic contact electrode structure.

[0014] Optionally, in the method according to the present invention, after forming the transmission line model on the epitaxial layer, it further includes:

[0015] In response to completing the formation of the transmission line model, control an image acquisition unit to acquire an image of the transmission line model to obtain a model top view corresponding to the transmission line model;

[0016] Determine an image area corresponding to the transmission line model based on the model top view, and determine an area contour corresponding to the image area;

[0017] Retrieve a standard contour corresponding to the transmission line model, compare the area contour with the standard contour, and determine a detection attribute of the transmission line model based on the comparison result, wherein the detection attribute includes a complete attribute, a missing attribute, and an excessive attribute;

[0018] In response to the transmission line model having a missing attribute, a preset missing repair operation is performed on the transmission line model.

[0019] Optionally, in the method according to the present invention, comparing the region contour with the standard contour includes:

[0020] Comparing the region contour with the standard contour based on the coincidence relationship;

[0021] In response to the region contour coinciding with the corresponding standard contour, the transmission line model corresponding to the region contour is determined to have a complete attribute;

[0022] In response to the region contour being larger than the corresponding standard contour, the transmission line model corresponding to the region contour is determined to have an excessive attribute;

[0023] In response to the region contour being smaller than the corresponding standard contour, the transmission line model corresponding to the region contour is determined to have a missing attribute.

[0024] Optionally, in the method according to the present invention, in response to the transmission line model having a missing attribute, performing a preset missing repair operation on the transmission line model includes:

[0025] In response to the transmission line model having a missing attribute, on the side of the epitaxial layer away from the buffer layer, a repair region corresponding to the standard contour and covering the transmission line model, and an entity region corresponding to the transmission line model are determined;

[0026] Comparing the entity region with the repair region, and determining a missing sub-region that only exists in the repair region based on the comparison result;

[0027] Forming a missing repair layer on the side of the epitaxial layer away from the buffer layer, and performing patterning on the missing repair layer to form a repair mask layer covering all other regions except the missing sub-region;

[0028] Etching the epitaxial layer based on the repair mask layer to obtain a repaired transmission line model.

[0029] Optionally, in the method according to the present invention, the method further includes:

[0030] In response to the transmission line model having an excessive attribute, determining the excessive area corresponding to the transmission line model based on the contour comparison of the region contour and the standard contour based on the coincidence relationship;

[0031] Summing up the excessive areas corresponding to all the transmission line models having an excessive attribute, and determining an area evaluation value for the corresponding area dimension based on the obtained total area;

[0032] Obtain the number of models of all transmission line models corresponding to the excessive attribute, and determine the number evaluation value of the corresponding number dimension based on the number of models;

[0033] Perform a product calculation on the area evaluation value and the number evaluation value respectively with the retrieved area weight value and number weight value, and perform a summation calculation based on the obtained first evaluation value and second evaluation value to obtain the excessive evaluation value;

[0034] In response to the excessive evaluation value being greater than the retrieved preset evaluation threshold, mark the silicon carbide substrate for scrapping.

[0035] Optionally, in the method according to the present invention, the method further includes:

[0036] Obtain the actual evaluation value input by the product production end based on the transmission line model, and compare the score of the excessive evaluation value with the actual evaluation value;

[0037] When the actual evaluation value is greater than the excessive evaluation value, perform an increase training on the number weight value and the area weight value;

[0038] When the actual evaluation value is less than the excessive evaluation value, perform a decrease training on the number weight value and the area weight value;

[0039] Obtain the trained number weight value and area weight value through the following formula:

[0040] Among them, is the number weight value The number of times of increase training, is the number weight value The training constant value of, is the number weight value The number of times of decrease training, is the trained number weight value, is the area weight value The number of times of increase training, is the area weight value The training constant value of, is the area weight value The number of times of decrease training, is the trained area weight value.

[0041] Optionally, in the method according to the present invention, perform metal deposition on the transmission line model to form a metal layer on the transmission line model, wherein the metal layer includes a titanium metal layer, a titanium carbide metal layer, and a platinum metal layer, including:

[0042] Use the DC magnetron sputtering process to deposit titanium metal on the transmission line model to form a titanium metal layer on the transmission line model;

[0043] Use the DC magnetron sputtering process to deposit titanium carbide metal on the side of the titanium metal layer away from the epitaxial layer to form a titanium carbide metal layer on the titanium metal layer;

[0044] Use the DC magnetron sputtering process to deposit platinum metal on the side of the titanium carbide metal layer away from the titanium metal layer to form a platinum metal layer on the titanium carbide metal layer.

[0045] Optionally, in the method according to the present invention, an annealing operation is performed on the metal layer to form an ohmic contact electrode structure, including:

[0046] Place the silicon carbide structure in a nitrogen atmosphere and perform an annealing operation on the metal layer at a preset annealing temperature for a preset annealing time to form an ohmic contact electrode structure.

[0047] According to another aspect of the present invention, there is provided an ohmic contact electrode structure obtained by the preparation method of the above-mentioned n-type SiC high-temperature resistant ohmic contact electrode structure, including:

[0048] A silicon carbide substrate, a buffer layer, and an epitaxial layer stacked;

[0049] Wherein, a transmission line model is formed on the side of the epitaxial layer away from the buffer layer, a metal layer is provided on the layer region corresponding to the transmission line model, and the metal layer includes a stacked titanium metal layer, a titanium carbide metal layer, and a platinum metal layer.

[0050] According to the solution of the present invention, the n-type SiC high-temperature resistant ohmic contact electrode structure obtained based on the present invention can maintain stable electrical performance in a high-temperature environment and can achieve a low contact resistivity, which is very important for improving the efficiency and performance of the device. Moreover, the stacked titanium metal layer, titanium carbide metal layer, and platinum metal layer can effectively control the metal / SiC contact performance through an effective interface control technology. A good ohmic contact is crucial for the application of SiC devices in extreme environments. In addition, the n-type SiC high-temperature resistant ohmic contact electrode structure proposed by the present invention can provide stable electrical performance, low resistivity, and good chemical and mechanical stability, which plays an important role in improving the performance and reliability of SiC-based devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Shows a flowchart of a preparation method of an n-type SiC high-temperature resistant ohmic contact electrode structure according to an embodiment of the present invention;

[0052] Figure 2 Schematic diagram showing the transmission line model in this embodiment;

[0053] Figure 3 Schematic diagram showing the n-type SiC high-temperature resistant ohmic contact electrode structure in this embodiment;

[0054] Figure 4 Shows the corresponding over-etched A region and the corresponding missing-etched B region existing in Figure 3 ;

[0055] Figure 5 Resistance-voltage characteristic curve diagram of an n-type SiC high-temperature resistant ohmic contact electrode structure according to another embodiment of the present invention. Specific embodiments

[0056] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0057] To solve the problems existing in the above-mentioned background technology, an embodiment of the present invention provides a preparation method for an n-type SiC high-temperature resistant ohmic contact electrode structure.

[0058] Figure 1 Shows a flowchart of a preparation method for an n-type SiC high-temperature resistant ohmic contact electrode structure proposed in this embodiment. As Figure 1 shown, the preparation method for the n-type SiC high-temperature resistant ohmic contact electrode structure proposed in this embodiment starts from step S101, and in step S101, the following contents are included:

[0059] Clean the silicon carbide structure, wherein the silicon carbide structure includes a silicon carbide substrate, a buffer layer, and an epitaxial layer stacked.

[0060] For example, in this embodiment, the silicon carbide structure may include a silicon carbide substrate, a buffer layer, and an epitaxial layer stacked. Among them, the material of the silicon carbide substrate may specifically be 4H-SiC, the corresponding buffer layer may be a p-type buffer layer, and the corresponding epitaxial layer may be an n-type epitaxial layer. Here, the p-type buffer layer and the n-type epitaxial layer can form a corresponding pn isolation, thereby preventing the occurrence of leakage.

[0061] It should be noted that the cleaning of the silicon carbide structure can be carried out by using the RCA standard cleaning method, and the RCA standard cleaning method is a commonly used cleaning operation in the art. Therefore, this embodiment will not elaborate on this process.

[0062] In step S102, the following is included:

[0063] Oxidize the silicon carbide structure that has completed the cleaning to form a silicon oxide layer on top of the epitaxial layer.

[0064] For example, in this embodiment, the silicon oxide layer (i.e., SiO2) can be formed by thermal oxidation through an oxidation diffusion furnace on top of the corresponding epitaxial layer (i.e., on the side of the epitaxial layer away from the buffer layer), and the corresponding thickness can be 2000 Å thick.

[0065] In step S103, the following is included:

[0066] Remove the silicon oxide layer based on wet etching, and perform hydrogen plasma treatment on the epitaxial layer after the removal of the silicon oxide layer.

[0067] For example, in this embodiment, after the formation of the silicon oxide layer, the silicon oxide layer can be removed by wet etching, and further, after the removal of the silicon oxide layer, hydrogen plasma treatment can be performed on the epitaxial layer. It should be noted that this step is mainly to eliminate the dangling bonds and defects remaining on the surface of the epitaxial layer; and after the removal of the silicon oxide layer, hydrogen plasma can be further used to perform corresponding treatment on the silicon carbide structure, which can play a role in passivating the surface states of the silicon carbide structure. Here, since surface impurity contamination is an important factor in forming the surface states of the silicon carbide structure, and using the corresponding hydrogen plasma to clean the silicon carbide structure will not cause corresponding ion radiation damage to the silicon carbide structure, and its corresponding strong reaction activity can also remove surface impurity ions such as carbon, OH-, and F-.

[0068] In step S104, the following is included:

[0069] Perform patterning on the side of the epitaxial layer away from the buffer layer to form a transmission line model on top of the epitaxial layer.

[0070] For example, in this embodiment, after the treatment of the silicon carbide structure (i.e., the epitaxial layer) based on hydrogen plasma is completed, patterning can be started on the side of the epitaxial layer away from the buffer layer to form a corresponding transmission line model on top of the epitaxial layer.

[0071] Furthermore, in this embodiment, the above "perform patterning on the side of the epitaxial layer away from the buffer layer to form a transmission line model on top of the epitaxial layer" may further include the following steps:

[0072] A photoresist layer is formed on the side of the epitaxial layer away from the buffer layer, and the photoresist layer is patterned to form a shielding layer;

[0073] Using the shielding layer as a mask, the epitaxial layer is etched to form a transmission line model on the epitaxial layer, where the transmission line model includes a rectangular transmission model and a circular ring transmission model.

[0074] For example, in this embodiment, patterning the side of the epitaxial layer away from the buffer layer can be mainly achieved based on a corresponding photoresist, and the specific process can be as follows:

[0075] First, a corresponding photoresist layer can be formed on the side of the epitaxial layer away from the buffer layer. The photoresist can correspond to AZ6130. After the corresponding photoresist layer is formed, a mask plate can be used to expose and develop the photoresist layer to form a corresponding shielding layer;

[0076] Finally, after obtaining the corresponding shielding layer, the shielding layer can be used again as a corresponding mask, and the epitaxial layer can be further etched to obtain a transmission line model formed on the epitaxial layer.

[0077] Here, it can be explained that the corresponding transmission line model can be etched based on a pre-designed layout. In this embodiment, as Figure 2 shown, the corresponding transmission line model can include a rectangular transmission model and a circular ring transmission model. Here, both the rectangular transmission model and the circular ring transmission model can include multiple ones, and the corresponding rectangular transmission model can be arranged in an array manner, while each corresponding circular ring model can include multiple concentrically arranged circular ring sub-models.

[0078] It should be noted that in this embodiment, the formation of the transmission line model is based on the patterning of the photoresist layer and etching the epitaxial layer. In some cases, as Figure 3 shown, if there are problems in the process operation, it may cause some defects in the formed transmission line model compared to the pre-designed layout, which are specifically reflected in the following two aspects:

[0079] 1. As shown in the A area in Figure 4 , due to some areas being over-etched, some structures are added to the transmission line model;

[0080] 2. As shown in the B area in Figure 4 , due to some areas not being etched, some structures are missing from the transmission line model.

[0081] However, due to the existence of the above-mentioned defects, the finally produced product may have a reduced corresponding usage effect. Therefore, in order to improve the production yield of the product, in this embodiment, after forming the transmission line model on the epitaxial layer, the following method steps may further be included:

[0082] In response to completing the formation of the transmission line model, control the image acquisition unit to perform image acquisition on the transmission line model to obtain a model top view corresponding to the transmission line model;

[0083] Based on the model top view, determine the image region corresponding to the transmission line model and determine the region contour corresponding to this image region;

[0084] Retrieve the standard contour corresponding to the transmission line model, compare the region contour with the standard contour, and determine the detection attribute of the transmission line model based on the comparison result, where the detection attribute includes a complete attribute, a missing attribute, and an excessive attribute;

[0085] In response to the transmission line model having a missing attribute, perform a preset missing repair operation on the transmission line model.

[0086] For example, in this embodiment, when the formation of the corresponding transmission line model is completed, since in the subsequent process, metal layer deposition needs to be performed based on the transmission line model to complete the preparation of the n-type SiC high-temperature ohmic contact electrode structure corresponding to this embodiment, it is necessary to determine whether there are defects in the obtained transmission line model. Specifically, the transmission line model can first be image-acquired based on the image acquisition method, and the corresponding model top view can be determined based on the obtained model top view, and the image region corresponding to the transmission line model and the corresponding region contour can be obtained based on the model top view; here, based on the above content, it can be known that the transmission line model is etched based on a pre-designed layout. Therefore, in order to determine whether there are defects in the transmission line model, the region contour can be compared with the standard contour of the corresponding layout, so as to determine the detection attribute of the transmission line model, and when the detection attribute is a missing attribute, the corresponding preset missing repair operation can be performed on the transmission line model.

[0087] It should be noted that in this embodiment, the corresponding detection attribute may include a complete attribute, a missing attribute, and an excessive attribute. Among them, the missing attribute can be understood as that some regions are not etched, resulting in a corresponding transmission line model lacking some structures; the excessive attribute can be understood as that some regions are over-etched, resulting in a corresponding transmission line model having some additional structures; and the complete attribute can be understood as that the obtained transmission line model does not have corresponding defects.

[0088] Further, in this embodiment, the above-mentioned "comparing the region contour with the standard contour" may further include the following steps:

[0089] Comparing the region contour with the standard contour based on the coincidence relationship;

[0090] In response to the region contour coinciding with the corresponding standard contour, determining the transmission line model corresponding to the region contour as having a sound property;

[0091] In response to the region contour being larger than the corresponding standard contour, determining the transmission line model corresponding to the region contour as having an excessive property;

[0092] In response to the region contour being smaller than the corresponding standard contour, determining the transmission line model corresponding to the region contour as having a missing property.

[0093] For example, in this embodiment, the above comparison process may be described as follows:

[0094] First, after obtaining the corresponding region contour and the standard contour, the corresponding region contour and the standard contour can be compared and analyzed based on the coincidence relationship to detect the coincidence degree between the region contour and the standard contour;

[0095] If the contour coincidence degree between the region contour and the corresponding standard contour is greater than or equal to the preset coincidence degree threshold, or they are exactly the same, it is determined that the transmission line model corresponding to the region contour has a sound property, indicating that its shape and size meet the design requirements, that is, there are no corresponding defects;

[0096] If the region contour completely coincides or approximately coincides with the corresponding standard contour, it is determined that the transmission line model corresponding to the region contour has a sound property, indicating that its shape and size meet the design requirements, that is, there are no corresponding defects;

[0097] If the region contour is larger than the corresponding standard contour, it is determined that the transmission line model corresponding to the region contour has an excessive property, that is, the transmission line model has been over-etched and some structures have been added;

[0098] If the region contour is smaller than the corresponding standard contour, it is determined that the transmission line model corresponding to the region contour has a missing property, that is, the transmission line model has a missing etch and some structures are missing.

[0099] In addition, in this embodiment, based on the above content, it can be known that when the determination of the detection attribute of the corresponding transmission line film line is completed and the detection attribute of the corresponding transmission line model is a missing attribute, the corresponding preset missing repair operation can be called to perform the missing repair on the transmission line model, so as to complete the supplement of the corresponding missing part. And the corresponding "responding to the transmission line model having a missing attribute, performing a preset missing repair operation on the transmission line model" can further include the following steps:

[0100] Responding to the transmission line model having a missing attribute, determining a repair area corresponding to the standard profile and covering the transmission line model, and an entity area corresponding to the transmission line model on the side of the epitaxial layer away from the buffer layer;

[0101] Comparing the entity area with the repair area, and determining a missing sub-area that only exists in the repair area based on the comparison result;

[0102] Forming a missing repair layer on the side of the epitaxial layer away from the buffer layer, and performing patterning on the missing repair layer to form a repair mask layer covering all other areas except the missing sub-area;

[0103] Etching the epitaxial layer based on the repair mask layer to obtain a repaired transmission line model.

[0104] For example, when the detection attribute of the corresponding transmission line model is a missing attribute, it indicates that the corresponding part that needs to be etched is missing from the transmission line model. Therefore, it is necessary to perform supplementary etching on the missing part. The corresponding process includes:

[0105] First, similar to the above patterning process, a repair area corresponding to the standard profile and covering the transmission line model can be formed on the side of the epitaxial layer away from the buffer layer. Here, the repair area can be understood as the area included in the standard profile. It can be determined that the repair area should be larger than the image area of the corresponding transmission line model and be able to cover the transmission line model;

[0106] Then, the entity area corresponding to the transmission line model can be determined synchronously, and the entity area is compared with the repair area to obtain the missing sub-area existing in the repair area. Among them, since the missing sub-area only exists in the sub-area of the repair area, that is, the missing sub-area is the area of the missing part of the corresponding transmission line model;

[0107] Next, a missing repair layer can be correspondingly formed on the side of the epitaxial layer away from the buffer layer (wherein, the material corresponding to the missing repair layer can be the same as the material of the photoresist layer mentioned above, that is, both are photoresists), and the missing repair layer is further subjected to corresponding patterning to form a repair mask layer covering all other regions except the missing sub-region;

[0108] Finally, based on the repair mask layer, the corresponding epitaxial layer can be etched. Since the repair mask layer covers all regions except the missing sub-region, only the missing sub-region can be etched accordingly, thereby completing the model repair of the transmission line model.

[0109] It can be explained that when the detection attribute of the corresponding transmission line model is a missing attribute, the supplementary etching of the missing sub-region can be realized based on the above method steps to obtain a repaired transmission line model; when the detection attribute of the corresponding transmission line model is an excessive attribute, that is, the corresponding epitaxial layer is over-etched, at this time, the corresponding repair cannot be performed based on the above method steps. Therefore, it is necessary to further evaluate the quality according to the etching situation of the transmission line model with the excessive attribute to determine whether the transmission line model meets the production conditions. Therefore, in this embodiment, the following steps can also be included:

[0110] In response to the transmission line model having an excessive attribute, the excessive area corresponding to the transmission line model is determined based on the contour comparison based on the coincidence relationship between the regional contour and the standard contour;

[0111] The excessive areas corresponding to all transmission line models with missing attributes are summed up, and the area evaluation value corresponding to the area dimension is determined based on the obtained total area;

[0112] The number of transmission line models corresponding to the missing attributes is obtained, and the number evaluation value corresponding to the number dimension is determined based on the model number;

[0113] The area evaluation value and the number evaluation value are respectively multiplied by the retrieved area weight value and the number weight value, and the first evaluation value and the second evaluation value obtained are summed up to obtain an excessive evaluation value;

[0114] In response to the excessive evaluation value being greater than the retrieved preset evaluation threshold, a scrapping processing mark is made on the silicon carbide substrate.

[0115] For example, in this embodiment, the evaluation process for the transmission line model with an excessive attribute can be specifically described as follows:

[0116] First, the excessive area corresponding to the transmission line model can be determined through the contour comparison between the aforementioned regional contour and the standard contour. Here, the excessive area can be understood as the area corresponding to excessive etching;

[0117] Next, as Figures 2 - 4 shown, since there can be multiple transmission line models, all the transmission line models respectively corresponding to the excessive attributes can be summed for each excessive area to obtain the corresponding total area. Then, by multiplying the total area by the retrieved area normalization value, the area evaluation value corresponding to the area dimension can be obtained;

[0118] Then, after obtaining the area evaluation value corresponding to the area dimension, the number of all transmission line models corresponding to the excessive attributes can be further obtained. By multiplying the number of models by the retrieved number normalization value, the number evaluation value corresponding to the number dimension can be obtained;

[0119] Then, after respectively multiplying the obtained area evaluation value and number evaluation value by the retrieved area weight value and number weight value, the corresponding first evaluation value and second evaluation value can be obtained. Further, based on the summation calculation of the first evaluation value and the second evaluation value, the corresponding excessive evaluation value can be obtained;

[0120] Finally, by numerically comparing the excessive evaluation value with the retrieved preset evaluation threshold, and when the excessive evaluation value is greater than the preset evaluation threshold, a corresponding scrapping mark is made on the silicon carbide substrate, thereby completing the corresponding production evaluation and the product screening based on the production requirements, and improving the corresponding product yield.

[0121] It should be noted that in this embodiment, the above preset evaluation threshold can be set in advance by the production personnel, and the specific value is not limited in this embodiment.

[0122] Furthermore, it can be explained that in this embodiment, since the excessive evaluation value is obtained through automated calculation, there may be a deviation from the actual situation. In order to improve the corresponding determination accuracy, the following method steps are used to perform real-time update and adjustment processing on the corresponding number weight value and area weight value, realizing the process of updating and iterating each weight value, and further improving the corresponding determination accuracy.

[0123] Specifically, the process of updating and iterating each weight value is as described in the following content:

[0124] Obtain the actual evaluation value input by the product production end based on the transmission line model, and compare the score of the excessive evaluation value with the actual evaluation value;

[0125] When the actual evaluation value is greater than the over-evaluation value, perform increasing training on the quantity weight value and the area weight value;

[0126] When the actual evaluation value is less than the over-evaluation value, perform decreasing training on the quantity weight value and the area weight value;

[0127] Obtain the trained quantity weight value and area weight value through the following formula:

[0128] Wherein, is the quantity weight value The number of times of performing increasing training, is the quantity weight value The training constant value of, is the quantity weight value The number of times of performing decreasing training, is the quantity weight value after training, is the area weight value The number of times of performing increasing training, is the area weight value The training constant value of, is the area weight value The number of times of performing decreasing training, is the area weight value after training.

[0129] It can be explained that the above product production end can be understood as the terminal used by the corresponding production personnel, such as a mobile phone or a computer.

[0130] In step S105, the following contents are included:

[0131] Perform metal deposition on the transmission line model to form a metal layer on the transmission line model, wherein the metal layer includes a titanium metal layer, a titanium carbide metal layer, and a platinum metal layer arranged in layers.

[0132] For example, in this embodiment, after the formation of the corresponding transmission line model is completed, metal deposition can be further performed on the transmission line model by means of metal deposition, so as to form a metal layer on the transmission line model, wherein the metal layer can include a corresponding titanium metal layer, a titanium carbide metal layer, and a corresponding platinum metal layer arranged in layers.

[0133] Furthermore, in this embodiment, the above "perform metal deposition on the transmission line model to form a metal layer on the transmission line model, wherein the metal layer includes a titanium metal layer, a titanium carbide metal layer, and a platinum metal layer" may further include the following steps:

[0134] The metal deposition based on titanium metal is carried out on the transmission line model by using the DC magnetron sputtering process to form a titanium metal layer on the transmission line model;

[0135] The metal deposition based on titanium carbide metal is carried out on the side of the titanium metal layer away from the epitaxial layer by using the DC magnetron sputtering process to form a titanium carbide metal layer on the titanium metal layer;

[0136] The metal deposition based on platinum metal is carried out on the side of the titanium carbide metal layer away from the titanium metal layer by using the DC magnetron sputtering process to form a platinum metal layer on the titanium carbide metal layer.

[0137] For example, in this embodiment, the deposition process of the metal layer can be specifically described as follows:

[0138] First, as can be seen from the above, when etching the corresponding transmission line model, it is mainly based on the formed shielding layer as a mask. Therefore, when depositing the corresponding metal layer, the shielding layer can also be used again as a mask to deposit the metal layer. For the titanium metal layer, the metal deposition based on titanium metal can be directly carried out on the side of the epitaxial layer of the silicon carbide structure by using the DC magnetron sputtering process to form a titanium metal layer on the transmission line model; among them, the purity of the titanium target can be 99.999%, and the thickness of the corresponding sputtered titanium metal layer can be 500 Å, the deposition power is 500W, the deposition rate is 616 Å / min, the gas flow rate is 14 Ar / sccm, and the chamber vacuum degree is ≤5e -6 mTorr;

[0139] Then, similarly, the shielding layer can be used as a mask to deposit the corresponding titanium carbide. The process used can also be the DC magnetron sputtering process to form a titanium carbide metal layer on the titanium metal layer; among them, the purity of the titanium carbide target is 99.999%, and the thickness of the corresponding sputtered titanium carbide metal layer is 2000 Å, the deposition power is 500W, the deposition rate is 717.4 Å / min, the gas flow rate is 14 Ar / sccm, and the chamber vacuum degree is ≤5e -6 mTorr;

[0140] Finally, the masking layer can be reused as a mask, and then metal deposition of corresponding platinum can be carried out. The process used can also be the DC magnetron sputtering process to form a platinum metal layer on the titanium carbide metal layer. Among them, the purity of the platinum target is 99.999%, the thickness of the corresponding sputtered platinum metal layer is 1000 Å, and the corresponding sputtering process can be divided into two steps: First, parameters with a deposition power of 500 W and a deposition rate of 900 Å / min can be used to sputter 200 Å. Second, then use a deposition power of 100 w, a deposition rate of 178.8 Å / min, a gas flow rate of 14 Ar / sccm, and a chamber vacuum of ≤ 5e -6 mTorr to sputter 800 Å. The high-power sputtering carried out first can enable the metal to form a film quickly, while the low-power sputtering carried out later can ensure that the formed metal layer is dense, thereby improving the corresponding preparation quality.

[0141] In step S106, the following content is included:

[0142] Anneal the metal layer to form an ohmic contact electrode structure.

[0143] For example, in this embodiment, after the above-mentioned metal deposition is completed, the corresponding masking layer can be removed, and the formed metal layer can be annealed, and then the corresponding ohmic contact electrode structure can be formed.

[0144] It should be noted that since the masking layer is formed by photoresist, the masking layer can be removed by soaking and ultrasonic cleaning the corresponding silicon carbide structure in acetone to make the masking layer completely fall off. Subsequently, the silicon carbide structure can be further placed in anhydrous ethanol and deionized water respectively for soaking and ultrasonic cleaning to remove the acetone remaining on the surface of the silicon carbide structure. Here, the soaking and ultrasonic cleaning time can be 5 minutes or 10 minutes.

[0145] Furthermore, in this embodiment, the above-mentioned "anneal the metal layer to form an ohmic contact electrode structure" can further include the following steps:

[0146] Place the silicon carbide structure in a nitrogen atmosphere and anneal the metal layer at a preset annealing temperature for a preset annealing time to form an ohmic contact electrode structure.

[0147] For example, when annealing the metal layer, the silicon carbide structure needs to be in the corresponding nitrogen atmosphere, and the metal layer is annealed at the corresponding preset annealing temperature for the preset annealing time to form the corresponding ohmic contact electrode structure. Here, the preset annealing temperature can be 900 °C - 1000 °C, and the corresponding preset annealing time can be 100 - 150 seconds.

[0148] It can be explained that in this embodiment, since surface impurity contamination is an important factor in forming SiC surface states, and the corresponding hydrogen plasma treatment has a surface passivation effect. ECR hydrogen plasma can generate low-energy (<2eV) high-ionization, high-concentration, and highly activated plasma, which does not cause ion radiation damage to the sample. Its strong reactivity can also remove impurities such as C, OH-, and F- on the surface and can reduce the oxygen content and enhance the surface antioxidant property;

[0149] Secondly, Ti reacts with SiC to form TiC. After the DC magnetron sputtering process, the work function of the TiC thin film is 3.74 - 3.94 eV, while the work function of n-type 4H-SiC is greater than 4.0 eV. When the work function of the metal is close to or lower than the work function of SiC, if the interface state density is not greater than 1012 / cm2, an ideal ohmic contact can be formed. And the melting point of TiC reaches 3150°C and it is difficult to decompose into other substances under high-temperature conditions, which improves the thermal stability of the ohmic contact;

[0150] Furthermore, the Pt layer included in the metal layer can combine with the C generated by the reaction of Ti and SiC to prevent free C atoms from aggregating on the surface, which may cause the surface to become rough or ineffective. The Pt layer is the key to preventing the oxidation of the ohmic contact electrode and plays an effective role in delaying the diffusion of O towards the interface.

[0151] In summary, the stacked titanium metal layer, titanium carbide metal layer, and platinum metal layer have good performance in high-temperature and air environments and have great advantages in applications in high-temperature and air environments. Specifically, they can maintain stable electrical performance in high-temperature environments and can achieve a low contact resistivity, which is very important for improving the efficiency and performance of devices. And the stacked titanium metal layer, titanium carbide metal layer, and platinum metal layer can effectively control the metal / SiC contact performance through effective interface control technology. A good ohmic contact is crucial for the application of SiC devices in extreme environments; in addition, the n-type SiC high-temperature resistant ohmic contact electrode structure proposed in this embodiment can provide stable electrical performance, has low resistivity, and good chemical and mechanical stability, and plays an important role in improving the performance and reliability of SiC-based devices.

[0152] Another embodiment of the present invention proposes an n-type SiC high-temperature resistant ohmic contact electrode structure, which is mainly prepared by the method for preparing the n-type SiC high-temperature resistant ohmic contact electrode structure mentioned in the foregoing embodiment. Among them, the n-type SiC high-temperature resistant ohmic contact electrode structure includes:

[0153] A silicon carbide substrate, a buffer layer, and an epitaxial layer stacked;

[0154] Wherein, a transmission line model is formed on a side of the epitaxial layer away from the buffer layer, a metal layer is disposed on a layer region corresponding to the transmission line model, and the metal layer includes a stacked titanium metal layer, a titanium carbide metal layer, and a platinum metal layer.

[0155] For example, in this embodiment, in order to verify the electrical characteristics of the n-type SiC high-temperature-resistant ohmic contact electrode structure in this embodiment, for example, a 4200-SCS semiconductor parameter analyzer can be used in cooperation with an EPS150TRIAX room-temperature probe station for testing, and the resistance (volt-ampere characteristics) between different electrode spacings can be tested according to the principle of the transmission line model; wherein, for example, rectangular ohmic contact electrodes with unequal spacings can be fabricated on a strip-shaped semiconductor material insulated from the surrounding environment, the electrode length is L, the width is W, and the spacing between the electrodes is d. By passing a constant current I between the rectangular electrodes at different distances dn respectively, measuring the corresponding voltage value V, and obtaining the total resistance value R. Further, taking the electrode spacing dn as the abscissa and the total resistance value R as the ordinate, plotting the tested points into a straight line to obtain a Figure 5 resistance volt-ampere characteristic curve graph as shown, so as to display the corresponding electrical characteristics. Among them, in Figure 5 it, Current refers to the constant current, and Voltage refers to the voltage value.

[0156] In the specification provided herein, the algorithms and displays are not inherently related to any particular computer, virtual system, or other device. Various general-purpose systems can also be used in conjunction with the examples of the present invention. Based on the above description, the structure required to construct such a system is obvious. In addition, the present invention is not directed to any particular programming language. It should be understood that the content of the present invention described herein can be implemented using various programming languages, and the description of the specific language above is for disclosing the preferred embodiments of the present invention.

[0157] In the specification provided herein, a large number of specific details are set forth. However, it can be understood that the embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures, and technologies have not been shown in detail so as not to obscure the understanding of this specification.

[0158] Similarly, it should be understood that, in order to streamline this disclosure and assist in understanding one or more of the various inventive aspects, in the above description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof.

[0159] Those skilled in the art should understand that the modules, units, or components of the devices in the examples disclosed herein can be arranged in the devices as described in the embodiments, or alternatively can be located in one or more devices different from the devices in the examples. The modules in the foregoing examples can be combined into one module or further divided into multiple sub-modules.

[0160] Those skilled in the art can understand that the modules in the devices of the embodiments can be adaptively changed and arranged in one or more devices different from the embodiments. The modules, units, or components in the embodiments can be combined into one module, unit, or component, and further can be divided into multiple sub-modules, sub-units, or sub-components.

[0161] In addition, those skilled in the art can understand that although some of the embodiments described herein include certain features included in other embodiments rather than other features, the combination of the features of different embodiments is within the scope of the present invention and forms different embodiments.

[0162] In addition, some of the embodiments herein are described as combinations of methods or method elements that can be implemented by a processor of a computer system or by other devices performing the functions. Therefore, a processor having the necessary instructions for implementing the method or method element forms a device for implementing the method or method element. In addition, the elements described herein in the device embodiments are examples of the following devices: the device is used to implement the functions performed by the elements for the purpose of implementing the invention.

[0163] As used herein, unless otherwise specified, the use of ordinal numbers "first", "second", "third", etc. to describe ordinary objects only indicates different instances of similar objects, and is not intended to imply that the objects so described must have a given order in terms of time, space, sorting, or in any other way.

[0164] Although the present invention has been described in terms of a limited number of embodiments, those skilled in the art within this technical field will appreciate that other embodiments can be conceived within the scope of the present invention as thus described. In addition, it should be noted that the language used in this specification is mainly selected for readability and teaching purposes, rather than for the purpose of interpreting or limiting the subject matter of the present invention.

Claims

1. A preparation method of an n-type SiC high-temperature resistant ohmic contact electrode structure, characterized in that, Including the following steps: Clean the silicon carbide structure, wherein the silicon carbide structure includes a silicon carbide substrate, a buffer layer, and an epitaxial layer arranged in a stacked manner; Oxidize the silicon carbide structure that has completed the cleaning to form a silicon oxide layer on the epitaxial layer; Remove the silicon oxide layer based on wet etching, and perform hydrogen plasma treatment on the epitaxial layer after the removal of the silicon oxide layer; Form a photoresist layer on the side of the epitaxial layer away from the buffer layer, and perform patterning on the photoresist layer to form a shielding layer; Use the shielding layer as a mask to etch the epitaxial layer to form a transmission line model on the epitaxial layer, wherein the transmission line model includes a rectangular transmission model and a circular ring transmission model; Deposit metal on the transmission line model to form a metal layer on the transmission line model, wherein the metal layer includes a titanium metal layer, a titanium carbide metal layer, and a platinum metal layer arranged in a stacked manner; In response to the completion of the formation of the transmission line model, control an image acquisition unit to perform image acquisition on the transmission line model to obtain an upper view of the model corresponding to the transmission line model; Determine an image area corresponding to the transmission line model based on the upper view of the model, and determine a regional contour corresponding to the image area; Perform a contour comparison based on the coincidence relationship between the regional contour and a standard contour; In response to the regional contour coinciding with the corresponding standard contour, determine the transmission line model corresponding to the regional contour as having a sound attribute; In response to the regional contour being larger than the corresponding standard contour, determine the transmission line model corresponding to the regional contour as having an excessive attribute; In response to the regional contour being smaller than the corresponding standard contour, determine the transmission line model corresponding to the regional contour as having a missing attribute; In response to the transmission line model having a missing attribute, perform a preset missing repair operation on the transmission line model; Perform an annealing operation on the metal layer to form an ohmic contact electrode structure; Wherein, the method further includes: In response to the transmission line model having an excessive attribute, determine an excessive area corresponding to the transmission line model based on the contour comparison based on the coincidence relationship between the regional contour and the standard contour; Sum up the excessive areas of all the transmission line models corresponding to having an excessive attribute respectively, and determine an area evaluation value corresponding to the area dimension based on the obtained total area; Obtain the model quantity of all the transmission line models corresponding to having an excessive attribute, and determine a quantity evaluation value corresponding to the quantity dimension based on the model quantity; Perform a product calculation on the area evaluation value and the quantity evaluation value respectively with the retrieved area weight value and quantity weight value, and perform a sum calculation based on the obtained first evaluation value and second evaluation value to obtain an excessive evaluation value; In response to the excessive evaluation value being greater than the retrieved preset evaluation threshold, perform a scrapping processing mark on the silicon carbide substrate.

2. The preparation method of the n-type SiC high-temperature resistant ohmic contact electrode structure according to claim 1, characterized in that In response to the transmission line model having a missing attribute, performing a preset missing repair operation on the transmission line model includes: In response to the transmission line model having missing attributes, a repair region corresponding to the standard profile and covering the transmission line model, and an entity region corresponding to the transmission line model are determined on the side of the epitaxial layer away from the buffer layer; The entity region is compared with the repair region, and a missing sub-region that only exists in the repair region is determined based on the comparison result; A missing repair layer is formed on the side of the epitaxial layer away from the buffer layer, and the missing repair layer is patterned to form a repair mask layer covering all other regions except the missing sub-region; Based on the repair mask layer, the epitaxial layer is etched to obtain a repaired transmission line model.

3. The method for preparing an n-type SiC high-temperature resistant ohmic contact electrode structure according to claim 2, wherein The method further includes: Obtaining an actual evaluation value input by the product production end based on the transmission line model, and comparing the over-evaluation value with the actual evaluation value in terms of scores; When the actual evaluation value is greater than the over-evaluation value, the quantity weight value and the area weight value are trained to increase; When the actual evaluation value is less than the over-evaluation value, the quantity weight value and the area weight value are trained to decrease; The trained quantity weight value and area weight value are obtained through the following formula: Among them, is the quantity weight value for the number of times of increasing training, is the quantity weight value of the training constant value, is the quantity weight value for the number of times of decreasing training, is the quantity weight value after training, is the area weight value for the number of times of increasing training, is the area weight value of the training constant value, is the area weight value for the number of times of decreasing training, is the area weight value after training.

4. The method for preparing an n-type SiC high-temperature resistant ohmic contact electrode structure according to claim 1, wherein Metal deposition is performed on the transmission line model to form a metal layer on the transmission line model, wherein the metal layer includes a titanium metal layer, a titanium carbide metal layer, and a platinum metal layer, including: Using a DC magnetron sputtering process to perform metal deposition based on titanium metal on the transmission line model to form a titanium metal layer on the transmission line model; Using a DC magnetron sputtering process to perform metal deposition based on titanium carbide metal on the side of the titanium metal layer away from the epitaxial layer to form a titanium carbide metal layer on the titanium metal layer; Using a DC magnetron sputtering process to perform metal deposition based on platinum metal on the side of the titanium carbide metal layer away from the titanium metal layer to form a platinum metal layer on the titanium carbide metal layer.

5. The method for preparing an n-type SiC high-temperature resistant ohmic contact electrode structure according to claim 1, wherein Annealing operation is performed on the metal layer to form an ohmic contact electrode structure, including: Placing the silicon carbide structure in a nitrogen atmosphere and performing an annealing operation on the metal layer at a preset annealing temperature for a preset annealing time to form an ohmic contact electrode structure.

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