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

Abstract

The invention provides a preparation method of an n-type SiC high-temperature-resistant ohmic contact electrode structure, and the method comprises the following steps: cleaning a silicon carbide structure which comprises a silicon carbide substrate, a buffer layer and an epitaxial layer which are 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 is completed; performing patterning processing on one side, far away from the buffer layer, of the epitaxial layer to form a transmission line model located on the epitaxial layer; the transmission line model is subjected to metal deposition, a metal layer located on the transmission line model is formed, and the metal layer comprises a titanium metal layer, a titanium carbide metal layer and a platinum metal layer which are arranged in a stacked mode; and performing annealing operation on the metal layer to form an ohmic contact electrode structure. The chemical and mechanical stability is at least improved.

Description

Technical Field

[0001] The invention relates to data processing technology, 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 suitable for high temperature environments have a wide range of application needs in the fields of engines, space exploration, rotating parts, etc. For example, in systems involving fuel combustion, such as aerospace and automotive systems, monitoring 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.), its temperature, pressure and other parameters must be monitored 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 of semiconductor Si have stable performance and wide applications in the field of integrated circuits and microelectromechanical systems (MEMS) devices. However, due to the intrinsic plastic deformation at high temperatures and the influence of heterojunction leakage current, it cannot work directly in harsh environments and temperatures exceeding 250°C.

[0003] SiC is a third-generation wide bandgap semiconductor material with the characteristics of wide bandgap, high breakdown voltage, and chemical inertness. It has the potential to be used in high-temperature and harsh environments. A large number of experimental results show that the main reason for the failure of sensors when working at high temperatures for a long time 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 systems (MEMS) devices including pressure sensors, radiation sensors, and acceleration sensors, the research on SiC devices is closely related to the preparation of SiC ohmic contact electrodes. As a key process step in device manufacturing, ohmic contact directly affects the gain, noise, efficiency, and reliability of the device. For example, even if the sensitive element of the MEMS sensor is intact, if the ohmic contact fails, the output of the sensor will be lost. Therefore, the ability of the ohmic contact to withstand high temperatures directly affects the performance of the resistor.

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

[0005] Based on 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 the above problems 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, comprising the following steps: Cleaning a silicon carbide structure, wherein the silicon carbide structure includes a stacked silicon carbide substrate, a buffer layer, and an epitaxial layer; Oxidizing the cleaned silicon carbide structure to form a silicon oxide layer located on the epitaxial layer; Removing the silicon oxide layer based on wet etching, and performing hydrogen plasma treatment on the epitaxial layer after completing the removal of the silicon oxide layer; forming a photoresist layer on a side of the epitaxial layer away from the buffer layer, and patterning the photoresist layer to form a shielding layer; Using the blocking layer as a mask, etching the epitaxial layer to form a transmission line model located on the epitaxial layer, wherein the transmission line model includes a rectangular transmission model and a circular transmission model; Performing metal deposition on the transmission line model to form a metal layer located on the transmission line model, wherein the metal layer includes a stacked titanium metal layer, a titanium carbide metal layer and a platinum metal layer; The metal layer is annealed to form an ohmic contact electrode structure.

[0007] Optionally, in the method according to the present invention, a transmission line model located on the epitaxial layer is formed, and then the method further comprises: In response to completing the formation of the transmission line model, controlling 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; Determine an image region corresponding to the transmission line model based on the upper view of the model, and determine a region contour corresponding to the image region; Retrieving a standard contour corresponding to the transmission line model, performing contour comparison between the regional contour and the standard contour, and determining the detection attributes of the transmission line model based on the comparison result, wherein the detection attributes include intact attributes, missing attributes, and excessive attributes; In response to the transmission line model having a missing attribute, a preset missing repair operation is performed on the transmission line model.

[0008] Optionally, in the method according to the present invention, performing contour comparison between the region contour and the standard contour comprises: Compare the regional contour with the standard contour based on the coincidence relationship; In response to the area contour coinciding with the corresponding standard contour, determining the transmission line model corresponding to the area contour as having intact properties; In response to the area profile being larger than the corresponding standard profile, determining the transmission line model corresponding to the area profile as a transition attribute; In response to the region profile being smaller than the corresponding standard profile, the transmission line model corresponding to the region profile is determined as a missing attribute.

[0009] 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 comprises: In response to the transmission line model having a missing attribute, determining a repair region corresponding to the standard profile and covering the transmission line model, and a physical region corresponding to the transmission line model on a side of the epitaxial layer away from the buffer layer; Performing a region comparison between the entity region and the repair region, and determining a missing sub-region that exists only in the repair region based on the comparison result; forming a defect repair layer on a side of the epitaxial layer away from the buffer layer, and patterning the defect repair layer to form a repair mask layer covering all regions except the defect sub-region; The epitaxial layer is etched based on the repair mask layer to obtain a repaired transmission line model.

[0010] Optionally, in the method according to the present invention, the method further comprises: In response to the transmission line model having a transition attribute, determining a transition area corresponding to the transmission line model based on a profile comparison between the regional profile and the standard profile based on a coincidence relationship; The transition areas of all transmission line models with transition attributes are summed up and the area evaluation value of the corresponding area dimension is determined based on the obtained summary area; Obtaining model quantities corresponding to all transmission line models with transition attributes, and determining quantity evaluation values ​​corresponding to quantity dimensions based on the model quantities; The area evaluation value and the quantity evaluation value are respectively multiplied by the retrieved area weight value and the quantity weight value, and the sum is calculated based on the obtained first evaluation value and the second evaluation value to obtain an over-evaluation value; In response to the over-evaluation value being greater than the retrieved preset evaluation threshold, the silicon carbide substrate is marked as scrapped.

[0011] Optionally, in the method according to the present invention, the method further comprises: Acquire an actual evaluation value inputted by the transmission line model at the product production end, and compare the over-evaluation value with the actual evaluation value by score; When the actual evaluation value is greater than the over-evaluation value, increasing training is performed on the quantity weight value and the area weight value; When the actual evaluation value is less than the over-evaluation value, performing reduction training on the quantity weight value and the area weight value; The number weight value and area weight value after training are obtained through the following formula: in, is the quantity weight value Increase the number of training sessions. is the quantity weight value The training constant value of is the quantity weight value Reduce the number of training sessions. is the quantity weight value after training, is the area weight value Increase the number of training sessions. is the area weight value The training constant value of is the area weight value Reduce the number of training sessions. is the area weight value after training.

[0012] Optionally, in the method according to the present invention, metal deposition is performed on the transmission line model to form a metal layer located 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 direct current magnetron sputtering process to perform metal deposition based on titanium metal on the transmission line model to form a titanium metal layer located on the transmission line model; Using a direct current magnetron sputtering process, a titanium carbide metal-based metal deposition is performed on a side of the titanium metal layer away from the epitaxial layer to form a titanium carbide metal layer located on the titanium metal layer; A direct current magnetron sputtering process is used to perform platinum metal deposition on a side of the titanium carbide metal layer away from the titanium metal layer to form a platinum metal layer located on the titanium carbide metal layer.

[0013] Optionally, in the method according to the present invention, the metal layer is annealed to form an ohmic contact electrode structure, comprising: The silicon carbide structure is placed in a nitrogen atmosphere, and an annealing operation is performed on the metal layer at a preset annealing temperature for a preset annealing time to form an ohmic contact electrode structure.

[0014] According to another aspect of the present invention, an ohmic contact electrode structure obtained based on the above-mentioned method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure is provided, comprising: A stacked silicon carbide substrate, a buffer layer, and an epitaxial layer; A transmission line model is formed on one side of the epitaxial layer away from the buffer layer, a metal layer is arranged 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.

[0015] 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 properties 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, and the stacked titanium metal layer, titanium carbide metal layer and platinum metal layer can achieve effective control of the metal / SiC contact performance through effective interface regulation technology, and 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 the present invention can provide stable electrical properties, 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

[0016] Figure 1 A flow chart showing a method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure according to an embodiment of the present invention is shown; Figure 2 A schematic diagram showing a transmission line model in this embodiment; Figure 3 A schematic diagram showing the n-type SiC high temperature resistant ohmic contact electrode structure in this embodiment is shown; Figure 4 Shows that there is Figure 3 The A region corresponding to the over-etching and the B region corresponding to the under-etching; Figure 5 A resistance-voltage-ampere characteristic curve of an n-type SiC high temperature resistant ohmic contact electrode structure according to another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0017] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying 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 to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0018] In order to solve the problems existing in the above-mentioned background technology, an embodiment of the present invention provides a method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure.

[0019] Figure 1 FIG. 1 is a flow chart showing a method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure proposed in this embodiment. Figure 1 As shown, the method for preparing the n-type SiC high temperature resistant ohmic contact electrode structure proposed in this embodiment begins with step S101. In step S101, the following contents are included: The silicon carbide structure is cleaned, wherein the silicon carbide structure includes a stacked silicon carbide substrate, a buffer layer and an epitaxial layer.

[0020] For example, in this embodiment, the silicon carbide structure may include a stacked silicon carbide substrate, a buffer layer and an epitaxial layer, wherein the material of the silicon carbide substrate may be specifically 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, wherein the p-type buffer layer and the n-type epitaxial layer may form corresponding pn isolation, thereby preventing leakage.

[0021] It should be noted that the cleaning of the silicon carbide structure may be performed using the RCA standard cleaning method, which is a commonly used cleaning operation in the art. Therefore, this embodiment does not describe this process in detail.

[0022] In step S102, the following contents are included: The cleaned silicon carbide structure is oxidized to form a silicon oxide layer located on the epitaxial layer.

[0023] For example, in this embodiment, a silicon oxide layer (ie, SiO2) can be formed by thermal oxidation on the corresponding epitaxial layer (ie, the side of the epitaxial layer away from the buffer layer) through an oxidation diffusion furnace, and the corresponding thickness can be 2000Å.

[0024] In step S103, the following contents are included: The silicon oxide layer is removed based on wet etching, and the epitaxial layer is treated with hydrogen plasma after the silicon oxide layer is removed.

[0025] For example, in this embodiment, after the formation of the silicon oxide layer is completed, the silicon oxide layer can be removed accordingly by wet etching, and the epitaxial layer can be treated with hydrogen plasma after the removal of the silicon oxide layer is completed. It can be explained that this step is mainly to eliminate dangling bonds and defects residing on the surface of the epitaxial layer; and after the removal of the silicon oxide layer is completed, the silicon carbide structure can be further treated with hydrogen plasma, which can play a role in passivating the surface state of the silicon carbide structure. Here, since surface impurity contamination is an important factor in the formation of the surface state of the silicon carbide structure, the corresponding hydrogen plasma is used to clean the silicon carbide structure, which will not only not cause corresponding ion radiation damage to the silicon carbide structure, but also its corresponding strong reaction activity can remove impurity ions such as carbon, OH-, and F- on the surface.

[0026] In step S104, the following contents are included: A patterning process is performed on a side of the epitaxial layer away from the buffer layer to form a transmission line model located on the epitaxial layer.

[0027] For example, in this embodiment, after completing the hydrogen plasma-based treatment of the silicon carbide structure (ie, the epitaxial layer), corresponding patterning treatment can be started on the side of the epitaxial layer away from the buffer layer to form a transmission line model corresponding to the epitaxial layer.

[0028] Furthermore, in this embodiment, the above-mentioned “patterning the side of the epitaxial layer away from the buffer layer to form a transmission line model located on the epitaxial layer” may also include the following steps: forming a photoresist layer on a side of the epitaxial layer away from the buffer layer, and patterning the photoresist layer to form a shielding layer; The blocking layer is used as a mask to etch the epitaxial layer to form a transmission line model located on the epitaxial layer, wherein the transmission line model includes a rectangular transmission model and a circular transmission model.

[0029] For example, in this embodiment, patterning of the side of the epitaxial layer away from the buffer layer can be mainly implemented based on the corresponding photoresist, and the specific process can be described as follows: 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. 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 accordingly, so as to obtain a transmission line model located on the epitaxial layer.

[0030] Here, it can be explained that the corresponding transmission line model can be obtained by etching based on a pre-designed layout. In this embodiment, Figure 2 As shown, the corresponding transmission line model may include a rectangular transmission model and a circular transmission model, where both the rectangular transmission model and the circular transmission model may include multiple ones, and the corresponding rectangular transmission model may be arranged in an array manner, while each corresponding circular ring model may include multiple concentrically arranged circular ring sub-models.

[0031] 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 the etching of the epitaxial layer. In some cases, such as Figure 3 As shown in the figure, if there is a problem with the process operation, the formed transmission line model may have some defects relative to the pre-designed layout, which is specifically reflected in the following two aspects: 1. If Figure 4 As shown in area A in the figure, some areas are over-etched, which results in the transmission line model adding some structures; 2. If Figure 4 As shown in area B in the figure, some areas are not etched, resulting in the transmission line model missing some structures.

[0032] Based on the existence of the above defects, the final product may reduce the corresponding use effect. Therefore, in order to improve the production yield of the product, in this embodiment, after forming the transmission line model located on the epitaxial layer, the following method steps may be further included: In response to completing the formation of the transmission line model, controlling 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; Determine an image region corresponding to the transmission line model based on the upper view of the model, and determine a region contour corresponding to the image region; Retrieving a standard contour corresponding to the transmission line model, performing contour comparison between the regional contour and the standard contour, and determining the detection attributes of the transmission line model based on the comparison result, wherein the detection attributes include intact attributes, missing attributes, and excessive attributes; In response to the transmission line model having a missing attribute, a preset missing repair operation is performed on the transmission line model.

[0033] For example, in the present embodiment, after the formation of the corresponding transmission line model is completed, since it is necessary to deposit the corresponding metal layer based on the transmission line model in the subsequent process to complete the preparation of the n-type SiC high temperature resistant ohmic contact electrode structure corresponding to the present embodiment, it is necessary to determine whether the corresponding transmission line model has defects. Specifically, the transmission line model can be firstly imaged based on image acquisition, the corresponding model top view can be determined based on the obtained model top view, and the image area corresponding to the transmission line model and the corresponding area 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 obtained by etching based on a pre-designed layout, therefore, in order to determine whether the transmission line model has defects, the area 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.

[0034] It should be noted that, in this embodiment, the corresponding detection attributes may include intact attributes, missing attributes and excessive attributes, wherein the missing attribute can be understood as some areas have not been etched, resulting in the corresponding transmission line model lacking some structure; the excessive attribute can be understood as some areas have been over-etched, resulting in the corresponding transmission line model adding some structure; and the intact attribute can be understood as the obtained transmission line model does not have the corresponding defects.

[0035] Furthermore, in this embodiment, the above-mentioned “contrasting the region contour with the standard contour” may further include the following steps: Compare the regional contour with the standard contour based on the coincidence relationship; In response to the area contour coinciding with the corresponding standard contour, determining the transmission line model corresponding to the area contour as having intact properties; In response to the area profile being larger than the corresponding standard profile, determining the transmission line model corresponding to the area profile as a transition attribute; In response to the region profile being smaller than the corresponding standard profile, the transmission line model corresponding to the region profile is determined as a missing attribute.

[0036] For example, in this embodiment, the above comparison process can be described as follows: First, after obtaining the corresponding regional contour and the standard contour, the corresponding regional contour and the standard contour can be compared and analyzed based on the coincidence relationship to detect the coincidence degree between the regional contour and the standard contour; If the degree of overlap between the regional contour and the corresponding standard contour is greater than or equal to the preset overlap threshold, or is exactly the same, then the transmission line model corresponding to the regional contour is determined to have intact properties, indicating that its shape and size meet the design requirements, that is, there are no corresponding defects; If the regional contour completely coincides with or approximately coincides with the corresponding standard contour, the transmission line model corresponding to the regional contour is judged to have intact properties, indicating that its shape and size meet the design requirements, that is, there are no corresponding defects; If the area outline is larger than the corresponding standard outline, it is determined that the transmission line model corresponding to the area outline has an excessive attribute, that is, the transmission line model is over-etched and some structures are added; If the regional outline is smaller than the corresponding standard outline, it is determined that the transmission line model corresponding to the regional outline has a missing attribute, that is, the transmission line model has missing etching and lacks certain structures.

[0037] In addition, in this embodiment, based on the above content, it can be known that when the detection attribute of the corresponding transmission line film line is determined, 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 missing repair of the transmission line model, thereby completing the supplement of the corresponding missing part, and the corresponding "in response 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: In response to the transmission line model having a missing attribute, determining a repair region corresponding to the standard profile and covering the transmission line model, and a physical region corresponding to the transmission line model on a side of the epitaxial layer away from the buffer layer; Performing a region comparison between the entity region and the repair region, and determining a missing sub-region that exists only in the repair region based on the comparison result; forming a defect repair layer on a side of the epitaxial layer away from the buffer layer, and patterning the defect repair layer to form a repair mask layer covering all regions except the defect sub-region; The epitaxial layer is etched based on the repair mask layer to obtain a repaired transmission line model.

[0038] For example, when the detection attribute of the corresponding transmission line model is a missing attribute, it indicates that the transmission line model lacks the corresponding part to be etched. Therefore, the missing part needs to be supplemented with etching. The corresponding process includes: First, similar to the above patterning process, a repair area corresponding to the standard contour 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 contour. It can be determined that the repair area should be larger than the image area corresponding to the transmission line model and can cover the transmission line model. Then, the physical area of ​​the corresponding transmission line model can be synchronously determined, and the physical area and the repair area are compared to obtain the missing sub-area existing in the repair area, wherein, since the missing sub-area only exists in the sub-area of ​​the repair area, the missing sub-area is the area of ​​the missing part of the corresponding transmission line model; Next, a defect repair layer may be formed on the side of the epitaxial layer away from the buffer layer (wherein the material of the defect repair layer may be the same as the material of the photoresist layer mentioned above, that is, both are photoresists), and the defect repair layer may be further patterned to form a repair mask layer covering all areas except the defect sub-area; Finally, the corresponding epitaxial layer can be etched based on the repair mask layer. Since the repair mask layer covers all areas except the missing sub-area, it is possible to only etch the missing sub-area, thereby completing the model repair of the transmission line model.

[0039] 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 implemented based on the above method steps to obtain a repaired transmission line model; and when the detection attribute of the corresponding transmission line model is an excessive attribute, that is, the corresponding epitaxial layer is over-etched, then the corresponding repair cannot be performed based on the above method steps. Therefore, it is necessary to further perform a quality assessment on the corresponding transmission line model with an excessive attribute according to the etching condition to determine whether the transmission line model meets the production conditions. Therefore, in this embodiment, the following steps may also be included: In response to the transmission line model having a transition attribute, determining a transition area corresponding to the transmission line model based on a profile comparison between the regional profile and the standard profile based on a coincidence relationship; The transition areas of all transmission line models with missing attributes are summed up, and the area evaluation value of the corresponding area dimension is determined based on the obtained summary area; Obtaining model quantities corresponding to all transmission line models having missing attributes, and determining quantity evaluation values ​​corresponding to quantity dimensions based on the model quantities; The area evaluation value and the quantity evaluation value are respectively multiplied by the retrieved area weight value and the quantity weight value, and the sum is calculated based on the obtained first evaluation value and the second evaluation value to obtain an over-evaluation value; In response to the over-evaluation value being greater than the retrieved preset evaluation threshold, the silicon carbide substrate is marked as scrapped.

[0040] For example, in this embodiment, the evaluation process for the transmission line model with transition attributes may be specifically described as follows: First, the transition area corresponding to the transmission line model can be determined by comparing the aforementioned regional profile with the standard profile. Here, the transition area can be understood as the area corresponding to the over-etching. Then, if Figure 2-4 As shown, since the transmission line model may include multiple ones, the corresponding transition areas of all the transmission line models corresponding to the transition attributes may be summed up to obtain the corresponding summary area, and the area evaluation value of the corresponding area dimension may be obtained by multiplying the summary area with the retrieved area normalization value; Then, after the area evaluation value of the corresponding area dimension is obtained, the model quantity of all transmission line models corresponding to the transition attribute can be further obtained, and the quantity evaluation value of the corresponding quantity dimension can be obtained by multiplying the model quantity with the retrieved quantity normalization value; Then, by performing corresponding product calculations on the obtained area evaluation value and quantity evaluation value and the retrieved area weight value and quantity weight value, the corresponding first evaluation value and second evaluation value can be obtained. Further, based on the sum of the first evaluation value and the second evaluation value, the corresponding over-evaluation value can be obtained. Finally, by comparing the over-evaluation value with the preset evaluation threshold, and when the over-evaluation value is greater than the preset evaluation threshold, the silicon carbide substrate is marked for scrapping, thereby completing the corresponding production evaluation and completing product screening based on production requirements, thereby improving the corresponding product yield.

[0041] It should be noted that, in this embodiment, the above-mentioned preset evaluation threshold can be set in advance by production personnel, and this embodiment does not limit its specific value.

[0042] Furthermore, it can be explained that, in this embodiment, since the over-assessment value is obtained based on automated calculations, it may differ from the actual situation. In order to improve the corresponding determination accuracy, the corresponding quantity weight values ​​and area weight values ​​are updated and adjusted in real time through the following method steps, thereby realizing the process of updating and iterating each weight value, and thus continuously improving the corresponding determination accuracy.

[0043] Specifically, the process of updating and iterating each weight value can be described as follows: Acquire an actual evaluation value inputted by the transmission line model at the product production end, and compare the over-evaluation value with the actual evaluation value by score; When the actual evaluation value is greater than the over-evaluation value, increasing training is performed on the quantity weight value and the area weight value; When the actual evaluation value is less than the over-evaluation value, performing reduction training on the quantity weight value and the area weight value; The number weight value and area weight value after training are obtained through the following formula: in, is the quantity weight value Increase the number of training sessions. is the quantity weight value The training constant value of is the quantity weight value Reduce the number of training sessions. is the quantity weight value after training, is the area weight value Increase the number of training sessions. is the area weight value The training constant value of is the area weight value Reduce the number of training sessions. is the area weight value after training.

[0044] It can be explained that the above-mentioned product production end can be understood as a terminal used by corresponding production personnel, such as a mobile phone or a computer.

[0045] In step S105, the following contents are included: Metal deposition is performed on the transmission line model to form a metal layer located on the transmission line model, wherein the metal layer includes a titanium metal layer, a titanium carbide metal layer and a platinum metal layer which are stacked.

[0046] For example, in this embodiment, after the corresponding transmission line model is formed, corresponding metal deposition can be further performed on the transmission line model by means of metal deposition, so as to form a metal layer located above the transmission line model, wherein the metal layer can include a corresponding stacked titanium metal layer, a titanium carbide metal layer and a corresponding platinum metal layer.

[0047] Furthermore, in this embodiment, the above-mentioned “performing metal deposition on the transmission line model to form a metal layer located 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 also include the following steps: Using a direct current magnetron sputtering process to perform metal deposition based on titanium metal on the transmission line model to form a titanium metal layer located on the transmission line model; Using a direct current magnetron sputtering process, a titanium carbide metal-based metal deposition is performed on a side of the titanium metal layer away from the epitaxial layer to form a titanium carbide metal layer located on the titanium metal layer; A direct current magnetron sputtering process is used to perform platinum metal deposition on a side of the titanium carbide metal layer away from the titanium metal layer to form a platinum metal layer located on the titanium carbide metal layer.

[0048] For example, in this embodiment, the deposition process of the metal layer may be specifically described as follows: First of all, it can be seen from the above content that when etching the corresponding transmission line model, the shielding layer formed is mainly used as a mask. Therefore, when depositing the corresponding metal layer, the shielding layer can be used as a mask again to deposit the metal layer. For the titanium metal layer, a DC magnetron sputtering process can be used to directly deposit a titanium metal on the epitaxial layer side of the silicon carbide structure to form a titanium metal layer located above the transmission line model; wherein the purity of the titanium target can be 99.999%, and the thickness of the corresponding titanium metal layer formed by sputtering can be 500 Å, the deposition power is 500 W, the deposition rate is 616 Å / min, the gas flow rate is 14 Ar / sccm, and the vacuum degree in the cavity is ≤5e -6 mTorr ; Then, similarly, the shielding layer can be used as a mask to deposit the corresponding titanium carbide metal, and the process used can also be a DC magnetron sputtering process to form a titanium carbide metal layer located on the titanium metal layer; wherein the purity of the titanium carbide target is 99.999%, the thickness of the corresponding titanium carbide metal layer formed by sputtering is 2000Å, the deposition power is 500W, the deposition rate is 717.4Å / min, the gas flow rate is 14Ar / sccm, and the vacuum degree in the chamber is ≤5e -6 mTorr; Finally, the shielding layer can be used as a mask again to deposit the corresponding platinum metal. The process used can also be a DC magnetron sputtering process to form a platinum metal layer on the titanium carbide metal layer; the purity of the platinum target is 99.999%, and the thickness of the corresponding platinum metal layer formed by sputtering is 1000Å. The corresponding sputtering process can be divided into two steps: first, the corresponding parameters of deposition power of 500W and deposition rate of 900Å / min can be used to sputter 200Å; secondly, the deposition power of 100w and deposition rate of 178.8Å / min are used. The gas flow rate is 14Ar / sccm and the vacuum degree in the chamber is ≤5e -6The corresponding parameters of mTorr are used to sputter 800Å; the high-power sputtering performed first can make the metal film form quickly, while the low-power sputtering performed later can ensure that the formed metal layer is dense, thereby improving the corresponding preparation quality.

[0049] In step S106, the following contents are included: The metal layer is annealed to form an ohmic contact electrode structure.

[0050] For example, in this embodiment, after the above-mentioned metal deposition is completed, the corresponding shielding layer can be removed, and the corresponding formed metal layer can be annealed, thereby forming a corresponding ohmic contact electrode structure.

[0051] It should be noted that, since the blocking layer is formed by photoresist, the corresponding silicon carbide structure can be placed in acetone for ultrasonic immersion to completely remove the blocking layer, and then the silicon carbide structure can be further placed in anhydrous ethanol and deionized water for ultrasonic immersion, so as to remove the acetone remaining on the surface of the silicon carbide structure; here, the ultrasonic immersion time can be 5 minutes or 10 minutes.

[0052] Furthermore, in this embodiment, the above-mentioned “annealing the metal layer to form an ohmic contact electrode structure” may also include the following steps: The silicon carbide structure is placed in a nitrogen atmosphere, and an annealing operation is performed on the metal layer at a preset annealing temperature for a preset annealing time to form an ohmic contact electrode structure.

[0053] For example, when annealing the metal layer, the silicon carbide structure needs to be placed in a corresponding nitrogen atmosphere, and the corresponding metal layer is annealed at a corresponding preset annealing temperature for a preset annealing time to form a 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 to 150 seconds.

[0054] It can be explained that, in this embodiment, since surface impurity contamination is an important factor in forming the surface state of SiC, and the corresponding hydrogen plasma treatment has a surface passivation effect, ECR hydrogen plasma can produce low-energy (<2eV) high ionization, high concentration and high activation plasma, which does not cause ion radiation damage to the sample, and its strong reactivity can also remove C and OH- and F- impurity ions on the surface, and can reduce the oxygen content and enhance the surface oxidation resistance; Secondly, Ti reacts with SiC to generate TiC. After the DC magnetron sputtering process, the work function of the TiC 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. In addition, the melting point of TiC reaches 3150℃, and it is difficult to decompose and generate other substances under high temperature conditions, which improves the thermal stability of the ohmic contact. Furthermore, the Pt layer included in the metal layer can bind C generated by the reaction between Ti and SiC to prevent free C atoms from aggregating on the surface and causing the surface to become rough or ineffective. The Pt layer is key to preventing the oxidation of the ohmic contact electrode and effectively delays the diffusion of O to the interface.

[0055] To sum up, the corresponding stacked titanium metal layers, titanium carbide metal layers and platinum metal layers have good performance in high temperature and air environments, and have great advantages in application in high temperature and air environments, including the ability to maintain stable electrical properties in high temperature environments and to achieve low contact resistivity, which is very important for improving the efficiency and performance of the device, and the stacked titanium metal layers, titanium carbide metal layers and platinum metal layers can achieve effective control of the metal / SiC contact performance through effective interface regulation technology, and 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 properties, low resistivity and good chemical and mechanical stability, which plays an important role in improving the performance and reliability of SiC-based devices.

[0056] Another embodiment of the present invention provides an n-type SiC high temperature resistant ohmic contact electrode structure, which is mainly prepared by the n-type SiC high temperature resistant ohmic contact electrode structure preparation method mentioned in the above embodiment, wherein the n-type SiC high temperature resistant ohmic contact electrode structure includes: A stacked silicon carbide substrate, a buffer layer, and an epitaxial layer; A transmission line model is formed on one side of the epitaxial layer away from the buffer layer, a metal layer is arranged 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.

[0057] For example, in this embodiment, in order to verify the electrical properties 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 conjunction 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, unequally spaced rectangular ohmic contact electrodes can be prepared on a strip semiconductor material insulated from the surrounding environment, with an electrode length of L, a width of W, and a spacing of d between the electrodes. A constant current I is passed between the rectangular electrodes at different distances dn, the corresponding voltage value V is measured, and the total resistance value R is obtained. Further, a graph is drawn with the electrode spacing dn as the horizontal axis and the total resistance value R as the vertical axis to connect the test points into a straight line to obtain the following: Figure 5 The resistance volt-ampere characteristic curve shown in the figure shows the corresponding electrical characteristics, where Figure 5 In the figure, Current refers to the constant current and Voltage refers to the voltage value.

[0058] In the description provided herein, algorithms and displays are not inherently related to any particular computer, virtual system or other device. Various general purpose systems can also be used together with the examples of the present invention. According to the above description, it is obvious that the structure required for constructing such systems. In addition, the present invention is not directed to any specific programming language either. It should be understood that various programming languages ​​can be utilized to implement the content of the present invention described herein, and the above description of specific languages ​​is for the purpose of disclosing the preferred embodiment of the present invention.

[0059] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0060] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof.

[0061] Those skilled in the art will appreciate that the modules or units or components of the devices in the examples disclosed herein may be arranged in the devices described in the embodiment, or alternatively may be located in one or more devices different from the devices in the examples. The modules in the foregoing examples may be combined into one module or may be divided into multiple submodules.

[0062] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and furthermore may be divided into a plurality of submodules or subunits or subcomponents.

[0063] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features from different embodiments is meant to be within the scope of the present invention and to form different embodiments.

[0064] In addition, some of the embodiments are described herein as methods or combinations of method elements that can be implemented by a processor of a computer system or by other devices that perform the functions. Therefore, a processor with necessary instructions for implementing the method or method elements forms a device for implementing the method or method elements. In addition, the elements described herein of the device embodiments are examples of devices for implementing the functions performed by the elements for the purpose of implementing the invention.

[0065] As used herein, unless otherwise specified, the use of ordinal numbers "first," "second," "third," etc. to describe common objects merely indicates that different instances of similar objects are involved, and is not intended to imply that the objects so described must have a given order in time, space, order, or in any other manner.

[0066] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is primarily selected for readability and instructional purposes, rather than for explaining or limiting the subject matter of the present invention.

Claims

1. A method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure, characterized in that: The following steps are involved: Cleaning a silicon carbide structure, wherein the silicon carbide structure includes a stacked silicon carbide substrate, a buffer layer, and an epitaxial layer; Oxidizing the cleaned silicon carbide structure to form a silicon oxide layer located on the epitaxial layer; Removing the silicon oxide layer based on wet etching, and performing hydrogen plasma treatment on the epitaxial layer after completing the removal of the silicon oxide layer; forming a photoresist layer on a side of the epitaxial layer away from the buffer layer, and patterning the photoresist layer to form a shielding layer; Using the blocking layer as a mask, etching the epitaxial layer to form a transmission line model located on the epitaxial layer, wherein the transmission line model includes a rectangular transmission model and a circular transmission model; Performing metal deposition on the transmission line model to form a metal layer located on the transmission line model, wherein the metal layer includes a stacked titanium metal layer, a titanium carbide metal layer and a platinum metal layer; The metal layer is annealed to form an ohmic contact electrode structure.

2. The method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure according to claim 1, characterized in that: forming a transmission line model located on the epitaxial layer, and then further comprising: In response to completing the formation of the transmission line model, controlling 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; Determine an image region corresponding to the transmission line model based on the upper view of the model, and determine a region contour corresponding to the image region; Retrieving a standard contour corresponding to the transmission line model, performing contour comparison between the regional contour and the standard contour, and determining the detection attributes of the transmission line model based on the comparison result, wherein the detection attributes include intact attributes, missing attributes, and excessive attributes; In response to the transmission line model having a missing attribute, a preset missing repair operation is performed on the transmission line model.

3. The method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure according to claim 2, characterized in that: Contour comparison of region contours with standard contours, including: Compare the regional contour with the standard contour based on the coincidence relationship; In response to the area contour coinciding with the corresponding standard contour, determining the transmission line model corresponding to the area contour as having intact properties; In response to the area profile being larger than the corresponding standard profile, determining the transmission line model corresponding to the area profile as a transition attribute; In response to the region profile being smaller than the corresponding standard profile, the transmission line model corresponding to the region profile is determined as a missing attribute.

4. The method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure according to claim 3, 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, including: In response to the transmission line model having a missing attribute, determining a repair region corresponding to the standard profile and covering the transmission line model, and a physical region corresponding to the transmission line model on a side of the epitaxial layer away from the buffer layer; Performing a region comparison between the entity region and the repair region, and determining a missing sub-region that exists only in the repair region based on the comparison result; forming a defect repair layer on a side of the epitaxial layer away from the buffer layer, and patterning the defect repair layer to form a repair mask layer covering all regions except the defect sub-region; The epitaxial layer is etched based on the repair mask layer to obtain a repaired transmission line model.

5. The method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure according to claim 3, characterized in that: The method further comprises: In response to the transmission line model having a transition attribute, determining a transition area corresponding to the transmission line model based on a profile comparison between the regional profile and the standard profile based on a coincidence relationship; The transition areas of all transmission line models with transition attributes are summed up and the area evaluation value of the corresponding area dimension is determined based on the obtained summary area; Obtaining model quantities corresponding to all transmission line models with transition attributes, and determining quantity evaluation values ​​corresponding to quantity dimensions based on the model quantities; The area evaluation value and the quantity evaluation value are respectively multiplied by the retrieved area weight value and the quantity weight value, and the sum is calculated based on the obtained first evaluation value and the second evaluation value to obtain an over-evaluation value; In response to the over-evaluation value being greater than the retrieved preset evaluation threshold, the silicon carbide substrate is marked as scrapped.

6. The method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure according to claim 5, characterized in that: The method further comprises: Acquire an actual evaluation value inputted by the transmission line model at the product production end, and compare the over-evaluation value with the actual evaluation value by score; When the actual evaluation value is greater than the over-evaluation value, increasing training is performed on the quantity weight value and the area weight value; When the actual evaluation value is less than the over-evaluation value, performing reduction training on the quantity weight value and the area weight value; The number weight value and area weight value after training are obtained through the following formula: in, is the quantity weight value Increase the number of training sessions. is the quantity weight value The training constant value of is the quantity weight value Reduce the number of training sessions. is the quantity weight value after training, is the area weight value Increase the number of training sessions. is the area weight value The training constant value of is the area weight value Reduce the number of training sessions. is the area weight value after training.

7. The method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure according to claim 1, characterized in that: Performing metal deposition on the transmission line model to form a metal layer located 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 direct current magnetron sputtering process to perform metal deposition based on titanium metal on the transmission line model to form a titanium metal layer located on the transmission line model; Using a direct current magnetron sputtering process, a titanium carbide metal-based metal deposition is performed on a side of the titanium metal layer away from the epitaxial layer to form a titanium carbide metal layer located on the titanium metal layer; A direct current magnetron sputtering process is used to perform platinum metal deposition on a side of the titanium carbide metal layer away from the titanium metal layer to form a platinum metal layer located on the titanium carbide metal layer.

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

9. An ohmic contact electrode structure obtained by the method for preparing an n-type SiC high temperature resistant ohmic contact electrode structure according to any one of claims 1 to 8, characterized in that: include: A stacked silicon carbide substrate, a buffer layer, and an epitaxial layer; A transmission line model is formed on one side of the epitaxial layer away from the buffer layer, a metal layer is arranged 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.

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