A method of manufacturing a dielectric structure, a dielectric structure

Abstract

The application belongs to the technical field of semiconductors, and provides a preparation method of a dielectric structure and a dielectric structure. The preparation method of the dielectric structure comprises the following steps: adopting a silicon nitride layer as a protective layer, performing oxidation treatment on the silicon nitride layer between the protective layer and a substrate to form a dielectric layer, and forming a contact metal layer with an angle at the position of the silicon nitride layer. In this way, the semiconductor reverse electric field of the metal edge of the metal semiconductor contact part is improved, and the purpose of improving the reverse withstand voltage and reliability of a power device is achieved.

Description

Technical Field

[0001] This application belongs to the field of semiconductor technology, and in particular relates to a method for preparing a dielectric structure and the dielectric structure itself. Background Technology

[0002] In the field of power electronics, various power components are frequently used. When an external voltage is applied, the metal edge of the metal-semiconductor contact (metal-semiconductor contact) in the power component usually exhibits a high reverse bias voltage, which limits the maximum reverse bias voltage of the device and reduces the reliability of the device. Summary of the Invention

[0003] To achieve the above objectives, embodiments of this application provide a method for fabricating a dielectric structure and a dielectric structure, which aims to create an angled dielectric layer at the edge of the gold-semiconductor contact to improve the reverse bias voltage and reliability of the device.

[0004] This application provides a method for preparing a dielectric structure, the method comprising:

[0005] A first semiconductor layer is formed on a substrate, the first semiconductor layer including a first semiconductor region and a second semiconductor region adjacent to the first semiconductor region;

[0006] A silicon nitride layer is formed on the first semiconductor region;

[0007] Using the silicon nitride layer as a protective layer, the first semiconductor material in the second semiconductor region is oxidized to form a dielectric layer;

[0008] Remove the silicon nitride layer;

[0009] Remove the first semiconductor region and form a contact metal layer at the location of the first semiconductor region.

[0010] In one embodiment, the step of oxidizing the first semiconductor material in the second semiconductor region using the silicon nitride layer as a protective layer to form a dielectric layer includes:

[0011] Under the protection of the silicon nitride layer, an oxidation process is used to process the first semiconductor material in the second semiconductor region to form a dielectric layer.

[0012] In one embodiment, the angle between the dielectric layer and the substrate is 20°-80°.

[0013] In one embodiment, the step of processing the first semiconductor material in the second semiconductor region using an oxidation process under the protection of the silicon nitride layer to form a dielectric layer includes:

[0014] The second semiconductor region is heated in an oxygen environment to oxidize the first semiconductor material in the second semiconductor region to form the dielectric layer, wherein the angle between the dielectric layer and the substrate is directly proportional to the heating time.

[0015] In one embodiment, the step of processing the first semiconductor material in the second semiconductor region using an oxidation process under the protection of the silicon nitride layer to form a dielectric layer includes:

[0016] Under the protection of the silicon nitride layer, oxygen ions are implanted into the second semiconductor region to form the dielectric layer, wherein the angle between the dielectric layer and the substrate is determined by the implantation angle of the oxygen ions.

[0017] In one embodiment, forming the first semiconductor layer on the substrate includes:

[0018] Silicon material is deposited on a silicon carbide substrate to form the first semiconductor layer.

[0019] In one embodiment, forming a silicon nitride layer on the first semiconductor region includes:

[0020] A silicon nitride layer is formed by depositing silicon nitride on the first semiconductor region using a contact metal mask.

[0021] In one embodiment, removing the first semiconductor region includes:

[0022] The first semiconductor region is etched using a hydrofluoric acid solution to remove the first semiconductor material within the first semiconductor region.

[0023] In one embodiment, forming a contact metal layer at the location of the first semiconductor region includes:

[0024] A contact metal layer is formed at the location of the first semiconductor region by depositing a metal material using a contact metal mask layer.

[0025] A second aspect of this application also provides a dielectric structure, which is prepared using the preparation method described in any of the preceding embodiments.

[0026] This application provides a method for fabricating a dielectric structure and the dielectric structure itself. By using a silicon nitride layer as a protective layer, the silicon nitride layer between the silicon nitride layer and the substrate is oxidized to form a dielectric layer, and an angled contact metal layer is formed at the position of the silicon nitride layer. This enhances the reverse electric field of the metal edge of the metal semiconductor contact portion, thereby improving the reverse breakdown voltage and reliability of the power device. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic flowchart of a method for preparing a dielectric structure according to an embodiment of this application;

[0029] Figure 2 This is a schematic diagram of a structure in which a first semiconductor layer is formed on a substrate, according to an embodiment of this application;

[0030] Figure 3 This is a schematic diagram of a structure in which a silicon nitride layer is formed on a first semiconductor region according to an embodiment of this application;

[0031] Figure 4 This is a schematic diagram of the structure for forming a dielectric layer provided in one embodiment of this application;

[0032] Figure 5 This is a schematic diagram of a structure for removing the silicon nitride layer according to an embodiment of this application;

[0033] Figure 6 This is a schematic diagram of a structure with the first semiconductor region removed, provided in one embodiment of this application;

[0034] Figure 7 This is a schematic diagram of the structure for forming a metal contact layer according to an embodiment of this application. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application.

[0036] The term "comprising," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or apparatus that comprises a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus. Furthermore, the terms "first," "second," and "third," etc., are used to distinguish different objects, not to describe a specific order.

[0037] When an external voltage is applied to a power component, the metal edge at the metal-semiconductor contact (metal-semiconductor contact) often has the greatest reverse bias. Therefore, the reverse bias at the metal edge limits the maximum reverse bias of the device and reduces the reliability of the device.

[0038] To address these issues, device engineers have proposed numerous compensation methods for both three-dimensional and planar structures. These methods employ potential edge ring technology, which involves reverse doping or reducing the doping concentration at a suitable distance from the metal edge to improve the reverse breakdown voltage of the metal-semiconductor contact edge. Alternatively, single-layer or multi-layer junction termination extensions (JTEs) can be used to alter the electric field distribution. However, these solutions typically increase the manufacturing cost of devices, leading to a decrease in product competitiveness.

[0039] This application provides a method for preparing a dielectric structure; see [link to relevant documentation]. Figure 1 As shown, the preparation method includes steps S100 to S500.

[0040] In step S100, a first semiconductor layer is formed on the substrate, the first semiconductor layer including a first semiconductor region and a second semiconductor region adjacent to the first semiconductor region.

[0041] Combination Figure 2 As shown, a first semiconductor layer 120 is formed on a substrate 110. The first semiconductor layer 120 is divided into a first semiconductor region 121 and a second semiconductor region 122, which are adjacent to each other.

[0042] In some embodiments, the substrate 110 may be silicon carbide, and the first semiconductor layer 120 may be a silicon layer formed by depositing silicon material on the silicon carbide layer.

[0043] In a specific application embodiment, step S100, forming a first semiconductor layer on the substrate, includes: depositing silicon material on a silicon carbide substrate to form a first semiconductor layer.

[0044] In this embodiment, a silicon carbide substrate is used as the substrate 110, and a first semiconductor layer 120 is formed on the silicon carbide substrate by depositing a first semiconductor material (e.g., silicon material).

[0045] In step S200, a silicon nitride layer is formed on the first semiconductor region.

[0046] Combination Figure 3 As shown, a silicon nitride layer 210 is formed on the first semiconductor region 121.

[0047] In a specific application embodiment, in one embodiment, forming a silicon nitride layer on the first semiconductor region includes: depositing silicon nitride on the first semiconductor region using a contact metal mask to form a silicon nitride layer.

[0048] In this embodiment, a contact metal mask can be used as a mask to deposit a second semiconductor material on the first semiconductor region 121 to form a silicon nitride layer 210.

[0049] In some embodiments, the contact metal mask can be a photoresist, and its pattern is designed to determine the position of the contact metal layer. For example, the contact metal layer can be formed by depositing metal in its exposed area. In this embodiment, a second semiconductor material is deposited on the first semiconductor region 121 to form a silicon nitride layer 210 using the same contact metal mask. The dielectric structure can be fabricated using a single mask, saving the number of masks required.

[0050] In some embodiments, the silicon nitride layer 210 may be silicon nitride.

[0051] In some embodiments, the thickness of the silicon nitride layer 210 is less than the thickness of the first semiconductor layer 120.

[0052] In some embodiments, the thickness of the silicon nitride layer 210 can be 1-3 μm.

[0053] In step S300, the first semiconductor material in the second semiconductor region is oxidized using the silicon nitride layer as a protective layer to form a dielectric layer.

[0054] Combination Figure 4 As shown, the first semiconductor material of the second semiconductor region 122 is oxidized using a silicon nitride layer 210 as a protective layer to form a dielectric layer 31, which can form an angled dielectric layer 310 without adding an additional photomask.

[0055] Specifically, during the oxidation process, oxygen ions enter the silicon nitride layer 210 and react with the second semiconductor material inside it. At this time, the volume of the second semiconductor region 122 increases, and there is an angle between the dielectric layer 310 formed and the substrate 110. By forming a dielectric layer 310 with an angle, the performance and reliability of the device can be improved.

[0056] In specific applications, since oxygen ions are implanted into the first semiconductor material of the second semiconductor region 122, due to the shielding of the silicon nitride layer 210, the closer the oxygen ions are to the silicon nitride layer 210, the more difficult it is for oxygen ions to enter the first semiconductor material under the silicon nitride layer 210, while the farther away the oxygen ions are from the silicon nitride layer 210, the easier it is for oxygen ions to enter. Therefore, the width of the dielectric layer portion near the substrate 110 is greater than the width of the dielectric layer portion far from the substrate 110, and at this time an angle is formed between the dielectric layer 310 and the substrate 110.

[0057] In some embodiments, the dielectric layer 310 may be divided into multiple dielectric regions, each with the same thickness, and the width of each dielectric region is inversely proportional to the distance between the dielectric layer and the substrate 110.

[0058] In some embodiments, the dielectric layer 310 may be trapezoidal.

[0059] In some embodiments, the angle between the dielectric layer 310 and the substrate 110 can be in the range of 20°-80°.

[0060] In one embodiment, step S300, using the silicon nitride layer as a protective layer, involves oxidizing the first semiconductor material in the second semiconductor region to form a dielectric layer, including:

[0061] Under the protection of the silicon nitride layer, an oxidation process is used to process the first semiconductor material in the second semiconductor region to form a dielectric layer.

[0062] Specifically, in this embodiment, the first semiconductor material in the second semiconductor region 122 can be oxidized by an oxidation process to form a dielectric layer 310.

[0063] For example, by injecting oxygen, the first semiconductor material in the second semiconductor region 122, which is not protected by the silicon nitride layer 210, undergoes an oxidation reaction, thereby forming the dielectric layer 310.

[0064] In some embodiments, the oxidation process in the above embodiments can be thermal oxidation, and the oxygen flow rate can be set according to the application scenario or determined according to the thickness of the second semiconductor region 122.

[0065] In one embodiment, step S300 involves processing the first semiconductor material in the second semiconductor region using an oxidation process under the protection of the silicon nitride layer to form a dielectric layer, including:

[0066] The second semiconductor region is heated in an oxygen environment to oxidize the first semiconductor material of the second semiconductor region to form the dielectric layer, wherein the angle between the dielectric layer 310 and the substrate 110 is directly proportional to the heating time.

[0067] In this embodiment, the device prepared in step S200 is placed in an oxygen environment and the reaction environment is heated, so that the first semiconductor material in the second semiconductor region 122 undergoes a thermal oxidation reaction, thereby forming a dielectric layer 310.

[0068] In practical applications, the angle between the dielectric layer 310 and the substrate 110 is directly proportional to the heating time. At this time, the longer the heating time, the more oxygen the second semiconductor region 122 absorbs, the thicker the dielectric layer 310 becomes, and the larger the angle between the dielectric layer 310 and the substrate 110 becomes. The shorter the heating time, the smaller the angle between the dielectric layer 310 and the substrate 110 becomes.

[0069] In one embodiment, step S300 involves processing the first semiconductor material in the second semiconductor region using an oxidation process under the protection of the silicon nitride layer to form a dielectric layer, including:

[0070] Under the protection of the silicon nitride layer, oxygen ions are implanted into the second semiconductor region to form the dielectric layer, wherein the angle between the dielectric layer and the substrate is determined by the implantation angle of the oxygen ions.

[0071] In this embodiment, oxygen ions can be implanted into the second semiconductor region 122 under the protection of the silicon nitride layer 210 to form a dielectric layer 310. For example, oxygen ions can be implanted into the second semiconductor region 122 by ion implantation. The angle between the dielectric layer 310 and the substrate 110 is determined by the implantation angle of the oxygen ions.

[0072] In step S400, the silicon nitride layer is removed.

[0073] Combination Figure 5 As shown, after the dielectric layer 310 is formed, the silicon nitride layer 210, which serves as a protective layer, is removed.

[0074] In step S500, the first semiconductor region is removed, and a contact metal layer is formed at the location of the first semiconductor region.

[0075] Combination Figure 6 As shown, after removing the silicon nitride layer 210, the first semiconductor region 121 is further removed.

[0076] In one embodiment, removing the first semiconductor region 121 specifically includes: etching the first semiconductor region 121 with a hydrofluoric acid solution to remove the first semiconductor material within the first semiconductor region 121.

[0077] Specifically, by preparing an appropriate amount of hydrofluoric acid solution, the first semiconductor material in the first semiconductor region 121 is etched to remove all the first semiconductor material in the first semiconductor region 121.

[0078] In one specific application embodiment, the substrate 110 is made of silicon carbide, the first semiconductor material in the first semiconductor region 121 is made of silicon, and the dielectric layer 310 is made of silicon oxide. By utilizing the hydrofluoric acid resistance of silicon carbide, the angled dielectric layer 310 is prepared without adding a photomask.

[0079] Hydrofluoric acid solution is corrosive to both silicon and silicon oxide materials. Due to the different corrosion rates and the fact that the thickness of dielectric layer 310 is greater than the thickness of the first semiconductor region 121, the etching is completed when the first semiconductor material in the first semiconductor region 121 is completely eliminated.

[0080] In specific applications, the first semiconductor material, the second semiconductor material, and the substrate material can meet the etching selectivity ratio, and are not limited to the silicon carbide substrate and silicon dioxide dielectric layer in the above embodiments.

[0081] Combination Figure 7 As shown, after removing the first semiconductor material in the first semiconductor region 121, the position of the contact metal layer 410 is determined by a contact metal mask, and then the contact metal layer 410 is formed at the position of the first semiconductor region 121 by depositing metal material under the cover of the contact metal mask.

[0082] This application also provides a dielectric structure, which is prepared using the preparation method described in any of the above embodiments.

[0083] This application provides a method for fabricating a dielectric structure and the dielectric structure itself. By using a silicon nitride layer as a protective layer, the silicon nitride layer between the silicon nitride layer and the substrate is oxidized to form a dielectric layer, and an angled contact metal layer is formed at the position of the silicon nitride layer. This enhances the reverse electric field of the metal edge of the metal semiconductor contact portion, thereby improving the reverse breakdown voltage and reliability of the power device.

[0084] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described steps are merely examples. In practical applications, the above steps can be completed by different functional units or modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0085] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0086] The functional areas in each step may or may not be physically separated. A functional area may or may not be a physical unit; it may be located in one place or distributed across multiple areas. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0087] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for preparing a dielectric structure, characterized in that, The preparation method includes: A first semiconductor layer is formed on a substrate, the first semiconductor layer including a first semiconductor region and a second semiconductor region adjacent to the first semiconductor region; A silicon nitride layer is formed on the first semiconductor region; Using the silicon nitride layer as a protective layer, the first semiconductor material in the second semiconductor region is oxidized to form a dielectric layer; Remove the silicon nitride layer; Remove the unoxidized portion of the first semiconductor region to form an angle between the dielectric layer and the substrate, and form a contact metal layer at the location of the first semiconductor region to form the angled contact metal layer.

2. The preparation method according to claim 1, characterized in that, The step of oxidizing the first semiconductor material in the second semiconductor region using the silicon nitride layer as a protective layer to form a dielectric layer includes: Under the protection of the silicon nitride layer, an oxidation process is used to process the first semiconductor material in the second semiconductor region to form a dielectric layer.

3. The preparation method according to claim 2, characterized in that, The dielectric layer and the contact metal layer have a contact interface, and the angle between the contact interface and the substrate is 20°-80°.

4. The preparation method according to claim 2, characterized in that, The process of forming a dielectric layer by treating the first semiconductor material in the second semiconductor region using an oxidation process under the protection of the silicon nitride layer includes: The second semiconductor region is heated in an oxygen environment to oxidize the first semiconductor material in the second semiconductor region to form the dielectric layer, wherein the angle between the dielectric layer and the substrate is directly proportional to the heating time.

5. The preparation method according to claim 2, characterized in that, The process of forming a dielectric layer by treating the first semiconductor material in the second semiconductor region using an oxidation process under the protection of the silicon nitride layer includes: Under the protection of the silicon nitride layer, oxygen ions are implanted into the second semiconductor region to form the dielectric layer, wherein the angle between the dielectric layer and the substrate is determined by the implantation angle of the oxygen ions.

6. The preparation method according to claim 1, characterized in that, The formation of the first semiconductor layer on the substrate includes: Silicon material is deposited on a silicon carbide substrate to form the first semiconductor layer.

7. The preparation method according to claim 6, characterized in that, The step of forming a silicon nitride layer on the first semiconductor region includes: A silicon nitride layer is formed by depositing silicon nitride on the first semiconductor region using a contact metal mask.

8. The preparation method according to claim 7, characterized in that, The removal of the first semiconductor region includes: The first semiconductor region is etched using a hydrofluoric acid solution to remove the first semiconductor material within the first semiconductor region.

9. The preparation method according to claim 7, characterized in that, The formation of a contact metal layer at the location of the first semiconductor region includes: A contact metal layer is formed at the location of the first semiconductor region by depositing a metal material using a contact metal mask layer.

10. A dielectric structure, characterized in that, The dielectric structure is prepared using the preparation method described in any one of claims 1-9.

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