Power device and preparation method thereof, power module, power conversion circuit and vehicle

Abstract

The invention discloses a power device and a preparation method thereof, a power module, a power conversion circuit and a vehicle. The preparation method comprises the following steps: forming an epitaxial layer on a substrate; forming a first mask layer on one side, far away from the substrate, of the epitaxial layer; the first mask layer comprises a first window, and the epitaxial layer is exposed at the first window; performing ion implantation on the epitaxial layer through the first window to form an amorphous region; forming a second mask layer; the second mask layer covers the side wall of the first window; processing the non-crystallization region to form a first groove; the depth of the first groove is larger than that of the non-crystallization region, and the width of the first groove is smaller than that of the non-crystallization region; and removing the non-crystallization region, the first mask layer and the second mask layer at the same time to form a second groove. The process is simple, the cost is low, and the reliability of the power device can be improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a power device and a preparation method thereof, a power module, a power conversion circuit and a vehicle. Background Art

[0002] In the field of silicon carbide power devices, due to the acid and alkali stability of silicon carbide materials, it cannot be directly corroded by conventional acid and alkali solutions. The main silicon carbide etching method is dry etching. When making a double trench structure, it is necessary to perform masking, photolithography, etching, dry etching and desizing, wet desizing, and mask removal twice, which consumes a lot of cost and time, and multiple photolithography will introduce more impurities or defects. Summary of the invention

[0003] The present invention provides a power device and a preparation method thereof, a power module, a power conversion circuit and a vehicle, which have simple processes, low costs and can improve the reliability of the power device.

[0004] According to one aspect of the present invention, there is provided a method for preparing a power device, comprising:

[0005] forming an epitaxial layer on a substrate;

[0006] Forming a first mask layer on a side of the epitaxial layer away from the substrate; wherein the first mask layer includes a first window, and the epitaxial layer is exposed at the first window;

[0007] Ion implantation is performed on the epitaxial layer through the first window to form an amorphous region;

[0008] forming a second mask layer; wherein the second mask layer covers the sidewalls of the first window;

[0009] The amorphized region is processed to form a first trench; the depth of the first trench is greater than the depth of the amorphized region, and the width of the first trench is less than the width of the amorphized region;

[0010] The amorphous region, the first mask layer and the second mask layer are removed simultaneously to form a second trench.

[0011] Optionally, forming a second mask layer includes:

[0012] A second mask layer is formed by adopting a sidewall spacer process.

[0013] Optionally, forming the second mask layer by using a sidewall spacer process includes:

[0014] A second mask sublayer is formed on a side of the first mask layer away from the substrate; wherein the second mask sublayer includes a first portion, a second portion and a third portion, the first portion covers a surface of the first mask layer away from the substrate, the second portion covers a side wall of the first window, and the third portion covers a surface of the epitaxial layer not covered by the first mask layer;

[0015] The first portion and the third portion of the second mask sublayer are removed to form a second mask layer.

[0016] Optionally, forming a second mask sublayer on a side of the first mask layer away from the substrate includes:

[0017] A second mask sub-layer is formed on a side of the first mask layer away from the substrate by a thermal oxidation process or a deposition process.

[0018] Optionally, the amorphized region is processed to form a first trench, including:

[0019] The amorphized region is dry-etched to form a first trench.

[0020] Optionally, removing the amorphized region, the first mask layer and the second mask layer simultaneously to form a second trench includes:

[0021] The amorphized region, the first mask layer and the second mask layer are removed simultaneously by wet etching to form a second trench.

[0022] Optionally, after simultaneously removing the amorphized region, the first mask layer and the second mask layer to form the second trench, the method further includes:

[0023] forming an oxide layer on a surface of the epitaxial layer away from the substrate and inside the second trench;

[0024] Remove the oxide layer;

[0025] A gate structure is formed inside the second trench.

[0026] Optionally, forming an oxide layer on a surface of the epitaxial layer away from the substrate and inside the second trench includes:

[0027] forming an oxide layer on the surface of the epitaxial layer away from the substrate and inside the second trench by an oxidation process;

[0028] Removal of oxide layers, including:

[0029] The oxide layer is removed using a wet buffered oxide etchant.

[0030] Optionally, forming a first mask layer on a side of the epitaxial layer away from the substrate includes:

[0031] forming a first mask sublayer on a side of the epitaxial layer away from the substrate; the first mask sublayer covers the epitaxial layer;

[0032] The first mask sublayer is etched by a photolithography process to form a first window; the epitaxial layer is exposed at the first window.

[0033] According to another aspect of the present invention, there is provided a power device, which is prepared by the method for preparing a power device according to any embodiment of the present invention.

[0034] According to another aspect of the present invention, a power module is provided, comprising a substrate and a power device according to any embodiment of the present invention, wherein the substrate is used for carrying the power device.

[0035] According to another aspect of the present invention, there is provided a power conversion circuit, the power conversion circuit being used for one or more of current conversion, voltage conversion, and power factor correction;

[0036] The power conversion circuit comprises a circuit board and a power device according to any embodiment of the present invention, and the power device is electrically connected to the circuit board.

[0037] According to another aspect of the present invention, a vehicle is provided, comprising a load and the power conversion circuit described in any embodiment of the present invention, the power conversion circuit being used to convert AC power into DC power, convert AC power into AC power, convert DC power into DC power, or convert DC power into AC power and then input it into the load.

[0038] The method for preparing a power device provided by the technical solution of the embodiment of the present invention comprises: forming an epitaxial layer on a substrate; forming a first mask layer on a side of the epitaxial layer away from the substrate; wherein the first mask layer comprises a first window, and the epitaxial layer is exposed at the first window; ion implantation is performed on the epitaxial layer through the first window to form an amorphized region; forming a second mask layer; wherein the second mask layer covers the sidewall of the first window; processing the amorphized region to form a first groove; the depth of the first groove is greater than the depth of the amorphized region, and the width of the first groove is less than the width of the amorphized region; and the amorphized region, the first mask layer and the second mask layer are removed at the same time to form a second groove. Compared with conventional power devices that require two photolithography processes for preparation, the embodiment of the present invention directly forms the second mask layer, which saves one photolithography process, is simple in process, and can save costs; and multiple photolithography processes will have the risk of introducing more impurities or defects. The embodiment of the present invention only uses one photolithography process to form the second groove, which can improve the reliability of the power device.

[0039] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 It is a flow chart of a method for preparing a power device provided by an embodiment of the present invention.

[0042] Figure 2 It is a schematic diagram of an intermediate structure of a power device provided by an embodiment of the present invention.

[0043] Figure 3 It is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention.

[0044] Figure 4 It is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention.

[0045] Figure 5 It is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention.

[0046] Figure 6 It is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention.

[0047] Figure 7 It is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention.

[0048] Figure 8 It is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention.

[0049] Fig. 9 yes Figure 1 A detailed flow chart included in S140.

[0050] Fig.10 It is an intermediate flow chart of a method for preparing a power device provided by an embodiment of the present invention.

[0051] Fig.11 It is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention.

[0052] Fig.12 yes Figure 1 A detailed flow chart included in S120. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0054] It should be noted that the terms "first", "second", etc. in the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0055] The embodiment of the present invention provides a method for preparing a power device. Figure 1 is a flow chart of a method for preparing a power device provided by an embodiment of the present invention, with reference to Figure 1 , the preparation method comprises:

[0056] S110 , forming an epitaxial layer on a substrate.

[0057] Wherein, the substrate may be a silicon carbide wafer substrate, and the epitaxial layer may be a silicon carbide epitaxial layer; Figure 2 is a schematic diagram of an intermediate structure of a power device provided by an embodiment of the present invention, with reference to Figure 2 , an epitaxial layer 20 may be epitaxially grown on the substrate 10 .

[0058] S120, forming a first mask layer on a side of the epitaxial layer away from the substrate; wherein the first mask layer includes a first window, and the epitaxial layer is exposed at the first window.

[0059] The first mask layer may be a polysilicon mask layer. Figure 3 is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention, with reference to Figure 2 and Figure 3 First, a first mask sublayer 31 is epitaxially grown on the epitaxial layer 20, a photoresist is formed on the first mask sublayer 31, a photoresist pattern is formed by exposure and development, and then the first mask sublayer 31 is dry-etched through the photoresist pattern to form a first window 32; and then the photoresist is removed by an ashing process and a wet etching process.

[0060] S130 , performing ion implantation into the epitaxial layer through the first window to form an amorphous region.

[0061] in, Figure 4 is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention, with reference to Figure 4 , a preset dose of ions is implanted into the epitaxial layer 20 at the formed first window 32. Different ions correspond to different preset doses. If the epitaxial layer 20 is made of silicon carbide material, a preset dose of ions needs to be implanted. The preset dose is a dose that makes the silicon carbide material amorphous. For example, the ions can be aluminum (Al) ions or argon (Ar) ions. The preset dose of Al ions is 1×10 15 cm -3 The preset dose of Ar ions is 4.8×10 14 cm -3 ; The epitaxial layer in the amorphized area can be directly removed by wet etching.

[0062] S140, forming a second mask layer; the second mask layer covers the sidewalls of the first window.

[0063] The material of the second mask layer may be tetraethoxysilane (TEOS). Figure 5 and Figure 6 is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention, with reference to Figure 5 and Figure 6 , a spacer process is used to form the second mask layer 40. Compared with conventional power devices that require two photolithography processes for preparation, the embodiment of the present invention uses a spacer process to form the second mask layer 40, which saves one photolithography process, is simple in process, and can save costs; and multiple photolithography processes will introduce more impurities or defects. The embodiment of the present invention only uses one photolithography process, which can improve the reliability of the power device. The size of the second mask layer can be set according to the width of the first trench formed subsequently, and can be set according to needs.

[0064] S150, processing the amorphized region to form a first trench; the depth of the first trench is greater than the depth of the amorphized region, and the width of the first trench is less than the width of the amorphized region.

[0065] in, Figure 7 is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention, with reference to Figure 7 , the amorphized region is dry-etched through the second mask layer 40 to form a first trench 51. The size of the first trench 51 can be set as required.

[0066] S160 , removing the amorphized region, the first mask layer, and the second mask layer simultaneously to form a second trench.

[0067] in, Figure 8 is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention, with reference to Figure 8 , using wet etching, HF / HNO3 mixed solution is selected to remove the amorphous region 40, the first mask layer 30 and the second mask layer 40 at the same time to form a second groove 52, the structure of the second groove 52 is a double groove structure morphology; the amorphous region 40, the first mask layer 30 and the second mask layer 40 are removed at the same time, which can reduce the preparation cost. The second groove 52 prepared by the embodiment of the present invention can make the ion implantation deeper along the groove direction, and the electric field shielding effect is better; at the same time, the reverse leakage current can be reduced, the breakdown voltage can be increased, and the on-resistance of the device can be reduced.

[0068] The method for preparing a power device provided by the technical solution of the embodiment of the present invention comprises: forming an epitaxial layer on a substrate; forming a first mask layer on a side of the epitaxial layer away from the substrate; wherein the first mask layer comprises a first window, and the epitaxial layer is exposed at the first window; ion implantation is performed on the epitaxial layer through the first window to form an amorphized region; forming a second mask layer; wherein the second mask layer covers the sidewall of the first window; processing the amorphized region to form a first groove; the depth of the first groove is greater than the depth of the amorphized region, and the width of the first groove is less than the width of the amorphized region; and the amorphized region, the first mask layer and the second mask layer are removed at the same time to form a second groove. Compared with conventional power devices that require two photolithography processes for preparation, the embodiment of the present invention directly forms the second mask layer, which saves one photolithography process, is simple in process, and can save costs; and multiple photolithography processes will have the risk of introducing more impurities or defects. The embodiment of the present invention only uses one photolithography process to form the second groove, which can improve the reliability of the power device.

[0069] Optionally, forming the second mask layer includes: forming the second mask layer by adopting a sidewall spacer process.

[0070] Among them, the second mask layer can be directly formed through the sidewall process without the need for a second photolithography process. Compared with conventional power devices that require two photolithography processes to prepare, the embodiment of the present invention directly forms the second mask layer, which saves one photolithography process, has a simple process, and can save costs.

[0071] Optional, Fig. 9 yes Figure 1 A detailed flow chart included in S140, refer to Fig. 9 , S140, forming a second mask layer by using a sidewall process, including:

[0072] S141. Form a second mask sublayer on a side of the first mask layer away from the substrate; wherein the second mask sublayer includes a first part, a second part and a third part, the first part covers the surface of the first mask layer away from the substrate, the second part covers the side wall of the first window, and the third part covers the surface of the epitaxial layer not covered by the first mask layer.

[0073] Among them, reference Figure 5 A second mask sub-layer 41 is epitaxially grown on a side of the first mask layer 30 away from the substrate 10 by using a thermal oxidation process or a deposition process.

[0074] S142 , removing the first portion and the third portion of the second mask sublayer to form a second mask layer.

[0075] Among them, reference Figure 6 The first and third portions of the second mask sublayer are removed by dry etching, and the formed second mask layer 40 includes a second window 42 , and the width of the second window 42 is smaller than the width of the first window 41 .

[0076] Optionally, forming the second mask sublayer on a side of the first mask layer away from the substrate includes: forming the second mask sublayer on a side of the first mask layer away from the substrate by a thermal oxidation process or a deposition process.

[0077] Among them, the thermal oxidation process or the deposition process is simple and easy to operate.

[0078] Optionally, processing the amorphized region to form a first trench includes: dry etching the amorphized region to form the first trench.

[0079] Among them, reference Figure 6 and Figure 7 , the amorphized region is dry-etched through the second window 42 of the second mask layer 40 to form a first trench 51 .

[0080] Optionally, the amorphous region, the first mask layer and the second mask layer are removed simultaneously to form the second trench, including: the amorphous region, the first mask layer and the second mask layer are removed simultaneously by wet etching to form the second trench.

[0081] The second trench is formed by wet etching using a HF / HNO3 mixed solution to remove the amorphous region, the first mask layer and the second mask layer at the same time.

[0082] Optional, Fig.10 is an intermediate flow chart of a method for preparing a power device provided by an embodiment of the present invention, with reference to Fig.10 , after simultaneously removing the amorphized region, the first mask layer and the second mask layer to form the second trench at S160, the method further includes:

[0083] S210, forming an oxide layer on a surface of the epitaxial layer away from the substrate and inside the second trench.

[0084] in, Fig.11 is a schematic diagram of an intermediate structure of another power device provided by an embodiment of the present invention, with reference to Fig.11 The surface epitaxial layer 20 is oxidized by oxygen (O2) at high temperature using a furnace tube device to form an oxide layer 60, and the process is simple.

[0085] S220, removing the oxide layer.

[0086] Among them, wet buffered oxide etching (BOE) is used to remove the oxide layer, and the structure of the removed oxide layer is as follows: Figure 8 The structure can obtain a smooth epitaxial layer surface with fewer defects, thereby improving the reliability of the device.

[0087] S230 , forming a gate structure inside the second trench.

[0088] Wherein, a gate structure may be formed inside the second trench by a deposition process.

[0089] Optionally, forming an oxide layer on the surface of the epitaxial layer away from the substrate and inside the second trench includes: forming an oxide layer on the surface of the epitaxial layer away from the substrate and inside the second trench through an oxidation process.

[0090] Removing the oxide layer includes: removing the oxide layer using a wet buffered oxide etching solution.

[0091] Optional, Fig.12 yes Figure 1 A detailed flow chart of S120, wherein S120, forming a first mask layer on a side of the epitaxial layer away from the substrate, comprises:

[0092] S121. Form a first mask sublayer on a side of the epitaxial layer away from the substrate; the first mask sublayer covers the epitaxial layer.

[0093] Among them, reference Figure 2 , a first mask sub-layer 31 is deposited and grown on a side of the epitaxial layer 20 away from the substrate 10 .

[0094] S122, etching the first mask sublayer through a photolithography process to form a first window; the epitaxial layer is exposed at the first window.

[0095] Among them, reference Figure 2 and Figure 3 A photoresist is formed on the first mask sublayer 31, a photoresist pattern is formed by exposure and development, and then the first mask sublayer 31 is dry-etched through the photoresist pattern to form a first window 32, and then the photoresist is removed by an ashing process and a wet etching process to finally form a first mask layer 30.

[0096] An embodiment of the present invention provides a power device based on the above embodiment, which is prepared by using the method for preparing a power device described in any embodiment of the present invention.

[0097] The power device provided by the embodiment of the present invention and the method for preparing the power device described in any embodiment of the present invention have the same beneficial effects.

[0098] An embodiment of the present invention provides a power module based on the above embodiments, including a substrate and a power device described in any embodiment of the present invention, wherein the substrate is used to carry the power device.

[0099] The power module provided by the technical solution of the embodiment of the present invention has the same beneficial effects as the power device described in any embodiment of the present invention.

[0100] An embodiment of the present invention provides a power conversion circuit based on the above embodiments, and the power conversion circuit is used for one or more of current conversion, voltage conversion, and power factor correction; the power conversion circuit includes a circuit board and the power device described in any embodiment of the present invention, and the power device is electrically connected to the circuit board.

[0101] The power conversion circuit provided by the technical solution of the embodiment of the present invention has the same beneficial effects as the power device described in any embodiment of the present invention.

[0102] An embodiment of the present invention is a vehicle based on the above embodiment, including a load and the power conversion circuit described in any embodiment of the present invention, the power conversion circuit is used to convert AC power into DC power, convert AC power into AC power, convert DC power into DC power, or convert DC power into AC power and then input it into the load.

[0103] The vehicle provided by the technical solution of the embodiment of the present invention and the power device described in any embodiment of the present invention have the same beneficial effects.

[0104] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0105] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a power device, characterized in that: include: forming an epitaxial layer on a substrate; forming a first mask layer on a side of the epitaxial layer away from the substrate; wherein the first mask layer comprises a first window, and the epitaxial layer is exposed at the first window; Performing ion implantation into the epitaxial layer through the first window to form an amorphous region; forming a second mask layer; wherein the second mask layer covers the sidewalls of the first window; Processing the amorphized region to form a first trench; the depth of the first trench is greater than the depth of the amorphized region, and the width of the first trench is less than the width of the amorphized region; The amorphized region, the first mask layer and the second mask layer are removed simultaneously to form a second trench.

2. The method for preparing a power device according to claim 1, characterized in that: Forming a second mask layer, comprising: The second mask layer is formed by a sidewall spacer process.

3. The method for preparing a power device according to claim 2, characterized in that: The second mask layer is formed by a sidewall process, including: forming a second mask sublayer on a side of the first mask layer away from the substrate; wherein the second mask sublayer comprises a first portion, a second portion and a third portion, the first portion covers a surface of the first mask layer away from the substrate, the second portion covers a sidewall of the first window, and the third portion covers a surface of the epitaxial layer not covered by the first mask layer; The first portion and the third portion of the second mask sublayer are removed to form a second mask layer.

4. The method for preparing a power device according to claim 3, characterized in that: Forming a second mask sublayer on a side of the first mask layer away from the substrate, comprising: A second mask sub-layer is formed on a side of the first mask layer away from the substrate by a thermal oxidation process or a deposition process.

5. The method for preparing a power device according to claim 1, characterized in that: The amorphized region is processed to form a first trench, comprising: The amorphized region is dry-etched to form a first trench.

6. The method for preparing a power device according to claim 1, characterized in that: Simultaneously removing the amorphized region, the first mask layer and the second mask layer to form a second trench, comprising: The amorphized region, the first mask layer and the second mask layer are removed simultaneously by wet etching to form a second trench.

7. The method for preparing a power device according to claim 1, characterized in that: After simultaneously removing the amorphized region, the first mask layer and the second mask layer to form a second trench, the method further includes: forming an oxide layer on a surface of the epitaxial layer away from the substrate and inside the second trench; removing the oxide layer; A gate structure is formed inside the second trench.

8. The method for preparing a power device according to claim 7, characterized in that: Forming an oxide layer on a surface of the epitaxial layer away from the substrate and inside the second trench, comprising: forming an oxide layer on the surface of the epitaxial layer away from the substrate and inside the second trench by an oxidation process; Removing the oxide layer comprises: The oxide layer is removed by using a wet buffered oxide etching solution.

9. The method for preparing a power device according to claim 1, characterized in that: Forming a first mask layer on a side of the epitaxial layer away from the substrate, comprising: forming a first mask sublayer on a side of the epitaxial layer away from the substrate; the first mask sublayer covers the epitaxial layer; The first mask sublayer is etched by a photolithography process to form a first window; the epitaxial layer is exposed at the first window.

10. A power device, characterized in that: The power device is prepared by the method for preparing the power device according to any one of claims 1 to 9.

11. A power module, characterized in that: The invention comprises a substrate and at least one power device according to claim 10, wherein the substrate is used for supporting the power device.

12. A power conversion circuit, characterized in that: The power conversion circuit is used for one or more of current conversion, voltage conversion, and power factor correction; The power conversion circuit comprises a circuit board and at least one power device as claimed in claim 10, wherein the power device is electrically connected to the circuit board.

13. A vehicle, characterized in that: It includes a load and a power conversion circuit as described in claim 12, wherein the power conversion circuit is used to convert AC power into DC power, convert AC power into AC power, convert DC power into DC power, or convert DC power into AC power and then input it into the load.

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