A positive-angle gallium oxide Schottky diode device and its preparation method

Abstract

This application applies to the field of semiconductor device manufacturing technology and provides a positive-angle-ground gallium oxide Schottky diode device and a method for fabricating the same. The method comprises: forming a photoresist layer with a preset pattern on a gallium oxide epitaxial layer, with portions of the gallium oxide epitaxial layer uncovered by the photoresist layer; forming the gallium oxide epitaxial layer on the upper surface of a gallium oxide substrate; forming a first electrode layer with a preset shape on the gallium oxide epitaxial layer and the photoresist layer; rotating the gallium oxide substrate in two opposite directions by first and second tilt angles, respectively, with respect to a horizontal plane, etching the gallium oxide epitaxial layer covered by an anode metal layer in the preset shape, with the first and second tilt angles both being less than 90°; and forming a second electrode layer on the lower surface of the gallium oxide substrate. This application can easily form a positive-angle-ground gallium oxide Schottky terminal structure, effectively improving the withstand voltage of the diode device.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor device manufacturing technology, and in particular relates to a positive-angle-ground gallium oxide Schottky diode device and a preparation method thereof. Background Art

[0002] Ultra-wide bandgap power electronics, exemplified by gallium oxide (GaO), have emerged as a key development area for power semiconductors in recent years, poised to replace traditional silicon-based power devices in certain applications. However, the image-induced barrier lowering effect is a bottleneck limiting the performance of GaO Schottky diodes. Due to the significant difficulty of P-type implantation in GaO, the demanding dielectric quality requirements of the field plate structure, and dielectric reliability issues, the development of novel terminal structures is imperative.

[0003] Angle-grinding termination is one of the important termination technologies for improving power diodes. Positive angle-grinding termination has stronger surface electric field control capability than negative angle-grinding termination and saves more area. However, conventional etching methods currently make it difficult to achieve positive angle-grinding termination structure. Summary of the Invention

[0004] To overcome the problems existing in the related art, the embodiments of the present application provide a positive-grinded-angle gallium oxide diode device and a preparation method thereof, which can easily realize a positive-grinded-angle gallium oxide Schottky terminal structure and effectively improve the voltage resistance of the diode device.

[0005] This application is achieved through the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a method for preparing a positive-angle-ground gallium oxide Schottky diode device, comprising:

[0007] Preparing a photoresist layer with a preset pattern on the gallium oxide epitaxial layer, wherein a portion of the gallium oxide epitaxial layer is not covered by the photoresist layer; the gallium oxide epitaxial layer is formed on the upper surface of the gallium oxide substrate;

[0008] forming a first electrode layer of a preset shape on the gallium oxide epitaxial layer and the photoresist layer;

[0009] With a horizontal plane as a reference, the gallium oxide substrate is rotated in two opposite directions by a first tilt angle and a second tilt angle, respectively, to etch the gallium oxide epitaxial layer covered by the anode metal layer in the preset shape, wherein the first tilt angle and the second tilt angle are both less than 90°;

[0010] A second electrode layer is formed on the lower surface of the gallium oxide substrate.

[0011] In a possible implementation of the first aspect, the step of preparing a photoresist layer with a preset pattern on the gallium oxide epitaxial layer includes:

[0012] preparing a photoresist layer on the gallium oxide epitaxial layer;

[0013] The photoresist layer is etched to expose a portion of the gallium oxide epitaxial layer, thereby forming a photoresist layer with a preset pattern.

[0014] In a possible implementation of the first aspect, preparing a first electrode layer of a preset shape on the gallium oxide epitaxial layer and the photoresist layer includes:

[0015] preparing the first electrode layer on the photoresist layer with the preset pattern and the exposed gallium oxide epitaxial layer;

[0016] A portion of the first electrode layer on the photoresist layer of the preset pattern is peeled off, and the photoresist layer of the preset pattern is removed to form the first electrode layer of the preset shape.

[0017] In a possible implementation manner of the first aspect, the first inclination angle and the second inclination angle are both in a range of 30° to 60°.

[0018] In a possible implementation manner of the first aspect, the first inclination angle is equal to the second inclination angle.

[0019] In a possible implementation of the first aspect, the gallium oxide epitaxial layer covered by the first electrode layer in the preset shape is etched multiple times; the etching times ensure that the accuracy after etching meets the preset accuracy.

[0020] In a possible implementation manner of the first aspect, the first electrode layer is obtained by electron beam evaporation or metal sputtering; and the second electrode layer is obtained by electron beam evaporation.

[0021] In a possible implementation of the first aspect, the gallium oxide substrate is an N-type highly doped gallium oxide substrate;

[0022] The gallium oxide epitaxial wafer is an N-type low-doped gallium oxide epitaxial wafer.

[0023] In a second aspect, an embodiment of the present application provides a gallium oxide diode device, comprising:

[0024] Gallium oxide substrate;

[0025] A gallium oxide epitaxial layer is formed on the upper surface of the gallium oxide substrate, wherein a boss structure is provided on the upper portion of the gallium oxide epitaxial layer; the width of the boss structure gradually decreases from the gallium oxide epitaxial layer to the gallium oxide substrate;

[0026] a first electrode formed on the gallium oxide epitaxial layer;

[0027] The second electrode is formed on the lower surface of the gallium oxide substrate.

[0028] In a possible implementation manner of the second aspect, the gallium oxide diode device is prepared by the method described in any one of the first aspects.

[0029] It can be understood that the beneficial effects of the second aspect mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0030] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0031] In the embodiment of the present application, a positive-angle terminal gallium oxide diode device is formed by rotating the gallium oxide substrate in two opposite directions, using multiple non-perpendicular angles to complement each other, and using an anode self-aligned filling and gallium oxide etching method to improve the device's withstand voltage characteristics.

[0032] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0034] Figure 1 This is a schematic flow chart of a method for preparing a gallium oxide diode device provided in one embodiment of the present application;

[0035] Figure 2 1 is a schematic structural diagram of a photoresist layer for preparing a preset pattern provided in one embodiment of the present application;

[0036] Figure 3 This is a schematic structural diagram of preparing a first electrode layer of a preset shape provided in one embodiment of the present application;

[0037] Figure 4 This is a schematic structural diagram of a gallium oxide epitaxial layer after preparation and etching provided in one embodiment of the present application;

[0038] Figure 5 Schematic diagram of the structure of a gallium oxide diode device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0039] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0040] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections thereof.

[0041] It will also be understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0042] As used in this specification and the appended claims, the term "if" can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0043] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0044] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0045] Angle-grinding termination is one of the important termination technologies for improving power diodes. Positive angle-grinding termination has stronger surface electric field control capability than negative angle-grinding termination and saves more area. However, conventional etching methods are currently difficult to achieve positive angle-grinding termination structure, and new preparation technologies are urgently needed.

[0046] Based on the above problems, the preparation method of the positive-grinded-angle gallium oxide Schottky diode device in the embodiment of the present application is as follows: a photoresist layer of a preset pattern is prepared on the gallium oxide epitaxial layer, and part of the gallium oxide epitaxial layer is not covered by the photoresist layer; the gallium oxide epitaxial layer is formed on the upper surface of the gallium oxide substrate; a first electrode layer of a preset shape is prepared on the gallium oxide epitaxial layer and the photoresist layer; with the horizontal plane as a reference, the gallium oxide substrate is rotated in two opposite directions by a first tilt angle and a second tilt angle, respectively, and the gallium oxide epitaxial layer covered by the anode metal layer in the preset shape is etched, and the first tilt angle and the second tilt angle are both less than 90°; and a second electrode layer is formed on the lower surface of the gallium oxide substrate.

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] Figure 1 This is a schematic flow chart of a method for preparing a positive-grinding-angle gallium oxide Schottky diode device provided in one embodiment of the present application, with reference to Figure 1 , the preparation method of the diode device is described in detail as follows:

[0049] In step 101 , a photoresist layer 3 with a preset pattern is prepared on the gallium oxide epitaxial layer 2 , and a portion of the gallium oxide epitaxial layer 2 is not covered by the photoresist layer 3 ; the gallium oxide epitaxial layer 2 is formed on the upper surface of the gallium oxide substrate 1 .

[0050] Specifically, preparing a photoresist layer 3 with a preset pattern on the gallium oxide epitaxial layer 2 includes:

[0051] A photoresist layer 3 is prepared on the gallium oxide epitaxial layer 2, such as Figure 2 As shown in (a);

[0052] The photoresist layer 3 is etched to expose a portion of the gallium oxide epitaxial layer 2, forming a photoresist layer 3 with a preset pattern, such as Figure 2 As shown in (b);

[0053] After cleaning the gallium oxide epitaxial layer 2, a photoresist layer 3 is prepared on the gallium oxide epitaxial layer 2;

[0054] Exemplary cleaning may be performed using acetone, isopropyl alcohol, and deionized water in sequence.

[0055] The etching of the photoresist layer 3 includes: performing photolithography, exposure, and development on the photoresist layer 3 to expose the gallium oxide epitaxial layer 2 .

[0056] In step 102 , a first electrode layer 4 of a preset shape is prepared on the gallium oxide epitaxial layer 2 and the photoresist layer 3 .

[0057] Specifically, a first electrode layer 4 having a preset shape is prepared on the gallium oxide epitaxial layer 2 and the photoresist layer 3, comprising:

[0058] A first electrode layer 4 is prepared on the photoresist layer 3 with a preset pattern and the exposed gallium oxide epitaxial layer 2; a portion of the first electrode layer 4 on the photoresist layer 3 with a preset pattern is peeled off, as shown in FIG. Figure 3 As shown in (a); removing the photoresist layer 3 of the preset pattern to form a first electrode layer 4 of a preset shape, as shown Figure 3 As shown in (b) in .

[0059] Specifically, the first electrode layer 4 is obtained by electron beam evaporation or metal sputtering.

[0060] For example, when the anode metal is sputtered in a self-aligned manner to form the first electrode layer 4 , the purity of the target material may be 99.99%, and the sputtering power may be 150W.

[0061] For example, after the anode metal is formed by electron beam evaporation to form the first electrode layer 4, excess metal is stripped off and then cleaned.

[0062] The thickness of the first electrode layer 4 and the thickness of the photoresist layer 3 may be equal or different.

[0063] For example, the material of the first electrode layer 4 can be Ni or Au. When the material of the first electrode layer 4 is Ni, the thickness of the first electrode layer 4 can be 50 nm; when the material of the first electrode layer 4 is Au, the thickness of the first electrode layer 4 can be 400 nm.

[0064] In step 103, see Figure 4 , with the horizontal plane as a reference, the gallium oxide substrate 1 is rotated in two opposite directions by a first tilt angle and a second tilt angle, respectively, and the gallium oxide epitaxial layer 2 covered by the first electrode layer 4 in a preset shape is etched, and the first tilt angle and the second tilt angle are both less than 90°.

[0065] Specifically, the first inclination angle and the second inclination angle are both in the range of 30° to 60°.

[0066] Specifically, the first inclination angle is equal to the second inclination angle.

[0067] Specifically, the gallium oxide epitaxial layer 2 covered by the first electrode layer 4 in the preset shape is etched multiple times; the etching times ensure that the accuracy after the etching is completed meets the preset accuracy.

[0068] After etching the gallium oxide epitaxial layer 2 , the gallium oxide epitaxial layer 2 is cleaned.

[0069] For example, the gallium oxide epitaxial layer 2 can be cleaned with acetone, isopropyl alcohol and deionized water.

[0070] Exemplarily, the gallium oxide substrate 1 is rotated at a first tilt angle θ, and the gallium oxide epitaxial layer 2 is etched along the etching direction A by ICP etching; the gallium oxide substrate 1 is rotated at a second tilt angle α, and the gallium oxide epitaxial layer 2 is etched along the etching direction B by ICP etching; the etching gas is SF6, Ar, BCl3, or other etching gas; the first tilt angle θ is 90°>θ>0°, and the optimal range is 60°≥θ≥30°; the second tilt angle α is 90°>α>0°, and the optimal range is 60°≥θ≥30°, α and θ can be equal or different, and the effect is better when they are equal, that is, the angles complement each other.

[0071] In step 104, see Figure 5 , a second electrode layer 5 is formed on the lower surface of the gallium oxide substrate.

[0072] Specifically, the second electrode layer 5 is obtained by electron beam evaporation.

[0073] For example, the second electrode layer 5 may be made of Ti or Au. When the second electrode layer 5 is made of Ti, the thickness of the second electrode layer 5 may be 20 nm; when the second electrode layer 5 is made of Au, the thickness of the second electrode layer 5 may be 400 nm.

[0074] The above-mentioned method for preparing a positive-angle gallium oxide Schottky diode device forms a gallium oxide diode device by rotating the gallium oxide substrate in two opposite directions, using multiple non-perpendicular angles to complement each other, and using an anode self-aligned filling and gallium oxide etching method, thereby providing a new method for preparing a gallium oxide diode device.

[0075] The present application also provides a positive-angle gallium oxide Schottky diode device, see Figure 5 The gallium oxide diode device includes: a gallium oxide substrate 1; a gallium oxide epitaxial layer 2 formed on the upper surface of the gallium oxide substrate 1, a boss structure is provided on the upper portion of the gallium oxide epitaxial layer 2, and the width of the boss structure gradually decreases from the gallium oxide epitaxial layer 2 to the gallium oxide substrate 1; a first electrode 4 formed on the gallium oxide epitaxial layer; and a second electrode 5 formed on the lower surface of the gallium oxide substrate.

[0076] The tilt angle of the mesa is 30° to 60° relative to the direction perpendicular to the substrate plane.

[0077] Exemplarily, the positive-angle-ground gallium oxide Schottky diode device can be prepared by the above-mentioned method for preparing the positive-angle-ground gallium oxide Schottky diode device.

[0078] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0079] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A method for preparing a positive-angle gallium oxide Schottky diode device, characterized in that: include: Preparing a photoresist layer with a preset pattern on the gallium oxide epitaxial layer, wherein a portion of the gallium oxide epitaxial layer is not covered by the photoresist layer; The gallium oxide epitaxial layer is formed on the upper surface of the gallium oxide substrate; forming a first electrode layer of a preset shape on the gallium oxide epitaxial layer and the photoresist layer; The gallium oxide substrate is rotated in two opposite directions by a first tilt angle and a second tilt angle, respectively, with a horizontal plane as a reference, and the gallium oxide epitaxial layer covered by the first electrode layer of the preset shape is etched to form a boss structure on the upper portion of the gallium oxide epitaxial layer, wherein the width of the boss structure gradually decreases from the gallium oxide epitaxial layer to the gallium oxide substrate; the first tilt angle and the second tilt angle are both less than 90°; A second electrode layer is formed on the lower surface of the gallium oxide substrate.

2. The method for preparing a positive-angle-ground gallium oxide Schottky diode device according to claim 1, wherein: The step of preparing a photoresist layer with a preset pattern on the gallium oxide epitaxial layer comprises: preparing a photoresist layer on the gallium oxide epitaxial layer; The photoresist layer is etched to expose a portion of the gallium oxide epitaxial layer, thereby forming a photoresist layer with a preset pattern.

3. The method for preparing a positive-angle-ground gallium oxide Schottky diode device according to claim 1, wherein: Preparing a first electrode layer of a preset shape on the gallium oxide epitaxial layer and the photoresist layer, comprising: preparing the first electrode layer on the photoresist layer with the preset pattern and the exposed gallium oxide epitaxial layer; A portion of the first electrode layer on the photoresist layer of the preset pattern is peeled off, and the photoresist layer of the preset pattern is removed to form the first electrode layer of the preset shape.

4. The method for preparing a positive-grinded-angle gallium oxide Schottky diode device according to claim 1, wherein: The first tilt angle and the second tilt angle are both in the range of 30° to 60°.

5. The method for preparing a diode device according to claim 1, wherein: The first inclination angle is equal to the second inclination angle.

6. The method for preparing a positive-grinded-angle gallium oxide Schottky diode device according to claim 1, wherein: The gallium oxide epitaxial layer covered by the first electrode layer in the preset shape is etched multiple times; the etching times ensure that the accuracy after etching meets the preset accuracy.

7. The method for preparing a positive-angle-ground gallium oxide Schottky diode device according to claim 1, wherein: The first electrode layer is obtained by electron beam evaporation or metal sputtering; the second electrode layer is obtained by electron beam evaporation.

8. The method for preparing a positive-angle-ground gallium oxide Schottky diode device according to claim 1, wherein: The gallium oxide substrate is an N-type highly doped gallium oxide substrate; The gallium oxide epitaxial wafer is an N-type low-doped gallium oxide epitaxial wafer.

9. A positive-angle gallium oxide Schottky diode device, characterized in that: The positive-angle-ground gallium oxide Schottky diode device is prepared by the method according to any one of claims 1 to 8, and the positive-angle-ground gallium oxide Schottky diode device comprises: Gallium oxide substrate; A gallium oxide epitaxial layer is formed on the upper surface of the gallium oxide substrate, wherein a boss structure is provided on the upper portion of the gallium oxide epitaxial layer; the width of the boss structure gradually decreases from the gallium oxide epitaxial layer to the gallium oxide substrate; a first electrode formed on the gallium oxide epitaxial layer; The second electrode is formed on the lower surface of the gallium oxide substrate.

10. A gallium oxide diode device, characterized in that: The gallium oxide diode device is prepared by the method according to any one of claims 1 to 8.

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