阅读说明：本技术 氮化镓基半导体器件及其制作方法 (Gallium nitride-based semiconductor device and manufacturing method thereof ) 是由 蔡文必 孙希国 刘胜厚 于 2020-08-03 设计创作，主要内容包括：一种氮化镓基半导体器件及其制作方法,涉及半导体器件技术领域。该氮化镓基半导体器件包括衬底、依次形成于衬底上的氮化镓基外延层和介质层。其中,介质层上形成有沉积孔,沉积孔内填充有正面金属层,衬底上形成有背面通孔,背面通孔贯穿氮化镓基外延层；衬底远离氮化镓基外延层的一侧及背面通孔内沉积有背面金属层,背面通孔内的背面金属分别与正面金属层和介质层接触连接。该氮化镓基半导体器件能够改善背面金属的粘附性,从而提高器件的可靠性。(A gallium nitride-based semiconductor device and a manufacturing method thereof relate to the technical field of semiconductor devices. The gallium nitride-based semiconductor device comprises a substrate, a gallium nitride-based epitaxial layer and a dielectric layer, wherein the gallium nitride-based epitaxial layer and the dielectric layer are sequentially formed on the substrate. Wherein, a deposition hole is formed on the dielectric layer, a front metal layer is filled in the deposition hole, a back through hole is formed on the substrate, and the back through hole penetrates through the gallium nitride-based epitaxial layer; and a back metal layer is deposited on one side of the substrate, which is far away from the gallium nitride-based epitaxial layer, and in the back through hole, and the back metal in the back through hole is respectively in contact connection with the front metal layer and the dielectric layer. The gallium nitride-based semiconductor device can improve the adhesion of the back metal, thereby improving the reliability of the device.)

1. A gallium nitride-based semiconductor device is characterized by comprising a substrate, a gallium nitride-based epitaxial layer and a dielectric layer, wherein the gallium nitride-based epitaxial layer and the dielectric layer are sequentially formed on the substrate;

the substrate is provided with a gallium nitride-based epitaxial layer, wherein a deposition hole is formed in the dielectric layer, a front metal layer is filled in the deposition hole, a back through hole is formed in the substrate, and the back through hole penetrates through the gallium nitride-based epitaxial layer; a back metal layer is deposited on one side of the substrate, which is far away from the gallium nitride-based epitaxial layer, in the back through hole, the back metal in the back through hole is respectively in contact connection with the front metal layer and the dielectric layer, the projection of the deposition hole on the substrate is positioned in the projection range of the back through hole on the substrate, and the projection edges are not intersected.

2. The gallium nitride-based semiconductor device according to claim 1, further comprising a protective dielectric layer formed on the dielectric layer, the protective dielectric layer covering the front-side metal layer.

3. The gallium nitride-based semiconductor device according to claim 1, wherein the front side metal layer covers edges of the deposition holes.

4. The gallium nitride-based semiconductor device according to claim 1, wherein the substrate is silicon carbide.

5. The gallium nitride-based semiconductor device of claim 4, wherein the substrate is between 50 μm and 100 μm thick.

6. The gallium nitride-based semiconductor device according to claim 1, wherein an overlapping region of the dielectric layer and the back metal layer is annular, and an annular width of the annular is between 3 μm and 20 μm.

7. A method for manufacturing a gallium nitride-based semiconductor device, comprising the gallium nitride-based semiconductor device according to any one of claims 1 to 6, the method comprising the steps of:

depositing a dielectric layer on the gallium nitride-based epitaxial layer of the gallium nitride-based semiconductor device after the gate process is finished;

forming a deposition hole on the dielectric layer through an etching process;

evaporating metal on one side of the dielectric layer far away from the gallium nitride-based epitaxial layer and in the deposition hole, and forming a front metal layer covering the deposition hole by an etching stripping process;

forming a back through hole on a substrate and the gallium nitride-based epitaxial layer through an etching process, wherein the projection of the deposition hole on the substrate is positioned in the projection range of the back through hole on the substrate, and the projection edges are not intersected;

and depositing metal on one side of the substrate, which is far away from the gallium nitride-based epitaxial layer, and in the back through hole to form a back metal layer, wherein the back metal part in the back through hole is in contact connection with the front metal layer, and part of the back metal part is in contact connection with the dielectric layer.

8. The method according to claim 7, wherein the backside via hole on the substrate is formed by a dry etching process.

9. The method for fabricating a gallium nitride-based semiconductor device according to claim 7, wherein the depositing metal on the substrate at a side away from the gallium nitride-based epitaxial layer and in the backside via hole to form a backside metal layer comprises:

sputtering and forming a seed layer on the substrate with the back through hole;

and electroplating to form a metal layer on the seed layer.

10. The method according to claim 7, further comprising, after the forming a front metal layer covering the deposition hole by an etching lift-off process:

and depositing a protective dielectric layer on the dielectric layer and one side of the front metal layer far away from the substrate.

Technical Field

The invention relates to the technical field of semiconductor devices, in particular to a gallium nitride-based semiconductor device and a manufacturing method thereof.

Background

Semiconductor material development has gone through three generations to date: silicon (Si) and germanium (Ge) belong to the first generation semiconductor materials; gallium arsenide (GaAs) and indium phosphide (InP) are the primary representatives of second-generation semiconductor materials; gallium nitride (GaN) and silicon carbide (SiC) are third generation semiconductor materials. Wherein, as the third generationGaN of semiconductor material having a breakdown electric field (1X 10) stronger than that of conventional semiconductor material¹⁰～3×10¹⁰V/cm), faster saturated electron drift velocity (2X 10)⁷cm/s), higher electron mobility, wider forbidden band width (3.4eV), and the like, so that the semiconductor device is more suitable for working under extreme conditions of high temperature, high pressure, high frequency and the like than Si-based and GaAs-based devices. Due to the characteristics, the gallium nitride device is a core device in the fields of power electronics, wireless communication, radar and the like, obtains great attention in the industry and has wide application prospect.

When a GaN-based HEMT (High electron mobility transistor) is applied to a microwave monolithic integrated circuit, a source electrode of a front device or other components needing grounding needs to be led out and grounded through a back through hole. Specifically, after the front circuit of the device is manufactured, a blind hole (or called a back hole) is etched on the back surface of the device, and a conductive metal layer is manufactured in the hole in a sputtering mode to realize connection with the front circuit. However, the prior art is limited by many factors such as material growth quality, preparation processing technology and/or device structure, and after the back hole is sputtered with the conductive metal layer, the edge around the back hole often has the defect of poor adhesion such as bubbling and even falling off of the conductive metal layer, thereby affecting the grounding resistance, so that the grounding effect is not ideal, and further affecting the reliability of the device.

Disclosure of Invention

The invention aims to provide a gallium nitride back hole structure and a manufacturing method thereof, wherein the gallium nitride-based semiconductor device and the manufacturing method thereof can improve the adhesion of back metal, so that the reliability of the device is improved.

The embodiment of the invention is realized by the following steps:

in one aspect of the present invention, a gallium nitride-based semiconductor device is provided, which includes a substrate, a gallium nitride-based epitaxial layer and a dielectric layer sequentially formed on the substrate. Wherein, a deposition hole is formed on the dielectric layer, a front metal layer is filled in the deposition hole, a back through hole is formed on the substrate, and the back through hole penetrates through the gallium nitride-based epitaxial layer; a back metal layer is deposited on one side of the substrate, which is far away from the gallium nitride-based epitaxial layer, and in the back through hole, the back metal in the back through hole is respectively in contact connection with the front metal layer and the dielectric layer, the projection of the deposition hole on the substrate is positioned in the projection range of the back through hole on the substrate, and the projection edges are not intersected. The gallium nitride-based semiconductor device can improve the adhesion of the back metal, thereby improving the reliability of the device.

In one embodiment, the gallium nitride-based semiconductor device further comprises a protective dielectric layer formed on the dielectric layer, the protective dielectric layer covering the front-side metal layer.

In one embodiment, the front side metal layer covers the edges of the deposition aperture.

In one embodiment, the material of the substrate is silicon carbide.

In one embodiment, the substrate has a thickness between 50 μm and 100 μm.

In one embodiment, the overlapped region of the dielectric layer and the back metal layer is in a ring shape, and the ring width of the ring is between 3 μm and 20 μm.

In another aspect of the present invention, a method for fabricating a gallium nitride-based semiconductor device is provided, the method comprising:

depositing a dielectric layer on the gallium nitride-based epitaxial layer of the gallium nitride-based semiconductor device after the gate process is finished;

forming a deposition hole on the dielectric layer through an etching process;

evaporating metal on one side of the dielectric layer far away from the gallium nitride-based epitaxial layer and in the deposition hole, and forming a front metal layer covering the deposition hole by an etching stripping process;

forming a back through hole on the substrate and the gallium nitride-based epitaxial layer through an etching process, wherein the projection of the deposition hole on the substrate is positioned in the projection range of the back through hole on the substrate, and the projection edges are not intersected;

and depositing metal on one side of the substrate far away from the gallium nitride-based epitaxial layer and in the back through hole to form a back metal layer, wherein the back metal part in the back through hole is in contact connection with the front metal layer, and part of the back metal part is in contact connection with the dielectric layer.

In one embodiment, the backside via on the substrate is formed using a dry etch process.

In one embodiment, depositing metal on the side of the substrate away from the gan-based epitaxial layer and in the backside via to form a backside metal layer includes:

sputtering and forming a seed layer on the substrate with the back through hole;

and electroplating to form a metal layer on the seed layer.

In one embodiment, after forming the front metal layer covering the deposition hole by an etching and stripping process, the method further includes:

and depositing a protective dielectric layer on the dielectric layer and the side of the front metal layer far away from the substrate.

The beneficial effects of the invention include:

the gallium nitride-based semiconductor device comprises a substrate, a gallium nitride-based epitaxial layer and a dielectric layer, wherein the gallium nitride-based epitaxial layer and the dielectric layer are sequentially formed on the substrate. Wherein, a deposition hole is formed on the dielectric layer, a front metal layer is filled in the deposition hole, a back through hole is formed on the substrate, and the back through hole penetrates through the gallium nitride-based epitaxial layer; a back metal layer is deposited on one side of the substrate, which is far away from the gallium nitride-based epitaxial layer, and in the back through hole, the back metal in the back through hole is respectively in contact connection with the front metal layer and the dielectric layer, the projection of the deposition hole on the substrate is positioned in the projection range of the back through hole on the substrate, and the projection edges are not intersected. Therefore, in the process of etching the back through hole, under the transitional action of the dielectric layer, the groove effect of the back through hole can be reduced to a certain extent, so that the metal reverse sputtering phenomenon possibly caused by etching the back through hole of the gallium nitride-based semiconductor device can be effectively reduced, and the back through hole can have a smooth inner wall after the etching is finished. Therefore, when the back metal layer is deposited in the back through hole, the adhesion of the back metal can be increased to a certain degree, and the defects of poor adhesion, such as bubbling and even falling-off of the back metal layer, can be prevented. Therefore, the gallium nitride-based semiconductor device provided by the application ensures a good grounding effect and improves the reliability of the gallium nitride-based semiconductor device.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is one of schematic structural diagrams of a gallium nitride-based semiconductor device according to an embodiment of the present invention;

fig. 2 is a second schematic structural diagram of a gallium nitride-based semiconductor device according to an embodiment of the present invention;

fig. 3 is a third schematic structural diagram of a gallium nitride-based semiconductor device according to an embodiment of the present invention;

FIG. 4 is a scanning electron microscope image of a GaN-based semiconductor device provided by the prior art;

fig. 5 is a scanning electron microscope image of a gallium nitride-based semiconductor device according to an embodiment of the present invention;

fig. 6 is a flowchart of a method for fabricating a gallium nitride-based semiconductor device according to an embodiment of the present invention;

fig. 7 is a second flowchart of a method for fabricating a gallium nitride-based semiconductor device according to an embodiment of the present invention;

fig. 8 is a third flowchart of the method for fabricating a gallium nitride-based semiconductor device according to the embodiment of the present invention.

Icon: 10-a substrate; 11-backside vias; 20-a gallium nitride-based epitaxial layer; 30-a dielectric layer; 31-deposition holes; 40-front metal layer; 50-a back metal layer; 60-protective dielectric layer; 70-an overlap region; h-ring width.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or the orientations or positional relationships that the products of the present invention are conventionally placed in use, and are only used for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal", "vertical" and the like do not imply that the components are required to be absolutely horizontal or pendant, but rather may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Referring to fig. 1, the present embodiment provides a gallium nitride-based semiconductor device, which includes a substrate 10, a gallium nitride-based epitaxial layer 20 and a dielectric layer 30 sequentially formed on the substrate 10. Wherein, a deposition hole 31 is formed on the dielectric layer 30, a front metal layer 40 is filled in the deposition hole 31, a back through hole 11 is formed on the substrate 10, and the back through hole 11 penetrates through the gallium nitride-based epitaxial layer 20; a back metal layer 50 is deposited on one side of the substrate 10 far away from the gallium nitride-based epitaxial layer 20 and in the back through hole 11, the back metal in the back through hole 11 is respectively in contact connection with the front metal layer 40 and the dielectric layer 30, the projection of the deposition hole 31 on the substrate 10 is located in the projection range of the back through hole 11 on the substrate 10, and the projection edges do not intersect. The gallium nitride-based semiconductor device can improve the adhesion of the back metal, thereby improving the reliability of the device.

The gallium nitride-based epitaxial layer 20 and the dielectric layer 30 are sequentially formed on the substrate 10. In this embodiment, the substrate 10 may be made of sapphire or silicon carbide material. In contrast, silicon carbide as the substrate 10 material has good thermal and electrical conductivity, and the silicon carbide material has a better matching degree with gallium nitride (the degree of mismatch is only 3.3%), which can effectively suppress the tensile stress caused by the lattice mismatch between silicon carbide and gallium nitride. Therefore, it is preferable that the substrate 10 employs a silicon carbide semiconductor material in the present embodiment. Of course, it should be understood that the use of silicon carbide as the substrate 10 material is only one example provided in the present application, and in other embodiments, a person skilled in the art may select other substrate 10 materials according to practical situations, and the present application is not limited thereto.

In addition, in the embodiment, the dielectric layer is silicon nitride, the deposition hole 31 is formed on the dielectric layer 30, and the deposition hole 31 is mainly formed to fill the front metal layer 40 therein, for example, the deposition hole 31 may be formed by etching, grooving, and the like, as long as the front metal layer 40 is conveniently filled in the deposition hole 31, and a specific forming manner of the deposition hole 31 is not limited in the present application.

The back metal layer 50 is in contact with the front metal layer 40 at a side of the back via 11 close to the dielectric layer 30, so that the ground region of the front metal layer 40 is electrically connected to the back metal layer 50. Therefore, the pressure of front wiring is reduced, the circuit loss is reduced, and better heat dissipation performance can be provided.

It should be noted that the back metal in the back via 11 is in contact with the front metal layer 40 and the dielectric layer 30, respectively, in other words, the back metal in the back via 11 is not only in contact with the front metal, but also partially in contact with the dielectric layer 30. Thus, in the process of etching the back hole (i.e. the back through hole 11), under the transitional action of the dielectric layer 30, compared with the prior art, the direct contact area between the back through hole 11 and the front metal can be reduced to a certain extent in the application, so that in the process of etching the back hole, the metal reverse sputtering possibly caused by the gallium nitride-based semiconductor device during etching the back hole can be reduced, the adhesion of the back metal is increased when the back metal layer 50 is deposited in the back through hole 11, the defect of poor adhesion such as bubbling and even falling of the back metal layer 50 is prevented, the good grounding effect is ensured, and the reliability of the gallium nitride-based semiconductor device is improved.

Fig. 4 is a scanning electron microscope image of a gallium nitride-based semiconductor device provided in the prior art, and fig. 5 is a scanning electron microscope image of a gallium nitride-based semiconductor device provided in an embodiment of the present invention, it can be found by comparison that the structure of the back side through hole 11, which is significantly smoother compared to the prior art, can be obtained by the gallium nitride-based semiconductor device provided in the present application, and then after performing back side metal deposition sputtering in the back side through hole 11, the adhesion effect of the back side metal can be better.

In this embodiment, the back metal in the back via 11 is respectively connected to the front metal layer 40 and the dielectric layer 30 in a contact manner, mainly to enable the dielectric layer 30 to perform a certain transition function during the etching process of the back via 11, so as to prevent the metal reverse sputtering from occurring when the back metal layer 50 and the front metal layer 40 are directly contacted. At least, the back via 11 should correspond to the ground region of the front metal layer 40 and a partial region of the dielectric layer 30 at the same time, so that the partial region of the dielectric layer 30 in contact with the back metal layer 50 can be used as a transition.

For example, referring to fig. 1 or fig. 2, the projection of the deposition hole 31 on the substrate 10 is located within the projection range of the backside via 11 on the substrate 10 and the projected edges do not intersect. It should be noted that what is said in the present application is within the projection range and the projection edges do not intersect, and the case where the projection of the deposition hole 31 on the substrate 10 completely coincides with the projection of the backside via hole 11 on the substrate 10, and the case where the projection of the deposition hole 31 on the substrate 10 intersects with the projection of the backside via hole 11 on the substrate 10 in a staggered manner are not included. In other words, the overlap region 70 between the backside metal in the backside via 11 and the dielectric layer 30 is in a ring shape (see fig. 1 and 3 in combination).

In addition, referring to fig. 3, in the embodiment, the overlapping region 70 of the dielectric layer 30 and the back metal layer 50 is annular (the overlapping region 70 can be seen from the cross-sectional line shown in fig. 3), and the annular width H of the annular overlapping region 70 is between 3 μm and 20 μm. It should be understood that the ring width H herein refers to the difference between the outer diameter and the inner diameter of the annular overlap region 70.

The gallium nitride-based semiconductor device of the present embodiment includes a substrate 10, a gallium nitride-based epitaxial layer 20 and a dielectric layer 30 sequentially formed on the substrate 10. Wherein, a deposition hole 31 is formed on the dielectric layer 30, a front metal layer 40 is filled in the deposition hole 31, a back through hole 11 is formed on the substrate 10, and the back through hole 11 penetrates through the gallium nitride-based epitaxial layer 20; a back metal layer 50 is deposited on one side of the substrate 10 far away from the gallium nitride-based epitaxial layer 20 and in the back through hole 11, the back metal in the back through hole 11 is respectively in contact connection with the front metal layer 40 and the dielectric layer 30, the projection of the deposition hole 31 on the substrate 10 is located in the projection range of the back through hole 11 on the substrate 10, and the projection edges do not intersect. Therefore, in the etching process of the back through hole 11, under the transitional action of the dielectric layer 30, the Trench effect (namely, the trench effect) of the back through hole 11 can be reduced to a certain extent, so that the metal reverse sputtering phenomenon possibly caused by the etching of the back through hole 11 by the gallium nitride-based semiconductor device can be effectively reduced, and the back through hole 11 can have a smoother inner wall after the etching is completed. In this way, when the back metal layer 50 is deposited in the back via hole 11, the adhesion of the back metal can be increased to some extent, and the defect of poor adhesion, such as bubbling or even peeling of the back metal layer 50, can be prevented. Therefore, the gallium nitride-based semiconductor device provided by the application ensures a good grounding effect and improves the reliability of the gallium nitride-based semiconductor device.

The thickness of the silicon carbide substrate 10 is generally between 300 μm and 500 μm, and the substrate 10 is usually required to be thinned to 50 μm to 100 μm to facilitate etching of the through holes and also to meet practical requirements for heat dissipation. Illustratively, the thinning of the substrate 10 may be performed by mechanical grinding. The specific thinning mode may be any feasible mode in the prior art, and details are not described herein.

In addition, it is necessary to ensure the transparency of the substrate 10 during the thinning process to facilitate the alignment in the subsequent photolithography process, and a polishing process can be added in one step in the case that the transparency is not required after the mechanical grinding, and the operation of the polishing process can be referred to the related documents in the prior art and will not be described in detail herein.

After the substrate 10 is thinned, photoresist is coated on the surface of the substrate 10, and photoetching and developing are performed, wherein the photoresist layer covers a region where the back through hole 11 needs to be etched, and the position of the back through hole 11 corresponds to the position of the front metal layer 40 by using the transparency of the substrate 10 in photoetching. In addition, it should be noted that in selecting the photoresist type, good adhesion of the photoresist layer to the substrate 10 should be ensured.

Optionally, the front metal layer 40 covers the edges of the deposition hole 31. Therefore, in the process of depositing and forming the front metal layer 40, the processing difficulty can be reduced, and the preparation efficiency can be improved.

Referring to fig. 2, in the present embodiment, optionally, the gallium nitride-based semiconductor device further includes a protective dielectric layer 60 formed on the dielectric layer 30, and the protective dielectric layer 60 covers the front metal layer 40. The protective dielectric layer 60 serves as an isolation layer for subsequent interconnection metal, and can protect devices or circuits below the protective dielectric layer from being damaged in subsequent processes. Optionally, in this embodiment, the protective dielectric layer 60 is made of silicon nitride.

Referring to fig. 6 to 8, the present invention further provides a method for fabricating a gallium nitride-based semiconductor device, the method comprising:

and S100, depositing a dielectric layer on the gallium nitride-based epitaxial layer 20 of the gallium nitride-based semiconductor device after the gate process is finished.

S200, forming a deposition hole 31 on the dielectric layer 30 through an etching process.

The formation process of the deposition hole 31 includes, but is not limited to, grooving or etching. Specifically, the forming process of the deposition hole 31 may be selected by a person skilled in the art according to the need, and is not limited herein.

S300, evaporating metal on one side of the dielectric layer 30, which is far away from the gallium nitride-based epitaxial layer 20, and in the deposition hole 31, and forming a front metal layer 40 covering the deposition hole 31 through an etching stripping process.

S400, forming a back through hole 11 on the substrate 10 and the gallium nitride-based epitaxial layer 20 through an etching process, wherein the projection of the deposition hole 31 on the substrate 10 is located in the projection range of the back through hole 11 on the substrate 10, and the projection edges do not intersect.

In the formation of the back-side via hole 11, the substrate 10 and the epitaxial layer thereon (i.e., the gallium nitride-based epitaxial layer 20) need to be etched to remove a portion corresponding to the front-side metal layer 40. Illustratively, the etching method mainly includes a wet method and a dry method. Since both the silicon carbide and the gallium nitride have good chemical stability and cannot be etched effectively by wet etching, in this embodiment, the back via 11 is formed by a dry etching process. The principle of the dry plasma etching technology is that electromagnetic radiation in radio frequency or microwave is transmitted to low-pressure gas in a reaction chamber to generate plasma discharge, so that the generated plasma etches a material to be etched in the reaction chamber.

In addition, the projection of the deposition hole 31 on the substrate 10 is located within the projection range of the backside via hole 11 on the substrate 10 (excluding the case where the projection of the deposition hole 31 on the substrate 10 coincides with the projection of the backside via hole 11 on the substrate 10 and the projection edge intersects), so that the backside via hole 11 is simultaneously communicated with the front metal layer 40 and the dielectric layer 30.

Therefore, in the process of etching the back through hole 11, under the transitional action of the dielectric layer 30, the direct contact area between the back through hole 11 and the front metal can be reduced to a certain extent, so that the metal reverse sputtering phenomenon possibly caused by etching the back through hole 11 of the gallium nitride-based semiconductor device can be effectively reduced, and the back through hole 11 can have a smoother inner wall after the etching is completed.

And S500, depositing metal on the side, far away from the gallium nitride-based epitaxial layer 20, of the substrate 10 and in the back through hole 11 to form a back metal layer 50, wherein the back metal in the back through hole 11 is in contact connection with the front metal layer 40 and the dielectric layer 30.

Thus, according to the method for manufacturing a gallium nitride-based semiconductor device provided by the present application, a relatively smooth inner wall surface of the back surface via hole 11 can be obtained, and therefore, the adhesion of the back surface metal in the back surface via hole 11 can be increased to a certain extent, and the occurrence of defects of poor adhesion, such as bubbling and even peeling of the back surface metal layer 50, can be prevented. Therefore, the gallium nitride-based semiconductor device formed by the manufacturing method of the gallium nitride-based semiconductor device has better grounding effect and higher reliability.

Referring to fig. 7, optionally, in step S500, depositing metal on the side of the substrate 10 away from the gallium nitride-based epitaxial layer 20 and in the back via 11 to form the back metal layer 50 includes the following steps:

s510, sputtering to form a seed layer on the substrate 10 with the back through hole 11;

and S520, forming a metal layer on the seed layer in an electroplating mode.

Illustratively, a seed layer may be formed on a side of the substrate 10 away from the gallium nitride-based epitaxial layer 20 by sputtering, and then a metal layer (which may be an Au layer) is electroplated to cover the bottom and the sidewalls of the back via 11 and a side of the substrate 10 away from the gallium nitride-based epitaxial layer 20 with the back metal layer 50, so that the front metal layer 40 is interconnected with the back metal layer 50 through the back via 11.

Referring to fig. 8, after forming the front metal layer covering the deposition hole 31 through the etching and stripping process in step S300, the method further includes the following steps:

and S600, depositing a protective dielectric layer 60 on the dielectric layer 30 and the side of the front metal layer 40 far away from the substrate 10.

The protective dielectric layer 60 covers the front metal layer 40, which can protect the underlying devices or circuits from damage in subsequent processes. Since silicon nitride has a strong function of masking contamination and a transparent and abrasion-resistant characteristic, it can be used to fabricate a protection film of a mask, and in this embodiment, the protection dielectric layer 60 is made of silicon nitride.

The above description is only an alternative embodiment of the present invention and is not intended to limit the present invention, and various modifications and variations of the present invention may occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.