CN111129163B - Schottky diode and preparation method thereof - Google Patents

Abstract

The invention relates to the field of semiconductors, in particular to a Schottky diode and a preparation method thereof. The method comprises the following steps: an n-type gallium oxide layer is epitaxially grown on the substrate; preparing a first mask layer on the n-type gallium oxide layer; the window of the first mask layer is a region corresponding to a thermal oxidation treatment region to be prepared, wherein the thermal oxidation treatment region comprises at least one first thermal oxidation region and two second thermal oxidation regions; performing first high-temperature annealing treatment on the front surface of the device to form a thermal oxidation treatment area; removing the first mask layer; preparing an anode metal layer on the front side and a cathode metal layer on the back side; wherein the first thermal oxidation zone is located below the anode metal and each second thermal oxidation zone is located partially below the anode metal. The method can form a terminal structure through thermal oxidation, and reduce the electric field below the anode metal and in the edge area, thereby reducing the reverse leakage of the anode and improving the breakdown and conduction characteristics.

Description

Schottky diode and its preparation method

technical field

The invention relates to the field of semiconductors, in particular to a Schottky diode and a preparation method thereof.

Background technique

With the application of semiconductor devices in more and more technical fields, traditional silicon-based and other narrow-bandgap semiconductor diodes have encountered many challenges. Among them, the breakdown voltage is difficult to meet the growing demand, which has become one of the key factors affecting the further improvement of device performance. one. Compared with the third-generation semiconductor materials represented by SiC and GaN, gallium oxide (Ga ₂ O ₃ ) has a wider forbidden band width, and the breakdown field strength is equivalent to more than 20 times that of Si, and twice that of SiC and GaN. Above, theoretically speaking, when manufacturing diode devices with the same withstand voltage, the on-resistance of the device can be reduced to 1/10 of SiC and 1/3 of GaN, and the Ballyga figure of merit of Ga ₂ O ₃ material is SiC 18 times that of GaN materials, and more than 4 times that of GaN materials, so Ga ₂ O ₃ is a wide-bandgap semiconductor material with excellent performance suitable for the preparation of power devices and high-voltage switching devices.

Wide bandgap gallium oxide Schottky diodes have the advantages of high breakdown and low on-resistance. At present, the device performance of Schottky diodes is continuously improved by improving the quality of Ga ₂ O ₃ crystal materials and optimizing the doping process. However, The breakdown voltage and conduction characteristics of existing Schottky diodes are still far below the expected values of materials.

Contents of the invention

In view of this, an embodiment of the present invention provides a Schottky diode and a manufacturing method thereof, so as to improve the breakdown voltage and conduction characteristics of the existing Schottky diode.

The first aspect of the embodiments of the present invention provides a method for preparing a Schottky diode, including:

epitaxial n-type gallium oxide layer on the substrate;

A first mask layer is prepared on the n-type gallium oxide layer; wherein, the window of the first mask layer is the area corresponding to the thermal oxidation treatment area to be prepared, and the thermal oxidation treatment area includes at least one first mask layer a thermal oxidation zone and two second thermal oxidation zones;

Performing a first high-temperature annealing treatment on the front of the device to form a thermal oxidation treatment area;

removing the first mask layer;

Prepare the anode metal layer on the front side and the cathode metal layer on the back side;

Wherein, the area corresponding to the projection of the anode metal layer on the n-type gallium oxide layer is the first area, and the area other than the area corresponding to the projection of the anode metal layer on the n-type gallium oxide layer is the second area. Two zones, the first thermal oxidation zone is located in the first zone; the first part of each second thermal oxidation zone is located in the first zone, and the second part of each second thermal oxidation zone is located in the second zone.

Optionally, the thermal oxidation treatment area further includes: a third thermal oxidation area located in the second area.

Optionally, after forming the thermal oxidation treatment region, the method further includes: performing high temperature annealing treatment on at least one of the first thermal oxidation region, the second thermal oxidation region and the third thermal oxidation region.

Optionally, the substrate is an n-type gallium oxide substrate, and the doping concentration is greater than that of the n-type gallium oxide layer.

Optionally, the n-type gallium oxide layer is non-uniformly doped, and the n-type gallium oxide layer has a multi-layer structure whose concentration increases from top to bottom.

Optionally, the preparation of the positive anode metal layer includes:

After removing the first mask layer, depositing an insulating dielectric layer;

Removing the insulating dielectric layer in the preset anode region by dry etching or wet etching;

preparing a positive anode metal layer with a field plate structure; wherein, the field plate structure includes a single-layer field plate structure, a multi-layer field plate structure and an oblique field plate structure;

Correspondingly, the preset anode area is the first area, and the area other than the preset anode area is the second area.

A second aspect of the embodiments of the present invention provides a Schottky diode, including:

Substrate;

an n-type gallium oxide layer formed on the substrate;

an anode metal layer formed on the n-type gallium oxide layer;

a cathode metal layer formed on the backside of the substrate;

Wherein, the n-type gallium oxide layer includes: at least one first thermal oxidation region and two second thermal oxidation regions, and the region corresponding to the projection of the anode metal layer on the n-type gallium oxide layer is the first In an area, the area other than the area corresponding to the projection of the anode metal layer on the n-type gallium oxide layer is a second area, and the first thermal oxidation area is located in the first area and is in contact with the anode metal layer; The first part of each second thermal oxidation region is located in the first region, the second part of each second thermal oxidation region is located in the second region, and the first part of each second thermal oxidation region is in contact with the anode metal layer.

Optionally, the n-type gallium oxide layer further includes: a third thermal oxidation region located in the second region, and the upper surface of the third thermal oxidation region is the upper surface of the n-type gallium oxide layer .

Optionally, the annealing temperature and annealing time are different during the formation of the first thermal oxidation region, the second thermal oxidation region and the third thermal oxidation region.

Optionally, the substrate is an n-type gallium oxide substrate, and the doping concentration is greater than that of the n-type gallium oxide layer;

The n-type gallium oxide layer is non-uniformly doped, and the n-type gallium oxide layer is a multi-layer structure whose concentration increases from top to bottom.

In the embodiment of the present invention, when preparing the Schottky diode, high-temperature annealing treatment is performed on the front of the device to form a thermal oxidation treatment area; wherein, preparing the first mask layer on the n-type gallium oxide layer can form a thermal oxidation treatment area at a specific position , including at least one first thermal oxidation zone located under the anode metal layer and two second thermal oxidation zones partially located under the anode metal layer. After removing the first mask layer, the anode metal layer is prepared at a specific position on the front of the device. Since the first thermal oxidation area and the second thermal oxidation area are included under the anode metal layer, the electric field under the anode metal layer and the edge area is reduced, and the anode The reverse leakage of the metal layer improves the breakdown voltage and conduction characteristics of the prepared Schottky diode.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the descriptions of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only of the present invention. For some embodiments, those of ordinary skill in the art can also obtain other drawings based on these drawings without paying creative efforts.

Fig. 1 is the schematic flow chart of the preparation method of Schottky diode provided by the embodiment of the present invention;

Fig. 2 is a schematic cross-sectional structure diagram of an epitaxial n-type gallium oxide layer on a substrate provided by an embodiment of the present invention;

Fig. 3 is a schematic cross-sectional structure after preparing a first mask layer on an n-type gallium oxide layer provided by an embodiment of the present invention;

Fig. 4 is a schematic cross-sectional structure diagram of a thermal oxidation treatment region formed by performing high-temperature annealing on the front of the device according to an embodiment of the present invention;

5 is a schematic diagram of a cross-sectional structure provided by an embodiment of the present invention after removing the first mask layer;

Fig. 6 is a schematic cross-sectional structure diagram after preparing an anode metal layer on the front side and a cathode metal layer on the back side provided by an embodiment of the present invention;

Fig. 7 is a schematic cross-sectional structure diagram of a device formed when there are two first oxidation regions provided by an embodiment of the present invention;

8 to 11 are schematic diagrams of the cross-sectional structures of the Schottky diodes provided by the embodiments of the present invention when the third thermal oxidation region is prepared;

12 is a schematic cross-sectional structure diagram of a Schottky diode with two first thermal oxidation regions and four third thermal oxidation regions provided by an embodiment of the present invention;

Fig. 13 is a schematic cross-sectional structure after depositing a mask layer on the n-type gallium oxide layer provided by an embodiment of the present invention;

Fig. 14 is a schematic cross-sectional structure diagram after depositing an insulating dielectric layer according to an embodiment of the present invention;

Fig. 15 is a schematic cross-sectional structure diagram provided by an embodiment of the present invention after removing the insulating medium layer in the preset anode region;

16 is a schematic cross-sectional structure diagram after preparing the front anode metal layer with field plate structure and the back cathode metal layer according to the embodiment of the present invention;

FIG. 17 is a schematic cross-sectional structure diagram of a Schottky diode having a front anode metal layer with a field plate structure and corresponding to FIG. 7 provided by an embodiment of the present invention;

FIG. 18 is a schematic cross-sectional structure diagram of a Schottky diode having a front anode metal layer with a field plate structure and corresponding to FIG. 11 provided by an embodiment of the present invention;

FIG. 19 is a schematic cross-sectional structure diagram of a Schottky diode having a front anode metal layer with a field plate structure and corresponding to FIG. 12 provided by an embodiment of the present invention;

FIG. 20 is a schematic cross-sectional structure diagram of a Schottky diode provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Fig. 1 is a schematic flow chart of the preparation method of the Schottky diode provided by the embodiment of the present invention, referring to Fig. 1, the preparation method of the Schottky diode may include:

Step S101, epitaxially growing an n-type gallium oxide layer on the substrate.

In the embodiment of the present invention, referring to FIG. 2 , the substrate 201 is an n-type heavily doped gallium oxide substrate. The n-type gallium oxide layer 202 is a lightly doped gallium oxide layer realized by doping Si or Sn, and the thickness of the n-type gallium oxide layer 202 is set according to actual requirements.

Step S102, preparing a first mask layer on the n-type gallium oxide layer; wherein, the window of the first mask layer is the area corresponding to the thermal oxidation treatment area to be prepared, and the thermal oxidation treatment area includes At least one first thermal oxidation zone and two second thermal oxidation zones.

In the embodiment of the present invention, referring to FIG. 3 , in order to form a thermal oxidation treatment area in a specific area in a subsequent step, the first mask layer 204 can be prepared in a corresponding area other than the thermal oxidation treatment area to be prepared, even The window of the first mask layer 204 is a region corresponding to the thermal oxidation treatment region to be prepared.

Step S103, performing high-temperature annealing treatment on the front surface of the device to form a thermal oxidation treatment area.

In the embodiment of the present invention, referring to FIG. 4, high-temperature annealing treatment is performed on the front of the device. Due to the shielding of the first mask layer 204, no heat will be formed in the n-type gallium oxide layer corresponding to the region where the first mask layer 204 exists. Oxidize the treatment area, and form a thermal oxidation treatment area in the n-type gallium oxide layer outside the corresponding area of the first mask layer.

Step S104, removing the first mask layer.

In the embodiment of the present invention, referring to FIG. 5 , the first mask layer is removed to form the device structure as shown in FIG. 5 . The thermal oxidation treatment area includes a first thermal oxidation area 2051 and a second thermal oxidation area 2052. The above oxidation treatment area is classified according to its relative position with the metal anode to be prepared. The first thermal oxidation area 2051 is located in The second thermal oxidation zone 2052 is partly located in the area directly below the metal anode to be prepared, and the number is fixed at two. Correspondingly, when a different number of the first thermal oxidation regions 2051 is to be prepared, the window of the first mask layer is also correspondingly changed.

Step S105, preparing the anode metal layer on the front and the cathode metal layer on the back; wherein, the area corresponding to the projection of the anode metal layer on the n-type gallium oxide layer is the first area, and the anode metal layer is in the The area other than the area corresponding to the projection on the n-type gallium oxide layer is the second area, and the first thermal oxidation area is located in the first area; the first part of each second thermal oxidation area is located in the first area, and each second thermal oxidation area is located in the first area. A second portion of the thermal oxidation zone is located in the second zone.

In the embodiment of the present invention, referring to FIG. 6 , an anode metal layer 206 is prepared on the front of the device after removing the first mask layer, so that the left and right edges of the anode metal layer 206 are respectively located in the regions corresponding to the two second thermal oxidation regions 2052 That is, the area corresponding to the projection of the anode metal layer on the n-type gallium oxide layer is the first area, and the area other than the area corresponding to the projection of the anode metal layer on the n-type gallium oxide layer is the second area The second region, when preparing the anode metal layer, the first thermal oxidation region 2051 is located in the first region, the first part of each second thermal oxidation region 2052 is located in the first region, and each second thermal oxidation region 2052 is located in the first region. The second part of is in the second region. Compared with the n-type gallium oxide layer that has not been subjected to high-temperature annealing, there is a difference in ion concentration in the thermal oxidation treatment area that has undergone high-temperature annealing treatment, and a thermal oxidation treatment area is formed at a specific position, and the anode metal layer 206 and the thermal oxidation treatment area are controlled. The relative position can reduce the electric field under the anode metal layer 206 and the edge region, reduce the reverse leakage of the anode, and improve the breakdown and conduction characteristics. When there are two first oxidation regions, the finally formed device is shown in FIG. 7 .

In the embodiment of the present invention, when preparing the Schottky diode, high-temperature annealing treatment is performed on the front of the device to form a thermal oxidation treatment area; the first mask layer is prepared on the n-type gallium oxide layer, and due to the shielding effect of the first mask layer, A thermal oxidation treatment region can be formed at a specific position in the n-type gallium oxide layer, that is, at least one first thermal oxidation region and two second thermal oxidation regions are formed. After removing the first mask layer, an anode metal layer is prepared on the front of the device, and a cathode metal layer is prepared on the back of the device; wherein, the left and right edges of the anode metal layer are respectively located in the regions corresponding to the second thermal oxidation region, and the The first thermal oxidation region is located under the anode metal layer, thereby reducing the electric field under the anode metal and the edge region, thereby reducing the reverse leakage of the anode, and improving the breakdown and conduction characteristics.

In some embodiments, referring to FIGS. 8-11 , the thermal oxidation treatment area further includes: a third thermal oxidation area located in the second area.

In the embodiment of the present invention, multiple thermal oxidation treatment regions can be formed in the drift layer by high-temperature annealing surface treatment, thereby introducing more concentration changes and further improving the breakdown characteristics of the device. Based on the device structure shown in FIG. 2 , a first mask layer 204 is prepared on the n-type gallium oxide layer 202 to form the device structure shown in FIG. 8 . Referring to FIG. 9 , high-temperature annealing treatment is performed on the front of the device to form a thermal oxidation treatment area; after the thermal oxidation treatment area is formed, the first mask layer 204 is removed to form the device structure as shown in FIG. 10 , except for the thermal oxidation treatment area. In addition to the first thermal oxidation zone 2051 and the second thermal oxidation zone 2052, it may further include: a third thermal oxidation zone 2053 located in the second region. After that, the anode metal layer 206 on the front side and the cathode metal layer 207 on the back side are prepared on the device structure shown in FIG. 10 to form the device structure shown in FIG. 11 . The structures provided in Figures 8-11 are only schematic, and there may be more first thermal oxidation zones and third thermal oxidation zones, for example, the number of first thermal oxidation zones may be two or more The number of the third thermal oxidation zone can also be two or more; such as the structure provided in Figure 12, in Figure 12, the number of the first thermal oxidation zone is two, the third thermal oxidation zone The number of zones is four. In the embodiment of the present invention, more lateral concentration changes are introduced into the n-type gallium oxide layer under the anode, which further improves the high-voltage resistance characteristics of the device.

In some embodiments, after forming the thermal oxidation treatment region, further comprising: performing high temperature annealing treatment on at least one of the first thermal oxidation region, the second thermal oxidation region and the third thermal oxidation region.

In the embodiment of the present invention, the high temperature annealing retreatment is to form thermal oxidation of the first thermal oxidation region, the second thermal oxidation region and the third thermal oxidation region with different concentrations and/or multiple depths. treatment area to improve the breakdown characteristics and conduction characteristics of the device. After the high-temperature annealing treatment is performed on the front of the device to form a thermal oxidation treatment area, multiple high-temperature annealing retreatments can be performed again, wherein, each time the high-temperature retreatment is performed, the processing power and processing time of the equipment can be changed, High-temperature annealing with various powers and various times is performed. Multiple thermal oxidation treatment regions with different concentrations and/or depths can be formed after multiple high-temperature retreatments, thereby further improving the breakdown characteristics and conduction characteristics of the device.

In some embodiments, the substrate is an n-type gallium oxide substrate, and the doping concentration is greater than that of the n-type gallium oxide layer.

In the embodiment of the present invention, referring to FIG. 2 , the substrate 201 is an n-type gallium oxide substrate. The n-type gallium oxide layer 202 is epitaxially grown on the n-type gallium oxide substrate 201 , wherein the doping concentration of the n-type gallium oxide layer 202 is lower than that of the n-type gallium oxide substrate 201 , which is more conducive to realizing high voltage resistance.

In some embodiments, the n-type gallium oxide layer is non-uniformly doped; the n-type gallium oxide layer is a multi-layer structure whose concentration increases from top to bottom.

In the embodiment of the present invention, the n-type gallium oxide layer is a multi-layer structure with increasing concentration from top to bottom, which is more conducive to realizing high voltage resistance.

In some embodiments, the preparation of the first mask layer on the n-type gallium oxide layer may include: depositing a mask layer on the n-type gallium oxide layer; The mask layer corresponding to the prepared thermal oxidation treatment area is removed to form a first mask layer.

In the embodiment of the present invention, referring to FIG. 13 , the mask layer 203 can be deposited on the n-type gallium oxide layer 202 first, and then the mask layer 203 corresponding to the thermal oxidation treatment area to be prepared is removed by photolithography and wet etching. A first mask layer is formed in a corresponding region other than the to-be-prepared thermal oxidation treatment region. In fact, the formation position and shape of the first mask layer are prepared according to the position of the thermal oxidation treatment area to be prepared, and finally formed is composed of multiple discontinuous parts, such as the first mask layer in Figure 3 and Figure 8 204 form.

In some embodiments, the first mask layer may include any one of SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , HfO ₂ and MgO.

In some embodiments, the removing the first mask layer may include: putting the device forming the thermal oxidation treatment region into a preset solution until the first mask layer is removed, wherein the preset The solution is an etching solution for the first mask layer.

In some embodiments, the preparation of the anode metal layer on the front side may include: depositing an insulating dielectric layer after removing the first mask layer; removing the insulating dielectric layer of the preset anode region by dry etching or wet etching layer; prepare a positive anode metal layer with a field plate structure; wherein, the field plate structure includes a single-layer field plate structure, a multi-layer field plate structure and an oblique field plate structure; correspondingly, the preset anode region is the first The first area, the area outside the anode area is preset as the second area.

In the embodiment of the present invention, after removing the first mask layer, an insulating dielectric layer is deposited, and then the insulating dielectric layer in the preset anode region is removed by dry etching or wet etching; wherein, the preset anode region is The contact portion between the anode metal layer and the n-type gallium oxide layer on the front side of the plate structure, correspondingly, the preset anode region is the first region, and the region other than the preset anode region is the second region, which is used to make the n-type gallium oxide layer under the anode The lateral concentration change is introduced into the gallium oxide layer, so as to optimize the electric field at the anode junction, improve the breakdown voltage, and take into account the on-resistance at the same time. At the same time, compared with the anode metal layer without field plate structure, the positive anode metal layer with field plate structure has better high voltage resistance and conduction characteristics. The structure of the field plate can be selected according to the actual situation, including single Layer field plate structure, multilayer field plate structure and inclined field plate structure.

In some embodiments, an anode metal layer with a field plate structure can be formed on the device structure shown in FIG. 5 and a cathode metal layer on the back side can be prepared. The structural diagrams corresponding to the steps are shown in FIGS. 14-16 .

In the embodiment of the present invention, referring to FIGS. 14-16 , after removing the first mask layer, an insulating dielectric layer 208 is deposited, and the insulating dielectric layer 208 in the preset anode region is removed by dry etching or wet etching, Prepare a positive anode metal layer 206 with a field plate structure; wherein, the preset anode region is the first region, and the region other than the preset anode region is the second region, which is used to introduce a lateral direction into the n-type gallium oxide layer below the anode. The concentration changes, thereby optimizing the electric field at the anode junction, increasing the breakdown voltage, and taking into account the on-resistance at the same time. Prepare the anode metal layer 206 with a field plate structure and prepare the cathode metal layer 207 on the back side to form a Schottky diode as shown in FIG. 16 . In actual operation, the cathode metal layer 207 can be prepared in any one of the above steps.

In some embodiments, in the Schottky diode structures shown in FIG. 7 , FIG. 11 and FIG. 12 , the anode metal layer 206 can be an anode metal layer with a field plate structure, and its preparation steps are the same as those described above, No more details are given here, and their corresponding field plate structures are shown in FIG. 17 , FIG. 18 and FIG. 19 .

Fig. 20 is a schematic cross-sectional structure diagram of a Schottky diode provided by an embodiment of the present invention, including:

substrate 201;

n-type gallium oxide layer 202, formed on the substrate 201;

an anode metal layer 206, formed on the n-type gallium oxide layer 202;

The cathode metal layer 207 is formed on the back side of the substrate 201;

Wherein, the n-type gallium oxide layer 202 includes: at least one first thermal oxidation region 2051 and two second thermal oxidation regions 2052, and the projection of the anode metal layer 206 on the n-type gallium oxide layer 202 corresponds to The area of the anode metal layer 206 on the n-type gallium oxide layer 202 corresponding to the area of the projection is the second area, the first thermal oxidation area 2051 is located in the first area, and In contact with the anode metal layer 206; the first part of each second thermal oxidation region 2052 is located in the first region, the second part of each second thermal oxidation region 2052 is located in the second region, and each second thermal oxidation region A first portion of 2052 is in contact with the anode metal layer 206 .

In the above-mentioned Schottky diode, a thermal oxidation treatment area is formed on a specific area on the upper surface of the n-type gallium oxide layer, including at least one first thermal oxidation area located under the anode metal layer and two second thermal oxidation areas partially located under the anode metal layer. The second thermal oxidation area can reduce the electric field under the anode metal and the edge area, thereby reducing the reverse leakage of the anode and improving the breakdown characteristics of the device.

In some embodiments, the n-type gallium oxide layer further includes: a third thermal oxidation region located in the second region, and the upper surface of the third thermal oxidation region is the upper surface of the n-type gallium oxide layer surface.

In some embodiments, the annealing temperature and annealing time are different during the formation of the first thermal oxidation region, the second thermal oxidation region and the third thermal oxidation region.

In some embodiments, the substrate is an n-type gallium oxide substrate, and the doping concentration is greater than that of the n-type gallium oxide layer;

In some embodiments, the n-type gallium oxide layer is non-uniformly doped, and the n-type gallium oxide layer is a multi-layer structure whose concentration increases from top to bottom.

For the forming process of each part of the above-mentioned Schottky diode, reference may be made to the corresponding process in the foregoing method embodiments, and details are not repeated here.

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 foregoing embodiments, those of ordinary skill in the art should understand that: it can still implement the foregoing embodiments Modifications to the technical solutions described in the examples, or equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the application, and should be included in the Within the protection scope of this application.

Claims (6)

1. A method of manufacturing a schottky diode comprising:

an n-type gallium oxide layer is epitaxially grown on the substrate;

preparing a first mask layer on the n-type gallium oxide layer; the window of the first mask layer is a region corresponding to a thermal oxidation treatment region to be prepared, and the thermal oxidation treatment region comprises at least one first thermal oxidation region and two second thermal oxidation regions;

carrying out high-temperature annealing treatment on the front surface of the device to form a thermal oxidation treatment area;

removing the first mask layer;

preparing an anode metal layer on the front side and a cathode metal layer on the back side;

the region corresponding to the projection of the anode metal layer on the n-type gallium oxide layer is a first region, the region outside the region corresponding to the projection of the anode metal layer on the n-type gallium oxide layer is a second region, and the first thermal oxidation region is located in the first region; a first portion of each second thermal oxidation zone is located in the first region and a second portion of each second thermal oxidation zone is located in the second region;

the thermal oxidation treatment zone further comprises: a third thermal oxidation zone located in the second region;

after forming the thermal oxidation treatment zone, further comprising:

carrying out high-temperature annealing retreatment on at least one of the first thermal oxidation zone, the second thermal oxidation zone and the third thermal oxidation zone;

the high temperature annealing retreatment is used for forming a plurality of first thermal oxidation areas, second thermal oxidation areas and third thermal oxidation areas with different concentrations and/or different depths.

2. The method of manufacturing a Schottky diode of claim 1,

the substrate is an n-type gallium oxide substrate, and the doping concentration is larger than that of the n-type gallium oxide layer.

3. The method of fabricating a schottky diode of claim 1 wherein said n-type gallium oxide layer is non-uniformly doped;

the n-type gallium oxide layer has a multilayer structure with an increased concentration from top to bottom.

4. The method of fabricating a schottky diode of claim 1 wherein said fabricating a front side anode metal layer comprises:

after the first mask layer is removed, depositing an insulating medium layer;

removing the insulating medium layer of the preset anode region by dry etching or wet etching;

preparing an anode metal layer with a front surface of a field plate structure; wherein the field plate structure comprises a single-layer field plate structure, a multi-layer field plate structure and an oblique field plate structure;

correspondingly, the preset anode region is a first region, and the region outside the preset anode region is a second region.

5. A schottky diode, comprising:

a substrate;

an n-type gallium oxide layer formed on the substrate;

an anode metal layer formed on the n-type gallium oxide layer;

a cathode metal layer formed on the back surface of the substrate;

wherein the n-type gallium oxide layer comprises: the anode metal layer is arranged on the n-type gallium oxide layer, the projection of the anode metal layer on the n-type gallium oxide layer corresponds to a first area, the area of the anode metal layer outside the area corresponding to the projection of the anode metal layer on the n-type gallium oxide layer corresponds to a second area, and the first thermal oxidation area is positioned in the first area and is in contact with the anode metal layer; a first portion of each second thermal oxidation zone is located in the first region, a second portion of each second thermal oxidation zone is located in the second region, and the first portion of each second thermal oxidation zone is in contact with the anodic metal layer;

the n-type gallium oxide layer further comprises:

the third thermal oxidation area is positioned in the second area, and the upper surface of the third thermal oxidation area is the upper surface of the n-type gallium oxide layer;

the annealing temperature and the annealing time are different in the forming process of the first thermal oxidation zone, the second thermal oxidation zone and the third thermal oxidation zone;

the first thermal oxidation zone, the second thermal oxidation zone, and the third thermal oxidation zone are different in concentration and/or different in depth.

6. The schottky diode of claim 5 wherein,

the substrate is an n-type gallium oxide substrate, and the doping concentration is larger than that of the n-type gallium oxide layer;

the n-type gallium oxide layer is unevenly doped, and the n-type gallium oxide layer has a multilayer structure with the concentration increased from top to bottom.

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