Junction barrier schottky diode

Abstract

The invention provides a junction barrier Schottky diode, which comprises a semiconductor substrate comprising a substrate layer and an epitaxial layer which are stacked, and the epitaxial layer is provided with a first surface; the first doped regions are arranged at intervals, each first doped region is located in the epitaxial layer, the epitaxial layer between two adjacent first doped regions is an epitaxial part, the first surface corresponding to the epitaxial part comprises a predetermined region, and the predetermined region comprises a first region, a second region and a third region which are adjacent in sequence; the barrier structure comprises a first Schottky contact part or an insulating dielectric layer covering the first region, a second Schottky contact part covering the second region and a third Schottky contact part covering the third region; a barrier height of the barrier structure at the first region is higher than a barrier height of the barrier structure at the second region and a barrier height of the barrier structure at the third region, respectively. According to the junction barrier Schottky diode, the problem that the junction barrier Schottky diode in the prior art is poor in conduction due to the addition of the PN junction is solved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more particularly, to a junction barrier Schottky diode. Background Art

[0002] Schottky barrier diodes (SBDs) have been widely used due to their ultra-low turn-on voltage and excellent reverse recovery characteristics. The design of power devices generally aims to minimize both the forward conduction resistance and conduction loss, and to maximize the reverse blocking voltage.

[0003] In the prior art, a PN diode is further added to the SBD to form a junction barrier Schottky diode (JBS). This device combines the advantages of SBDs and PiN diodes. It has the low turn-on voltage of SBDs and suppresses the reverse leakage current through the depletion layer formed in the PN junction region, enabling high breakdown voltage, so that the device also has high blocking characteristics similar to PiN diodes. However, in the traditional design paradigm of simply juxtaposing the PN junction region and the Schottky region, either increasing the PN junction region sacrifices the conduction characteristics, or reducing the PN junction region reduces the blocking ability. That is, there is an inherent contradiction in traditional JBS diodes between the PN junction region and the Schottky region - increasing the PN junction region improves the breakdown voltage, but deteriorates the conduction characteristics due to squeezing the Schottky contact area.

[0004] Therefore, there is an urgent need for a junction barrier Schottky diode structure with a smaller forward conduction resistance and conduction loss, and a stronger reverse breakdown voltage capability. Summary of the Invention

[0005] The main object of the present invention is to provide a junction barrier Schottky diode to solve the problem of poor conduction of the junction barrier Schottky diode caused by the addition of the PN junction region in the prior art.

[0006] To achieve the above object, according to one aspect of the present invention, a junction barrier Schottky diode is provided, comprising: a semiconductor substrate including a stacked substrate layer and an epitaxial layer, a side surface of the epitaxial layer facing away from the substrate layer being a first surface of the semiconductor substrate; a plurality of first doped regions spaced along a first direction, each first doped region extending from the first surface into the epitaxial layer, the doping types of the first doped regions and the epitaxial layer being opposite, the epitaxial layer between two adjacent first doped regions being an epitaxial portion, a first surface corresponding to the epitaxial portion including a predetermined region, the predetermined region including a first region, a second region, and a third region, wherein the second region and the third region are located on opposite sides of the first region in the first direction; a barrier structure including a first Schottky metal portion or an insulating dielectric layer covering the first region, a second Schottky metal portion covering the second region, and a third Schottky metal portion covering the third region; in the case where the barrier structure includes the first Schottky metal portion, the barrier height between the first Schottky metal portion and the epitaxial portion is higher than the barrier height between the second Schottky metal portion and the epitaxial portion and the barrier height between the third Schottky metal portion and the epitaxial portion respectively; in the case where the barrier structure includes the insulating dielectric layer, the barrier height between the insulating dielectric layer material and the epitaxial portion is higher than the barrier height between the second Schottky metal portion and the epitaxial portion and the barrier height between the third Schottky metal portion and the epitaxial portion respectively.

[0007] Optionally, in the case where the barrier structure includes the first Schottky metal portion, the work function of the material of the first Schottky metal portion is greater than the work function of the material of the second Schottky metal portion and the work function of the material of the third Schottky metal portion respectively, or the work function of the material of the first Schottky metal portion is less than the work function of the material of the second Schottky metal portion and the work function of the material of the third Schottky metal portion respectively.

[0008] Optionally, the second Schottky metal portion includes a plurality of first sub-Schottky metal portions in contact along the first direction, and the work functions of the materials of any two first sub-Schottky metal portions are different; and / or, the third Schottky metal portion includes a plurality of second sub-Schottky metal portions in contact along the first direction, and the work functions of the materials of any two second sub-Schottky metal portions are different.

[0009] Optionally, in the case where the work function of the material of the first Schottky metal portion is greater than the work function of the material of the second Schottky metal portion and the work function of the material of the third Schottky metal portion respectively, the work functions of the materials of the plurality of first sub-Schottky metal portions of the second Schottky metal portion decrease in the direction away from the first Schottky metal portion; in the case where the work function of the material of the first Schottky metal portion is less than the work function of the material of the second Schottky metal portion and the work function of the material of the third Schottky metal portion respectively, the work functions of the materials of the plurality of first sub-Schottky metal portions of the second Schottky metal portion increase in the direction away from the first Schottky metal portion.

[0010] Optionally, there is a first contact surface between the first Schottky metal part and the epitaxial part, a second contact surface between the second Schottky metal part and the epitaxial part, and a third contact surface between the third Schottky metal part and the epitaxial part, and the first contact surface, the second contact surface, and the third contact surface are flush.

[0011] Optionally, there is a first contact surface between the first Schottky metal part and the epitaxial part or between the insulating dielectric layer and the epitaxial part, a second contact surface between the second Schottky metal part and the epitaxial part, and a third contact surface between the third Schottky metal part and the epitaxial part. The height of the first contact surface from the substrate layer is a first height, and the heights of the second contact surface and the third contact surface from the substrate layer are a second height, and the first height is greater than or less than the second height.

[0012] Optionally, there is a first recess in the first surface, the first contact surface is the first surface corresponding to the first recess, and the second contact surface and the third contact surface are flush.

[0013] Optionally, the first contact surface includes a bottom surface and a side surface, and in a cross-section perpendicular to the first surface, the bottom surface and the side surface are connected by an arc.

[0014] Optionally, the barrier structure further includes a fourth Schottky metal part. When the barrier structure includes an insulating dielectric layer, the insulating dielectric layer covers the bottom surface, and the fourth Schottky metal part covers the side surface.

[0015] Optionally, when the barrier structure includes an insulating dielectric layer, the insulating dielectric layer includes a first part covering the bottom surface and a second part covering the side surface; the material of the first part is a first insulating dielectric material, and the material of the second part is a second insulating dielectric material.

[0016] Optionally, there is a protrusion in the first surface, the first contact surface is the first surface corresponding to the top surface of the protrusion, and the second contact surface and the third contact surface are respectively the first surfaces corresponding to the side surfaces of the protrusion.

[0017] Optionally, the top surface and the side surface of the protrusion are connected by an arc.

[0018] Optionally, when the barrier structure includes the first Schottky metal part, the second Schottky metal part and the third Schottky metal part are arranged axially symmetrically with respect to the first Schottky metal part.

[0019] Optionally, the junction barrier Schottky diode further includes: an ohmic contact structure covering the first doped region; the ohmic contact structure is in contact with the side of the second Schottky metal part away from the first Schottky metal part, and / or, the ohmic contact structure is in contact with the side of the third Schottky metal part away from the first Schottky metal part.

[0020] Optionally, a second recess is provided in the first surface, and the ohmic contact structure is located in the second recess.

[0021] Applying the technical solution of the present invention, the first Schottky metal part or the insulating dielectric layer covers the first region, the second Schottky metal part covers the second region, and the third Schottky metal part covers the third region. The first region, the second region, and the third region are respectively three regions where the epitaxial part is located on the first surface. The epitaxial part is the region in the epitaxial layer located between two adjacent first doped regions. Since the barrier height at the contact interface between the first Schottky metal part (or the insulating dielectric layer) and the epitaxial part is higher than the barrier height at the contact interface between the second Schottky metal part and the epitaxial part and the barrier height at the contact interface between the third Schottky metal part and the epitaxial part. It can be seen that in this application, when the barrier structure includes the first Schottky metal part, a multi-level barrier structure is introduced by different Schottky metals. Thus, without changing the physical proportion of the PN junction region, the conduction loss of the PN junction region is compensated by the early conduction effect of the low-barrier regions (the second region and the third region), and at the same time, the reverse depletion ability is enhanced by the high-barrier region (the first region). This energy band design based on the spatial modulation of the barrier height breaks through the traditional "area trade-off" design paradigm and realizes the collaborative optimization of the on-resistance and the blocking voltage. In addition, in this application, when the barrier structure includes an insulating dielectric layer, the insulating dielectric layer (such as SiO2) is introduced into the junction barrier Schottky diode as a barrier control element. Since the voltage withstand efficiency of the insulating dielectric layer under reverse bias is far higher than that of the metal Schottky contact, a multi-level barrier structure is introduced by the insulating dielectric material and the Schottky metal; when conducting forward, the low work function metal regions corresponding to the second Schottky metal part and the third Schottky metal part provide current channels, avoiding the conduction disadvantage of the dielectric layer. This "dielectric + metal" composite barrier design combines the high voltage withstand of the MOS structure and the low conduction advantage of the Schottky structure, providing a new design dimension for power devices, thereby realizing the collaborative optimization of the on-resistance and the blocking voltage. In summary, through the synergistic effect of the multi-level barrier structure, this application solves the problem that the junction barrier Schottky diode in the prior art has poor conduction due to the addition of the PN junction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0023] Figure 1 FIG. 1 shows a schematic cross-sectional structure diagram of a junction barrier Schottky diode according to a first embodiment of the present invention;

[0024] Figure 2Shows a schematic cross-sectional structure diagram of a junction barrier Schottky diode provided according to the second embodiment of the present invention;

[0025] Figure 3 Shows a position distribution diagram of a barrier structure on a first surface in a junction barrier Schottky diode provided according to the third embodiment of the present invention;

[0026] Figure 4 Shows a position distribution diagram of a barrier structure on a first surface in a junction barrier Schottky diode provided according to the fourth embodiment of the present invention;

[0027] Figure 5 Shows a schematic cross-sectional structure diagram of a junction barrier Schottky diode provided according to the fifth embodiment of the present invention;

[0028] Figure 6 Shows a schematic cross-sectional structure diagram of a junction barrier Schottky diode provided according to the sixth embodiment of the present invention.

[0029] Among them, the above-mentioned drawings include the following reference numerals:

[0030] 100, semiconductor substrate; 101, substrate layer; 102, buffer layer; 103, epitaxial layer; 200, first doped region; 301, first region; 302, second region; 303, third region; 3010, insulating dielectric layer; 3011, first Schottky metal part; 3021, second Schottky metal part; 3031, third Schottky metal part; 3041, fourth Schottky metal part; 300, bottom surface; 310, side surface; 400, terminal region; 500, transition region; 600, passivation layer; 700, ohmic contact structure; 800, protrusion. Detailed implementation manners

[0031] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0032] In order to enable those skilled in the art to better understand the solution of the present invention, 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. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so as to implement the embodiments of the present invention described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0034] As described in the background art, the design of power devices usually pursues both minimizing the forward conduction resistance and conduction loss, and maximizing the reverse blocking voltage. In the prior art, a SiC semiconductor device of a junction barrier Schottky diode (JBS) formed by further adding a PN diode to an SBD combines the advantages of an SBD and a PiN diode. It has both excellent conduction and switching characteristics of an SBD, a low turn-on voltage and a fast recovery effect of majority carriers, and also has a high blocking characteristic close to that of a PiN diode. The depletion layer formed by the PN junction region shields the electric field at the Schottky barrier position. However, the addition of the PN junction region reduces the area ratio of the SBD region. Since the turn-on voltage of the PN junction region is relatively large, ultimately, compared with the Schottky barrier diode, the junction barrier Schottky diode has an increased conduction resistance and a decreased current-carrying capacity, thereby resulting in poor performance of the junction barrier Schottky diode. Based on this, in order to solve the problem of poor conduction of the junction barrier Schottky diode caused by the addition of the PN junction region in the prior art, the present application provides a junction barrier Schottky diode.

[0035] The present application provides a junction barrier Schottky diode, such as Figures 1 to 6As shown in the figure, it includes: a semiconductor substrate 100, which includes a substrate layer 101 and an epitaxial layer 103 arranged in a stacked manner. The surface of the epitaxial layer 103 facing away from the substrate layer 101 is the first surface of the semiconductor substrate 100; a plurality of first doping regions 200 arranged at intervals along the first direction A. Each first doping region 200 extends from the first surface into the epitaxial layer 103, and the doping types of the first doping region 200 and the epitaxial layer 103 are opposite; the epitaxial layer 103 between two adjacent first doping regions 200 is an epitaxial portion, and the first surface corresponding to the epitaxial portion includes a predetermined region. The predetermined region includes a first region 301, a second region 302, and a third region 303. Among them, the second region 302 and the third region 303 are located on opposite sides of the first region 301 in the first direction A; a barrier structure, which includes a first Schottky metal portion 3011 or an insulating dielectric layer 3010 covering the first region 301, a second Schottky metal portion 3021 covering the second region 302, and a third Schottky metal portion 3031 covering the third region 303; in the case where the barrier structure includes the first Schottky metal portion 3011, the barrier height between the first Schottky metal portion 3011 and the epitaxial portion is higher than the barrier height between the second Schottky metal portion 3021 and the epitaxial portion and the barrier height between the third Schottky metal portion 3031 and the epitaxial portion respectively; in the case where the barrier structure includes the insulating dielectric layer 3010, the barrier height between the material of the insulating dielectric layer 3010 and the epitaxial portion is higher than the barrier height between the second Schottky metal portion 3021 and the epitaxial portion and the barrier height between the third Schottky metal portion 3031 and the epitaxial portion respectively.

[0036] In the above embodiments, such as Figure 1 , Figure 2 , Figure 5 and Figure 6As shown, since the first Schottky metal part 3011 covers the first region 301, the second Schottky metal part 3021 covers the second region 302, and the third Schottky metal part 3031 covers the third region 303, and the first region 301, the second region 302, and the third region 303 are respectively three regions where the epitaxial part is located in the first surface (i.e., the above-mentioned predetermined regions), the epitaxial part is the region in the epitaxial layer 103 located between two adjacent first doping regions 200. Since the barrier height at the contact interface between the first Schottky metal part 3011 and the epitaxial part is higher than the barrier height at the contact interface between the second Schottky metal part 3021 and the epitaxial part and the barrier height at the contact interface between the third Schottky metal part 3031 and the epitaxial part, a multi-level Schottky barrier can be formed in the device. The lower Schottky barriers in the multi-level Schottky barrier (the barrier heights at the contact surfaces between the second Schottky metal part 3021 and the third Schottky metal part 3031 and the epitaxial part respectively) can be turned on earlier, providing more effective current paths. The current flowing through more effective current paths further reduces the contact resistance, which means that at the same current level, the voltage to be applied is smaller, and the forward conduction voltage drop of the junction barrier Schottky diode can be reduced. In addition, Schottky has unipolar conductivity, and during the reverse recovery process, the extraction process of minority carriers is avoided, thus improving the switching speed; the higher Schottky barrier in the multi-level Schottky barrier (the barrier height at the contact interface between the first Schottky metal part 3011 and the epitaxial part) can improve the reverse voltage withstand capacity of the junction barrier Schottky diode and suppress reverse leakage current. It can be seen that this application does not change the proportion of the junction barrier region of the junction barrier Schottky diode, but solves the problem that the junction barrier Schottky diode in the prior art has poor conduction due to the addition of the PN junction through the synergistic effect of the multi-level Schottky barrier.

[0037] Similarly, as Figure 3 and Figure 4As shown, when the barrier structure includes the above-mentioned insulating dielectric layer 3010, the insulating dielectric layer 3010 covers at least part of the first region 301, the second Schottky metal part 3021 covers the second region 302, the third Schottky metal part 3031 covers the third region 303, and the first region 301, the second region 302, and the third region 303 are respectively three regions (i.e., the above-mentioned predetermined regions) where the epitaxial part is located in the first surface. The epitaxial part is the region between two adjacent first doping regions (not shown in the figure) in the epitaxial layer (not shown in the figure). Since it is difficult for electrons to pass through the contact interface between the insulating dielectric layer 3010 and the epitaxial part, a high barrier will be formed at the contact interface between the insulating dielectric layer 3010 and the epitaxial part. The difficulty for electrons to pass through the metal material is relatively small. Therefore, a low barrier will be formed at the contact interface between the second Schottky metal part 3021 and the epitaxial part and at the contact interface between the third Schottky metal part 3031 and the epitaxial part. Thus, the junction barrier Schottky diode of the present application has a multi-level barrier. Further, the barrier height at the contact interface between the insulating dielectric layer 3010 and the epitaxial part is greater than the barrier height at the contact interface between the second Schottky metal part 3021 and the epitaxial part and the barrier height at the contact interface between the third Schottky metal part 3031 and the epitaxial part. Therefore, the lower Schottky barriers (the barrier height at the contact interface between the second Schottky metal part 3021 and the epitaxial part and the barrier height at the contact interface between the third Schottky metal part 3031 and the epitaxial part) in the multi-level barrier can be turned on earlier, providing more effective current paths. The current flowing through more effective current paths further reduces the contact resistance, which means that at the same current level, the applied voltage is smaller, and the forward conduction voltage drop of the junction barrier Schottky diode can be reduced. In addition, Schottky has unipolar conductivity. During the reverse recovery process, the extraction process of minority carriers is avoided, thus improving the switching speed. The higher barrier (the barrier height at the contact interface between the insulating dielectric layer 3010 and the epitaxial part) in the multi-level barrier can improve the reverse voltage withstand ability of the junction barrier Schottky diode and suppress reverse leakage current. Among them, the barrier structure is composed of a material that contacts the epitaxial part and can form a barrier or an insulating material with a high dielectric constant. Specifically, the barrier structure may include a first barrier structure covering the first region 301 and a second barrier structure covering the second region 302 and the third region 303. It should be noted here that regardless of whether the material covering the first region 301 is a material that contacts the epitaxial part and can form a barrier or an insulating material with a high dielectric constant, the barrier height at the contact interface between the first barrier structure and the epitaxial part is greater than the barrier height at the contact interface between the second barrier structure and the epitaxial part.

[0038] The conduction band offset (ΔEc) between insulating materials (such as SiO2, Al2O3) and SiC is usually greater than 2.5 eV (for example, ΔEc of SiO2 / SiC is approximately 2.7 - 3.2 eV). This energy difference is much higher than the thermal electron energy at room temperature (~0.026 eV), making it extremely difficult for electrons to cross the potential barrier through quantum tunneling or thermionic emission with a very low probability. The breakdown field strength of insulating materials (such as SiO2) > 10 MV / cm, which is much higher than the critical breakdown field strength of SiC (~3 MV / cm), ensuring the blocking of carriers under high electric fields. Precise control of the interface chemistry and spatial distribution of insulating materials converts theoretical advantages into device performance, achieving an insulating interface design of "high potential barrier, low leakage, and high reliability".

[0039] The material of the first barrier structure can be at least one of a metal material and an insulating dielectric material, and the material of the second barrier structure is a metal material. Further, the first barrier structure is composed of the first Schottky metal part 3011 shown in Figure 1 , Figure 2 , Figure 5 and Figure 6 , or the first barrier structure is composed of the insulating dielectric layer 3010 shown in Figure 3 , or the first barrier structure is composed of the fourth Schottky metal part 3041 and the insulating dielectric layer 3010 shown in Figure 4 , and the second barrier structure includes the second Schottky metal part 3021 and the third Schottky metal part 3031 shown in Figures 1 to 6 .

[0040] Specifically, as shown in Figures 1 to 6 , the materials of the second Schottky metal part 3021 and the third Schottky metal part 3031 can be independently selected from any one or more of the following: titanium (Ti), aluminum (Al), tungsten (W), molybdenum (Mo), titanium carbide (TiC), titanium tungsten alloy (TiW), nickel chromium alloy (NiCr), gold (Au), and nickel (Ni).

[0041] As shown in Figure 3 and Figure 4 , the above-mentioned insulating dielectric layer 3010 can be a silicon dioxide layer. Among them, the silicon dioxide can be directly formed by deposition, or silicon can be deposited first, and then oxygen is introduced and oxidized to form. In addition, if the semiconductor substrate 100 is the above-mentioned silicon carbide substrate, the silicon dioxide layer can also be formed by oxidizing silicon carbide. Specifically, as shown in Figure 4 , the material of the fourth Schottky metal part 3041 can be independently selected from any one or more of the following: titanium (Ti), aluminum (Al), tungsten (W), molybdenum (Mo), titanium carbide (TiC), titanium tungsten alloy (TiW), nickel chromium alloy (NiCr), gold (Au), and nickel (Ni).

[0042] Specifically, asFigure 1 , Figure 2 , Figure 5 and Figure 6 As shown in Figure 5 and Figure 6 , the material of the first Schottky metal part 3011 can independently select any one or more of the following: titanium (Ti), aluminum (Al), tungsten (W), molybdenum (Mo), titanium carbide (TiC), titanium tungsten alloy (TiW), nickel chromium alloy (NiCr), gold (Au), and nickel (Ni). Additionally, the semiconductor substrate 100 can be a silicon carbide substrate. Further, the semiconductor substrate 100 can include a buffer layer 102 located between the substrate layer 101 and the epitaxial layer 103.

[0043] Optionally, as shown in Figure 1 , Figure 2 , Figure 5 and Figure 6 the doping concentration of the substrate layer 101 is 1e18 cm -3 ~1e22 cm -3 , and the doping concentration of the epitaxial layer 103 is 1e14 cm -3 ~5e18 cm -3 .

[0044] Specifically, as shown in Figure 1 , Figure 2 , Figure 5 and Figure 6 the first doping region 200 and the semiconductor substrate 100 have different conduction types (doping types). Correspondingly, the first doping region 200 and the epitaxial layer 103 have different conduction types. Among them, when the conduction type of the semiconductor substrate 100 is N-type, correspondingly, the conduction type of the epitaxial layer 103 is N-type, and the conduction type of the first doping region 200 is P-type; when the conduction type of the semiconductor substrate 100 is P-type, correspondingly, the conduction type of the epitaxial layer 103 is P-type, and the conduction type of the first doping region 200 is N-type. It can be understood that the first doping region 200 and the epitaxial layer 103 form a PN junction.

[0045] In some embodiments, when the barrier structure includes the first Schottky metal part 3011, the work function of the material of the first Schottky metal part 3011 is respectively greater than the work function of the material of the second Schottky metal part 3021 and the work function of the material of the third Schottky metal part 3031, or the work function of the material of the first Schottky metal part 3011 is respectively less than the work function of the material of the second Schottky metal part 3021 and the work function of the material of the third Schottky metal part 3031; when the barrier structure includes an insulating dielectric layer, the work function of the material of the insulating dielectric layer is greater than the work function of the material of the second Schottky metal part 3021 and the work function of the material of the third Schottky metal part 3031.

[0046] In the above embodiments, since the work function of the material of the first Schottky metal part (or the insulating dielectric layer) is greater than the work function of the material of the second Schottky metal part and the work function of the material of the third Schottky metal part respectively, or the work function of the material of the first Schottky metal part is less than the work function of the material of the second Schottky metal part and the work function of the material of the third Schottky metal part respectively, thus, the Schottky barriers formed at the contact interface between the first Schottky metal part and the epitaxial part are different from the Schottky barriers formed at the contact interface between the second Schottky metal part and the epitaxial part and the Schottky barriers formed at the contact interface between the third Schottky metal part and the epitaxial part respectively. Therefore, the junction barrier Schottky diode of the present application has multiple Schottky barriers; in addition, the barrier heights at the contact interfaces between the insulating dielectric layer and the epitaxial part are greater than the barrier heights at the contact surfaces between the second Schottky metal part and the epitaxial part and the contact surfaces between the third Schottky metal part and the epitaxial part respectively. Therefore, the junction barrier Schottky diode of the present application has multiple Schottky barriers. In summary, the junction barrier Schottky diode in the present application has a multi-barrier structure. The lower Schottky barriers (the barrier heights at the contact surfaces between the second Schottky metal part and the epitaxial part and the contact surfaces between the third Schottky metal part and the epitaxial part) can conduct earlier, providing more effective current paths. The current flowing through more effective current paths further reduces the contact resistance, which means that at the same current level, the applied voltage is smaller, and the forward conduction voltage drop of the junction barrier Schottky diode can be reduced. In addition, Schottky has unipolar conductivity, and during the reverse recovery process, the extraction process of minority carriers is avoided, thus improving the switching speed; the higher Schottky barriers (the barrier heights at the contact interface between the first Schottky metal part and the epitaxial part or the barrier heights at the contact interface between the insulating dielectric layer and the epitaxial part) in the multi-barrier structure can improve the reverse voltage withstand capacity of the junction barrier Schottky diode and suppress the reverse leakage current.

[0047] It should be noted here that when the conductivity type of the semiconductor substrate 100 is N-type and the barrier structure includes the first Schottky metal part 3011, the work function of the material of the first Schottky metal part 3011 is greater than the work function of the material of the second Schottky metal part 3021 and the work function of the material of the third Schottky metal part 3031 respectively, so that the Schottky barrier at the contact interface between the first Schottky metal part 3011 and the epitaxial part is higher than the Schottky barrier height at the contact interface between the second Schottky metal part 3021 and the epitaxial part and the Schottky barrier height at the contact interface between the third Schottky metal part 3031 and the epitaxial part respectively; when the conductivity type of the semiconductor substrate 100 is P-type and the barrier structure includes the first Schottky metal part 3011, the work function of the material of the first Schottky metal part 3011 is less than the work function of the material of the second Schottky metal part 3021 and the work function of the material of the third Schottky metal part 3031 respectively, so that the Schottky barrier at the contact interface between the first Schottky metal part 3011 and the epitaxial part is higher than the Schottky barrier height at the contact interface between the second Schottky metal part 3021 and the epitaxial part and the Schottky barrier height at the contact interface between the third Schottky metal part 3031 and the epitaxial part respectively.

[0048] In addition, as Figure 1 , Figure 2 , Figure 5 and Figure 6 shown, the above-mentioned junction barrier Schottky diode may further include a terminal region 400, a transition region 500, a passivation layer 600 and an ohmic contact structure 700. Among them, in order to adjust the electric field distribution of the device, the terminal region 400 and the transition region 500 extend from the first surface into the epitaxial layer 103, and the conductivity type of the terminal region 400 and the transition region 500 is the same as that of the first doping region 200. The passivation layer 600 covers the above-mentioned terminal region 400. In order to reduce the ohmic contact resistance, the ohmic contact structure 700 may be arranged in contact with the above-mentioned first doping region 200.

[0049] Optionally, as Figure 1 , Figure 2 , Figure 5 and Figure 6 shown, the above-mentioned terminal region 400 is a field ring, a field plate, a junction termination extension or a lateral variable doping, etc. Exemplarily, the terminal region 400 includes a plurality of field rings arranged at intervals along the first direction A. The ring widths of the plurality of field rings may be the same or different, and the distances between adjacent two field rings may be the same or different. The doping concentrations and doping depths of the plurality of field rings may be the same or different.

[0050] In some embodiments, to further improve the breakdown voltage capability of the device, the ring widths of multiple field rings may show a decreasing trend in a first direction, and the spacing between adjacent field rings may show an increasing trend in the first direction. Exemplarily, the ring width decreases from 4 μm to 3 μm, and the ring spacing increases from 1.2 μm to 5 μm.

[0051] Exemplarily, to simplify the process, multiple field rings may have the same doping concentration and doping depth. Additionally, compared with the first doping region and the transition region, the doping parameters of the field rings, the doping parameters of the transition region, and the doping parameters of the first doping region may be the same or different. For ease of comparison, the same doping parameters may be adopted.

[0052] Optionally, multiple field rings include a first main ring and at least one second field ring located on a side of the first main ring away from the active region. The ring width of the first main ring has an optimal value, which is related to the substrate thickness, the substrate concentration, and the impurity concentration within the ring. When the ring width of the first main ring takes the optimal value, the overall terminal has the strongest reliability in the presence of positive charges in the oxide layer. Moreover, compared with solutions with other ring width values, this solution reduces the electric field strength in the transition region near the cell region, and during the turn-off process, the degree of current filament formation at this location is reduced. Exemplarily, in the case where the semiconductor substrate includes the above-mentioned epitaxial layer, the curvature radius of the inner ring of the first main ring at the corner position takes a value of 2 to 5 times the epitaxial layer thickness. The optimal ring width of the first main ring is between 13 and 16 μm. The distance between the first main ring and the first doping region or the doped region of the transition region can be 1 to 1.2 μm.

[0053] Furthermore, as Figure 1 、 Figure 2 、 Figure 5 and Figure 6 shown, the above-mentioned passivation layer 600 can be selected from any one of an oxide passivation layer, a silicon nitride passivation layer, and a polyimide passivation layer.

[0054] Furthermore, as Figure 1 、 Figure 2 、 Figure 5 and Figure 6As shown, the above-mentioned ohmic contact structure 700 can cover the first doped region 200. Moreover, the ohmic contact structure 700 is in contact with the side of the second Schottky metal part 3021 away from the first Schottky metal part 3011, and / or the ohmic contact structure 700 is in contact with the side of the third Schottky metal part 3031 away from the first Schottky metal part 3011. Additionally, in order to further reduce the ohmic contact resistance, a second recess (not shown in the figure) may be present in the first surface, and the ohmic contact structure 700 is located in this second recess (in other words, there is a second recess in the first surface, the surface of the second recess is the first surface corresponding to the first doped region 200, and the ohmic contact structure 700 is located in the second recess), so as to increase the contact area between the ohmic contact structure 700 and the first doped region 200, thereby achieving the purpose of reducing the ohmic contact resistance.

[0055] Optionally, as Figure 1 , Figure 2 , Figure 5 and Figure 6 shown, the material of the above-mentioned ohmic contact structure 700 may include, but is not limited to, any one or a combination of more than one of nickel (Ni), titanium (Ti), aluminum (Al), silver (Ag), gold (Au), aluminum-silicon alloy (AlSi), platinum (Pt), palladium (Pd), tantalum (Ta), and cobalt (Co).

[0056] As Figure 1 , Figure 2 , Figure 5 and Figure 6 shown, when both the terminal region 400 and the first doped region 200 are P-type doped, the doping concentration of the above-mentioned first doped region 200 can be 1e16 cm -3 ~5e20 cm -3 , and the doping concentration of the above-mentioned terminal region 400 can be 1e16 cm -3 ~5e20 cm -3 .

[0057] It should be noted here that Figures 1 to 6 the second Schottky metal part 3021 in Figures 1 to 6 can all include a plurality of first sub-Schottky metal parts in contact along the first direction,

[0058] In some alternative embodiments, as Figure 6As shown, the second Schottky metal part 3021 includes a plurality of first sub-Schottky metal parts (not labeled in the figure) arranged in contact along a first direction, and the work functions of the materials of any two first sub-Schottky metal parts are different; and / or, the third Schottky metal part 3031 includes a plurality of second sub-Schottky metal parts (not labeled in the figure) arranged in contact along the first direction, and the work functions of the materials of any two second sub-Schottky metal parts are different.

[0059] In the above embodiment, the work functions of the materials of the plurality of first sub-Schottky metal parts included in the second Schottky metal part 3021 are different, and the work functions of the materials of the plurality of second sub-Schottky metal parts included in the third Schottky metal part 3031 are different. Thus, the plurality of first sub-Schottky metal parts included in the second Schottky metal part 3021 respectively form a multi-level Schottky barrier with the epitaxial part, and the plurality of first sub-Schottky metal parts correspond to the multi-level Schottky barrier one by one. The plurality of second sub-Schottky metal parts included in the third Schottky metal part 3031 respectively form a multi-level Schottky barrier with the epitaxial part, and the plurality of second sub-Schottky metal parts correspond to the multi-level Schottky barrier one by one. Therefore, the lower Schottky barrier at the contact interface between the second Schottky metal part 3021 and the epitaxial part and the lower Schottky barrier at the contact interface between the third Schottky metal part 3031 and the epitaxial part further reduce the forward conduction voltage drop of the junction barrier Schottky diode. The higher Schottky barrier at the contact interface between the second Schottky metal part 3021 and the epitaxial part and the higher Schottky barrier at the contact interface between the third Schottky metal part 3031 and the epitaxial part further improve the reverse voltage withstand capacity of the junction barrier Schottky diode. Thus, the synergistic effect of the multi-level Schottky barrier is further strengthened, making the junction barrier Schottky diode have more excellent conduction and switching characteristics.

[0060] Specifically, as Figure 6 shown, when the junction barrier structure of the junction barrier Schottky diode includes the first Schottky metal part 3011 and the semiconductor substrate 100 is of N type, the work functions of the materials of the plurality of first sub-Schottky metal parts included in the second Schottky metal part 3021 are less than the work function of the material of the first Schottky metal part 3011. When the junction barrier structure of the junction barrier Schottky diode includes the first Schottky metal part 3011 and the semiconductor substrate 100 is of P type, the work functions of the materials of the plurality of first sub-Schottky metal parts included in the second Schottky metal part 3021 are greater than the work function of the material of the first Schottky metal part 3011. The work functions of the materials of the plurality of second sub-Schottky metal parts included in the third Schottky metal part 3031 are less than the work function of the material of the first Schottky metal part 3011; when the junction barrier structure of the junction barrier Schottky diode includes the first Schottky metal part 3011 and the semiconductor substrate 100 is of P type, the work functions of the materials of the plurality of second sub-Schottky metal parts included in the third Schottky metal part 3031 are greater than the work function of the material of the first Schottky metal part 3011.

[0061] Specifically, asFigure 6 As shown, the number of multiple first sub-Schottky metal parts included in the second Schottky metal part 3021 and the number of multiple second sub-Schottky metal parts included in the third Schottky metal part 3031 may be the same or different. Among them, when the above numbers are the same, the multiple first sub-Schottky metal parts included in the second Schottky metal part 3021 and the multiple second sub-Schottky metal parts included in the third Schottky metal part 3031 are located on opposite sides of the first Schottky metal part 3011 in a one-to-one correspondence in the first direction.

[0062] Furthermore, as Figure 6 shown, for any one of the first sub-Schottky metal parts of the second Schottky metal part 3021 and any one of the second sub-Schottky metal parts in the third Schottky metal part 3031 having the above corresponding relationship, the work function of the material of the first sub-Schottky metal part may be the same as or different from the work function of the material of the second sub-Schottky metal part.

[0063] In some alternative embodiments, as Figure 6 shown, in order to achieve uniform distribution of the electric field strength in the contact region between the barrier structure and the epitaxial part, avoid the formation of electric field hot spots, and enhance the stability and breakdown voltage of the device, when the work function of the material of the first Schottky metal part 3011 is greater than the work function of the material of the second Schottky metal part 3021 and the work function of the material of the third Schottky metal part 3031 respectively, the work function of the material of the multiple first sub-Schottky metal parts of the second Schottky metal part 3021 decreases in the direction away from the first Schottky metal part 3011; when the work function of the material of the first Schottky metal part 3011 is less than the work function of the material of the second Schottky metal part 3021 and the work function of the material of the third Schottky metal part 3031 respectively, the work function of the material of the multiple first sub-Schottky metal parts of the second Schottky metal part 3021 increases in the direction away from the first Schottky metal part 3011.

[0064] As Figure 1 、 Figure 2 、 Figure 5 and Figure 6 shown, when the barrier structure includes the first Schottky metal part 3011, the first Schottky metal part 3011 and the epitaxial part have a first contact surface; as Figure 3 and Figure 4 shown, when the barrier structure includes the insulating dielectric layer 3010, the insulating dielectric layer 3010 and the epitaxial part have a first contact surface. For the second Schottky metal part 3021 and the third Schottky metal part 3031 in the barrier structure, the second Schottky metal part 3021 and the epitaxial part have a second contact surface, and the third Schottky metal part 3031 and the epitaxial part have a third contact surface.

[0065] On this basis, asFigure 1 As shown, in order to enable the junction barrier Schottky diode to have excellent conduction and switching characteristics and further improve the trade-off characteristics between the on-resistance and the blocking voltage, the height of the first contact surface from the substrate layer 101 is the first height, and the heights of the second contact surface and the third contact surface from the substrate layer 101 are the second height. The first height can be equal to the second height (in other words, the first contact surface, the second contact surface, and the third contact surface can be flush with the first surface respectively). It can be understood that in the case where the barrier structure includes the first Schottky metal portion 3011, due to the relatively high barrier height of the first contact surface between the first Schottky metal portion 3011 and the epitaxial portion, the ability of the Schottky electrode region of the device to withstand the electric field intensity is enhanced, the blocking current of the device can be reduced, and the blocking voltage of the device can be increased. On this basis, in the present embodiment, the second contact surface and the third contact surface are located on opposite sides of the first contact surface and are both flush with the first contact surface. Therefore, compared with the junction barrier Schottky diode in the prior art, the junction barrier Schottky diode in the present embodiment can increase the blocking voltage of the device without reducing the Schottky electrode region, achieving the effect of further improving the trade-off characteristics between the on-resistance and the blocking voltage.

[0066] In addition, in the case where the first height can be equal to the second height (in other words, the first contact surface, the second contact surface, and the third contact surface can be flush with the first surface respectively), Figure 1 the first Schottky metal portion 3011 in the shown junction barrier Schottky diode can be replaced with an insulating dielectric layer. Thus, in the case where the barrier structure includes the insulating dielectric layer, due to the relatively high dielectric constant of the insulating dielectric layer, the electric field can be further reduced by the insulating dielectric layer, the leakage current of the device is reduced, the reverse bias blocking ability is improved, and further the blocking voltage of the device is increased. On this basis, in the present embodiment, the second contact surface and the third contact surface are located on opposite sides of the first contact surface and are both flush with the first contact surface, so that the device still has a relatively wide Schottky electrode region. That is, compared with the junction barrier Schottky diode in the prior art, the junction barrier Schottky diode in the present embodiment can still have good on-current conduction ability on the basis of increasing the blocking voltage of the device, thereby further improving the trade-off characteristics between the on-resistance and the blocking voltage.

[0067] In some embodiments, as Figure 2 、 Figure 3 and Figure 4 shown, the first height can be less than the second height (in other words, the second contact surface and the third contact surface can be flush with the first surface respectively, while the first contact surface can be lower than the first surface in the direction perpendicular to the first surface). It can be understood that as Figure 2As shown, when the barrier structure includes the above-mentioned first Schottky metal part 3011, such a setting increases the Schottky contact area. Since the Schottky contact resistance is inversely proportional to the Schottky contact area, the Schottky contact resistance is reduced, and further the on-resistance of the device is reduced; as Figure 3 and Figure 4 As shown, when the barrier structure includes the above-mentioned insulating dielectric layer 3010, since the insulating dielectric layer 3010 has a high dielectric constant, the electric field can be further reduced by the insulating dielectric layer 3010, so that the leakage current of the device is reduced, the reverse bias blocking ability is improved, and further the blocking voltage of the device is improved.

[0068] In some embodiments, as Figure 5 and Figure 6 As shown, the first height can be greater than the second height (in other words, the second contact surface and the third contact surface can be flush with the first surface respectively, while the first contact surface can be higher than the first surface in the direction perpendicular to the first surface). At this time, the barrier structure can include the above-mentioned first Schottky metal part 3011, the second Schottky metal part 3021 and the third Schottky metal part 3031. Such a setting increases the Schottky contact area, improves the on-current carrying capacity of the device, further reduces the on-resistance of the device, and increases the thickness of the epitaxial layer in the direction perpendicular to the first surface, so that the breakdown voltage resistance of the device is further improved, and thus the blocking voltage of the device is further improved.

[0069] It should be noted that in combination with Figures 1 to 4 As shown, when the first contact surface, the second contact surface and the third contact surface can be flush with the first surface respectively (the first height is equal to the second height) or when the first height is less than the second height, the barrier structure can include the first Schottky metal part 3011 and / or the insulating dielectric layer 3010, the second Schottky metal part 3021 and the third Schottky metal part 3031; as Figure 5 and Figure 6 As shown, when the first height can be greater than the second height, the barrier structure can include the first Schottky metal part 3011, the second Schottky metal part 3021 and the third Schottky metal part 3031.

[0070] In some other embodiments, in order to make the junction barrier Schottky diode have excellent conduction and switching characteristics and further improve the blocking voltage, the barrier structure of the junction barrier Schottky diode may include a first Schottky metal part, an insulating dielectric layer, a second Schottky metal part, and a third Schottky metal part. Among them, the second Schottky metal part and the third Schottky metal part are located on opposite sides of the first Schottky metal part in the first direction, and there is an insulating dielectric layer between the adjacent first Schottky metal part and the second Schottky metal part, and there is an insulating dielectric layer between the adjacent first Schottky metal part and the third Schottky metal part.

[0071] Furthermore, when the second Schottky metal part includes a plurality of first sub-Schottky metal parts along the direction away from the first Schottky metal part, there is an insulating dielectric layer between any two adjacent first sub-Schottky metal parts; when the third Schottky metal part includes a plurality of second sub-Schottky metal parts along the direction away from the first Schottky metal part, there is an insulating dielectric layer between any two adjacent second sub-Schottky metal parts. Among them, the insulating dielectric materials of the insulating dielectric layers between different two second sub-Schottky metals may be the same or different, and / or the insulating dielectric materials of the insulating dielectric layers between different two third sub-Schottky metals may be the same or different.

[0072] In some alternative embodiments, as Figure 2 、 Figure 3 and Figure 4 shown, in order to further reduce the on-resistance of the device, the first surface has a first recess (not marked in the figure), the first contact surface is the surface of the first recess, and the second contact surface and the third contact surface are flush with the first surface.

[0073] As Figure 2 shown, when the barrier structure includes the first Schottky metal part 3011, the first Schottky metal part 3011 covers the surface of the above-mentioned first recess (corresponding to the first region 301), the second Schottky metal part 3021 covers the second contact surface (corresponding to the second region 302), and the third Schottky metal part 3031 covers the above-mentioned third contact surface (corresponding to the third region 303). In this embodiment, the first recess can increase the Schottky contact area in the device by 5%-30% without laterally expanding the core device size, so as to further improve the current-carrying capacity of the junction barrier Schottky diode, and further reduce the on-resistance of the device.

[0074] As Figure 3As shown, when the barrier structure includes the insulating dielectric layer 3010, the insulating dielectric layer 3010 covers the surface of the first recess, the second Schottky metal portion 3021 covers the second contact surface, and the third Schottky metal portion 3031 covers the third contact surface. In this embodiment, the first recess increases the contact area between the insulating dielectric layer 3010 and the epitaxial portion, thereby further improving the leakage current problem and further enhancing the blocking voltage of the device. As Figure 4 shown, the surface of the first recess (corresponding to the first region 301) includes a bottom surface 300 and a side surface 310. The barrier structure includes a second Schottky metal portion 3021, a fourth Schottky metal portion 3041, an insulating dielectric layer 3010, and a third Schottky metal portion 3031. The insulating dielectric layer 3010 covers the bottom surface 300, and the fourth Schottky metal portion 3041 covers the side surface 310. In addition, the second Schottky metal portion 3021 covers the second contact surface (the second region 302), and the third Schottky metal portion 3031 covers the third contact surface (the third region 303). In this embodiment, a Schottky contact is formed at the contact interface between the fourth Schottky metal portion 3041 and the side surface 310, so that the addition of the fourth Schottky metal portion 3041 on the side surface of the first recess increases the Schottky contact area. In this embodiment, since the first recess increases the Schottky contact area and there is a contact interface between the insulating dielectric layer 3010 and the epitaxial portion in the device, the leakage current problem of the device can be further improved while further enhancing the current-carrying capacity of the device, thereby further improving the trade-off characteristics of the on-resistance and blocking voltage of the device.

[0075] Specifically, the work function of the material of the fourth Schottky metal portion 3041 may be the same as or different from the work function of the material of the first Schottky metal portion. Exemplarily, when the work function of the material of the fourth Schottky metal portion 3041 is the same as the work function of the material of the first Schottky metal portion, the material of the fourth Schottky metal portion 3041 is the same as the material of the first Schottky metal portion, so that the fourth Schottky metal portion 3041 forms a multi-level Schottky barrier with the second Schottky metal portion 3021 and the third Schottky metal portion 3031 respectively; when the work function of the material of the fourth Schottky metal portion 3041 is different from the work function of the material of the first Schottky metal portion, the work function of the material of the fourth Schottky metal portion 3041 may be greater than the work function of the material of the second Schottky metal portion 3021 and the work function of the material of the third Schottky metal portion 3031 respectively, so that the fourth Schottky metal portion 3041 forms a multi-level Schottky barrier with the second Schottky metal portion 3021 and the third Schottky metal portion 3031 respectively.

[0076] In some alternative embodiments, when the barrier structure includes an insulating dielectric layer, the insulating dielectric layer includes a first portion covering the bottom surface and a second portion covering the side surface; the material of the first portion is a first insulating dielectric material, and the material of the second portion is a second insulating dielectric material. Among them, the first insulating dielectric material and the second insulating dielectric material can be the same or different insulating dielectric materials.

[0077] Further, in a cross-section perpendicular to the first surface, in order to further reduce the electric field concentration at the connection between the bottom and the side of the first recess, the bottom surface and the side surface are connected by an arc. It can be understood that, as Figures 2 to 4 shown, the bottom surface and the side surface of the first recess (not labeled in the figure) are connected by an arc.

[0078] In some alternative embodiments, as Figure 5 shown, there is a protrusion 800 in the first surface. The first contact surface (corresponding to the first region 301) is the top surface of the protrusion 800, and the second contact surface (corresponding to the second region 302) and the third contact surface (corresponding to the third region 303) are respectively the two side surfaces of the protrusion 800 in the first direction A.

[0079] It can be understood that the protrusion structure raises the thickness of the central barrier region through the local epitaxial layer thickness (i.e., the thickness of the epitaxial portion), making the central barrier region away from the bottom of the first doped region. In this way, the electric field intensity at the Schottky interface position is reduced, thereby reducing the leakage current and increasing the blocking voltage of the junction barrier Schottky diode.

[0080] Specifically, the barrier structure in this embodiment is the first Schottky metal portion 3011, the second Schottky metal portion 3021, and the third Schottky metal portion 3031. Among them, the first Schottky metal portion 3011 covers the first contact surface or the top surface of the protrusion 800, the second Schottky metal portion 3021 covers one of the side surfaces of the second contact surface or the protrusion 800, and the third Schottky metal portion 3031 covers the other side surface of the third contact surface or the protrusion 800.

[0081] In the above embodiment, the high barrier at the contact interface between the first Schottky metal portion 3011 and the protrusion 800 can further increase the blocking voltage of the junction barrier Schottky diode; the low barriers at the contact interfaces between the second Schottky metal portion 3021 and the third Schottky metal portion 3031 and the protrusion 800 respectively can further increase the current-carrying capacity of the junction barrier Schottky diode. It can be seen that through this embodiment, the trade-off characteristic between the blocking voltage and the on-resistance of the junction barrier Schottky diode is further improved.

[0082] In some alternative embodiments, as Figure 6As shown, the first surface has a protrusion 800. The first contact surface (corresponding to the first region 301) is the top surface of the protrusion 800, and the second contact surface (corresponding to the second region 302) and the third contact surface (corresponding to the third region 303) are respectively the surfaces of the protrusion 800 that are axisymmetric with respect to the top surface in the first direction A except for the above-mentioned top surface. In this embodiment, the protrusion 800 may have multiple stepped surfaces. By setting metal materials with different work functions on different stepped surfaces, a multi-level Schottky metal can be formed.

[0083] Furthermore, in order to further reduce the electric field concentration at the connection between the top surface and the side surface of the protrusion, the top surface and the side surface of the protrusion are connected by an arc.

[0084] In some alternative embodiments, as Figure 1 , Figure 2 , Figure 5 and Figure 6 shown, when the barrier structure includes the first Schottky metal part 3011, the second Schottky metal part 3021 and the third Schottky metal part 3031 are symmetrically arranged with respect to the first Schottky metal part 3011; as Figure 3 and Figure 4 shown, when the barrier structure includes the insulating dielectric layer 3010, the second Schottky metal part 3021 and the third Schottky metal part 3031 are symmetrically arranged with respect to the insulating dielectric layer 3010.

[0085] In the above embodiments, when the second Schottky metal part 3021 and the third Schottky metal part 3031 are arranged on the first Schottky metal part 3011 or when the second Schottky metal part 3021 and the third Schottky metal part 3031 are symmetrically arranged on the opposite sides of the insulating dielectric layer 3010, the conduction path of the overall Schottky contact is increased, the on-current capacity of the device is improved, and the on-resistance is further reduced. Furthermore, the second Schottky metal part 3021 and the third Schottky metal part 3031 are symmetrically arranged with respect to the first Schottky metal part 3011 or the second Schottky metal part 3021 and the third Schottky metal part 3031 are symmetrically arranged with respect to the insulating dielectric layer 3010, so that the junction barrier Schottky diode corresponding to this embodiment can have a uniform current distribution on the basis of having more Schottky barrier regions.

[0086] It can be understood that the above-mentioned junction barrier Schottky diode can be applied to semiconductor structures with junction barrier Schottky diodes in JBS devices, MPS devices, SBD embedded MOSFET devices, IGBT devices, etc.

[0087] According to another aspect of the present application, a method for manufacturing a junction barrier Schottky diode is further provided, including: providing an N-type substrate layer, preparing an N-type buffer layer on the N-type substrate layer, forming an N-type epitaxial layer (drift region) on a side of the N-type buffer layer away from the N-type substrate layer, performing ion implantation on a surface of the N-type epitaxial layer away from the N-type substrate layer to form a P-type terminal field stop region in a terminal region and a P-type first doping region in an active region, the terminal region surrounding the active region, and the active region being discontinuously distributed with the first doping region and an epitaxial portion (Schottky contact region).

[0088] The step of performing ion implantation may include: using the PECVD method to deposit a layer of SiO2 on the upper surface of the N-epitaxial layer, applying a photolithography process to form an implantation window, implanting Al ions with a specific energy and dose, then activating in an inert gas at 1650 °C to 1850 °C, and finally etching away the SiO2 mask layer.

[0089] Among them, the materials of the N-type substrate layer, the N-type buffer layer, and the N-type epitaxial layer are all 4H-SiC. Optionally, the thickness of the N-type substrate layer may be 350 μm, and the doping concentration may be 1e19 cm -3 . The thickness of the N-type epitaxial layer may be 32 μm, and the doping concentration may be 3e15 cm -3 . Optionally, the doping element of the terminal field stop region may be Al, and the doping concentration may be 1e18 to 1e19 cm -3 . Optionally, the doping element of the first doping region may be Al, and the doping concentration may be 5e18 cm -3 . Optionally, the distance between two adjacent first doping regions in a first direction is less than or equal to 8 μm. Optionally, the projected shape of each first doping region on a surface of the N-type epitaxial layer away from the N-type substrate layer may be one of the following shapes or a combination of multiple shapes: square, circular, and hexagonal.

[0090] Then, the PECVD method may be used to deposit 1 μm thick SiO2 on the surface of the N-type epitaxial layer as a passivation layer, and then an active region window is obtained through photolithography and wet etching. Finally, electrodes are formed in the active region.

[0091] The step of forming contacts includes: first, depositing a layer of a high work function metal material Ni by magnetron sputtering, then etching away the metal outside the high barrier Schottky contact region (the region corresponding to the first Schottky metal part or the insulating dielectric layer) and the P-type doped contact region (the region corresponding to the first doping region) by means of a photolithography process, then sputtering and depositing a layer of a low work function metal material Ti to form a Schottky contact electrode (the second Schottky metal part and the third Schottky metal part) and an ohmic contact structure, and then depositing a Ti / Al thick metal layer.

[0092] Finally, after forming the front contact electrodes and passivation, a protective film is attached to the front of the chip. The chip is flipped, and on the back of the chip (on the side of the N-type substrate layer away from the N-type epitaxial layer), Ni / Ti / Ni / Ag are sequentially deposited by magnetron sputtering, and a back ohmic contact structure (ohmic contact electrode) is formed by alloying.

[0093] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0094] The first Schottky metal part or the insulating dielectric layer covers the first region, the second Schottky metal part covers the second region, and the third Schottky metal part covers the third region. The first region, the second region, and the third region are respectively three regions of the epitaxial part located in the first surface. The epitaxial part is the region in the epitaxial layer located between two adjacent first doping regions. Since the barrier height at the contact interface between the first Schottky metal part (or insulating dielectric layer) and the epitaxial part is higher than the barrier height at the contact interface between the second Schottky metal part and the epitaxial part and the barrier height at the contact interface between the third Schottky metal part and the epitaxial part. It can be seen that in this application, when the barrier structure includes the first Schottky metal part, a multi-level barrier structure is introduced by different Schottky metals. Thus, without changing the physical proportion of the PN junction region, the conduction loss of the PN junction region is compensated by the early conduction effect of the low-barrier regions (the second region and the third region), and at the same time, the reverse depletion ability is enhanced by the high-barrier region (the first region). This energy band design based on the spatial modulation of the barrier height breaks through the traditional "area trade-off" design paradigm and realizes the collaborative optimization of the on-resistance and the blocking voltage. In addition, in this application, when the barrier structure includes an insulating dielectric layer, the insulating dielectric layer (such as SiO2) is introduced as a barrier control element into the junction barrier Schottky diode. Since the breakdown voltage efficiency of the insulating dielectric layer under reverse bias is much higher than that of the metal Schottky contact, a multi-level barrier structure is introduced by the insulating dielectric material and the Schottky metal; and when conducting forward, the low work function metal regions corresponding to the second Schottky metal part and the third Schottky metal part provide current channels, avoiding the conduction disadvantage of the dielectric layer. This "dielectric + metal" composite barrier design combines the high breakdown voltage of the MOS structure and the low conduction advantage of the Schottky structure, providing a new design dimension for power devices, and thus realizing the collaborative optimization of the on-resistance and the blocking voltage. In summary, through the synergistic effect of the multi-level barrier structure, this application solves the problem that the junction barrier Schottky diode in the prior art has poor conduction due to the addition of the PN junction.

[0095] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A junction barrier Schottky diode, characterized in that, Including: A semiconductor substrate, including a substrate layer and an epitaxial layer arranged in a stacked manner, and a side surface of the epitaxial layer facing away from the substrate layer is a first surface of the semiconductor substrate; A plurality of first doping regions arranged at intervals along a first direction, each of the first doping regions extending from the first surface into the epitaxial layer, the doping types of the first doping regions and the epitaxial layer being opposite, and the epitaxial layer between two adjacent first doping regions is an epitaxial portion, and the first surface corresponding to the epitaxial portion includes a predetermined region, and the predetermined region includes a first region, a second region, and a third region, wherein the second region and the third region are located on opposite sides of the first region in the first direction; A barrier structure, including a first Schottky metal portion or an insulating dielectric layer covering the first region, a second Schottky metal portion covering the second region, and a third Schottky metal portion covering the third region; When the barrier structure includes the first Schottky metal portion, the barrier height between the first Schottky metal portion and the epitaxial portion is respectively higher than the barrier height between the second Schottky metal portion and the epitaxial portion and the barrier height between the third Schottky metal portion and the epitaxial portion; When the barrier structure includes the insulating dielectric layer, the barrier height between the insulating dielectric layer material and the epitaxial portion is respectively higher than the barrier height between the second Schottky metal portion and the epitaxial portion and the barrier height between the third Schottky metal portion and the epitaxial portion.

2. The junction barrier Schottky diode according to claim 1, characterized in that, When the barrier structure includes the first Schottky metal portion, the work function of the material of the first Schottky metal portion is respectively greater than the work function of the material of the second Schottky metal portion and the work function of the material of the third Schottky metal portion, or the work function of the material of the first Schottky metal portion is respectively less than the work function of the material of the second Schottky metal portion and the work function of the material of the third Schottky metal portion.

3. The junction barrier Schottky diode according to claim 1, wherein The second Schottky metal portion includes a plurality of first sub-Schottky metal portions arranged in contact along the first direction, and the work functions of the materials of any two of the first sub-Schottky metal portions are different; and / or, the third Schottky metal portion includes a plurality of second sub-Schottky metal portions arranged in contact along the first direction, and the work functions of the materials of any two of the second sub-Schottky metal portions are different.

4. The junction barrier Schottky diode according to claim 3, wherein When the work function of the material of the first Schottky metal portion is respectively greater than the work function of the material of the second Schottky metal portion and the work function of the material of the third Schottky metal portion, the work functions of the materials of the plurality of first sub-Schottky metal portions of the second Schottky metal portion decrease in a direction away from the first Schottky metal portion; When the work function of the material of the first Schottky metal part is less than the work function of the material of the second Schottky metal part and the work function of the material of the third Schottky metal part respectively, the work function of the material of the plurality of first sub-Schottky metal parts of the second Schottky metal part increases in a direction away from the first Schottky metal part.

5. The junction barrier Schottky diode according to claim 1, characterized in that, There is a first contact surface between the first Schottky metal part and the epitaxial part, a second contact surface between the second Schottky metal part and the epitaxial part, and a third contact surface between the third Schottky metal part and the epitaxial part. The first contact surface, the second contact surface and the third contact surface are flush.

6. The junction barrier Schottky diode according to claim 1, characterized in that, There is a first contact surface between the first Schottky metal part and the epitaxial part or between the insulating dielectric layer and the epitaxial part, a second contact surface between the second Schottky metal part and the epitaxial part, and a third contact surface between the third Schottky metal part and the epitaxial part. The height of the first contact surface from the substrate layer is a first height, and the height of the second contact surface and the third contact surface from the substrate layer is a second height. The first height is greater than or less than the second height.

7. The junction barrier Schottky diode according to claim 6, wherein There is a first recess in the first surface, and the first contact surface is the first surface corresponding to the first recess. The second contact surface and the third contact surface are flush.

8. The junction barrier Schottky diode according to claim 7, characterized in that, The first contact surface includes a bottom surface and a side surface. In a cross-section perpendicular to the first surface, the bottom surface and the side surface are connected by an arc.

9. The junction barrier Schottky diode according to claim 8, characterized in that, The barrier structure further includes a fourth Schottky metal part. When the barrier structure includes the insulating dielectric layer, the insulating dielectric layer covers the bottom surface, and the fourth Schottky metal part covers the side surface.

10. The junction barrier Schottky diode according to claim 8, wherein When the barrier structure includes the insulating dielectric layer, the insulating dielectric layer includes a first part covering the bottom surface and a second part covering the side surface; The material of the first part is a first insulating dielectric material, and the material of the second part is a second insulating dielectric material.

11. The junction barrier Schottky diode according to claim 6, characterized in that, There is a protrusion in the first surface, the first contact surface is the first surface corresponding to the top surface of the protrusion, and the second contact surface and the third contact surface are the first surfaces corresponding to the side surfaces of the protrusion respectively.

12. The junction barrier Schottky diode according to claim 11, characterized in that, The top surface of the protrusion and the side surface of the protrusion are connected by an arc.

13. The junction barrier Schottky diode according to any one of claims 1 to 12, characterized in that, When the barrier structure includes the first Schottky metal part, the second Schottky metal part and the third Schottky metal part are symmetrically arranged about the first Schottky metal part.

14. The junction barrier Schottky diode according to any one of claims 1 to 12, characterized in that, The junction barrier Schottky diode further includes: An ohmic contact structure covering the first doped region; The ohmic contact structure is in contact with the side of the second Schottky metal part away from the first Schottky metal part, and / or the ohmic contact structure is in contact with the side of the third Schottky metal part away from the first Schottky metal part.

15. The junction barrier Schottky diode according to claim 14, characterized in that, There is a second recess in the first surface, and the ohmic contact structure is located in the second recess.

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