Junction Barrier Schottky Diode

Abstract

The present invention provides a junction barrier Schottky diode, comprising: a semiconductor substrate including a stacked substrate layer and an epitaxial layer, the epitaxial layer having a first surface; a plurality of spaced-apart first doped regions, each first doped region being located in the epitaxial layer, the epitaxial layer between two adjacent first doped regions being an epitaxial portion, the 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 that are sequentially adjacent; a barrier structure including a first Schottky contact portion or an insulating dielectric layer covering the first region, a second Schottky contact portion covering the second region, and a third Schottky contact portion covering the third region; the barrier height of the barrier structure in the first region being higher than the barrier height of the barrier structure in the second region and the barrier height of the barrier structure in the third region. This application solves the problem of poor conduction of junction barrier Schottky diodes in the prior art due to the addition of PN junctions.

Description

Technical Field

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

[0002] Schottky barrier diodes (SBDs) are widely used due to their ultra-low turn-on voltage and excellent reverse recovery characteristics. The design of power devices typically seeks to minimize forward resistance and conduction losses while maximizing reverse blocking voltage.

[0003] In existing technology, a PN diode is further added to the SBD, thereby forming a junction barrier Schottky diode (JBS). This device combines the advantages of both the SBD and the PiN diode, with the low turn-on voltage of the SBD. The depletion layer formed in the PN junction region suppresses reverse leakage current, achieving a high withstand voltage and giving the device high blocking characteristics close to those of the PiN diode. However, the traditional design paradigm of simply juxtaposing the PN junction and the Schottky region either increases the PN junction region at the expense of conduction characteristics, or reduces the PN junction region to reduce blocking capability. In other words, the traditional JBS diode has an inherent contradiction between the PN junction region and the Schottky region. Increasing the PN junction region improves the withstand voltage, but it degrades the conduction characteristics due to the compression of the Schottky contact area.

[0004] Therefore, there is an urgent need for a junction barrier Schottky diode structure with small forward on-resistance and conduction loss and strong reverse voltage withstand capability. Summary of the Invention

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

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

[0007] Optionally, in the case where the barrier structure includes a 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 smaller 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 arranged 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 arranged 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, when the work function of the material of the first Schottky metal part 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, the work function of the material of the multiple first sub-Schottky metal parts of the second Schottky metal part decreases in the direction away from the first Schottky metal part; 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, the work function of the material of the multiple first sub-Schottky metal parts of the second Schottky metal part increases in the direction away from the first Schottky metal part.

[0010] Optionally, a first contact surface is provided between the first Schottky metal portion and the epitaxial portion, a second contact surface is provided between the second Schottky metal portion and the epitaxial portion, and a third contact surface is provided between the third Schottky metal portion and the epitaxial portion, 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 height of the second contact surface and the third contact surface from the substrate layer is a second height, and the first height is greater than or less than the second height.

[0012] Optionally, the first surface has a first recess, the first contact surface is the first surface corresponding to the first recess, and the second contact surface is flush with the third contact surface.

[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 line.

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

[0015] Optionally, 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 first portion is made of a first insulating dielectric material, and the second portion is made of a second insulating dielectric material.

[0016] Optionally, the first surface has a protrusion, 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.

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

[0018] Alternatively, in the case where the barrier structure includes a first Schottky metal portion, the second Schottky metal portion and the third Schottky metal portion are arranged axially symmetrically with respect to the first Schottky metal portion.

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

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

[0021] In the technical solution of the present invention, a first Schottky metal portion or insulating dielectric layer covers the first region, a second Schottky metal portion covers the second region, and a third Schottky metal portion covers the third region. The first region, the second region, and the third region are respectively three regions of the epitaxial portion located on the first surface. The epitaxial portion is the region of the epitaxial layer located between two adjacent first doped regions. Since the barrier height at the contact interface between the first Schottky metal portion (or insulating dielectric layer) and the epitaxial portion is higher than the barrier height at the contact interface between the second Schottky metal portion and the epitaxial portion, and the barrier height at the contact interface between the third Schottky metal portion and the epitaxial portion, it can be seen that in the present application, when the barrier structure includes the first Schottky metal portion, a multi-level barrier structure is introduced using 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 turn-on effect of the low barrier region (the second and third regions), while the reverse depletion capability is enhanced by the high barrier region (the first region). This energy band design, based on spatial modulation of the barrier height, breaks through the traditional "area trade-off" design paradigm and achieves the coordinated optimization of on-resistance and blocking voltage. Furthermore, 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. Because the dielectric layer's withstand voltage efficiency under reverse bias far exceeds that of a metal Schottky contact, a multi-level barrier structure is introduced from the insulating dielectric material and the Schottky metal. During forward conduction, the low-work-function metal regions corresponding to the second and third Schottky metal sections provide current paths, circumventing the conduction disadvantages of the dielectric layer. This "dielectric + metal" composite barrier design combines the high withstand voltage of the MOS structure with the low on-state conduction of the Schottky structure, providing a new design dimension for power devices and achieving the coordinated optimization of on-resistance and blocking voltage. In summary, through the synergistic effect of the multi-level barrier structure, this application solves the problem of poor conduction in junction barrier Schottky diodes in the prior art due to the addition of a PN junction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 FIG2 shows a schematic cross-sectional structure diagram of a junction barrier Schottky diode provided according to a first embodiment of the present invention;

[0024] Figure 2FIG2 shows a schematic cross-sectional structure diagram of a junction barrier Schottky diode provided according to a second embodiment of the present invention;

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

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

[0027] Figure 5 FIG4 shows a schematic cross-sectional structure diagram of a junction barrier Schottky diode provided according to a fifth embodiment of the present invention;

[0028] Figure 6 FIG2 shows a schematic cross-sectional structure diagram of a junction barrier Schottky diode provided according to a sixth embodiment of the present invention.

[0029] The above 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 portion; 3021. Second Schottky metal portion; 3031. Third Schottky metal portion; 3041. Fourth Schottky metal portion; 300. Bottom surface; 310. Side surface; 400. Terminal region; 500. Transition region; 600. Passivation layer; 700. Ohmic contact structure; 800. Protrusion. DETAILED DESCRIPTION

[0031] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0032] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0033] It should be noted that the terms "first," "second," and the like in the specification and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate for the embodiments of the present invention described herein. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, products, or apparatuses.

[0034] As described in the background art, the design of power devices typically pursues both minimizing forward on-resistance and conduction losses, and maximizing reverse blocking voltage. Prior art SiC semiconductor devices, which combine the advantages of SBDs and PiN diodes by further adding a PN diode to an SBD, employ junction barrier Schottky diodes (JBSs). These devices possess the excellent conduction and switching characteristics, low turn-on voltage, and fast majority-carrier recovery of SBDs, while also possessing high blocking characteristics approaching those of PiN diodes. The depletion layer formed by the PN junction region shields the electric field at the Schottky barrier. However, the addition of the PN junction region reduces the area proportion of the SBD region. Due to the higher turn-on voltage of the PN junction region, the JBS ultimately increases the on-resistance and decreases the current carrying capacity compared to Schottky barrier diodes, resulting in inferior performance. To address this issue, the present application provides a JBS diode to address the prior art issue of poor conduction in JBS diodes due to the addition of a PN junction region.

[0035] The present application provides a junction barrier Schottky diode, such as Figures 1 to 6As shown, it includes: a semiconductor substrate 100, including a stacked substrate layer 101 and an epitaxial layer 103, wherein 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 spaced apart along a first direction A, each first doping region 200 extending 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 area, the predetermined area includes a first area 301, a second area 302 and a third area 303, wherein the second area 302 and the third area 303 are located on opposite sides of the first area 301 in the first direction A; a barrier structure including a barrier covering the first area 301, a first Schottky metal part 3011 or an insulating dielectric layer 3010 covering the second area 302, a second Schottky metal part 3021 covering the second area 302, and a third Schottky metal part 3031 covering the third area 303; in the case where the barrier structure includes the first Schottky metal part 3011, the barrier height between the first Schottky metal part 3011 and the epitaxial part is higher than the barrier height between the second Schottky metal part 3021 and the epitaxial part and the barrier height between the third Schottky metal part 3031 and the epitaxial part, 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 part is higher than the barrier height between the second Schottky metal part 3021 and the epitaxial part and the barrier height between the third Schottky metal part 3031 and the epitaxial part, respectively.

[0036] In the above embodiment, if Figure 1 、 Figure 2 、 Figure 5 and Figure 6As shown, since the first Schottky metal portion 3011 covers the first region 301, the second Schottky metal portion 3021 covers the second region 302, and the third Schottky metal portion 3031 covers the third region 303, and the first region 301, the second region 302 and the third region 303 are respectively three regions of the epitaxial portion located in the first surface (i.e., the predetermined regions mentioned above), and the epitaxial portion is the region between two adjacent first doped regions 200 in the epitaxial layer 103, since the barrier height at the contact interface between the first Schottky metal portion 3011 and the epitaxial portion is higher than the barrier height at the contact interface between the second Schottky metal portion 3021 and the epitaxial portion and the barrier height at the contact interface between the third Schottky metal portion 3031 and the epitaxial portion, a multi-level Schottky barrier can be formed in the device. The lower Schottky barrier in the Schottky barrier (the barrier height at the contact surface 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 required applied voltage is smaller, which can reduce the forward conduction voltage drop of the junction barrier Schottky diode. In addition, Schottky has unipolar conductivity, and during the reverse recovery process, the extraction process of minority carriers is avoided, thereby 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 capability of the junction barrier Schottky diode and suppress reverse leakage current. It can be seen that the present application does not change the junction barrier area ratio of the junction barrier Schottky diode, but solves the problem of poor conduction of the junction barrier Schottky diode in the prior art due to the addition of the PN junction through the synergistic effect of multiple Schottky barriers.

[0037] Likewise, if 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 a portion of 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. The first region 301, the second region 302, and the third region 303 are respectively three regions (i.e., the above-mentioned predetermined regions) of the epitaxial part located in the first surface. The epitaxial part is the region in the epitaxial layer (not shown in the figure) located between two adjacent first doped regions (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 potential barrier is 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, so low potential barriers are formed at the contact interface between the second Schottky metal part 3021 and the epitaxial part and the contact interface between the third Schottky metal part 3031 and the epitaxial part. Therefore, the junction barrier Schottky diode of the present application has a multi-level barrier. Furthermore, the barrier height at the contact interface between the insulating dielectric layer 3010 and the epitaxial portion is greater than the barrier height at the contact surface between the second Schottky metal portion 3021 and the epitaxial portion and the barrier height at the contact surface between the third Schottky metal portion 3031 and the epitaxial portion. As a result, the lower Schottky barriers in the multi-stage barrier (the barrier height at the interface between the second Schottky metal portion 3021 and the epitaxial portion, and the barrier height at the interface between the third Schottky metal portion 3031 and the epitaxial portion) can turn on earlier, providing more effective current paths. The current flowing through more effective current paths further reduces contact resistance, meaning that at the same current level, a lower applied voltage is required, which can reduce the forward voltage drop of the junction barrier Schottky diode. Furthermore, the Schottky diode has unipolar conductivity, which avoids the extraction of minority carriers during reverse recovery, thereby improving switching speed. The higher barrier in the multi-stage barrier (the barrier height at the interface between the insulating dielectric layer 3010 and the epitaxial portion) can improve the reverse withstand voltage capability of the junction barrier Schottky diode and suppress reverse leakage current. The barrier structure is composed of a material that contacts the epitaxial portion 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 that, regardless of whether the material covering the first region 301 is a material that contacts the epitaxial portion 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 portion is greater than the barrier height at the contact interface between the second barrier structure and the epitaxial portion.

[0038] The conduction band offset (ΔEc) between insulating materials (such as SiO2 and Al2O3) and SiC is typically greater than 2.5 eV (e.g., ΔEc for SiO2 / SiC is ≈2.7-3.2 eV). This energy difference is significantly higher than the energy of hot electrons at room temperature (~0.026 eV), requiring electrons to cross the potential barrier through quantum tunneling or thermal emission, an extremely low probability. The breakdown field strength of insulating materials (such as SiO2) is >10 MV / cm, significantly higher than the critical breakdown field strength of SiC (~3 MV / cm), ensuring carrier blocking even under high electric fields. Precise control of the interface chemistry and spatial distribution of insulating materials translates theoretical advantages into device performance, achieving a "high barrier, low leakage, and high reliability" insulating interface design.

[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. Figure 1 、 Figure 2 、 Figure 5 and Figure 6 The first Schottky metal portion 3011 shown is composed of, or the first barrier structure is composed of Figure 3 The insulating dielectric layer 3010 shown is composed of, or the first barrier structure is composed of Figure 4 The fourth Schottky metal portion 3041 and the insulating dielectric layer 3010 are formed, and the second barrier structure includes Figures 1 to 6 The second Schottky metal portion 3021 and the third Schottky metal portion 3031 are shown.

[0040] Specifically, if Figures 1 to 6 As shown, the materials of the second Schottky metal portion 3021 and the third Schottky metal portion 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] like Figure 3 and Figure 4 As shown, the insulating dielectric layer 3010 can be a silicon dioxide layer, wherein the silicon dioxide can be formed directly by deposition, or silicon can be deposited first and then oxygen is introduced and oxidized. In addition, if the semiconductor substrate 100 is the silicon carbide substrate, the silicon dioxide layer can also be formed by oxidizing silicon carbide. Specifically, as Figure 4 As shown, the material of the fourth Schottky metal portion 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, if Figure 1 、 Figure 2 、 Figure 5 and Figure 6 As shown, the material of the first Schottky metal portion 3011 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). Furthermore, the semiconductor substrate 100 can be a silicon carbide substrate. Furthermore, the semiconductor substrate 100 can include a buffer layer 102 located between the substrate layer 101 and the epitaxial layer 103.

[0043] Alternatively, as Figure 1 、 Figure 2 、 Figure 5 and Figure 6 As shown, the doping concentration of the substrate layer 101 is 1e18 cm -3 ~1e22cm -3 The doping concentration of the epitaxial layer 103 is 1e14 cm -3 ~5e18cm -3 .

[0044] Specifically, if Figure 1 、 Figure 2 、 Figure 5 and Figure 6 As shown, the first doped region 200 and the semiconductor substrate 100 have different conductivity types (doping types). Accordingly, the first doped region 200 and the epitaxial layer 103 have different conductivity types. If the conductivity type of the semiconductor substrate 100 is N-type, the conductivity type of the epitaxial layer 103 is N-type, and the conductivity type of the first doped region 200 is P-type. If the conductivity type of the semiconductor substrate 100 is P-type, the conductivity type of the epitaxial layer 103 is P-type, and the conductivity type of the first doped region 200 is N-type. It is understood that the first doped region 200 and the epitaxial layer 103 form a PN junction.

[0045] In some embodiments, when the barrier structure includes a first Schottky metal portion 3011, the work function of the material of the first Schottky metal portion 3011 is 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, or the work function of the material of the first Schottky metal portion 3011 is smaller 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; 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 portion 3021 and the work function of the material of the third Schottky metal portion 3031.

[0046] In the above embodiment, since the work function of the material of the first Schottky metal part (or the insulating dielectric layer) is respectively 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, or the work function of the material of the first Schottky metal part is respectively 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, the Schottky barrier formed at the contact interface between the first Schottky metal part and the epitaxial part is different from the Schottky barrier formed at the contact interface between the second Schottky metal part and the epitaxial part and the Schottky barrier 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 a multi-stage Schottky barrier. In addition, the barrier height at the contact interface between the insulating dielectric layer and the epitaxial part is respectively greater than the barrier height at the contact surface between the second Schottky metal part and the epitaxial part and the barrier height at the contact surface between the third Schottky metal part and the epitaxial part. Therefore, the junction barrier Schottky diode of the present application has a multi-stage Schottky barrier. In summary, the junction barrier Schottky diode in the present application has a multi-level barrier structure. The lower Schottky barrier (the barrier height at the contact surface between the second Schottky metal part and the epitaxial part and the barrier height at the contact surface between the third Schottky metal part and the epitaxial part) can be turned on earlier and provide 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 required applied voltage is smaller, which can reduce the forward conduction voltage drop of the junction barrier Schottky diode. In addition, Schottky has unipolar conductivity, and the extraction process of minority carriers is avoided during the reverse recovery process, thereby improving the switching speed; the higher Schottky barrier in the multi-level barrier structure (the barrier height at the contact interface between the first Schottky metal part and the epitaxial part or the barrier height at the contact interface between the insulating dielectric layer and the epitaxial part) can improve the reverse withstand voltage capability of the junction barrier Schottky diode and suppress reverse leakage current.

[0047] It is explained 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 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, 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. Barrier height; when the conductivity type of the semiconductor base 100 is P type and the barrier structure includes a first Schottky metal part 3011, the work function of the material of the first Schottky metal part 3011 is smaller 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.

[0048] In addition, if Figure 1 、 Figure 2 、 Figure 5 and Figure 6 As shown, the junction barrier Schottky diode may further include a termination region 400, a transition region 500, a passivation layer 600, and an ohmic contact structure 700. To adjust the electric field distribution of the device, the termination region 400 and the transition region 500 extend from the first surface into the epitaxial layer 103, and the conductivity type of the termination region 400 and the transition region 500 is the same as that of the first doped region 200. The passivation layer 600 covers the termination region 400. To reduce ohmic contact resistance, the ohmic contact structure 700 may be disposed in contact with the first doped region 200.

[0049] Alternatively, as Figure 1 、 Figure 2 、 Figure 5 and Figure 6 As shown, the termination region 400 may be a field ring, field plate, junction termination extension, or lateral variable doping. For example, the termination region 400 includes multiple field rings spaced apart along a first direction A. The field rings may have the same or different ring widths, and the spacing between adjacent field rings may be the same or different. The field rings may have the same or different doping concentrations and doping depths.

[0050] In some embodiments, to further enhance the device's withstand voltage, the widths of the field rings can decrease in the first direction, while the spacing between adjacent field rings can increase in the first direction. For example, the width decreases from 4 μm to 3 μm, while the spacing increases from 1.2 μm to 5 μm.

[0051] For example, to simplify the process, multiple field rings can use the same doping concentration and doping depth. Furthermore, compared to the first doping region and the transition region, the doping parameters of the field rings, the transition region, and the first doping region can be the same or different. For ease of comparison, the same doping parameters can be used.

[0052] Optionally, the multiple field rings include a first main ring and at least one second field ring located on the side of the first main ring away from the active area. The first main ring has an optimal width, which is related to the substrate thickness, substrate concentration, and impurity concentration within the ring. When the first main ring has the optimal width, the entire terminal achieves the highest reliability when positive charge exists in the oxide layer. Furthermore, compared with other ring width options, this option reduces the electric field strength in the transition region near the cell region, thereby reducing the occurrence of current filaments there during the shutdown process. For example, when the semiconductor substrate includes the aforementioned epitaxial layer, the radius of curvature of the inner ring of the first main ring at the corner is 2 to 5 times the thickness of the epitaxial layer. The optimal width of the first main ring is between 13 and 16 μm. The spacing between the first main ring and the first doped region, or the distance between the first main ring and the doped region of the transition region, can be 1 to 1.2 μm.

[0053] Furthermore, if Figure 1 、 Figure 2 、 Figure 5 and Figure 6 As shown, the 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, if Figure 1 、 Figure 2 、 Figure 5 and Figure 6As shown, the ohmic contact structure 700 may cover the first doped region 200. Furthermore, the ohmic contact structure 700 is disposed in contact with a side of the second Schottky metal portion 3021 that is away from the first Schottky metal portion 3011, and / or the ohmic contact structure 700 is disposed in contact with a side of the third Schottky metal portion 3031 that is away from the first Schottky metal portion 3011. Furthermore, to further reduce the ohmic contact resistance, a second recess (not shown) may be provided in the first surface, with the ohmic contact structure 700 located in the second recess (in other words, the first surface has a second recess, the surface of the second recess being the first surface corresponding to the first doped region 200, and the ohmic contact structure 700 being located in the second recess). This increases the contact area between the ohmic contact structure 700 and the first doped region 200, thereby reducing the ohmic contact resistance.

[0055] Alternatively, as Figure 1 、 Figure 2 、 Figure 5 and Figure 6 As shown, the material of the above-mentioned ohmic contact structure 700 may include but is not limited to any one or more combinations 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] like Figure 1 、 Figure 2 、 Figure 5 and Figure 6 As shown, in the case where both the terminal region 400 and the first doping region 200 are P-type doped, the doping concentration of the first doping region 200 can be 1e16 cm -3 ~5e20cm -3 The doping concentration of the terminal region 400 may be 1e16 cm -3 ~5e20cm -3 .

[0057] It is explained here that Figures 1 to 6 The second Schottky metal portion 3021 in each embodiment may include a plurality of first sub-Schottky metal portions arranged in contact with each other along the first direction. Figures 1 to 6 Each of the third Schottky metal portions 3031 may include a plurality of second sub-Schottky metal portions that are arranged in contact with each other along the first direction.

[0058] In some optional embodiments, such as Figure 6As shown, the second Schottky metal portion 3021 includes a plurality of first sub-Schottky metal portions (not marked in the figure) arranged 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 3031 includes a plurality of second sub-Schottky metal portions (not marked in the figure) arranged in contact along the first direction, and the work functions of the materials of any two second sub-Schottky metal portions are different.

[0059] In the above embodiment, the work functions of the materials of the multiple first sub-Schottky metal parts included in the second Schottky metal part 3021 are different, and the work functions of the materials of the multiple second sub-Schottky metal parts included in the third Schottky metal part 3031 are different, so that the multiple first sub-Schottky metal parts included in the second Schottky metal part 3021 will form a multi-level Schottky barrier with the epitaxial part, and the multiple first sub-Schottky metal parts correspond to the multi-level Schottky barriers one-to-one, and the multiple second sub-Schottky metal parts included in the third Schottky metal part 3031 will form a multi-level Schottky barrier with the epitaxial part, and the multiple second sub-Schottky metal parts correspond to the multi-level Schottky barriers one-to-one, so that the second Schottky metal part 3021 includes a plurality of first sub-Schottky metal parts included in the second Schottky metal part 3021 and the epitaxial part respectively. The lower Schottky barrier at the contact interface between the junction 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 withstand voltage capability of the junction barrier Schottky diode, thereby further strengthening the synergistic effect of the multi-level Schottky barriers, so that the junction barrier Schottky diode has more excellent conduction and switching characteristics.

[0060] Specifically, if Figure 6 As shown, when the junction barrier structure of the junction barrier Schottky diode includes a first Schottky metal part 3011 and the semiconductor substrate 100 is N-type, the work function of the material of the multiple first sub-Schottky metal parts included in the second Schottky metal part 3021 is smaller than the work function of the material of the first Schottky metal part 3011, and the work function of the material of the multiple second sub-Schottky metal parts included in the third Schottky metal part 3031 is smaller 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 a first Schottky metal part 3011 and the semiconductor substrate 100 is P-type, the work function of the material of the multiple first sub-Schottky metal parts included in the second Schottky metal part 3021 is greater than the work function of the material of the first Schottky metal part 3011, and the work function of the material of the multiple second sub-Schottky metal parts included in the third Schottky metal part 3031 is greater than the work function of the material of the first Schottky metal part 3011.

[0061] Specifically, if Figure 6 As shown, the number of the multiple first sub-Schottky metal parts included in the second Schottky metal part 3021 and the number of the multiple second sub-Schottky metal parts included in the third Schottky metal part 3031 can be the same or different. In the case where 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, if Figure 6 As shown, for any first sub-Schottky metal part of the second Schottky metal part 3021 and any second sub-Schottky metal part in the third Schottky metal part 3031 having the above-mentioned 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 optional embodiments, such as Figure 6 As shown, in order to achieve uniform distribution of electric field strength in the contact area between the barrier structure and the epitaxial portion, avoid the formation of electric field hotspots, and enhance the stability and voltage resistance of the device, when the work function of the material of the first Schottky metal portion 3011 is respectively 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, the work function of the material of the multiple first sub-Schottky metal portions of the second Schottky metal portion 3021 decreases in the direction away from the first Schottky metal portion 3011; when the work function of the material of the first Schottky metal portion 3011 is respectively less 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, the work function of the material of the multiple first sub-Schottky metal portions of the second Schottky metal portion 3021 increases in the direction away from the first Schottky metal portion 3011.

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

[0065] On this basis, if Figure 1 As shown, in order to make the junction barrier Schottky diode 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 a first height, and the height of the second contact surface and the third contact surface from the substrate layer 101 is a second height, and 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, since the first Schottky metal portion 3011 is in contact with the external The barrier height of the first contact surface between the extensions is relatively high, so that the ability of the Schottky electrode region of the device to withstand electric field strength is enhanced, which can reduce the blocking current of the device and increase the blocking voltage of the device. On this basis, the second contact surface and the third contact surface in this embodiment 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 this embodiment can increase the blocking voltage of the device without reducing the Schottky electrode area, thereby achieving the effect of further improving the compromise characteristics between on-resistance and blocking voltage.

[0066] In addition, in the case where the first height may be equal to the second height (in other words, the first contact surface, the second contact surface, and the third contact surface may be flush with the first surface, respectively), Figure 1 The first Schottky metal part 3011 in the junction barrier Schottky diode shown can be replaced by an insulating dielectric layer. Therefore, when the barrier structure includes an insulating dielectric layer, since the insulating dielectric layer has a higher dielectric constant, the electric field can be further reduced by the insulating dielectric layer, so that the leakage current of the device is reduced, the reverse bias blocking capability is improved, and the blocking voltage of the device is further improved. On this basis, the second contact surface and the third contact surface in this embodiment 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 wider Schottky electrode area, that is, the junction barrier Schottky diode in this embodiment can still have better conduction and current-carrying capability on the basis of improving the blocking voltage of the device compared to the junction barrier Schottky diode in the prior art, thereby further improving the compromise characteristics between the on-resistance and the blocking voltage.

[0067] In some embodiments, as Figure 2 、 Figure 3 and Figure 4 As shown, the first height may be smaller than the second height (in other words, the second contact surface and the third contact surface may be flush with the first surface, respectively, while the first contact surface may be lower than the first surface in a direction perpendicular to the first surface). Figure 2As shown, when the barrier structure includes the first Schottky metal portion 3011, this arrangement increases the Schottky contact area. Since the Schottky contact resistance is inversely proportional to the Schottky contact area, the Schottky contact resistance is reduced, thereby further reducing the on-resistance of the device; as shown in FIG. 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 higher 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 capability is improved, and the blocking voltage of the device is further 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, and 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. This arrangement increases the Schottky contact area, improves the conductive current-carrying capability 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 voltage resistance of the device is further improved, thereby further improving the blocking voltage of the device.

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

[0070] In other embodiments, in order to further improve the blocking voltage while ensuring that the junction barrier Schottky diode has excellent conduction and switching characteristics, the barrier structure of the junction barrier Schottky diode may include a first Schottky metal portion, an insulating dielectric layer, a second Schottky metal portion, and a third Schottky metal portion. The second Schottky metal portion and the third Schottky metal portion are located on opposite sides of the first Schottky metal portion in the first direction, and an insulating dielectric layer is provided between adjacent first and second Schottky metal portions, and an insulating dielectric layer is provided between adjacent first and third Schottky metal portions.

[0071] Furthermore, when the second Schottky metal portion includes multiple first sub-Schottky metal portions along a direction away from the first Schottky metal portion, an insulating dielectric layer is provided between any two adjacent first sub-Schottky metal portions; and when the third Schottky metal portion includes multiple second sub-Schottky metal portions along a direction away from the first Schottky metal portion, an insulating dielectric layer is provided between any two adjacent second sub-Schottky metal portions. The insulating dielectric material of the insulating dielectric layer between two different second sub-Schottky metal portions may be the same or different, and / or the insulating dielectric material of the insulating dielectric layer between two different third sub-Schottky metal portions may be the same or different.

[0072] In some optional embodiments, such as Figure 2 、 Figure 3 and Figure 4 As shown, in order to further reduce the on-resistance of the device, a first recess (not marked in the figure) is provided in the first surface, 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] like Figure 2 As shown, when the barrier structure includes a first Schottky metal portion 3011, the first Schottky metal portion 3011 covers the surface of the first recess (corresponding to the first region 301), the second Schottky metal portion 3021 covers the second contact surface (corresponding to the second region 302), and the third Schottky metal portion 3031 covers the 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, thereby further improving the current conduction capability of the junction barrier Schottky diode and further reducing the on-resistance of the device.

[0074] like Figure 3As shown, when the barrier structure includes an insulating dielectric layer 3010, the insulating dielectric layer 3010 covers the surface of the first concave portion, 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 concave portion increases the contact area between the insulating dielectric layer 3010 and the epitaxial portion, thereby further improving the leakage current problem and further improving the blocking voltage of the device. Figure 4 As 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. Furthermore, 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 interface between the fourth Schottky metal portion 3041 and the side surface 310. Therefore, the provision 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, the device has a contact interface between the insulating dielectric layer 3010 and the epitaxial portion, thereby further improving the leakage current problem of the device while further improving the current flow capacity of the device, thereby further improving the compromise characteristics of the device's on-resistance and blocking voltage.

[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 part 3041 is the same as the work function of the material of the first Schottky metal part, the material of the fourth Schottky metal part 3041 is the same as the material of the above-mentioned first Schottky metal part, so that the fourth Schottky metal part 3041 forms a multi-level Schottky barrier with the second Schottky metal part 3021 and the third Schottky metal part 3031 respectively; when the work function of the material of the fourth Schottky metal part 3041 is different from the work function of the material of the first Schottky metal part, the work function of the material of the fourth Schottky metal part 3041 can be made 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, so that the fourth Schottky metal part 3041 forms a multi-level Schottky barrier with the second Schottky metal part 3021 and the third Schottky metal part 3031 respectively.

[0076] In some optional 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 first portion is made of a first insulating dielectric material, and the second portion is made of a second insulating dielectric material. The first insulating dielectric material and the second insulating dielectric material may be the same insulating dielectric material or different insulating dielectric materials.

[0077] Furthermore, in the 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 and the side are connected by an arc. Figures 2 to 4 The bottom surface and side surfaces of the first recess (not marked in the figure) are connected by an arc line.

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

[0079] It can be understood that the raised structure raises the thickness of the central barrier region through the local epitaxial layer thickness (i.e., the thickness of the epitaxial part), so that the central barrier region is away from the bottom of the first doped region, thereby reducing the electric field strength at the Schottky interface position, 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 a first Schottky metal part 3011, a second Schottky metal part 3021 and a third Schottky metal part 3031, wherein the first Schottky metal part 3011 covers the top surface of the first contact surface or the protrusion 800, the second Schottky metal part 3021 covers one of the side surfaces of the second contact surface or the protrusion 800, and the third Schottky metal part 3031 covers the other side surface of the third contact surface or the protrusion 800.

[0081] In the above embodiment, the high potential barrier at the contact interface between the first Schottky metal portion 3011 and the raised portion 800 can further increase the blocking voltage of the junction barrier Schottky diode; and the low potential barrier at the contact interface between the second Schottky metal portion 3021 and the third Schottky metal portion 3031 and the raised portion 800 can further increase the current flow capacity of the junction barrier Schottky diode. It can be seen that this embodiment further improves the trade-off between the blocking voltage and on-resistance of the junction barrier Schottky diode.

[0082] In some optional embodiments, such as Figure 6As shown, the first surface includes a raised portion 800. The first contact surface (corresponding to the first region 301) is the top surface of the raised portion 800. The second contact surface (corresponding to the second region 302) and the third contact surface (corresponding to the third region 303) are surfaces of the raised portion 800 other than the top surface that are symmetrical about the top surface in the first direction A. In this embodiment, the raised portion 800 may have multiple stepped surfaces. By disposing 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 line.

[0084] In some optional embodiments, such as Figure 1 、 Figure 2 、 Figure 5 and Figure 6 As shown, in the case where the barrier structure includes the first Schottky metal portion 3011, the second Schottky metal portion 3021 and the third Schottky metal portion 3031 are arranged symmetrically about the first Schottky metal portion 3011; Figure 3 and Figure 4 As shown, when the barrier structure includes the insulating dielectric layer 3010 , the second Schottky metal portion 3021 and the third Schottky metal portion 3031 are arranged symmetrically with respect to the insulating dielectric layer 3010 .

[0085] In the above embodiment, when the second Schottky metal portion 3021 and the third Schottky metal portion 3031 are arranged on the first Schottky metal portion 3011 or when the second Schottky metal portion 3021 and the third Schottky metal portion 3031 are arranged axially symmetrically on opposite sides of the insulating dielectric layer 3010, the conductive path of the overall Schottky contact is increased, thereby improving the device's on-current capability and further reducing the on-resistance. Furthermore, when the second Schottky metal portion 3021 and the third Schottky metal portion 3031 are arranged axially symmetrically about the first Schottky metal portion 3011 or the second Schottky metal portion 3021 and the third Schottky metal portion 3031 are arranged axially symmetrically about the insulating dielectric layer 3010, the junction barrier Schottky diode corresponding to this embodiment can have a uniform current distribution while having more levels of Schottky barrier regions.

[0086] It is understandable that the above-mentioned junction barrier Schottky diode can be applicable to semiconductor structures having a junction barrier Schottky diode in JBS devices, MPS devices, SBD-embedded MOSFET devices, IGBT devices, and the like.

[0087] According to another aspect of the present application, a method for preparing a junction barrier Schottky diode is also provided, including: providing an N-type substrate layer, forming 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, and 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 the terminal region and a P-type first doped region in the active region, wherein the terminal region surrounds the active region, and the first doped region and the epitaxial portion (Schottky contact region) are discontinuously distributed in the active region.

[0088] The steps of 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, injecting Al ions of specific energy and dosage, then activating in an inert gas at 1650°C~1850°C, and finally etching away the SiO2 mask layer.

[0089] 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 can be 350 μm, and the doping concentration can be 1e19 cm -3 The thickness of the N-type epitaxial layer can be 32μm and the doping concentration can be 3e15cm -3 Optionally, the doping element of the terminal field stop region may be Al, and the doping concentration may be 1e18~1e19cm -3 Alternatively, the doping element of the first doping region may be Al, and the doping concentration may be 5e18 cm -3 Optionally, the spacing between two adjacent first doping regions in the first direction is less than or equal to 8 μm. Optionally, the projection shape of each first doping region on the surface of the N-type epitaxial layer away from the N-type substrate layer can be one of the following shapes or a combination of multiple shapes: square, circle and hexagon.

[0090] Next, a 1μm thick SiO2 layer can be deposited on the surface of the N-type epitaxial layer using PECVD as a passivation layer, and then the active area window is obtained through photolithography and wet etching. Finally, electrodes are formed in the active area.

[0091] The steps of forming the contact include: first, depositing a layer of high-work-function metal material Ni by magnetron sputtering, then etching away the metal outside the high-barrier Schottky contact area (the first Schottky metal part or the corresponding area of ​​the insulating dielectric layer) and the P-type doped contact area (the corresponding area of ​​the first doped area) with the help of a photolithography process, and then sputtering and depositing a layer of 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 thick metal layer of Ti / Al.

[0092] Finally, after forming the front contact electrode and passivation, a protective film is attached to the front of the chip. The chip is flipped over, and Ni / Ti / Ni / Ag are deposited in sequence on the back of the chip (on the side of the N-type substrate layer away from the N-type epitaxial layer) by magnetron sputtering, and the 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 portion or insulating dielectric layer covers the first region, the second Schottky metal portion covers the second region, and the third Schottky metal portion covers the third region. The first region, the second region, and the third region are respectively three regions of the epitaxial portion located on the first surface. The epitaxial portion is the region of the epitaxial layer located between two adjacent first doped regions. Since the barrier height at the contact interface between the first Schottky metal portion (or insulating dielectric layer) and the epitaxial portion is higher than the barrier height at the contact interface between the second Schottky metal portion and the epitaxial portion, and the barrier height at the contact interface between the third Schottky metal portion and the epitaxial portion, it can be seen that in the present application, when the barrier structure includes the first Schottky metal portion, a multi-level barrier structure is introduced using different Schottky metals. Therefore, without changing the physical proportion of the PN junction region, the early turn-on effect of the low barrier region (the second region and the third region) is utilized to compensate for the conduction loss of the PN junction region, while the reverse depletion capability is enhanced by the high barrier region (the first region). This energy band design, based on spatial modulation of the barrier height, breaks through the traditional "area trade-off" design paradigm and achieves the coordinated optimization of on-resistance and blocking voltage. Furthermore, 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. Because the dielectric layer's withstand voltage efficiency under reverse bias far exceeds that of a metal Schottky contact, a multi-level barrier structure is introduced from the insulating dielectric material and the Schottky metal. During forward conduction, the low-work-function metal regions corresponding to the second and third Schottky metal sections provide current paths, circumventing the conduction disadvantages of the dielectric layer. This "dielectric + metal" composite barrier design combines the high withstand voltage of the MOS structure with the low on-state conduction of the Schottky structure, providing a new design dimension for power devices and achieving the coordinated optimization of on-resistance and blocking voltage. In summary, through the synergistic effect of the multi-level barrier structure, this application solves the problem of poor conduction in junction barrier Schottky diodes in the prior art due to the addition of a PN junction.

[0095] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A junction barrier Schottky diode, characterized in that: include: A semiconductor substrate comprises a stacked substrate layer and an epitaxial layer, wherein a surface of the epitaxial layer facing away from the substrate layer is a first surface of the semiconductor substrate; a plurality of first doped regions spaced apart along a first direction, each of the first doped regions extending from the first surface into the epitaxial layer, the first doped regions and the epitaxial layer having opposite doping types, the epitaxial layer between two adjacent first doped regions being an epitaxial portion, the 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 comprising 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 a first Schottky metal portion, a barrier height between the first Schottky metal portion and the epitaxial portion is higher than a barrier height between the second Schottky metal portion and the epitaxial portion and a barrier height between the third Schottky metal portion and the epitaxial portion, respectively; When 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.

2. The junction barrier Schottky diode according to claim 1, wherein: In the case where the barrier structure includes a 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, or the work function of the material of the first Schottky metal portion is smaller 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 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 materials of any two of the second sub-Schottky metal portions are different.

4. The junction barrier Schottky diode according to claim 3, characterized in that: When 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, 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 respectively smaller 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, the work function of the materials of the multiple 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, wherein: There is a first contact surface between the first Schottky metal portion and the epitaxial portion, a second contact surface between the second Schottky metal portion and the epitaxial portion, and a third contact surface between the third Schottky metal portion and the epitaxial portion. 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, wherein: 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, characterized in that: The first surface has a first concave portion, the first contact surface is the first surface corresponding to the first concave portion, and the second contact surface is flush with the third contact surface.

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 line.

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

10. The junction barrier Schottky diode according to claim 8, characterized in that: In the case where the barrier structure includes the 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.

11. The junction barrier Schottky diode according to claim 6, characterized in that: The first surface has a protrusion, 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.

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

13. The junction barrier Schottky diode according to any one of claims 1 to 12, characterized in that: In a case where the barrier structure includes the first Schottky metal portion, the second Schottky metal portion and the third Schottky metal portion are arranged axially symmetrically with respect to the first Schottky metal portion.

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

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

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