Schottky diode and groove structure thereof

Abstract

The utility model provides a Schottky diode and a groove structure thereof. The Schottky diode comprises a substrate, an epitaxy and the groove structure. A first region groove structure, a second region groove structure and a third region groove structure of the groove structure form a rounded rectangle on the epitaxy and form a cellular region groove: the first region groove structure comprises I first grooves which are parallel to one another and are spaced from one another, and the I first grooves are positioned in a middle region on the epitaxy; the second region groove structure comprises J second grooves which are parallel to one another and are spaced from one another, and the J second grooves are located on the outer sides of the I first grooves; the third area groove structure comprises J third grooves which are parallel to one another and are spaced from one another, the J third grooves are located at the four rounded corners of the rounded rectangle, the first ends of the third grooves are connected with the second grooves, and the second ends of the third grooves are connected with the first grooves on the outermost side in the first groove structure. The Schottky diode provided by the utility model is small in forward conduction voltage drop and good in surge current resistance.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of semiconductor, especially to a Schottky diode and its trench structure. BACKGROUND

[0002] Trench MOS Barrier Schottky Diode (TMBS) is a mature trench MOS device, after years of technology iteration and industry chain improvement, the chip cost of Schottky diode has become the key point of competition for each company. The smaller the chip size of Schottky diode is, the higher the single wafer out-chip rate is, but the forward conduction characteristic of the device is also worse. Therefore, for the optimization of the out-chip rate of Schottky diode, it is necessary to improve the forward voltage drop capability without affecting the surge current and reverse voltage withstand capability of the device. SUMMARY

[0003] The utility model discloses a Schottky diode and its trench structure, which can reduce the forward voltage drop capability of the device while maintaining the surge current resistance and reverse voltage withstand capability of the device.

[0004] In order to achieve the above-mentioned purpose, the utility model provides a trench structure of Schottky diode, characterized by comprising:

[0005] a substrate;

[0006] an epitaxial layer located on the front surface of the substrate;

[0007] a trench structure extending from the surface of the epitaxial layer to the inside of the epitaxial layer;

[0008] The trench structure comprises a first region trench structure, a second region trench structure and a third region trench structure, the first region trench structure, the second region trench structure and the third region trench structure form a rounded rectangle on the epitaxial layer, and the first region trench structure, the second region trench structure and the third region trench structure are cell region trenches.

[0009] The first region trench structure comprises I first trenches parallel to each other and spaced apart, the I first trenches are located in the middle region on the epitaxial layer, and I is a positive integer;

[0010] The second region trench structure comprises J second trenches parallel to each other and spaced apart, the J second trenches are located outside the I first trenches, the length of the first trench is longer than the length of the second trench, and J is a positive integer;

[0011] The third region groove structure comprises J third grooves parallel to each other and spaced apart from each other, the J third grooves are located at four rounded corners of the rounded rectangle, the number of the third grooves is equal to the number of the second grooves, a first end of the third groove is connected to the second groove, and a second end of the third groove is connected to the outermost first groove in the first groove structure.

[0012] Optionally, the first groove and the second groove are straight lines, and the third groove is an arc.

[0013] Optionally, the first groove and the second groove extend in a first direction and are arranged at intervals in a second direction, and the third groove is arranged at intervals in a third direction, and the third groove communicates with the first groove and the second groove.

[0014] The first direction and the second direction are perpendicular to each other, and the third direction intersects the first direction and the second direction.

[0015] Optionally, the angle between the third direction and the first direction and the second direction is 45°.

[0016] Optionally, in the third groove and the second groove connected to each other, the sum of the width of the second groove in the second direction and the spacing between adjacent two second grooves is equal to the sum of the width of the third groove in the third direction and the spacing between adjacent two third grooves.

[0017] Optionally, the width of the first groove and the second groove in the second direction is equal, and the first groove and the second groove are arranged at equal intervals in the second direction.

[0018] Optionally, the width of the third groove in the third direction is equal, and the third groove is arranged at equal intervals in the third direction.

[0019] Optionally, the width of the third groove in the third direction is greater than the width of the first groove and the second groove in the second direction.

[0020] Optionally, the width of the third groove in the third direction is greater than or equal to 1.02 times the width of the first groove and the second groove in the second direction.

[0021] Optionally, the trench structure further comprises a terminal trench structure, the terminal trench structure is a round rectangular trench, the terminal trench structure comprises a first part, a second part and a third part, the first part connects two ends of the first trench, the second part is parallel to the second trench and is spaced from the outermost second trench in the second trench structure, and the third part is connected to the first part and the second part in a circular arc.

[0022] Optionally, the width of each terminal trench of the terminal trench structure is greater than the width of the first trench, the second trench and the third trench.

[0023] Optionally, the width of the first trench and the second trench in the second direction is 0.12um-5um, and the distance between adjacent first trenches and the distance between adjacent second trenches is 0.33um-11um.

[0024] Optionally, the width of the second trench in the first direction is gradually changed.

[0025] Optionally, the third trench is a circular ring, and the width of the first end of the third trench connected with the second trench is equal.

[0026] Optionally, the third trench comprises a first sub-trench and a second sub-trench, the shape of the first sub-trench is a circular ring, and the shape of the second sub-trench is a figure formed by an elliptical fitting line between the inner ring surface and the two end points of the inner ring surface of the first.

[0027] The present application provides a Schottky diode comprising the trench structure.

[0028] Optionally, it further comprises:

[0029] An insulating dielectric layer is located on the inner wall of the trench structure.

[0030] A gate conductive layer is located on the insulating dielectric layer and fills the trench structure.

[0031] A Schottky barrier layer covers the epitaxial layer without the trench structure, the insulating dielectric layer on the epitaxial surface part, the gate conductive layer on the epitaxial surface part, part of the gate conductive layer and part of the insulating dielectric layer in the terminal area are not covered by the Schottky barrier layer.

[0032] A terminal metal layer covers the insulating dielectric layer in the terminal area which is not covered by the Schottky barrier layer.

[0033] An oxide layer covers the surface and sidewall of the terminal metal layer.

[0034] an anode electrode covering the Schottky barrier layer and part of the termination metal layer;

[0035] a cathode electrode located on the back surface of the substrate.

[0036] In the Schottky diode and the groove structure thereof, the Schottky diode comprises a substrate, an epitaxial layer located on the front surface of the substrate, and a groove structure extending from the surface of the epitaxial layer into the epitaxial layer; the groove structure comprises a first region groove structure, a second region groove structure, and a third region groove structure, the first region groove structure, the second region groove structure, and the third region groove structure form a rounded rectangle on the epitaxial layer, and the first region groove structure, the second region groove structure, and the third region groove structure are cell region grooves; the first region groove structure comprises I first grooves that are parallel to each other and spaced apart, the I first grooves are located in a middle region on the epitaxial layer, and I is a positive integer; the second region groove structure comprises J second grooves that are parallel to each other and spaced apart, the J second grooves are located outside the I first grooves, the length of the first grooves is longer than the length of the second grooves, and J is a positive integer; and the third region groove structure comprises J third grooves that are parallel to each other and spaced apart, the J third grooves are located at four rounded corners of the rounded rectangle, the number of the third grooves is equal to that of the second grooves, a first end of the third groove is connected to the second groove, and a second end of the third groove is connected to the outermost first groove in the first groove structure. The Schottky diode has a smaller forward conduction voltage drop and a better surge current resistance. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of a Schottky diode;

[0038] Figure 2 It is a structural schematic diagram of a Schottky diode; Figure 1

[0039] Figure 3 It is a schematic diagram of a cell region provided in the embodiment one of the utility model;

[0040] Figure 4 It is a schematic diagram of a cell region provided in the embodiment one of the utility model; Figure 3

[0041] Figure 5 It is a sectional schematic diagram of the A-A square in the embodiment one of the utility model; Figure 4

[0042] It is a schematic diagram of the connection between the first end of the third groove and the first end of the second groove provided in the embodiment one of the utility model; Figure 6

[0043] ​​​Figure 7 Figure 2 is a schematic view of the connection between the first end of the third groove and the first end of the second groove according to Embodiment Two of the present application;

[0044] In the drawings, reference numerals are used:

[0045] 100, 110 - substrate; 101, 111 - epitaxial; 201 - cell region trench; 202 - terminal region trench; 301, 311 - insulating dielectric layer; 302, 312 - gate conductive layer; 401 - anode electrode; 402 - cathode electrode; 500 - Schottky barrier layer; 600 - oxide layer; 700 - terminal metal layer; Q1 - corner region; Q2 - first region; Q3 - second region; Q4 - third region; 211 - first groove; 212 - second groove; 213 - third groove; 214 - terminal region large groove; 215 - terminal region small groove; x - first direction; y - second direction; z - third direction. DETAILED DESCRIPTION

[0046] Figure 1 Figure 1 is a structural schematic diagram of a Schottky diode. As shown in Figure 1 , the manufacturing method of the Schottky diode comprises:

[0047] A plurality of equally spaced cell region trenches 201 (Trench) and terminal region trenches 202 surrounding the cell region trenches 201 are formed in the epitaxial layer 101 on the substrate 100. The width W1 of the plurality of cell region trenches 201 is equal, except for the terminal region trenches 202. The terminal region trenches 202 are usually multiple and have a larger width than the cell region trenches 201;

[0048] An insulating dielectric layer 301 is formed on the inner wall of the cell region trench 201 as a gate oxide layer;

[0049] A gate conductive layer 302 (material such as polysilicon) is formed in the cell region trench 201;

[0050] A stacked Schottky barrier layer and anode electrode (not shown in Figure 1 ) are sequentially formed on the top surface of the epitaxial layer 101, and a cathode electrode (not shown in Figure 1 ) is formed on the bottom surface of the substrate 100.

[0051] The Schottky diode utilizes a trench gate structure combined with a junction barrier structure. When the Schottky diode is subjected to reverse voltage, the electric field peak is concentrated at the bottom position of the cell region trench 201. As the voltage continues to rise, the depletion region at the bottom position of the cell region trench 201 is pinched off, thereby effectively reducing the surface electric field of the Schottky contact surface (the contact surface of the Schottky barrier layer and the epitaxial layer 101), and further significantly reducing the leakage of the Schottky barrier.

[0052] The forward conduction voltage drop of the Schottky diode is greatly reduced with the increase of the effective area of the Schottky contact surface when the work function of the Schottky barrier layer is unchanged, the effective area of the Schottky contact surface can be increased by increasing the spacing d1 between the cell region trenches 201, thereby reducing the forward conduction voltage drop, and the leakage problem caused by the increase of the spacing d1 can be compensated by increasing the width W1 of the cell region trench 201. However, there is a limitation in compensating for the leakage by increasing the width W1 of the cell region trench 201, when the spacing d1 is increased to a certain value, the leakage cannot be reduced by increasing the width W1 of the cell region trench 201.

[0053] The effective area of the Schottky contact surface can also be increased by reducing the width W1 of the cell region trench 201, but after the width W1 of the cell region trench 201 is reduced, the aspect ratio of the width W1 of the cell region trench 201 will increase, and the reaction gas is more difficult to reach the bottom of the trench when the insulating medium layer 301 is formed in the cell region trench 201, resulting in a thin thickness of the insulating medium layer 301 at the bottom of the trench, and a reduced surge current resistance of the device. Figure 2 For Figure 1 The shape of the Schottky diode provided in the embodiment is shown in the schematic diagram. Figure 2 As shown in the schematic diagram, the shape of the Schottky diode is generally a rounded rectangle, and the side length of the rounded rectangle is equal, and the rounded rectangle has a corner region Q1 at each corner, the bottom of the cell region trench 201 in the corner region Q1 has a crystal direction of <110> at an inclined angle of 45°, so the insulating medium layer 301 in the corner region Q1 is the thinnest (<110> crystal direction has a smaller oxidation growth rate than <100> crystal direction). The corner region Q1 is very close to the terminal region trench 202, and when the Schottky diode is broken down, the electric field intensity at the bottom of the terminal region trench 202 is twice or more than that at the bottom of the cell region trench 201, so if the insulating medium layer 301 of the cell region trench 201 in the corner region Q1 is too thin, the surge current resistance of the device will be greatly reduced.

[0054] The specific embodiments of the present application will be described in more detail below with reference to the schematic diagrams. The advantages and features of the present application will be more apparent from the following description. It should be noted that the drawings are greatly simplified and use non-precise proportions, and are only used to facilitate and clarify the purpose of assisting in the description of the embodiments of the present application.

[0055] Embodiment one

[0056] The embodiment provides a Schottky diode, Figure 3 The schematic diagram of the shape of the Schottky diode provided in the embodiment,Figure 4 As Figure 3 An enlarged view of the dashed box area, Figure 5 As Figure 4 A cross-sectional view of the A-A square, Figure 3 , Figure 4 and Figure 5 As shown in FIG. 1, the Schottky diode includes a substrate 110, an epitaxial layer 111, and a trench structure. The epitaxial layer 111 is located on the front surface of the substrate 110, and the trench structure extends from the surface of the epitaxial layer 111 into the epitaxial layer 111.

[0057] The trench structure includes a cell region trench structure and a termination region trench structure, and the termination region trench structure is arranged around the cell region trench structure. The cell region trench structure includes a first region trench structure, a second region trench structure, and a third region trench structure, which form a rounded rectangle on the epitaxial layer 111. The first region trench structure includes I first trenches 211 that are parallel to each other and spaced apart, and the I first trenches 211 are located in the middle region on the epitaxial layer 111, where I is a positive integer. The second region trench structure includes J second trenches 212 that are parallel to each other and spaced apart, and the J second trenches 212 are located outside the I first trenches 211. The length of the first trench 211 is longer than the length of the second trench 212, and J is a positive integer. The third region trench structure includes J third trenches 213 that are parallel to each other and spaced apart, and the number of the third trenches 213 is equal to the number of the second trenches 212. The first end of the third trench 213 is connected to the second trench 212, and the second end of the third trench 213 is connected to the outermost first trench 211 in the first trench structure.

[0058] The cell region trench structure is approximately a rounded rectangle, which includes a first region Q2, a second region Q3, and a third region Q4. The first region Q2, the second region Q3, and the third region Q4 form a rounded rectangle. The first region Q2 is located in the middle region, the second region Q3 is located outside the second region Q3, and the second region Q3 is located at the four corners of the rounded rectangle, which is approximately a sector region.

[0059] Further, the first trench 211 is located in the first region Q2, the first trench 211 extends along the first direction x and is spaced along the second direction y; the second trench 212 is located in the second region Q3, the second trench 212 extends along the first direction x and is spaced along the second direction y; the third trench 213 is located in the third region Q4 and is spaced along the third direction z. The third trench 213 is in communication with the first trench 211 and the second trench 212.

[0060] The first direction x and the second direction y are perpendicular to each other, and the third direction z intersects the first direction x and the second direction y. As shown in the embodiment, the first direction x is the column direction, the second direction y is the row direction, and the angle between the third direction z and the first direction x and the second direction y is 45°. Specifically, the width of the Schottky diode along the first direction x and the second direction y is equal, and the third direction z is the direction of the diagonal of the Schottky diode. In some embodiments, the angle between the third direction z and the first direction x and the second direction y is not limited to 45°. Figure 4

[0061] It should be noted that, as shown in the embodiment, since the third region Q4 is at the four corners of the rounded rectangle, the third region Q4 has four, each of the third region Q4 is at one corner, and the third direction z corresponding to the two third regions Q4 on the same diagonal is the same (i.e. both are the direction of the diagonal), while the third direction z corresponding to the two third regions Q4 on different diagonals is different (perpendicular to each other), but no matter how, the third direction z intersects the first direction x and the second direction y, and is along the direction of the line connecting the center of the third region Q4 and the center of the Schottky diode. Figure 3

[0062] In the embodiment, the projection of the first trench 211 and the second trench 212 is a straight line, and the projection of the third trench 213 is an arc.

[0063] Please continue to refer to Figure 4 The first end of each third trench 213 is connected to the second trench 212, and the third trench 213 is connected to the outermost first trench 211 in the first trench structure. Specifically, the first end of the third trench 213 is in communication with the first end of the corresponding first trench 211, and the second end of the third trench 213 is in communication with the side of the closest first trench 211.

[0064] ​​Further, in order to enable the first end of the third groove 213 to be connected to the first end of the corresponding second groove 212 respectively, in the second groove 212 and the third groove 213 connected to each other, the sum of the width W3 of the second groove 212 in the second direction y and the spacing d3 between the adjacent second groove 212 is equal to the sum of the width W2 of the third groove 213 in the third direction z and the spacing d2 between the adjacent third groove 213, i.e. W2+d2=W3+d3.

[0065] It should be noted that since one second groove 212 can have two adjacent second grooves 212 in the second direction y, the spacing d3 between the second groove 212 and the adjacent second groove 212 can be the spacing between the second groove 212 and any one of the adjacent second grooves 212, or the sum of 1 / 2 of the spacing between the second groove 212 and each of the adjacent second grooves 212. Similarly, since one third groove 213 can have two adjacent third grooves 213 in the second direction z, the spacing d2 between the third groove 213 and the adjacent third groove 213 can be the spacing between the third groove 213 and any one of the adjacent third grooves 213, or the sum of 1 / 2 of the spacing between the third groove 213 and each of the adjacent third grooves 213.

[0066] In the embodiment, the width W3 of each first groove 211 in the second direction y is equal, and the first grooves 211 are arranged at equal intervals in the second direction y; the width W3 of each second groove 212 in the second direction y is equal, and the second grooves 212 are arranged at equal intervals in the second direction y; and the width W2 of each third groove 213 in the third direction z is equal, and the third grooves 213 are arranged at equal intervals in the third direction z. In some embodiments, the width W3 of the first groove 211 in the second direction y can also be unequal, and the first grooves 211 can also not be arranged at equal intervals in the second direction y; similarly, the width W3 of the second groove 212 in the second direction y can also be unequal, and the second grooves 212 can also not be arranged at equal intervals in the second direction y; and the width W2 of the third groove 213 in the third direction z can also be unequal, and the third grooves 213 can also not be arranged at equal intervals in the third direction z. However, in any case, it is necessary to ensure that W3+d3=W2+d2, so that the first end of the third groove 213 can be connected to the first end of the corresponding second groove 212 respectively.

[0067] Please continue to refer to Figure 4 , the third trench 213 has a width W2 in the third direction z that is greater than a width W3 of the second trench 212 in the second direction y and a width W3 of the first trench 211 in the second direction y, so that the width W2 of the third trench 213 in the third direction z, the width W3 of the second trench 212 in the second direction y, and the width W3 of the first trench 211 in the second direction y can be reduced at the same time, greatly reducing the forward conduction voltage drop of the device by increasing the effective area of the Schottky contact surface, and even if the width W2 of the third trench 213 in the third direction z is reduced, the aspect ratio of the third trench 213 will not be too small, which can ensure the thickness of the insulating medium layer at the bottom of the third trench 213, reduce the electric field strength at the bottom of the termination zone trench 213, optimize the bottom current distribution of the third trench 213 and the peak electric field at the bottom of the termination zone trench 213, reduce the leakage current, and ensure the surge current resistance of the device.

[0068] Further, the width W2 of the third trench 213 in the third direction z is greater than or equal to 1.02 times the width W3 of the second trench 212 in the second direction y and the width W3 of the first trench 211 in the second direction y (W3*1.02≤W2), so that the thickness of the insulating medium layer formed in the third trench 213 corresponding to the trench can be greater than the thickness of the insulating medium layer formed in the second trench 212 and the first trench 211 corresponding to the trench, which can maintain the surge capacity of the device on the basis of reducing the forward voltage drop of the device. According to the measurement, the embodiment compared to Figure 1 and Figure 2 , the Schottky contact area can be increased by more than 15% (the wafer core yield is increased by more than 15%), which improves the wafer core yield, at the same time, the forward voltage drop of the device can be reduced by more than 13mV, and the surge current resistance of the device will not be affected.

[0069] It should be noted that the difference between the width W2 of the third trench 213 in the third direction z and the width W3 of the second trench 212 in the second direction y and the width W3 of the first trench 211 in the second direction y should not be too large, so as to avoid the trench etching load effect of the device during preparation.

[0070] Further, the trench structure further comprises a terminal trench structure, the terminal trench structure is a round rectangular trench, the terminal trench structure comprises a first part, a second part and a third part, the first part connects two ends of the first trench 211, the second part is parallel to the second trench 212 and is spaced from the outermost second trench 212 in the second trench structure, and the third part 216 is connected to the first part 214 and the second part 215 through a circular arc.

[0071] The width (W4 or W5) of each terminal trench of the terminal trench structure is greater than the width W2 of the third trench 213 in the third direction z, the width W3 of the first trench 211 in the second direction y and the width W3 of the second trench 212 in the second direction y (W4>W2>W3), and the width W4 of the terminal large groove in the terminal trench is preferably greater than 2 times the order of magnitude of the width W2 of the third trench 213 in the third direction z, the width W3 of the second trench 212 in the second direction y and the width W3 of the first trench 211 in the second direction y, which can ensure that the breakdown voltage of the terminal structure is higher than that of the cell structure, and can improve the breakdown voltage at the corner of the cell structure, thereby improving the breakdown voltage of the entire device. The width W5 of the terminal small groove 215 in the terminal trench is smaller than the width W4 of the terminal large groove 214, but the width W5 of the terminal small groove 215 can be greater than the width W3 of the second trench 212 in the second direction y and the width W3 of the first trench 211 in the second direction y.

[0072] The terminal large groove 214 and the terminal small groove 215 are arranged in a spaced manner and surround the cell region trench in sequence, the terminal large groove 214 is closer to the cell region trench than the terminal small groove 215, and the number of the terminal large groove 214 is usually 1, and the number of the terminal small groove 215 can be more than 3.

[0073] Optionally, the width W3 of the second trench 212 in the second direction y is 0.12um-5um, the distance d3 between adjacent second trenches 212 is 0.33um-11um, the width W2 of the third trench 213 in the third direction z can be appropriately increased on the basis of the width W3 of the second trench 212 in the second direction y, and the distance d2 between adjacent third trenches 213 can be calculated according to W2+d2=W3+d3. Preferably, the width W3 of the second trench 212 in the second direction y can be 0.22um-0.3um, and the distance d3 between adjacent second trenches 212 can be 0.8um-1.9um.

[0074] Figure 6 The schematic diagram of the connection between the first end of the third trench 213 and the first end of the second trench 212 is provided for this embodiment. As shown, in this embodiment, the shape of the third trench 213 is circular ring, the width of the first end of the third trench 213 is equal to the width of the first end of the second trench 212, and the width of the section of the second trench 212 connected with the third trench 213 gradually decreases (tapered) in the direction away from the third trench 213, at this time, the second trench 212 is approximately inverted trapezoidal. In this way, the transition of the connection between the third trench 213 and the second trench 212 is natural, avoiding the problem of step at the connection between the third trench 213 and the second trench 212, which leads to the concentration of electric field at the step and the easy breakdown of the step. Figure 6

[0075] Further, as shown, the Schottky diode further comprises an insulating dielectric layer 311, a gate conductive layer 312, a Schottky barrier layer 500, an oxide layer 600, a terminal metal layer 700, an anode electrode 401 and a cathode electrode 402. Among them, the insulating dielectric layer 311 is located on the inner wall of the trench structure (the cell region trench and the terminal region trench), the gate conductive layer 312 is located on the insulating dielectric layer 311 and fills the trench structure, that is, the insulating dielectric layer 311 covers the inner wall of the first trench 211, the second trench 212, the third trench 213 and the terminal region trench, and the gate conductive layer 312 fills the first trench 211, the second trench 212, the third trench 213 and the terminal region trench. The Schottky barrier layer 500 covers the epitaxial layer 111 without the trench structure, the insulating dielectric layer 311 on the surface part of the epitaxial layer 111, the gate conductive layer 312 on the surface part of the epitaxial layer 111, part of the gate conductive layer 312 and part of the insulating dielectric layer 311 of the terminal region are not covered by the Schottky barrier layer 500, the terminal metal layer 700 covers the insulating dielectric layer 311 of the terminal region not covered by the Schottky barrier layer 500, and the oxide layer 600 covers the surface and the sidewall of the terminal metal layer 700. The anode electrode 401 covers the Schottky barrier layer 500 and the terminal metal layer 700, and the cathode electrode 402 is located on the back of the substrate 110. Figure 5

[0076] Embodiment Two

[0077] Figure 7 The schematic diagram of the connection between the first end of the third trench 213 and the first end of the second trench 212 is provided for this embodiment. As shown, in this embodiment, the shape of the third trench 213 is circular ring, the width of the first end of the third trench 213 is equal to the width of the first end of the second trench 212, and the width of the section of the second trench 212 connected with the third trench 213 gradually decreases (tapered) in the direction away from the third trench 213, at this time, the second trench 212 is approximately inverted trapezoidal. In this way, the transition of the connection between the third trench 213 and the second trench 212 is natural, avoiding the problem of step at the connection between the third trench 213 and the second trench 212, which leads to the concentration of electric field at the step and the easy breakdown of the step. Figure 7 ​​As shown, the difference between the embodiment and the embodiment one is that, in the embodiment, the third groove 213 comprises a first sub-groove and a second sub-groove, the first sub-groove is in the shape of a circular ring, the second sub-groove is in the shape of an elliptical fitting line between the inner ring surface of the first sub-groove and the two end points of the inner ring surface, the first end of the third groove 213 is equal in width to the first end of the second groove 212, at this time, the second groove 212 can be rectangular. In this way, the width of the connection between the third groove 213 and the second groove 212 is equal, avoiding the problem of step at the connection between the third groove 213 and the second groove 212, leading to the problem of easy breakdown due to electric field concentration at the step; at the same time, the shape of the second groove 212 also does not need to be changed (without modifying the rectangle into an inverted trapezoid).

[0078] In summary, in the Schottky diode and the groove structure thereof provided in the embodiment of the present application, the Schottky diode comprises a substrate, an epitaxial layer located on the front surface of the substrate, and a groove structure extending from the surface of the epitaxial layer into the epitaxial layer. The groove structure comprises a first region groove structure, a second region groove structure, and a third region groove structure, the first region groove structure, the second region groove structure, and the third region groove structure form a rounded rectangle on the epitaxial layer, and the first region groove structure, the second region groove structure, and the third region groove structure are cell region grooves. The first region groove structure comprises I first grooves that are parallel to and spaced from each other, the I first grooves are located in a middle region on the epitaxial layer, and I is a positive integer. The second region groove structure comprises J second grooves that are parallel to and spaced from each other, the J second grooves are located outside the I first grooves, the length of the first groove is longer than the length of the second groove, and J is a positive integer. The third region groove structure comprises J third grooves that are parallel to and spaced from each other, the J third grooves are located at four rounded corners of the rounded rectangle, the number of the third grooves is equal to that of the second grooves, the first end of the third groove is connected to the second groove, and the second end of the third groove is connected to the outermost first groove in the first groove structure. The Schottky diode in the present application has a smaller forward conduction voltage drop and a better surge current resistance.

[0079] It should be noted that the embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to each other. For the system disclosed in the embodiments, the description is relatively simple because it corresponds to the method disclosed in the embodiments. The relevant parts can be referred to the method part.

[0080] It should also be noted that, although the utility model has disclosed as above with preferred embodiments, the above embodiments are not used to limit the utility model. For any skilled person in the art, without departing from the scope of the utility model technical scheme, the above disclosed technical content can be used to make many possible changes and modifications to the utility model technical scheme, or modified as equivalent examples of equivalent changes. Therefore, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the utility model, which does not deviate from the content of the utility model technical scheme, still belongs to the scope of the utility model technical scheme protection.

[0081] It should also be understood that, unless specifically described or indicated, the terms "first", "second", "third" and the like in the specification are merely used to distinguish different components, elements, steps and the like in the specification, and not to indicate a logical relationship or sequence relationship between the components, elements, steps and the like.

[0082] In addition, it should be recognized that the terms described herein are used only to describe particular embodiments and not to limit the scope of the utility model. It must be noted that the singular forms "a", "an" and "the" used herein and in the appended claims include plural referents unless the context clearly dictates otherwise. For example, reference to "a step" or "a means" means reference to one or more steps or means and can include sub-steps and sub-means. All conjunctions used herein should be interpreted in the broadest possible manner. Also, the word "or" should be interpreted as having the logical definition of "or" rather than the logical definition of "exclusive or" unless the context clearly dictates otherwise. In addition, the implementation of the methods and / or the devices of the embodiments of the utility model can include performing selected tasks manually, automatically or a combination thereof.

Claims

1. A trench structure of a Schottky diode, characterized by, The application relates to a semiconductor device, comprising: a substrate; an epitaxial layer on the front side of the substrate; trench structures extending from the surface of the epitaxial layer into the epitaxial layer; the trench structures comprise first region trench structures, second region trench structures and third region trench structures, the first region trench structures, the second region trench structures and the third region trench structures form a rounded rectangle on the epitaxial layer, and the first region trench structures, the second region trench structures and the third region trench structures are cell region trenches; the first region trench structures comprise I first trenches parallel to and spaced from each other, the I first trenches are located in a middle region on the epitaxial layer, and I is a positive integer; the second region trench structures comprise J second trenches parallel to and spaced from each other, the J second trenches are located outside the I first trenches, the length of the first trenches is longer than the length of the second trenches, and J is a positive integer; the third region trench structures comprise J third trenches parallel to and spaced from each other, the J third trenches are located at four rounded corners of the rounded rectangle, the number of the third trenches is equal to that of the second trenches, the first ends of the third trenches are connected to the second trenches, and the second ends of the third trenches are connected to the outermost first trenches in the first trench structure.

2. The trench structure of a Schottky diode according to claim 1, wherein The projections of the first trenches and the second trenches are straight lines, and the projection of the third trench is an arc.

3. The trench structure of the Schottky diode according to claim 1, wherein The first trenches and the second trenches extend in a first direction and are arranged at intervals in a second direction, and the third trenches are arranged at intervals in a third direction, and the third trenches communicate with the first trenches and the second trenches; the first direction and the second direction are perpendicular to each other, and the third direction intersects the first direction and the second direction.

4. The trench structure of a Schottky diode according to claim 3, wherein The angle between the third direction and the first direction and the second direction is 45 degrees.

5. The trench structure of the Schottky diode according to claim 3, wherein In the third trenches and the second trenches connected to each other, the sum of the width of the second trench in the second direction and the interval between adjacent two second trenches is equal to the sum of the width of the third trench in the third direction and the interval between adjacent two third trenches.

6. The trench structure of a Schottky diode according to claim 3, wherein The widths of the first trenches and the second trenches in the second direction are equal, and the first trenches and the second trenches are arranged at equal intervals in the second direction.

7. The trench structure of a Schottky diode according to claim 3, wherein The widths of the third trenches in the third direction are equal, and the third trenches are arranged at equal intervals in the third direction.

8. The trench structure of a Schottky diode according to claim 3, wherein The width of the third trench in the third direction is greater than the width of the first trench and the second trench in the second direction.

9. The trench structure of a Schottky diode according to claim 8, wherein The width of the third trench in the third direction is greater than or equal to 1.02 times the width of the first trench and the second trench in the second direction.

10. The trench structure of a Schottky diode according to claim 3, wherein The trench structure further comprises a terminal trench structure, the terminal trench structure is a round rectangular trench, the terminal trench structure comprises a first part, a second part and a third part, the first part connects two ends of the first trench, the second part is parallel to the second trench and is spaced from the outermost second trench in the second trench structure, and the third part is a circular arc connecting the first part and the second part.

11. The trench structure of a Schottky diode according to claim 10, wherein The width of each terminal trench of the terminal trench structure is greater than the width of the first trench, the second trench and the third trench.

12. The trench structure of a Schottky diode according to claim 3, wherein The width of the first trench and the second trench in the second direction is 0.12um-5um, and the distance between adjacent first trenches and the distance between adjacent second trenches is 0.33um-11um.

13. The trench structure of a Schottky diode according to claim 8, wherein The width of the second trench in the first direction gradually changes.

14. The trench structure of a Schottky diode according to claim 13, wherein The third trench is a circular ring, and the width of the first end of the third trench connected with the second trench is equal.

15. The trench structure of a Schottky diode according to claim 8, wherein The third trench comprises a first sub-trench and a second sub-trench, the shape of the first sub-trench is a circular ring, and the shape of the second sub-trench is a figure formed by an elliptical fitting line between the inner ring surface and the two end points of the inner ring surface.

16. A Schottky diode, characterized by The trench structure comprises the trench structure according to any one of claims 1-15.

17. The Schottky diode as claimed in claim 16, characterized in that, Further comprising: An insulating dielectric layer on the inner wall of the trench structure; A gate conductive layer on the insulating dielectric layer and filling the trench structure; A Schottky barrier layer covering the epitaxial layer without the trench structure, the insulating dielectric layer on the epitaxial surface part, the gate conductive layer on the epitaxial surface part, part of the gate conductive layer and part of the insulating dielectric layer in the terminal area are not covered by the Schottky barrier layer; A terminal metal layer covering the insulating dielectric layer in the terminal area not covered by the Schottky barrier layer; An oxide layer covering the surface and sidewall of the terminal metal layer; An anode electrode covering the Schottky barrier layer and part of the terminal metal layer; A cathode electrode on the back surface of the substrate.

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