Silicon carbide floating junction structure with improved switching characteristics along the P-channel of the inclined terminal

Abstract

This invention provides a silicon carbide floating junction structure with improved switching characteristics along a sloped-terminated P-channel, relating to the field of semiconductor power device technology. It includes an N-type drift region formed on an N-type substrate; multiple first P-type floating junctions, multiple second P-type floating junctions, and multiple P-type doped regions, all formed in the middle region of the N-type drift region and spaced apart, respectively positioned vertically opposite each other; a first P-type floating junction transition region formed within the N-type drift region and surrounding the multiple first P-type floating junctions; a second P-type floating junction transition region formed within the N-type drift region and surrounding the multiple second P-type floating junctions; a P-type transition region formed within the N-type drift region and surrounding the multiple P-type doped regions; and a sloped-terminated P-channel formed on the slopes at both ends of the N-type drift region, the slopes at both ends of the first P-type floating junction transition region, the slopes at both ends of the second P-type floating junction transition region, and both ends of the P-type transition region. This results in better switching characteristics, lower process costs, and lower time costs.

Description

Technical Field

[0001] This invention relates to the field of semiconductor power device technology, and more particularly to a silicon carbide floating junction structure with improved switching characteristics along a sloped terminal P-channel. Background Technology

[0002] In recent years, energy conservation, emission reduction, and low-carbon development have become the mainstream development model. Semiconductor power devices are a crucial link in the energy generation-storage-distribution cycle, and are essential for energy conservation, emission reduction, and low-carbon development. Among them, silicon carbide (SiC) power semiconductor devices, due to their high-voltage blocking capability, high-frequency switching characteristics, and high-temperature operation, are expected to become the next generation of mainstream high-power devices and have gained widespread favor from researchers. Commercial SiC devices have already emerged, and these are ideal alternatives to silicon power devices. However, due to the properties of SiC materials, some mature silicon power devices cannot be commercially manufactured using SiC. To enable commercial use of SiC for silicon power devices, it is necessary to combine floating junction technology with SiC, leveraging their respective advantages to break the one-dimensional limitations of SiC unipolar devices.

[0003] Currently, power devices that break the one-dimensional limit of silicon carbide typically use silicon carbide floating junction Schottky diodes (JBS diodes). However, because the floating junction of a silicon carbide floating junction JBS diode expands significantly into the drift region under reverse voltage, when the bias voltage changes from reverse to forward, the depletion region of the floating junction, which has expanded under reverse bias, lacks a channel, making it difficult for minority carriers to be quickly extracted and depleted. This significantly affects the switching characteristics of the silicon carbide floating junction JBS diode. Furthermore, the use of field-limiting ring termination in silicon carbide floating junction JBS diodes results in a high number of ion implantation cycles, leading to higher process and time costs. Summary of the Invention

[0004] The purpose of this invention is to provide a silicon carbide floating junction structure with improved switching characteristics along the P-channel at the sloping end, which solves the problem that the switching characteristics of silicon carbide floating junction JBS diodes are greatly affected by the difficulty in quickly removing and depleting minority carriers, as well as the problem of high process and time costs.

[0005] To address the aforementioned technical problems, the embodiments of the present invention provide the following technical solutions:

[0006] The first aspect of this invention provides a silicon carbide floating junction structure with improved switching characteristics along the terminal P-channel of a slope, comprising:

[0007] N-type substrate;

[0008] The N-type drift region is formed on an N-type substrate and both ends of the N-type drift region are bevels;

[0009] Multiple first P-type floating knots are formed in the middle region of the N-type drift region and are arranged at intervals;

[0010] The first P-type floating knot transition area is formed within the N-type drift area and surrounds multiple first P-type floating knots. Both ends of the first P-type floating knot transition area are slopes.

[0011] Multiple second P-type floating knots are formed in the middle region of the N-type drift region and are arranged at intervals, and the multiple second P-type floating knots are arranged vertically opposite to the multiple first P-type floating knots;

[0012] The second P-type floating knot transition area is formed inside the N-type drift area and surrounds multiple second P-type floating knots. Both ends of the second P-type floating knot transition area are sloped.

[0013] Multiple P-type doped regions are formed in the middle region of the N-type drift region and are arranged at intervals. The multiple P-type doped regions and multiple second P-type floating junctions are arranged vertically opposite each other. The upper surface of the multiple P-type doped regions and the upper surface of the N-type drift region are on the same horizontal plane.

[0014] The P-type transition region is formed inside the N-type drift region and surrounds multiple P-type doped regions;

[0015] The inclined terminal P-channel is formed on the inclined surfaces at both ends of the N-type drift region, the inclined surfaces at both ends of the first P-type floating junction transition region, the inclined surfaces at both ends of the second P-type floating junction transition region, and both ends of the P-type transition region.

[0016] In some modified embodiments of the first aspect of the invention, the silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P channel further includes an ohmic contact metal and a Schottky contact metal.

[0017] Ohmic contact metal is formed on the lower surface of the N-type substrate;

[0018] Schottky contact metals are formed on N-type drift regions, multiple P-type doped regions, and part of the P-type transition region.

[0019] In some modified embodiments of the first aspect of the present invention, the implanted ions in the sloped terminal P-channel are Al, the implantation energy ranges from 10 KeV to 1000 KeV, and the doping concentration ranges from 1e15 to 1e18 cm⁻¹. -3 .

[0020] In some modified embodiments of the first aspect of the present invention, the inclination angles of the inclined surfaces at both ends of the N-type drift region, the inclined surfaces at both ends of the first P-type floating junction transition region, and the inclined surfaces at both ends of the second P-type floating junction transition region are all 30°.

[0021] In some modified embodiments of the first aspect of the present invention, the upper surface of the transition region of the first P-type floating junction is at the same horizontal plane as the upper surfaces of the plurality of first P-type floating junctions, and the thickness of the transition region of the first P-type floating junction is the same as the thickness of the plurality of first P-type floating junctions.

[0022] In some modified embodiments of the first aspect of the present invention, the upper surface of the transition region of the second P-type floating junction is at the same horizontal plane as the upper surface of the plurality of second P-type floating junctions, and the thickness of the transition region of the second P-type floating junction is the same as the thickness of the plurality of second P-type floating junctions.

[0023] In some modified embodiments of the first aspect of the invention, the thickness of the plurality of first P-type floating junctions is the same as the thickness of the plurality of second P-type floating junctions.

[0024] In some modified embodiments of the first aspect of the present invention, the N-type substrate includes a first N-type substrate and a second N-type substrate, the second N-type substrate being formed on the first N-type substrate, the first N-type substrate being rectangular in shape, and the second N-type substrate being trapezoidal in shape.

[0025] A second aspect of the present invention provides a method for preparing a silicon carbide floating junction structure with improved switching characteristics along a sloped terminal P-channel, comprising:

[0026] An N-type substrate is selected, and the material of the N-type substrate is silicon carbide;

[0027] A first N-type drift region is grown on the surface of an N-type substrate;

[0028] Ion implantation is performed on the surface of the first N-type drift region to form multiple first P-type floating junctions and a first P-type floating junction transition region, so that the multiple first P-type floating junctions are arranged at intervals and the first P-type floating junction transition region surrounds the multiple first P-type floating junctions.

[0029] On the surface of multiple first P-type floating junctions, first P-type floating junction transition regions, and first N-type drift regions, a second N-type drift region is grown;

[0030] Ion implantation is performed on the surface of the second N-type drift region to form multiple second P-type floating junctions and a transition region between the second P-type floating junctions, so that the multiple second P-type floating junctions are arranged at intervals and the transition region between the second P-type floating junctions surrounds the multiple second P-type floating junctions.

[0031] A third N-type drift region is grown on the surface of multiple second P-type floating junctions, the transition region of the second P-type floating junction, and the second N-type drift region;

[0032] Ion implantation is performed on the surface of the third N-type drift region to form multiple P-type doped regions and P-type transition regions, so that the multiple P-type doped regions are arranged at intervals and the P-type transition regions surround multiple second P-type floating junctions.

[0033] SiO2 layers are deposited on the surface of multiple P-type doped regions, P-type transition regions and the third N-type drift region;

[0034] A photoresist etching mask is formed on the upper surface of the SiO2 layer, and the SiO2 layer is etched so that the two ends of the SiO2 layer are beveled to form an etching mask of SiO2.

[0035] Using a SiO2 etching mask as a mask, etching is performed from the third N-type drift region into the N-type substrate to form a beveled sidewall;

[0036] Ion implantation is performed on the angled sidewalls to form a sloped terminal P-channel;

[0037] Ni metal is deposited on the bottom of an N-type substrate by magnetron sputtering or electron beam evaporation, and then rapidly thermally annealed to form ohmic contact metal.

[0038] Metals are deposited on the surfaces of multiple P-type doped regions, P-type transition regions, and a third N-type drift region, and Schottky contact metals are obtained by passivation, patterning, and selective etching.

[0039] Compared to existing technologies, the present invention provides a silicon carbide floating junction structure with improved switching characteristics along a sloped terminal P-channel, comprising an N-type substrate; an N-type drift region formed on the N-type substrate with both ends of the N-type drift region being sloped; a plurality of first P-type floating junctions formed in the middle region of the N-type drift region and arranged at intervals; a first P-type floating junction transition region formed within the N-type drift region and surrounding the plurality of first P-type floating junctions, with both ends of the first P-type floating junction transition region being sloped; a plurality of second P-type floating junctions formed in the middle region of the N-type drift region and arranged at intervals, with the plurality of second P-type floating junctions and the plurality of first P-type floating junctions arranged vertically opposite each other; the second P-type floating junctions... A transition region is formed inside the N-type drift region and surrounds multiple second P-type floating junctions. Both ends of the transition region of the second P-type floating junctions are sloped. Multiple P-type doped regions are formed in the middle region of the N-type drift region and are arranged at intervals. The multiple P-type doped regions and the multiple second P-type floating junctions are arranged vertically opposite each other. The upper surface of the multiple P-type doped regions is at the same horizontal plane as the upper surface of the N-type drift region. A P-type transition region is formed inside the N-type drift region and surrounds multiple P-type doped regions. A sloped terminal P-channel is formed on the slopes at both ends of the N-type drift region, the slopes at both ends of the first P-type floating junction transition region, the slopes at both ends of the second P-type floating junction transition region, and both ends of the P-type transition region. In this way, inclined terminal P-channels can be formed on the inclined surfaces at both ends of the N-type drift region, the inclined surfaces at both ends of the first P-type floating junction transition region, the inclined surfaces at both ends of the second P-type floating junction transition region, and both ends of the P-type transition region. The inclined terminal P-channels accelerate the extraction speed of minority carriers, reduce the depletion region disappearance time, and reduce the overcharge voltage. This results in better switching characteristics of the silicon carbide floating junction structure along the inclined terminal P-channels, leading to faster turn-on speed after turn-off. The inclined terminal P-channels are formed on inclined surfaces. Compared with field-limiting ring terminals, the introduction of inclined terminals greatly reduces the number of ion implantation steps and the process difficulty, resulting in lower process costs and lower time costs. Attached Figure Description

[0040] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, with the same or corresponding reference numerals denoteing the same or corresponding parts, wherein:

[0041] Figure 1 A schematic diagram of a silicon carbide floating junction structure with improved switching characteristics along the P-channel at the inclined terminal is shown.

[0042] Figure 2 A schematic top view of a silicon carbide floating junction structure with improved switching characteristics along a sloped terminal P-channel without deposited Schottky contact metal is shown.

[0043] Figure 3 A schematic top view of a silicon carbide floating junction structure with improved switching characteristics along the sloped terminal P-channel, shown along the dashed line;

[0044] Figure 4 A flowchart illustrating the fabrication method of a silicon carbide floating junction structure with improved switching characteristics along the P-channel of the inclined surface is shown.

[0045] Explanation of reference numerals in the attached figures:

[0046] 1. N-type substrate; 101. First N-type substrate; 102. Second N-type substrate; 2. N-type drift region; 3. Multiple first P-type floating junctions; 4. First P-type floating junction transition region; 5. Multiple second P-type floating junctions; 6. Second P-type floating junction transition region; 7. Multiple P-type doped regions; 8. P-type transition region; 9. Sloping terminal P-channel; 10. Ohmic contact metal; 11. Schottky contact metal. Detailed Implementation

[0047] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention. The present invention can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0048] The following is a detailed description of a silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P channel 9 in an embodiment of the present invention.

[0049] See Figure 1 As shown, Figure 1 A schematic diagram of a silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel 9 is shown. This embodiment of the invention proposes a structural diagram of a silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel 9, including:

[0050] N-type substrate 1;

[0051] N-type drift region 2 is formed on N-type substrate 1 and both ends of N-type drift region 2 are bevels;

[0052] Multiple first P-type floating knots 3 are formed in the middle region of the N-type drift region 2 and are arranged at intervals;

[0053] The first P-type floating knot transition region 4 is formed within the N-type drift region 2 and surrounds multiple first P-type floating knots 3. Both ends of the first P-type floating knot transition region 4 are inclined surfaces.

[0054] Multiple second P-type floating knots 5 are formed in the middle region of the N-type drift region 2 and are arranged at intervals, and the multiple second P-type floating knots 5 are arranged vertically opposite to the multiple first P-type floating knots 3;

[0055] The second P-type floating knot transition region 6 is formed inside the N-type drift region 2 and surrounds multiple second P-type floating knots 5. Both ends of the second P-type floating knot transition region 6 are inclined surfaces.

[0056] Multiple P-type doped regions 7 are formed in the middle region of the N-type drift region 2 and are arranged at intervals. The multiple P-type doped regions 7 and multiple second P-type floating junctions 5 are arranged vertically opposite each other. The upper surface of the multiple P-type doped regions 7 and the upper surface of the N-type drift region 2 are on the same horizontal plane.

[0057] P-type transition region 8 is formed inside N-type drift region 2 and surrounds multiple P-type doped regions 7;

[0058] The inclined terminal P channel 9 is formed on the inclined surfaces at both ends of the N-type drift region 2, the inclined surfaces at both ends of the first P-type floating junction transition region 4, the inclined surfaces at both ends of the second P-type floating junction transition region 6, and the two ends of the P-type transition region 8.

[0059] Specifically, the N-type substrate 1 is a silicon carbide substrate. The reasons for choosing a silicon carbide substrate are as follows: First, silicon carbide substrates have mature production technology and good device quality; second, silicon carbide has high thermal conductivity and good stability, and can be used in high-temperature growth processes; finally, silicon carbide has excellent physicochemical properties, which can realize high-performance, high-power power electronic devices.

[0060] Inside the N-type drift region 2, multiple second P-type floating junctions 5 are arranged relative to each other at a certain distance above multiple first P-type floating junctions 3, and multiple P-type doped regions 7 are arranged relative to each other at a certain distance above multiple second P-type floating junctions 5.

[0061] The implanted ions in the multiple first P-type floating junctions 3, the first P-type floating junction transition region 4, the multiple second P-type floating junctions 5, the second P-type floating junction transition region 6, the multiple P-type doped regions 7, and the P-type transition region 8 are all Al.

[0062] Multiple first P-type floating junctions 3 can be arranged at equal intervals or at unequal intervals; multiple second P-type floating junctions 5 can be arranged at equal intervals or at unequal intervals; and multiple P-type doped regions 7 can be arranged at equal intervals or at unequal intervals.

[0063] In this invention, the thickness of the N-type drift region 2 is increased due to the inclusion of two layers of P-type floating junctions and a two-layer P-type floating junction transition region, resulting in higher withstand voltage. The inclusion of two layers of P-type floating junctions and a two-layer P-type floating junction transition region also increases the depletion region under reverse bias, thereby enhancing withstand voltage.

[0064] In this embodiment, the silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P channel 9 also includes an ohmic contact metal 10 and a Schottky contact metal 11.

[0065] Ohmic contact metal 10 is formed on the lower surface of N-type substrate 1;

[0066] Schottky contact metal 11 is formed on N-type drift region 2, multiple P-type doped regions 7 and part of P-type transition region 8.

[0067] Specifically, the ohmic contact metal 10 can be Ni metal, and the Schottky contact metal 11 can be Al, or Al doped with Si or Cu, or Ag or Cu. There are no specific limitations on the Schottky contact metal 11.

[0068] In this embodiment, the implanted ions in the sloped terminal P-channel 9 are Al, the implantation energy ranges from 10 KeV to 1000 KeV, and the doping concentration ranges from 1e15 to 1e18 cm⁻¹. -3 .

[0069] In this embodiment, the inclination angles of the inclined surfaces at both ends of the N-type drift region 2, the inclined surfaces at both ends of the first P-type floating junction transition region 4, and the inclined surfaces at both ends of the second P-type floating junction transition region 6 are all 30°.

[0070] Specifically, the inclination angle of the inclined surfaces at both ends of the N-type drift region 2 is the angle between the inclined surfaces at both ends of the N-type drift region 2 and the upper surface of the N-type substrate 1, and this angle is 30°.

[0071] The inclination angles of the slopes at both ends of the N-type drift region 2, the slopes at both ends of the first P-type floating junction transition region 4, and the slopes at both ends of the second P-type floating junction transition region 6 are all set to 30°, which makes the electric field at the edge of the slope smaller, the terminal withstand voltage better, and the terminal efficiency higher.

[0072] In this embodiment, the upper surface of the first P-type floating junction transition region 4 is at the same horizontal plane as the upper surfaces of the plurality of first P-type floating junctions 3, and the thickness of the first P-type floating junction transition region 4 is the same as the thickness of the plurality of first P-type floating junctions 3.

[0073] In this embodiment, the upper surface of the second P-type floating junction transition region 6 is at the same horizontal plane as the upper surfaces of the plurality of second P-type floating junctions 5, and the thickness of the second P-type floating junction transition region 6 is the same as the thickness of the plurality of second P-type floating junctions 5.

[0074] The upper surfaces of the multiple P-type doped regions 7 are at the same level as the upper surface of the N-type drift region 2, and the thickness of the multiple P-type doped regions 7 is greater than the thickness of the P-type transition region 8.

[0075] In this embodiment, the thickness of the plurality of first P-type floating junctions 3 and the thickness of the plurality of second P-type floating junctions 5 are the same.

[0076] Correspondingly, the thickness of the first P-type floating junction transition region 4 is the same as the thickness of the second P-type floating junction transition region 6.

[0077] In this embodiment, the N-type substrate 1 includes a first N-type substrate 101 and a second N-type substrate 102. The second N-type substrate 102 is formed on the first N-type substrate 101. The first N-type substrate 101 is rectangular in shape, and the second N-type substrate 102 is trapezoidal in shape.

[0078] Specifically, the trapezoid can be an isosceles trapezoid with an interior angle of 30°.

[0079] The silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel 9 of the present invention solves the problem of turn-on speed when turning on again after turn-off, making it possible to realize high-frequency and high-voltage silicon carbide floating junction diodes, which can greatly broaden the application range of silicon carbide floating junction devices in the field of future power semiconductor devices.

[0080] Figure 2 A schematic top view of a silicon carbide floating junction structure with improved switching characteristics along the beveled terminal P-channel 9 of the undeposited Schottky contact metal 11 is shown. See [link to relevant documentation]. Figure 2 As shown, the multiple P-type doped regions 7 arranged at intervals in the middle region are the source regions, the rounded rectangular rings surrounding the multiple P-type doped regions 7 are the P-type transition regions 8, the rounded rectangular rings surrounding the P-type transition regions 8 are the sloped terminal P-channels 9, the rounded rectangular rings surrounding the sloped terminal P-channels 9 are the N-type substrates 1, and the N-type substrates 1 and the sloped terminal P-channels 9 are sloped terminals.

[0081] Figure 3 A schematic cross-sectional top view of a silicon carbide floating junction structure with improved switching characteristics along the sloped terminal P-channel 9, shown along the dashed line, is illustrated. See also: Figure 3 As shown, the dashed line passes horizontally through multiple second P-type floating knots 5, a second P-type floating knot transition zone 6, and a sloped terminal P-channel 9. Multiple second P-type floating knots 5 are arranged at intervals in the middle region. The rounded rectangular rings surrounding the multiple second P-type floating knots 5 are the second P-type floating knot transition zones 6, and the rounded rectangular rings surrounding the second P-type floating knot transition zones 6 are the sloped terminal P-channels 9.

[0082] Based on the above Figure 1As can be seen from the implementation method, the silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel 9 of this embodiment includes an N-type substrate 1; an N-type drift region 2 formed on the N-type substrate 1, with both ends of the N-type drift region 2 being inclined surfaces; a plurality of first P-type floating junctions 3 formed in the middle region of the N-type drift region 2 and arranged at intervals; a first P-type floating junction transition region 4 formed within the N-type drift region 2 and surrounding the plurality of first P-type floating junctions 3, with both ends of the first P-type floating junction transition region 4 being inclined surfaces; a plurality of second P-type floating junctions 5 formed in the middle region of the N-type drift region 2 and arranged at intervals, with the plurality of second P-type floating junctions 5 and the plurality of first P-type floating junctions 3 arranged vertically opposite each other; the second P-type floating junction transition region 5... Transition region 6 is formed inside N-type drift region 2 and surrounds multiple second P-type floating junctions 5. Both ends of the second P-type floating junction transition region 6 are sloped. Multiple P-type doped regions 7 are formed in the middle region of N-type drift region 2 and are arranged at intervals. The multiple P-type doped regions 7 and multiple second P-type floating junctions 5 are arranged vertically opposite each other. The upper surface of the multiple P-type doped regions 7 is at the same horizontal plane as the upper surface of N-type drift region 2. P-type transition region 8 is formed inside N-type drift region 2 and surrounds multiple P-type doped regions 7. Sloping terminal P-channel 9 is formed on the slopes at both ends of N-type drift region 2, the slopes at both ends of first P-type floating junction transition region 4, the slopes at both ends of second P-type floating junction transition region 6, and both ends of P-type transition region 8. In this way, inclined terminal P-channels 9 can be formed on the inclined surfaces at both ends of the N-type drift region 2, the inclined surfaces at both ends of the first P-type floating junction transition region 4, the inclined surfaces at both ends of the second P-type floating junction transition region 6, and both ends of the P-type transition region 8. The inclined terminal P-channels 9 accelerate the extraction speed of minority carriers, reduce the depletion region disappearance time, and reduce the overcharge voltage. This results in better switching characteristics of the silicon carbide floating junction structure along the inclined terminal P-channels 9, which improves the switching characteristics and makes the turn-on speed faster after being turned off. The inclined terminal P-channels 9 are formed on the inclined surfaces. Compared with field-limiting ring terminals, the introduction of inclined terminals greatly reduces the number of ion implantation times and the process difficulty, resulting in lower process costs and lower time costs.

[0083] Figure 4 A schematic flowchart illustrating the fabrication method of a silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel 9 is shown below. Figure 4 As shown, the method for fabricating a silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel 9 may include:

[0084] S401, Select N-type substrate 1.

[0085] The material of the N-type substrate 1 is silicon carbide.

[0086] Specifically, silicon carbide is chosen as the material for N-type substrate 1 because its production technology is mature, its device quality is good, its thermal conductivity is high, its stability is very good, it can be used in high-temperature growth processes, and its physical and chemical properties are excellent, enabling the realization of high-performance, high-power power electronic devices.

[0087] S402. A first N-type drift region is grown on the surface of the N-type substrate 1.

[0088] N-type drift zone 2 includes a first N-type drift zone, a second N-type drift zone, and a third N-type drift zone.

[0089] Specifically, the N-type substrate 1 is an N+ substrate. On the surface of the N+ substrate, the first N-type drift region is grown by chemical vapor deposition (CVD) at a growth temperature of 1600℃-1900℃.

[0090] S403. Ion implantation is performed on the surface of the first N-type drift region to form a plurality of first P-type floating junctions 3 and a first P-type floating junction transition region 4, so that the plurality of first P-type floating junctions 3 are arranged at intervals and the first P-type floating junction transition region 4 surrounds the plurality of first P-type floating junctions 3.

[0091] The implanted ions in the multiple first P-type floating junctions 3 and the first P-type floating junction transition region 4 are all Al.

[0092] S404. A second N-type drift region is grown on the surface of multiple first P-type floating junctions 3, first P-type floating junction transition regions 4 and first N-type drift regions.

[0093] Specifically, a second N-type drift region is grown on the surface of multiple first P-type floating junctions 3, first P-type floating junction transition regions 4, and first N-type drift regions using a CVD method at a growth temperature of 1600℃-1900℃.

[0094] S405, Ion implantation is performed on the surface of the second N-type drift region to form multiple second P-type floating junctions 5 and second P-type floating junction transition regions 6, so that the multiple second P-type floating junctions 5 are arranged at intervals and the second P-type floating junction transition regions 6 surround the multiple second P-type floating junctions 5.

[0095] Specifically, the implanted ions in the multiple second P-type floating junctions 5 and the transition region 6 of the second P-type floating junction are all Al.

[0096] S406. On the surfaces of multiple second P-type floating junctions 5, second P-type floating junction transition regions 6, and second N-type drift regions, a third N-type drift region is grown.

[0097] Specifically, a third N-type drift region is grown on the surfaces of multiple second P-type floating junctions 5, second P-type floating junction transition regions 6, and second N-type drift regions using a CVD method at a growth temperature of 1600℃-1900℃.

[0098] S407. Ion implantation is performed on the surface of the third N-type drift region to form multiple P-type doped regions 7 and P-type transition regions 8, so that the multiple P-type doped regions 7 are arranged at intervals and the P-type transition regions 8 surround multiple second P-type floating junctions 5.

[0099] The implanted ions in multiple P-type doped regions 7 and P-type transition regions 8 are all Al.

[0100] The active region of the silicon carbide floating junction diode is formed through steps S402-S407.

[0101] S408, SiO2 layers are deposited on the surfaces of multiple P-type doped regions 7, P-type transition regions 8 and the third N-type drift region.

[0102] S409. A photoresist etching mask is formed on the upper surface of the SiO2 layer, and the SiO2 layer is etched so that the two ends of the SiO2 layer are inclined surfaces to form an etching mask of SiO2.

[0103] The two ends of the SiO2 layer are steep.

[0104] S410. Using the SiO2 etching mask as a mask, etch from the third N-type drift region 2 into the N-type substrate 1 to form a beveled sidewall.

[0105] Specifically, dry etching is used to sequentially etch the third N-type drift region, the second P-type floating junction transition region 6, the second N-type drift region, the first P-type floating junction transition region 4, and the first N-type drift region until the N-type substrate 1 is etched in, and then etching is stopped to form a beveled sidewall.

[0106] After the above etching, both ends of the third N-type drift region, both ends of the second P-type floating junction transition region 6, both ends of the second N-type drift region, both ends of the first P-type floating junction transition region 4, both ends of the first N-type drift region, and part of the ends of the N-type substrate 1 are all inclined surfaces.

[0107] The angle θ between the beveled sidewall and the upper surface of the N-type substrate 1 is 30°.

[0108] S411. Ion implantation is performed on the angled sidewall to form the inclined terminal P-channel 9.

[0109] Specifically, the implanted ions in the sloped terminal P-channel 9 are Al, with an implantation energy range of 10 KeV-1000 KeV and a doping concentration range of 1e15-1e18 cm⁻¹. -3 .

[0110] S412. Ni metal is deposited on the bottom of the N-type substrate 1 by magnetron sputtering or electron beam evaporation, and then rapid thermal annealing is performed to form ohmic contact metal 10.

[0111] Ohmic contact metal 10 is the cathode metal layer.

[0112] S413. Metal is deposited on the surface of multiple P-type doped regions 7, P-type transition regions 8 and the third N-type drift region, and Schottky contact metal 11 is obtained by passivation medium, patterning and selective etching.

[0113] Specifically, an anode metal layer is prepared on the surface of multiple P-type doped regions 7, P-type transition regions 8 and a third N-type drift region. The metal is deposited by a deposition method to form the desired anode metal, wherein the anode metal can be Al, or Al doped with Si or Cu, or Ag or Cu. Schottky contact metal 117 is obtained by passivating the medium, patterning and selective etching.

[0114] While specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of the invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any manner.

[0115] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A silicon carbide floating junction structure with improved switching characteristics along the terminal P-channel of an inclined plane, characterized in that, The silicon carbide floating junction structure with improved switching characteristics along the sloped terminal P-channel includes: N-type substrate; An N-type drift region is formed on the N-type substrate, and both ends of the N-type drift region are bevels; Multiple first P-type floating junctions are formed in the middle region of the N-type drift region and are arranged at intervals; The first P-type floating junction transition region is formed within the N-type drift region and surrounds the plurality of first P-type floating junctions, and both ends of the first P-type floating junction transition region are inclined surfaces. Multiple second P-type floating junctions are formed in the middle region of the N-type drift region and arranged at intervals, and the multiple second P-type floating junctions are arranged vertically opposite to the multiple first P-type floating junctions; The second P-type floating junction transition region is formed inside the N-type drift region and surrounds the plurality of second P-type floating junctions. Both ends of the second P-type floating junction transition region are sloped surfaces. Multiple P-type doped regions are formed in the middle region of the N-type drift region and arranged at intervals. The multiple P-type doped regions and the multiple second P-type floating junctions are arranged vertically opposite each other. The upper surface of the multiple P-type doped regions and the upper surface of the N-type drift region are at the same horizontal plane. A P-type transition region is formed inside the N-type drift region and surrounds the plurality of P-type doped regions; The inclined terminal P-channel is formed on the inclined surfaces at both ends of the N-type drift region, the inclined surfaces at both ends of the first P-type floating junction transition region, the inclined surfaces at both ends of the second P-type floating junction transition region, and both ends of the P-type transition region.

2. The silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel according to claim 1, characterized in that, The silicon carbide floating junction structure for improving switching characteristics along the inclined terminal P-channel also includes ohmic contact metal and Schottky contact metal. The ohmic contact metal is formed on the lower surface of the N-type substrate; The Schottky contact metal is formed on the N-type drift region, the plurality of P-type doped regions, and a portion of the P-type transition region.

3. The silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel according to claim 1, characterized in that, The implanted ions in the sloped terminal P-channel are Al, with an implantation energy range of 10 KeV-1000 KeV and a doping concentration range of 1e15-1e18 cm⁻¹. -3 .

4. The silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel according to claim 1, characterized in that, The inclination angles of the slopes at both ends of the N-type drift region, the slopes at both ends of the first P-type floating junction transition region, and the slopes at both ends of the second P-type floating junction transition region are all 30°.

5. The silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel according to claim 1, characterized in that, The upper surface of the first P-type floating junction transition region is at the same horizontal plane as the upper surfaces of the plurality of first P-type floating junctions, and the thickness of the first P-type floating junction transition region is the same as the thickness of the plurality of first P-type floating junctions.

6. The silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel according to claim 1, characterized in that, The upper surface of the transition region of the second P-type floating junction is at the same horizontal plane as the upper surface of the plurality of second P-type floating junctions, and the thickness of the transition region of the second P-type floating junction is the same as the thickness of the plurality of second P-type floating junctions.

7. The silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel according to claim 1, characterized in that, The thickness of the plurality of first P-type floating junctions is the same as the thickness of the plurality of second P-type floating junctions.

8. The silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel according to claim 1, characterized in that, The N-type substrate includes a first N-type substrate and a second N-type substrate, the second N-type substrate being formed on the first N-type substrate, the first N-type substrate being rectangular in shape, and the second N-type substrate being trapezoidal in shape.

9. A method for preparing a silicon carbide floating junction structure with improved switching characteristics along the terminal P-channel of an inclined plane, characterized in that, The silicon carbide floating junction structure for improved switching characteristics along the sloped terminal P-channel as described in any one of claims 1-8 comprises: An N-type substrate is selected, and the material of the N-type substrate is silicon carbide; A first N-type drift region is grown on the surface of the N-type substrate; Ion implantation is performed on the surface of the first N-type drift region to form a plurality of first P-type floating junctions and a first P-type floating junction transition region, such that the plurality of first P-type floating junctions are arranged at intervals and the first P-type floating junction transition region surrounds the plurality of first P-type floating junctions; On the surfaces of the plurality of first P-type floating junctions, the first P-type floating junction transition region and the first N-type drift region, a second N-type drift region is grown; Ion implantation is performed on the surface of the second N-type drift region to form a plurality of second P-type floating junctions and a transition region between the second P-type floating junctions, such that the plurality of second P-type floating junctions are arranged at intervals and the transition region between the second P-type floating junctions surrounds the plurality of second P-type floating junctions; A third N-type drift region is grown on the surface of the plurality of second P-type floating junctions, the transition region of the second P-type floating junctions, and the second N-type drift region; Ion implantation is performed on the surface of the third N-type drift region to form multiple P-type doped regions and P-type transition regions, such that the multiple P-type doped regions are spaced apart and the P-type transition regions surround the multiple second P-type floating junctions; SiO2 layers are deposited on the surfaces of the plurality of P-type doped regions, the P-type transition regions, and the third N-type drift region; A photoresist etching mask is formed on the upper surface of the SiO2 layer, and the SiO2 layer is etched so that the two ends of the SiO2 layer are beveled to form the etching mask of SiO2; Using the SiO2 etching mask as a mask, etching is performed from the third N-type drift region into the N-type substrate to form a beveled sidewall; Ion implantation is performed on the angled sidewalls to form a sloped terminal P-channel; Ni metal is deposited on the bottom of the N-type substrate by magnetron sputtering or electron beam evaporation, and then rapidly thermally annealed to form ohmic contact metal. Metal is deposited on the surfaces of the plurality of P-type doped regions, the P-type transition region and the third N-type drift region, and Schottky contact metal is obtained by passivation medium, patterning and selective etching.

10. The method for preparing a silicon carbide floating junction structure with improved switching characteristics along the inclined terminal P-channel according to claim 9, characterized in that, The implanted ions in the sloped terminal P-channel are Al, with an implantation energy range of 10 KeV-1000 KeV and a doping concentration range of 1e15-1e18 cm⁻¹. -3 .

Images