SiC-based current aperture vertical epitaxial structure, preparation method thereof and power device

Abstract

The invention relates to a SiC-based current aperture vertical epitaxial structure, a preparation method thereof and a power device, in particular to the field of semiconductor power devices, and the SiC-based current aperture vertical epitaxial structure comprises a buffer layer, a drift layer, a conduction aperture layer, a 4H-SiC channel layer and a 3C-SiC layer which are sequentially arranged on a substrate. According to the current aperture vertical epitaxial structure provided by the invention, the voltage withstanding performance of the current aperture vertical epitaxial structure is improved on the premise that the current aperture vertical epitaxial structure has good conduction performance through matching of a specifically designed structure and a silicon carbide material; the defect that the GaN-based current aperture vertical epitaxial structure is easy to generate avalanche breakdown when the device works in a high-voltage state under an electric field concentration effect is avoided.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor power devices, and in particular to a SiC-based current aperture vertical epitaxial structure and a preparation method thereof, and a power device. Background Art

[0002] At present, GaN CAVET devices can be used in inverters or switching power supplies in power electronic systems to achieve low switching losses and high voltage resistance, thereby improving power conversion efficiency.

[0003] For example, CN117995882A discloses an ultra-high withstand voltage diamond CAVET device and a preparation method thereof, which relates to the technical field of diamond vertical power devices, including a drain metal, wherein the drain metal is located at the bottom of the device, an n-type diamond substrate is arranged above the drain metal, an n-type drift layer is arranged above the n-type diamond substrate, a current blocking region is arranged above the n-type drift layer, an n+ conductive region is arranged above the current blocking region, a p-type blocking region is arranged above the n+ conductive region, a source metal is arranged above the p-type blocking region, and a gate metal is arranged above the source metal.

[0004] CN116053312A discloses a p-type gate enhanced gallium oxide-based CAVET device and a preparation method thereof. The CAVET device comprises a drain electrode, a gallium oxide substrate, and a gallium oxide drift layer which are stacked in sequence from bottom to top; and further comprises: a current aperture, which is arranged on the gallium oxide drift layer; a current blocking layer, which is arranged on the gallium oxide drift layer and on two opposite sides of the current aperture; a channel layer, which is arranged on the current aperture and the current blocking layer; a high conductivity layer, which is arranged on the current blocking layer and on two opposite sides of the channel layer; a p-type semiconductor layer, which is arranged on the channel layer and forms a PN junction with the channel layer; a gate electrode, which is arranged on the p-type semiconductor layer; and a source electrode, which is arranged on the high conductivity layer.

[0005] However, when the vertical AlGaN / GaN current aperture vertical electron transistor is in the off state, the n-GaN drift region bears most of the voltage, and the current passes through the drift region in the vertical direction to the drain electrode. Although the low n-GaN doping concentration can increase the breakdown voltage of the device, it will increase the on-resistance of the device. In summary, the current CAVET device has the defect that the voltage resistance and conduction performance cannot be taken into account at the same time. Summary of the invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a SiC-based current aperture vertical epitaxial structure and a preparation method thereof, and a power device, so as to solve the defect that the gallium nitride-based current aperture vertical epitaxial structure is prone to avalanche breakdown when the device works under high voltage state due to the electric field concentration effect.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a SiC-based current aperture vertical epitaxial structure, which comprises: a buffer layer, a drift layer, a conductive aperture layer, a 4H-SiC channel layer and a 3C-SiC layer sequentially arranged on a substrate.

[0009] The current aperture vertical epitaxial structure provided by the present invention improves the voltage resistance performance of the current aperture vertical epitaxial structure while having good conduction performance by adopting a specifically designed structure and cooperating with silicon carbide materials, thereby avoiding the defect that the gallium nitride-based current aperture vertical epitaxial structure is prone to avalanche breakdown when the device works under high voltage state due to the electric field concentration effect.

[0010] As a preferred technical solution of the present invention, the thickness of the buffer layer is 0.9-1.1 μm.

[0011] The nitrogen doping concentration in the buffer layer is 7×10 17 -1.3×10 18 atom / cm 3 .

[0012] Wherein, the thickness of the drift layer is 10-20 μm.

[0013] The nitrogen doping concentration in the drift layer is 5×10 15 -9×10 15 atom / cm 3 .

[0014] As a preferred technical solution of the present invention, the conductive aperture layer includes an intrinsic 4H-SiC layer and a current blocking layer with a width of 0.5-1 μm.

[0015] Preferably, the thickness of the current blocking layer is 0.45-0.55 times the thickness of the conductive aperture layer.

[0016] Preferably, the thickness of the conductive aperture layer is 1-10 μm.

[0017] Preferably, the P-type doping concentration in the current blocking layer is 1×10 15 -1.3×10 16 atom / cm 3 .

[0018] As a preferred technical solution of the present invention, the thickness of the 4H-SiC channel layer is 1-2 μm.

[0019] As a preferred technical solution of the present invention, the thickness of the 3C-SiC layer is 1-5 μm.

[0020] Preferably, the nitrogen doping concentration in the 3C-SiC layer is 1×10 15 -1×10 18 atom / cm 3 .

[0021] In a second aspect, the present invention provides a method for preparing a SiC-based current aperture vertical epitaxial structure as described in the first aspect, the preparation method comprising:

[0022] The substrate is sequentially subjected to buffer layer growth, drift layer growth, conduction aperture layer growth, current blocking layer growth, 4H-SiC channel layer growth and 3C-SiC layer growth.

[0023] As a preferred technical solution of the present invention, the substrate comprises a 4H-SiC substrate which is biased 4° towards the <11-20> direction.

[0024] Preferably, the flow rate of the carrier gas during the growth of the buffer layer is 100-800 slm.

[0025] Preferably, the flow rate of the silicon source gas during the growth of the buffer layer is 300-600 sccm.

[0026] Preferably, the flow rate of the carbon source gas during the growth of the buffer layer is 200-500 sccm.

[0027] Preferably, the flow rate of the N-type dopant during the growth of the buffer layer is 80-120 sccm.

[0028] Preferably, the growth temperature of the buffer layer is 1580-1680°C.

[0029] Preferably, the growth pressure of the buffer layer is 50-100 mbar.

[0030] Preferably, the flow rate of the carrier gas during the drift layer growth is 100-800 slm.

[0031] Preferably, the flow rate of the silicon source gas during the growth of the drift layer is 300-600 sccm.

[0032] Preferably, the flow rate of the carbon source gas during the drift layer growth is 200-500 sccm.

[0033] Preferably, the flow rate of the N-type dopant during the growth of the drift layer is 20-60 sccm.

[0034] Preferably, the growth temperature of the drift layer is 1580-1650°C.

[0035] Preferably, the growth pressure of the drift layer is 50-500 mbar.

[0036] As a preferred technical solution of the present invention, the flow rate of the carrier gas during the growth of the conductive aperture layer is 50-300slm.

[0037] Preferably, the flow rate of the silicon source gas during the growth of the conductive aperture layer is 80-200 sccm.

[0038] Preferably, the flow rate of the carbon source gas during the growth of the conductive aperture layer is 80-200 sccm.

[0039] Preferably, the growth temperature of the conductive aperture layer is 1580-1650°C.

[0040] Preferably, the growth pressure of the conductive aperture layer is 50-500 mbar.

[0041] Preferably, the growth of the current blocking layer comprises performing mask processing on the layer obtained by growing the conductive aperture layer, and then performing ion implantation.

[0042] Preferably, the ion implantation includes an implantation energy of 300-400 keV and an implantation dose of 1×10 15 -1×10 16 atom / cm 2 p-type element.

[0043] As a preferred technical solution of the present invention, the flow rate of the carrier gas during the growth of the 4H-SiC channel layer is 50-300 slm.

[0044] Preferably, the flow rate of the silicon source gas during the growth of the 4H-SiC channel layer is 80-200 sccm.

[0045] Preferably, the flow rate of the carbon source gas during the growth of the 4H-SiC channel layer is 80-200 sccm.

[0046] Preferably, the growth temperature of the 4H-SiC channel layer is 1580-1650°C.

[0047] Preferably, the growth pressure of the 4H-SiC channel layer is 50-500 mbar.

[0048] Preferably, the flow rate of the carrier gas during the growth of the 3C-SiC layer is 10-50 slm.

[0049] Preferably, the flow rate of the silicon source gas during the growth of the 3C-SiC layer is 100-500 sccm.

[0050] Preferably, the flow rate of the carbon source gas during the growth of the 3C-SiC layer is 80-150 sccm.

[0051] Preferably, the flow rate of the N-type dopant during the growth of the 3C-SiC layer is 15-50 sccm.

[0052] Preferably, the growth temperature of the 3C-SiC layer is 1350-1400°C.

[0053] Preferably, the growth pressure of the 3C-SiC layer is 100-500 mbar.

[0054] In a third aspect, the present invention provides a power device, the power device comprising:

[0055] The drain, gate, source and SiC-based current aperture vertical epitaxial structure as described in the first aspect.

[0056] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0057] The SiC-based current aperture vertical epitaxial structure provided by the present invention improves the performance of the epitaxial structure by specifically designing the epitaxial structure, specifically by controlling the doping concentration of the buffer layer and the drift layer and setting a specific 3C-SiC layer combination, so that the breakdown voltage of the obtained epitaxial structure is ≥1534V and the on-resistance is ≤34mΩ. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a schematic diagram of a SiC-based current aperture vertical epitaxial structure provided by an embodiment of the present invention;

[0059] Figure 2 It is a schematic diagram of a power device provided by an embodiment of the present invention.

[0060] In the figure: 1. substrate, 2. buffer layer, 3. drift layer, 4. intrinsic 4H-SiC layer, 5. current blocking layer, 6. 4H-SiC channel layer, 7. 3C-SiC layer, 8. drain, 9. source, 10. gate.

[0061] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0062] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0063] This embodiment provides a SiC-based current aperture vertical epitaxial structure, such as Figure 1As shown, the SiC-based current aperture vertical epitaxial structure includes: a buffer layer 2, a drift layer 3, a conductive aperture layer, a 4H-SiC channel layer 6 and a 3C-SiC layer 7 which are sequentially arranged on a substrate 1.

[0064] Among them, the thickness of the buffer layer 2 is 0.9-1.1μm, for example, it can be 0.9μm, 0.92μm, 0.94μm, 0.96μm, 0.98μm, 1μm, 1.02μm, 1.04μm, 1.06μm, 1.08μm or 1.1μm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0065] The nitrogen doping concentration in the buffer layer 2 is 7×10 17 -1.3×10 18 atom / cm 3 , for example, it can be 7×10 17 atom / cm 3 , 8×10 17 atom / cm 3 ,9×10 17 atom / cm 3 , 1×10 18 atom / cm 3 , 1.1×10 18 atom / cm 3 , 1.2×10 18 atom / cm 3 or 1.3 × 10 18 atom / cm 3 The above values ​​are not limited to the above values. Other values ​​not listed in the above values ​​also meet the requirements.

[0066] In the present invention, the unit is atom / cm 3 Refers to the number of atoms contained in a unit volume.

[0067] The thickness of the drift layer 3 is 10-20 μm, for example, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm or 20 μm, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0068] The nitrogen doping concentration in the drift layer 3 is 5×10 15 -9×10 15 atom / cm 3 , for example, it can be 5×10 15 atom / cm 3 , 6×10 15 atom / cm 3 ,7×1015 atom / cm 3 , 8×10 15 atom / cm 3 or 9×10 15 atom / cm 3 The above values ​​are not limited to the above values. Other values ​​not listed in the above values ​​also meet the requirements.

[0069] The conductive aperture layer includes an intrinsic 4H-SiC layer 4 and a current blocking layer 5 with a width of 0.5-1 μm.

[0070] In the present invention, the current blocking layer 5 is disposed at the convex platform position of the convex intrinsic 4H-SiC layer.

[0071] In the present invention, the width of the current blocking layer 5 is 0.5-1 μm, for example, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0072] Among them, the thickness of the current blocking layer 5 is 0.45-0.55 times the thickness of the conductive aperture layer, for example, it can be 0.45 times, 0.46 times, 0.48 times, 0.5 times, 0.52 times, 0.54 times or 0.55 times, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0073] The thickness of the conductive aperture layer is 1-10 μm, for example, 1 μm, 2 μm, 4 μm, 6 μm, 8 μm or 10 μm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0074] The P-type doping concentration in the current blocking layer 5 is 1×10 15 -1.3×10 16 atom / cm 3 , for example, it can be 1×10 15 atom / cm 3 , 2×10 15 atom / cm 3 , 4×10 15 atom / cm 3 , 6×10 15 atom / cm 3 , 8×10 15 atom / cm 3 , 1×10 16 atom / cm 3 , 1.2×10 16 atom / cm 3or 1.3 × 10 16 atom / cm 3 The above values ​​are not limited to the above values. Other values ​​not listed in the above values ​​also meet the requirements.

[0075] The thickness of the 4H-SiC channel layer 6 is 1-2 μm, for example, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm or 2 μm, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0076] The thickness of the 3C-SiC layer 7 is 1-5 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0077] The nitrogen doping concentration in the 3C-SiC layer 7 is 1×10 15 -1×10 18 atom / cm 3 , for example, it can be 1×10 15 atom / cm 3 , 2×10 15 atom / cm 3 , 4×10 15 atom / cm 3 , 6×10 15 atom / cm 3 , 8×10 15 atom / cm 3 , 1×10 16 atom / cm 3 , 2×10 16 atom / cm 3 , 4×10 16 atom / cm 3 , 6×10 16 atom / cm 3 , 8×10 16 atom / cm 3 , 1×10 17 atom / cm 3 , 2×10 17 atom / cm 3 , 4×10 17 atom / cm 3 , 6×10 17 atom / cm 3 , 8×10 17 atom / cm 3 or 1×10 18 atom / cm3 The above values ​​are not limited to the above values. Other values ​​not listed in the above values ​​also meet the requirements.

[0078] Furthermore, the present invention provides a method for preparing the aforementioned SiC-based current aperture vertical epitaxial structure, the preparation method comprising:

[0079] The substrate is sequentially subjected to buffer layer growth, drift layer growth, conduction aperture layer growth, current blocking layer growth, 4H-SiC channel layer growth and 3C-SiC layer growth.

[0080] The substrate comprises a 4H-SiC substrate with an angle of 4° in the <11-20> direction.

[0081] Among them, the flow rate of the carrier gas during the growth of the buffer layer is 100-800slm, for example, it can be 100slm, 200slm, 300slm, 400slm, 500slm, 600slm, 700slm or 800slm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0082] Among them, the flow rate of the silicon source gas in the growth of the buffer layer is 300-600sccm, for example, it can be 300sccm, 350sccm, 400sccm, 450sccm, 500sccm, 550sccm or 600sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0083] Among them, the flow rate of the carbon source gas in the growth of the buffer layer is 200-500sccm, for example, it can be 200sccm, 250sccm, 300sccm, 350sccm, 400sccm, 450sccm or 500sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0084] Among them, the flow rate of the N-type dopant in the growth of the buffer layer is 80-120sccm, for example, it can be 80sccm, 85sccm, 90sccm, 95sccm, 100sccm, 105sccm, 110sccm, 115sccm or 120sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0085] The growth temperature of the buffer layer is 1580-1680°C, for example, 1580°C, 1600°C, 1620°C, 1640°C, 1660°C or 1680°C, but is not limited to the listed values, and other values ​​not listed in the range also meet the requirements.

[0086] The growth pressure of the buffer layer is 50-100 mbar, for example, 50 mbar, 60 mbar, 70 mbar, 80 mbar, 90 mbar or 100 mbar, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0087] The flow rate of the carrier gas in the drift layer growth is 100-800slm, for example, 100slm, 200slm, 300slm, 400slm, 500slm, 600slm, 700slm or 800slm, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0088] Among them, the flow rate of the silicon source gas in the drift layer growth is 300-600sccm, for example, it can be 300sccm, 350sccm, 400sccm, 450sccm, 500sccm, 550sccm or 600sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0089] Among them, the flow rate of the carbon source gas in the drift layer growth is 200-500sccm, for example, it can be 200sccm, 250sccm, 300sccm, 350sccm, 400sccm, 450sccm or 500sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0090] Among them, the flow rate of N-type dopant in the drift layer growth is 20-60sccm, for example, it can be 20sccm, 25sccm, 30sccm, 35sccm, 40sccm, 45sccm, 50sccm, 55sccm or 60sccm, but is not limited to the listed values. Other values ​​not listed in this range also meet the requirements.

[0091] The growth temperature of the drift layer is 1580-1650°C, for example, 1580°C, 1600°C, 1620°C, 1640°C, 1660°C or 1680°C, but is not limited to the listed values, and other values ​​not listed in the range also meet the requirements.

[0092] The growth pressure of the drift layer is 50-500 mbar, for example, 50 mbar, 100 mbar, 200 mbar, 300 mbar, 400 mbar or 500 mbar, but is not limited to the listed values, and other values ​​not listed in the range also meet the requirements.

[0093] The flow rate of the carrier gas during the growth of the conductive aperture layer is 50-300slm, for example, 50slm, 100slm, 150slm, 200slm, 250slm or 300slm, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0094] Among them, the flow rate of the silicon source gas in the growth of the conductive aperture layer is 80-200sccm, for example, it can be 80sccm, 100sccm, 120sccm, 140sccm, 160sccm, 180sccm or 200sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0095] Among them, the flow rate of the carbon source gas in the growth of the conductive aperture layer is 80-200sccm, for example, it can be 80sccm, 100sccm, 120sccm, 140sccm, 160sccm, 180sccm or 200sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0096] Among them, the growth temperature of the conductive aperture layer is 1580-1650°C, for example, it can be 1580°C, 1590°C, 1600°C, 1610°C, 1620°C, 1630°C, 1640°C or 1650°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0097] The growth pressure of the conductive aperture layer is 50-500 mbar, for example, 50 mbar, 100 mbar, 200 mbar, 300 mbar, 400 mbar or 500 mbar, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0098] The growth of the current blocking layer includes performing mask processing on the layer obtained by growing the conductive aperture layer, and then performing ion implantation.

[0099] The ion implantation includes an implantation energy of 300-400 keV and an implantation dose of 1×10 15 -1×10 16 atom / cm 2 p-type element.

[0100] In the present invention, when ion implantation is used to form a current blocking layer, the energy of the ion implantation is 300-400keV, for example, it can be 300keV, 320keV, 340keV, 360keV, 380keV or 400keV, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0101] In the present invention, when the current blocking layer is formed by ion implantation, the implantation dose of the ion implantation is 1×10 15 -1×10 16 atom / cm 2 , for example, it can be 1×10 15 atom / cm 2 , 2×10 15 atom / cm 2 , 4×10 15 atom / cm 2 , 6×10 15 atom / cm 2 , 8×10 15 atom / cm 2 or 1×10 16 atom / cm 2 The above values ​​are not limited to the above values. Other values ​​not listed in the above values ​​also meet the requirements.

[0102] In the present invention, the unit is atom / cm 2 Refers to the number of atoms implanted per unit area.

[0103] In the present invention, the p-type element used in the ion implantation includes aluminum and the like.

[0104] The flow rate of the carrier gas in the growth of the 4H-SiC channel layer is 50-300 slm, for example, 50 slm, 100 slm, 150 slm, 200 slm, 250 slm or 300 slm, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0105] Among them, the flow rate of the silicon source gas in the growth of the 4H-SiC channel layer is 80-200sccm, for example, it can be 80sccm, 100sccm, 120sccm, 140sccm, 160sccm, 180sccm or 200sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0106] Among them, the flow rate of the carbon source gas in the growth of the 4H-SiC channel layer is 80-200sccm, for example, it can be 80sccm, 100sccm, 120sccm, 140sccm, 160sccm, 180sccm or 200sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0107] Among them, the growth temperature of the 4H-SiC channel layer is 1580-1650°C, for example, it can be 1580°C, 1590°C, 1600°C, 1610°C, 1620°C, 1630°C, 1640°C or 1650°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0108] The growth pressure of the 4H-SiC channel layer is 50-500 mbar, for example, 50 mbar, 100 mbar, 200 mbar, 300 mbar, 400 mbar or 500 mbar, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0109] The flow rate of the carrier gas during the growth of the 3C-SiC layer is 10-50 slm, for example, 10 slm, 20 slm, 30 slm, 40 slm or 50 slm, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0110] Among them, the flow rate of the silicon source gas in the growth of the 3C-SiC layer is 100-500sccm, for example, it can be 100sccm, 150sccm, 200sccm, 250sccm, 300sccm, 350sccm, 400sccm, 450sccm or 500sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0111] Among them, the flow rate of the carbon source gas in the growth of the 3C-SiC layer is 80-150sccm, for example, it can be 80sccm, 90sccm, 100sccm, 110sccm, 120sccm, 130sccm, 140sccm or 150sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0112] Among them, the flow rate of the N-type dopant in the growth of the 3C-SiC layer is 15-50sccm, for example, it can be 15sccm, 20sccm, 25sccm, 30sccm, 35sccm, 40sccm, 45sccm or 50sccm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0113] The growth temperature of the 3C-SiC layer is 1350-1400°C, for example, 1350°C, 1360°C, 1370°C, 1380°C, 1390°C or 1400°C, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0114] The growth pressure of the 3C-SiC layer is 100-500 mbar, for example, 100 mbar, 200 mbar, 300 mbar, 400 mbar or 500 mbar, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0115] In the present invention, the silicon source gas used includes one or a combination of at least two of SiCl4, SiHCl3, SiH2C12 or SiH3Cl.

[0116] In the present invention, the carbon source gas used includes C2H4 and / or C3H8.

[0117] In the present invention, the carrier gas used includes hydrogen.

[0118] In the present invention, the N-type dopant used includes nitrogen.

[0119] Furthermore, the present invention provides a power device, such as Figure 2 As shown, the power device includes the aforementioned SiC-based current aperture vertical epitaxial structure, a drain 8 , a gate 10 and a source 9 .

[0120] The drain electrode 8 is arranged on the lower surface of the substrate 1 in the SiC-based current aperture vertical epitaxial structure.

[0121] The source electrode 9 and the gate electrode 10 are arranged on the surface of the 3C-SiC layer 7 in the SiC-based current aperture vertical epitaxial structure.

[0122] Further, in order to illustrate the good withstand voltage effect that can be achieved by the SiC-based current aperture vertical epitaxial structure provided by the present invention, the following actual example is used for illustration, as follows:

[0123] Example 1

[0124] This embodiment provides a SiC-based current aperture vertical epitaxial structure, and the SiC-based current aperture vertical epitaxial structure includes:

[0125] A buffer layer, a drift layer, a conductive aperture layer, a 4H-SiC channel layer and a 3C-SiC layer are sequentially arranged on the substrate;

[0126] The substrate is a 4H-SiC substrate that is 4° inclined in the <11-20> direction;

[0127] The thickness of the buffer layer is 1 μm; the nitrogen doping concentration in the buffer layer is 1.1×10 18 atom / cm 3 ;

[0128] The thickness of the drift layer is 16 μm; the nitrogen doping concentration in the drift layer is 8×10 15 atom / cm 3 ;

[0129] The conductive aperture layer is an intrinsic 4H-SiC layer and a current blocking layer with a width of 0.8 μm; the thickness of the current blocking layer is 0.5 times the thickness of the conductive aperture layer; the thickness of the conductive aperture layer is 8 μm; the P-type doping concentration in the current blocking layer is 1×10 16 atom / cm 3 , is the aluminum element;

[0130] The thickness of the 4H-SiC channel layer is 1.8 μm;

[0131] The thickness of the 3C-SiC layer is 4 μm; the nitrogen doping concentration in the 3C-SiC layer is 1×10 17 atom / cm 3 .

[0132] The preparation process is as follows:

[0133] The substrate is sequentially subjected to buffer layer growth, drift layer growth, conduction aperture layer growth, current blocking layer growth, 4H-SiC channel layer growth and 3C-SiC layer growth;

[0134] The flow rate of the carrier gas during the growth of the buffer layer is 600 slm; the flow rate of the silicon source gas during the growth of the buffer layer is 500 sccm; the flow rate of the carbon source gas during the growth of the buffer layer is 400 sccm; the flow rate of the N-type dopant during the growth of the buffer layer is 1100 sccm; the growth temperature of the buffer layer is 1650° C.; the growth pressure of the buffer layer is 80 mbar;

[0135] The flow rate of the carrier gas in the drift layer growth is 300 slm; the flow rate of the silicon source gas in the drift layer growth is 500 sccm; the flow rate of the carbon source gas in the drift layer growth is 400 sccm; the flow rate of the N-type dopant in the drift layer growth is 50 sccm; the growth temperature of the drift layer growth is 1620°C; the growth pressure of the drift layer growth is 400 mbar;

[0136] The flow rate of the carrier gas in the growth of the conductive aperture layer is 200 slm; the flow rate of the silicon source gas in the growth of the conductive aperture layer is 150 sccm; the flow rate of the carbon source gas in the growth of the conductive aperture layer is 150 sccm; the growth temperature of the conductive aperture layer is 1620°C; the growth pressure of the conductive aperture layer is 300 mbar; the growth of the current blocking layer includes performing mask processing on the layer obtained by the growth of the conductive aperture layer, and then performing ion implantation; the implantation energy of the ion implantation is 360 keV, and the implantation dose is 8×10 15 atom / cm 2 The p-type element is aluminum;

[0137] The flow rate of the carrier gas during the growth of the 4H-SiC channel layer is 200 slm; the flow rate of the silicon source gas during the growth of the 4H-SiC channel layer is 1500 sccm; the flow rate of the carbon source gas during the growth of the 4H-SiC channel layer is 100 sccm; the growth temperature of the 4H-SiC channel layer is 1620° C.; the growth pressure of the 4H-SiC channel layer is 400 mbar;

[0138] The flow rate of the carrier gas during the growth of the 3C-SiC layer is 20 slm; the flow rate of the silicon source gas during the growth of the 3C-SiC layer is 300 sccm; the flow rate of the carbon source gas during the growth of the 3C-SiC layer is 120 sccm; the flow rate of the N-type dopant during the growth of the 3C-SiC layer is 40 sccm; the growth temperature of the 3C-SiC layer is 1380°C; and the growth pressure of the 3C-SiC layer is 300 mbar.

[0139] In this embodiment, the silicon source gas used is SiCl4; the carbon source gas used is C3H8; the carrier gas used is hydrogen; and the N-type dopant used is nitrogen.

[0140] Example 2

[0141] This embodiment provides a SiC-based current aperture vertical epitaxial structure, and the SiC-based current aperture vertical epitaxial structure includes:

[0142] A buffer layer, a drift layer, a conductive aperture layer, a 4H-SiC channel layer and a 3C-SiC layer are sequentially arranged on the substrate;

[0143] The substrate is a 4H-SiC substrate with a 4° orientation in the <11-20> direction;

[0144] The thickness of the buffer layer is 1 μm; the nitrogen doping concentration in the buffer layer is 9×10 17 atom / cm 3 ;

[0145] The thickness of the drift layer is 14 μm; the nitrogen doping concentration in the drift layer is 7×10 15 atom / cm 3 ;

[0146] The conductive aperture layer is an intrinsic 4H-SiC layer and a current blocking layer with a width of 0.6 μm; the thickness of the current blocking layer is 0.5 times the thickness of the conductive aperture layer; the thickness of the conductive aperture layer is 5 μm; the P-type doping concentration in the current blocking layer is 8×10 15 atom / cm 3 , is the aluminum element;

[0147] The thickness of the 4H-SiC channel layer is 1.5 μm;

[0148] The thickness of the 3C-SiC layer is 3 μm; the nitrogen doping concentration in the 3C-SiC layer is 1×10 16 atom / cm 3 .

[0149] The preparation process is as follows:

[0150] The substrate is sequentially subjected to buffer layer growth, drift layer growth, conduction aperture layer growth, current blocking layer growth, 4H-SiC channel layer growth and 3C-SiC layer growth;

[0151] The flow rate of the carrier gas during the growth of the buffer layer is 400 slm; the flow rate of the silicon source gas during the growth of the buffer layer is 400 sccm; the flow rate of the carbon source gas during the growth of the buffer layer is 300 sccm; the flow rate of the N-type dopant during the growth of the buffer layer is 100 sccm; the growth temperature of the buffer layer is 1600°C; the growth pressure of the buffer layer is 60 mbar;

[0152] The flow rate of the carrier gas in the drift layer growth is 500 slm; the flow rate of the silicon source gas in the drift layer growth is 400 sccm; the flow rate of the carbon source gas in the drift layer growth is 300 sccm; the flow rate of the N-type dopant in the drift layer growth is 40 sccm; the growth temperature of the drift layer growth is 1600° C.; the growth pressure of the drift layer growth is 200 mbar;

[0153] The flow rate of the carrier gas in the growth of the conductive aperture layer is 100 slm; the flow rate of the silicon source gas in the growth of the conductive aperture layer is 100 sccm; the flow rate of the carbon source gas in the growth of the conductive aperture layer is 100 sccm; the growth temperature of the conductive aperture layer is 1600°C; the growth pressure of the conductive aperture layer is 200 mbar; the growth of the current blocking layer includes performing mask processing on the layer obtained by the growth of the conductive aperture layer, and then performing ion implantation; the implantation energy of the ion implantation is 350 keV, and the implantation dose is 5×10 15 atom / cm 2 The p-type element is aluminum;

[0154] The flow rate of the carrier gas during the growth of the 4H-SiC channel layer is 100 slm; the flow rate of the silicon source gas during the growth of the 4H-SiC channel layer is 100 sccm; the flow rate of the carbon source gas during the growth of the 4H-SiC channel layer is 150 sccm; the growth temperature of the 4H-SiC channel layer is 1600° C.; the growth pressure of the 4H-SiC channel layer is 200 mbar;

[0155] The flow rate of the carrier gas during the growth of the 3C-SiC layer is 30 slm; the flow rate of the silicon source gas during the growth of the 3C-SiC layer is 200 sccm; the flow rate of the carbon source gas during the growth of the 3C-SiC layer is 100 sccm; the flow rate of the N-type dopant during the growth of the 3C-SiC layer is 300 sccm; the growth temperature of the 3C-SiC layer is 1360° C.; the growth pressure of the 3C-SiC layer is 200 mbar;

[0156] In this embodiment, the silicon source gas used is SiHCl3; the carbon source gas used is C2H4; the carrier gas used is hydrogen; and the N-type dopant used is nitrogen.

[0157] Example 3

[0158] This embodiment provides a SiC-based current aperture vertical epitaxial structure, and the SiC-based current aperture vertical epitaxial structure includes:

[0159] A buffer layer, a drift layer, a conductive aperture layer, a 4H-SiC channel layer and a 3C-SiC layer are sequentially arranged on the substrate;

[0160] The substrate is a 4H-SiC substrate with a 4° orientation in the <11-20> direction;

[0161] The thickness of the buffer layer is 0.9 μm; the nitrogen doping concentration in the buffer layer is 1.3×10 18 atom / cm 3 ;

[0162] The thickness of the drift layer is 20 μm; the nitrogen doping concentration in the drift layer is 9×10 15 atom / cm 3 ;

[0163] The conductive aperture layer includes an intrinsic 4H-SiC layer and a current blocking layer with a width of 0.5 μm; the thickness of the current blocking layer is 0.45 times the thickness of the conductive aperture layer; the thickness of the conductive aperture layer is 1 μm; the P-type doping concentration in the current blocking layer is 1×10 15 atom / cm 3 ;

[0164] The thickness of the 4H-SiC channel layer is 1 μm;

[0165] The thickness of the 3C-SiC layer is 5 μm; the nitrogen doping concentration in the 3C-SiC layer is 1×10 15 atom / cm 3 .

[0166] The preparation process is as follows:

[0167] The substrate is sequentially subjected to buffer layer growth, drift layer growth, conduction aperture layer growth, current blocking layer growth, 4H-SiC channel layer growth and 3C-SiC layer growth;

[0168] The flow rate of the carrier gas during the growth of the buffer layer is 100 slm; the flow rate of the silicon source gas during the growth of the buffer layer is 300 sccm; the flow rate of the carbon source gas during the growth of the buffer layer is 200 sccm; the flow rate of the N-type dopant during the growth of the buffer layer is 80 sccm; the growth temperature of the buffer layer is 1580°C; the growth pressure of the buffer layer is 100 mbar;

[0169] The flow rate of the carrier gas in the drift layer growth is 100 slm; the flow rate of the silicon source gas in the drift layer growth is 300 sccm; the flow rate of the carbon source gas in the drift layer growth is 500 sccm; the flow rate of the N-type dopant in the drift layer growth is 60 sccm; the growth temperature of the drift layer growth is 1580°C; the growth pressure of the drift layer growth is 500 mbar;

[0170] The flow rate of the carrier gas in the growth of the conductive aperture layer is 50 slm; the flow rate of the silicon source gas in the growth of the conductive aperture layer is 80 sccm; the flow rate of the carbon source gas in the growth of the conductive aperture layer is 80 sccm; the growth temperature of the conductive aperture layer is 1580°C; the growth pressure of the conductive aperture layer is 500 mbar; the growth of the current blocking layer includes performing mask processing on the layer obtained by the growth of the conductive aperture layer, and then performing ion implantation; the implantation energy of the ion implantation is 300 keV, and the implantation dose is 1×1015 atom / cm 2 The p-type element is aluminum;

[0171] The flow rate of the carrier gas during the growth of the 4H-SiC channel layer is 50 slm; the flow rate of the silicon source gas during the growth of the 4H-SiC channel layer is 80 sccm; the flow rate of the carbon source gas during the growth of the 4H-SiC channel layer is 200 sccm; the growth temperature of the 4H-SiC channel layer is 1580° C.; the growth pressure of the 4H-SiC channel layer is 500 mbar;

[0172] The flow rate of the carrier gas during the growth of the 3C-SiC layer is 10 slm; the flow rate of the silicon source gas during the growth of the 3C-SiC layer is 100 sccm; the flow rate of the carbon source gas during the growth of the 3C-SiC layer is 80 sccm; the flow rate of the N-type dopant during the growth of the 3C-SiC layer is 15 sccm; the growth temperature of the 3C-SiC layer is 1350° C.; the growth pressure of the 3C-SiC layer is 500 mbar;

[0173] In this embodiment, the silicon source gas used is SiH2C12; the carbon source gas used is C3H8; the carrier gas used is hydrogen; and the N-type dopant used is nitrogen.

[0174] Example 4

[0175] This embodiment provides a SiC-based current aperture vertical epitaxial structure, and the SiC-based current aperture vertical epitaxial structure includes:

[0176] A buffer layer, a drift layer, a conductive aperture layer, a 4H-SiC channel layer and a 3C-SiC layer are sequentially arranged on the substrate;

[0177] The substrate is a 4H-SiC substrate with a 4° orientation in the <11-20> direction;

[0178] The thickness of the buffer layer is 1.1 μm; the nitrogen doping concentration in the buffer layer is 7×10 17 atom / cm 3 ;

[0179] The thickness of the drift layer is 10 μm; the nitrogen doping concentration in the drift layer is 5×10 15 atom / cm 3 ;

[0180] The conductive aperture layer includes an intrinsic 4H-SiC layer and a current blocking layer with a width of 1 μm; the thickness of the current blocking layer is 0.55 times the thickness of the conductive aperture layer; the thickness of the conductive aperture layer is 10 μm; the P-type doping concentration in the current blocking layer is 1.3×10 16 atom / cm3 ;

[0181] The thickness of the 4H-SiC channel layer is 2 μm;

[0182] The thickness of the 3C-SiC layer is 1 μm; the nitrogen doping concentration in the 3C-SiC layer is 1×10 18 atom / cm 3 .

[0183] The preparation process is as follows:

[0184] The substrate is sequentially subjected to buffer layer growth, drift layer growth, conduction aperture layer growth, current blocking layer growth, 4H-SiC channel layer growth and 3C-SiC layer growth;

[0185] The flow rate of the carrier gas during the growth of the buffer layer is 800 slm; the flow rate of the silicon source gas during the growth of the buffer layer is 600 sccm; the flow rate of the carbon source gas during the growth of the buffer layer is 500 sccm; the flow rate of the N-type dopant during the growth of the buffer layer is 120 sccm; the growth temperature of the buffer layer is 1680°C; the growth pressure of the buffer layer is 50 mbar;

[0186] The flow rate of the carrier gas in the drift layer growth is 800 slm; the flow rate of the silicon source gas in the drift layer growth is 600 sccm; the flow rate of the carbon source gas in the drift layer growth is 200 sccm; the flow rate of the N-type dopant in the drift layer growth is 20 sccm; the growth temperature of the drift layer growth is 1650° C.; the growth pressure of the drift layer growth is 50 mbar;

[0187] The flow rate of the carrier gas in the growth of the conductive aperture layer is 300 slm; the flow rate of the silicon source gas in the growth of the conductive aperture layer is 200 sccm; the flow rate of the carbon source gas in the growth of the conductive aperture layer is 200 sccm; the growth temperature of the conductive aperture layer is 1650°C; the growth pressure of the conductive aperture layer is 50 mbar; the growth of the current blocking layer includes performing mask processing on the layer obtained by the growth of the conductive aperture layer, and then performing ion implantation; the implantation energy of the ion implantation is 400 keV, and the implantation dose is 1×10 16 atom / cm 2 The p-type element is aluminum;

[0188] The flow rate of the carrier gas during the growth of the 4H-SiC channel layer is 300 slm; the flow rate of the silicon source gas during the growth of the 4H-SiC channel layer is 200 sccm; the flow rate of the carbon source gas during the growth of the 4H-SiC channel layer is 80 sccm; the growth temperature of the 4H-SiC channel layer is 1650° C.; the growth pressure of the 4H-SiC channel layer is 50 mbar;

[0189] The flow rate of the carrier gas during the growth of the 3C-SiC layer is 50 slm; the flow rate of the silicon source gas during the growth of the 3C-SiC layer is 500 sccm; the flow rate of the carbon source gas during the growth of the 3C-SiC layer is 150 sccm; the flow rate of the N-type dopant during the growth of the 3C-SiC layer is 50 sccm; the growth temperature of the 3C-SiC layer is 1400° C.; the growth pressure of the 3C-SiC layer is 100 mbar;

[0190] In this embodiment, the silicon source gas used is SiH3Cl; the carbon source gas used is C3H8; the carrier gas used is hydrogen; and the N-type dopant used is nitrogen.

[0191] Example 5

[0192] The only difference from Example 1 is that the nitrogen doping concentration in the buffer layer is 1×10 15 atom / cm 3 .

[0193] Example 6

[0194] The only difference from Example 1 is that the nitrogen doping concentration in the buffer layer is 1×10 19 atom / cm 3 .

[0195] Example 7

[0196] The only difference from Example 1 is that the nitrogen doping concentration in the drift layer is 1.5×10 16 atom / cm 3 .

[0197] Example 8

[0198] The only difference from Example 1 is that the nitrogen doping concentration in the drift layer is 1.5×10 14 atom / cm 3 .

[0199] Example 10

[0200] The only difference from Example 1 is that no 3C-SiC layer is provided.

[0201] Embodiment 11

[0202] The only difference from Example 1 is that the 3C-SiC layer is replaced by a GaN layer with the same parameters.

[0203] Example 12

[0204] The only difference from Example 1 is that the 3C-SiC layer is replaced by a 4H-SiC layer with the same parameters.

[0205] The SiC-based current aperture vertical epitaxial structure obtained in the above embodiment was tested for breakdown voltage according to GB / T 29332-2012 to characterize the withstand voltage performance, and for on-resistance according to GB / T 14028-2018 to perform performance testing. The test results are detailed in Table 1.

[0206] Table 1

[0207]

[0208]

[0209] As can be seen from Table 1, the current aperture vertical epitaxial structure provided by the present invention, by adopting a specifically designed structure in combination with silicon carbide materials, improves the voltage resistance of the current aperture vertical epitaxial structure while having good conduction performance, and avoids the defect that the gallium nitride-based current aperture vertical epitaxial structure is prone to avalanche breakdown when the device works under high voltage state due to the electric field concentration effect.

[0210] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0211] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0212] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A SiC-based current aperture vertical epitaxial structure, characterized in that: The SiC-based current aperture vertical epitaxial structure comprises: a buffer layer, a drift layer, a conductive aperture layer, a 4H-SiC channel layer and a 3C-SiC layer which are sequentially arranged on a substrate.

2. The SiC-based current aperture vertical epitaxial structure according to claim 1, characterized in that: The thickness of the buffer layer is 0.9-1.1 μm; Preferably, the nitrogen doping concentration in the buffer layer is 7×10 17 -1.3×10 18 atom / cm 3 ; Preferably, the drift layer has a thickness of 10-20 μm; Preferably, the nitrogen doping concentration in the drift layer is 5×10 15 -9×10 15 atom / cm 3 .

3. The SiC-based current aperture vertical epitaxial structure according to claim 1, characterized in that: The conductive aperture layer includes an intrinsic 4H-SiC layer and a current blocking layer with a width of 0.5-1 μm; Preferably, the thickness of the current blocking layer is 0.45-0.55 times the thickness of the conductive aperture layer; Preferably, the thickness of the conductive aperture layer is 1-10 μm; Preferably, the P-type doping concentration in the current blocking layer is 1×10 15 -1.3×10 16 atom / cm 3 .

4. The SiC-based current aperture vertical epitaxial structure according to claim 1, characterized in that: The thickness of the 4H-SiC channel layer is 1-2 μm.

5. The SiC-based current aperture vertical epitaxial structure according to claim 1, characterized in that: The thickness of the 3C-SiC layer is 1-5 μm; Preferably, the nitrogen doping concentration in the 3C-SiC layer is 1×10 15 -1×10 18 atom / cm 3 .

6. A method for preparing a SiC-based current aperture vertical epitaxial structure according to any one of claims 1 to 5, characterized in that: The preparation method comprises: The substrate is sequentially subjected to buffer layer growth, drift layer growth, conduction aperture layer growth, current blocking layer growth, 4H-SiC channel layer growth and 3C-SiC layer growth.

7. The preparation method according to claim 6, characterized in that: The substrate comprises a 4H-SiC substrate biased 4° in the <11-20> direction; Preferably, the flow rate of the carrier gas during the growth of the buffer layer is 100-800slm; Preferably, the flow rate of the silicon source gas during the growth of the buffer layer is 300-600 sccm; Preferably, the flow rate of the carbon source gas during the growth of the buffer layer is 200-500 sccm; Preferably, the flow rate of the N-type dopant during the growth of the buffer layer is 80-120 sccm; Preferably, the growth temperature of the buffer layer is 1580-1680°C; Preferably, the growth pressure of the buffer layer is 50-100 mbar; Preferably, the flow rate of the carrier gas during the drift layer growth is 100-800slm; Preferably, the flow rate of the silicon source gas in the drift layer growth is 300-600 sccm; Preferably, the flow rate of the carbon source gas in the drift layer growth is 200-500 sccm; Preferably, the flow rate of the N-type dopant during the growth of the drift layer is 20-60 sccm; Preferably, the growth temperature of the drift layer is 1580-1650°C; Preferably, the growth pressure of the drift layer is 50-500 mbar.

8. The preparation method according to claim 6 or 7, characterized in that: The flow rate of the carrier gas during the growth of the conductive aperture layer is 50-300 slm; Preferably, the flow rate of the silicon source gas in the growth of the conductive aperture layer is 80-200 sccm; Preferably, the flow rate of the carbon source gas during the growth of the conductive aperture layer is 80-200 sccm; Preferably, the growth temperature of the conductive aperture layer is 1580-1650°C; Preferably, the growth pressure of the conductive aperture layer is 50-500 mbar; Preferably, the current blocking layer growth comprises performing mask processing on the layer obtained by growing the conductive aperture layer, and then performing ion implantation; Preferably, the ion implantation includes an implantation energy of 300-400 keV and an implantation dose of 1×10 15 -1×10 16 atom / cm 2 p-type element.

9. The preparation method according to any one of claims 6 to 8, characterized in that: The flow rate of the carrier gas during the growth of the 4H-SiC channel layer is 50-300 slm; Preferably, the flow rate of the silicon source gas in the growth of the 4H-SiC channel layer is 80-200 sccm; Preferably, the flow rate of the carbon source gas in the growth of the 4H-SiC channel layer is 80-200 sccm; Preferably, the growth temperature of the 4H-SiC channel layer is 1580-1650° C.; Preferably, the growth pressure of the 4H-SiC channel layer is 50-500 mbar; Preferably, the flow rate of the carrier gas during the growth of the 3C-SiC layer is 10-50 slm; Preferably, the flow rate of the silicon source gas during the growth of the 3C-SiC layer is 100-500 sccm; Preferably, the flow rate of the carbon source gas during the growth of the 3C-SiC layer is 80-150 sccm; Preferably, the flow rate of the N-type dopant during the growth of the 3C-SiC layer is 15-50 sccm; Preferably, the growth temperature of the 3C-SiC layer is 1350-1400°C; Preferably, the growth pressure of the 3C-SiC layer is 100-500 mbar.

10. A power device, characterized in that: The power device comprises: A drain, a gate, a source and a SiC-based current aperture vertical epitaxial structure as claimed in any one of claims 1 to 5.

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