Gallium oxide Schottky diode and manufacturing method thereof

Abstract

The invention relates to the technical field of semiconductor power devices, in particular to a gallium oxide Schottky diode and a manufacturing method thereof. The gallium oxide Schottky diode comprises a substrate; the gallium oxide epitaxial layer is arranged on the substrate; the atomic nitrogen processing layer is arranged on the gallium oxide epitaxial layer; the first electrode is arranged on the gallium oxide epitaxial layer, and the second electrode is arranged below the gallium oxide substrate. According to the gallium oxide Schottky diode provided by the invention, the breakdown voltage can be remarkably improved, the oxygen vacancy density is reduced, and the reverse leakage current is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor power devices, and in particular to a gallium oxide Schottky diode and a manufacturing method thereof. Background Art

[0002] Ga2O3, due to its exceptional properties, such as its ultra-wide bandgap (~4.8eV) and high critical electric field, is an ideal material for next-generation high-power electronic devices. Ga2O3 Schottky barrier diodes, due to their fast switching speed and low on-state voltage, are key components in high-power electronic products such as power converters and inverters. However, planar Ga2O3 SBDs often experience severe electric field crowding at the Schottky contact edge under reverse bias conditions, leading to premature breakdown and increased reverse leakage current.

[0003] Advanced trench Schottky barrier diode (TSBD) structures can effectively redistribute the electric field away from the contact by vertically embedding the Schottky contact in the trench, suppressing electric field crowding and ultimately improving the effective breakdown strength. Although the trench structure can effectively improve the breakdown strength, the presence of oxygen vacancies in the trench structure and the sidewall damage caused by etching remain a key challenge, which significantly limits the full development of β-Ga2O3 TSBDs. Further improving the trench interface quality, especially through oxygen vacancy passivation and interface engineering, is crucial to unlocking the ultimate performance of Ga2O3-based power devices. Summary of the Invention

[0004] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a gallium oxide Schottky diode and a method for manufacturing the same.

[0005] One of the technical solutions provided by the present invention is as follows:

[0006] A gallium oxide Schottky diode, comprising:

[0007] substrate;

[0008] a gallium oxide epitaxial layer, disposed on the substrate;

[0009] an atomic nitrogen treatment layer disposed on the gallium oxide epitaxial layer;

[0010] A first electrode is disposed on the gallium oxide epitaxial layer;

[0011] The second electrode is disposed under the gallium oxide substrate.

[0012] In one embodiment, the substrate is formed of β-Ga2O3 and has a predetermined crystal plane direction;

[0013] Preferably, the predetermined crystal plane direction includes one of (100), (010) and (001) crystal plane directions.

[0014] Optionally, the substrate is made of N-type heavily doped gallium oxide;

[0015] Preferably, the doping element is selected from any one or at least two of Sn, Si, and Ge, and the doping concentration is 1×10 18 cm -3 above.

[0016] Optionally, the gallium oxide epitaxial layer is made of N-type lightly doped gallium oxide;

[0017] Preferably, the doping element is selected from any one or at least two of Sn, Si, and Ge, and the doping concentration is 1×10 17 cm -3 the following.

[0018] In one embodiment, the following characteristic peaks are present in the X-ray photoelectron spectrum of the atomic nitrogen treatment layer: two characteristic peaks appear in the 1s electron spectrum of nitrogen; and / or

[0019] Three characteristic peaks appear in the 1s electron spectrum of oxygen; and / or

[0020] There are three characteristic peaks in the 3d electron energy spectrum of gallium.

[0021] In one embodiment, the oxygen vacancy concentration of the atomic nitrogen treatment layer is less than the oxygen vacancy concentration of the gallium oxide epitaxial layer.

[0022] The second technical solution provided by the present invention is as follows:

[0023] A gallium oxide Schottky diode, comprising:

[0024] substrate;

[0025] a gallium oxide epitaxial layer, disposed on the gallium oxide substrate;

[0026] A groove is provided in the gallium oxide epitaxial layer and opens at the upper surface of the gallium oxide epitaxial layer;

[0027] an atomic nitrogen treatment layer disposed in the trench to passivate oxygen vacancies and surface defects induced by the etching process;

[0028] A first electrode is disposed on the gallium oxide epitaxial layer;

[0029] a second electrode disposed under the gallium oxide substrate;

[0030] The insulating dielectric layer is disposed on the atomic nitrogen treated layer and is used to electrically insulate the first electrode from the atomic nitrogen treated layer.

[0031] In one embodiment, the substrate is formed of β-Ga2O3 and has a first predetermined crystal plane direction;

[0032] Preferably, the first predetermined crystal plane direction includes one of the (100), (010) and (001) crystal plane directions;

[0033] Optionally, the substrate is made of N-type heavily doped gallium oxide;

[0034] Preferably, the doping element is selected from any one or at least two of Sn, Si, and Ge, and the doping concentration is 1×10 18 cm -3 above;

[0035] Optionally, the gallium oxide epitaxial layer is made of N-type lightly doped gallium oxide;

[0036] Preferably, the doping element is selected from any one or at least two of Sn, Si, and Ge, and the doping concentration is 1×10 17 cm -3 the following.

[0037] In one embodiment, the gallium oxide epitaxial layer is formed of β-Ga2O3 and has a second predetermined crystal plane direction;

[0038] Preferably, the second predetermined crystal plane direction is consistent with the first predetermined crystal plane direction.

[0039] In one embodiment, the insulating dielectric layer is selected from dielectric materials having a dielectric constant in the range of 10-25;

[0040] Preferably, the insulating dielectric layer is selected from any one of Al2O3, Gd2O3, HfO2, or a combination of at least two thereof.

[0041] In one embodiment, the width of the groove in the first direction decreases linearly along the second direction;

[0042] The first direction is a direction perpendicular to the thickness of the gallium oxide epitaxial layer, and the second direction is a direction from the gallium oxide epitaxial layer to the substrate;

[0043] Preferably, a first width of the top of the trench in the first direction is in a range of 2 μm to 10 μm, and the top of the trench is away from the substrate; a second width of the bottom of the trench in the first direction is in a range of 1 μm to 7 μm; and a thickness of the trench in the second direction is in a range of 1 μm to 5 μm.

[0044] Preferably, the distance between the tops of two adjacent grooves in the plurality of grooves ranges from 1 μm to 10 μm.

[0045] In one embodiment, the following characteristic peaks are present in the X-ray photoelectron spectrum of the atomic nitrogen treatment layer:

[0046] Two characteristic peaks appear in the 1s electron spectrum of nitrogen; and / or

[0047] Three characteristic peaks appear in the 1s electron spectrum of oxygen; and / or

[0048] There are three characteristic peaks in the 3d electron energy spectrum of gallium.

[0049] In one embodiment, the oxygen vacancy concentration of the atomic nitrogen treatment layer is less than the oxygen vacancy concentration of the gallium oxide epitaxial layer.

[0050] The third technical solution provided by the present invention is as follows:

[0051] A method for manufacturing a gallium oxide Schottky diode comprises the following steps:

[0052] providing a substrate comprising a first surface and a second surface that are opposed to each other;

[0053] forming a gallium oxide epitaxial layer on the first surface of the substrate;

[0054] forming a second electrode on the second surface of the substrate;

[0055] forming a trench on the gallium oxide epitaxial layer;

[0056] performing atomic nitrogen treatment on at least a portion of the gallium oxide in the trench to form an atomic nitrogen treated layer;

[0057] forming an insulating dielectric layer on the atomic nitrogen treated layer;

[0058] A first electrode is formed on the gallium oxide epitaxial layer.

[0059] Based on the above, in the gallium oxide Schottky diode provided by the present invention, an atomic nitrogen treatment layer is provided, thereby significantly improving the breakdown voltage, reducing the oxygen vacancy concentration, and reducing the reverse leakage current.

[0060] Other features and beneficial effects of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The objectives and other beneficial effects of the present invention can be achieved and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work. The positional relationships described in the drawings in the following description are based on the directions of the components drawn in the diagrams, unless otherwise specified.

[0062] Figure 1 FIG2 shows a schematic structural diagram of a gallium oxide Schottky diode provided by the first embodiment of the present invention;

[0063] Figure 2 Shown are semi-logarithmic plots of the forward IV characteristics of treated and untreated SBDs;

[0064] Figure 3 (a) shows the forward IV characteristics of the untreated sample tested over a temperature range of 50 to 150 degrees Celsius.

[0065] Figure 3 (b) shows the Richardson curve of SBD;

[0066] Figure 4 (a) Shown are the frequency-dependent conductance-voltage (G / ω-V) plots of treated and untreated SBDs;

[0067] Figure 4 (b) shows the Nss characteristics of the treated and untreated SBDs;

[0068] Figure 5 FIG2 shows a schematic structural diagram of a gallium oxide Schottky diode provided by a second embodiment of the present invention;

[0069] Figures 6 to 13 The figure shows a process flow chart of a gallium oxide Schottky diode provided by the second embodiment of the present invention;

[0070] Figure 14 (a) shows the reverse bias IV characteristics of Ga2O3 TSBD.

[0071] Figure 14 (b) shows the R of β-Ga2O3 diodes (including lateral, vertical and trench Schottky barrier diodes). on,sp and the benchmark plot of breakdown voltage;

[0072] Figure 15 (a) shows the XPS survey spectrum after atomic nitrogen treatment;

[0073] Figure 15 (b) shows the N1s XPS spectrum of the Ga2O3 epitaxial sample treated with atomic nitrogen;

[0074] Figure 15 (c) Figure 15 (d) shows the O1s XPS spectra of Ga2O3 epitaxial samples without and after atomic nitrogen treatment;

[0075] Figure 15 (e) Figure 15 (f) shows the Ga 3dXPS spectra of samples without and after atomic nitrogen treatment;

[0076] Figure 16 (a) shows a schematic diagram of a Ga2O3 metal oxide semiconductor capacitor (MOSCAP) treated with atomic nitrogen;

[0077] Figure 16 (b) shows the high-frequency CV graph of Ga2O3 MOSCAP measured at 1MHz.

[0078] Figure 16 (c) Figure 16 (d) shows the energy band diagram of Al2O3 / Ga2O3 contacts with and without atomic nitrogen treatment under reverse bias conditions;

[0079] Figure 17 (a) shows the simulated electric field distribution of a Ga2O3 TSBD without fixed negative charge;

[0080] Figure 17 (b) shows the simulated electric field distribution of Ga2O3 TSBD with fixed negative charge;

[0081] Figure 17 (c) shows the overall simulation structure of Ga2O3 TSBD;

[0082] Figure 17 (d) shows the electric field profile of Ga2O3 TSBD extracted along the ABCD tangent line;

[0083] Figure 18 Shown is a schematic structural diagram of a gallium oxide Schottky diode provided by a third embodiment of the present invention.

[0084] Reference numerals:

[0085] 10. Substrate; 10a. First surface; 10b. Second surface; 20. Gallium oxide epitaxial layer; 30. Second electrode; 40. Atomic nitrogen treatment layer; 50. First electrode; 60. Insulating dielectric layer; 70. Trench. DETAILED DESCRIPTION

[0086] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0087] In the description of the present invention, it should be noted that all terms used in the present invention (including technical terms and scientific terms) have the same meanings as those generally understood by ordinary technicians in the field to which the present invention belongs, and should not be understood as limiting the present invention; it should be further understood that the terms used in the present invention should be understood to have meanings consistent with the meanings of these terms in the context of this specification and in the relevant fields, and should not be understood in an idealized or overly formal sense, unless explicitly defined as such in the present invention.

[0088] Please refer to Figure 1 A first embodiment of the present invention provides a gallium oxide Schottky diode, comprising: a second electrode 30 , a substrate 10 , a gallium oxide epitaxial layer 20 , an atomic nitrogen treated layer 40 , and a first electrode 50 .

[0089] In this embodiment, the substrate 10 is conductive, and the substrate 10 has a first surface 10a and a second surface 10b relative to each other; the substrate is formed of β-Ga2O3 and has a first predetermined crystal plane direction, and the first predetermined crystal plane direction includes one of the (100), (010) and (001) crystal plane directions, wherein the (001) crystal plane has an ultra-high breakdown field strength, making it an ideal choice for high-voltage Schottky diodes, and the (001) crystal plane matches the symmetry of the β-Ga2O3 monoclinic system, and is more suitable for vertical device design (such as vertical channel Schottky barrier diodes), thereby reducing interface defects caused by lattice mismatch and improving carrier transport efficiency. The (010) crystal plane has high thermal conductivity and can effectively alleviate the heat accumulation problem caused by the high power density of gallium oxide Schottky diodes, while the (100) crystal plane has excellent deep ultraviolet absorption characteristics.

[0090] Preferably, the substrate material is N-type heavily doped gallium oxide to facilitate ohmic contact with the second electrode 30. The use of an N-type heavily doped substrate can effectively reduce the ohmic contact resistance and suppress the parasitic diode effect. In addition, since β-phase gallium oxide itself is a wide bandgap semiconductor (~4.8eV), the N-type doping (such as Si, Sn) process is mature and has high carrier mobility (theoretical electron mobility ~300cm2 / V·s), while the P-type doping technology has extremely low hole mobility, making it difficult to achieve effective ohmic contact.

[0091] In some preferred embodiments, the doping element is selected from any one or at least two of Sn, Si, and Ge, and the doping concentration is 1×10 18 cm -3 above to ensure low resistance ohmic contact with the cathode metal.

[0092] In some preferred embodiments, the thickness of the substrate 10 is 400 μm-600 μm.

[0093] In this embodiment, the gallium oxide epitaxial layer 20 is conductive and is disposed on the first surface 10 a of the substrate 10 ;

[0094] Preferably, the material of the gallium oxide epitaxial layer is N-type lightly doped gallium oxide. The use of N-type lightly doped gallium oxide can better balance conductivity and device performance, more easily control defect density (such as dislocations and oxygen vacancies), reduce the interference of interface states on carrier transport, and ensure the stability of ohmic contact;

[0095] In some embodiments, the gallium oxide epitaxial layer is formed of β-Ga2O3 and has a second predetermined crystal plane direction; preferably, the second predetermined crystal plane direction is consistent with the first predetermined crystal plane direction.

[0096] In some preferred embodiments, the doping element is selected from any one or at least two of Sn, Si, and Ge, and the doping concentration is 1×10 17 cm -3 Below, in order to reduce leakage current and increase breakdown voltage.

[0097] It should be noted that heavily doped substrates require high concentration donors (e.g. Si doping up to 10 18 cm -3 More than) to induce tunneling effect and reduce contact resistance; while the lightly doped epitaxial layer needs to have precise concentration control (such as Si doping 10 16 -10 17 cm -3 ) to optimize breakdown voltage and mobility.

[0098] In this embodiment, the second electrode 30 is disposed on the second surface 10b of the substrate 10. The second electrode 30 can be made of any known electrode material, without particular limitation. Preferably, the second electrode 30 contains at least one metal from Group 4 or Group 11 of the periodic table, such as titanium (Ti). Alternatively, the second electrode 30 can be a laminated structure formed by stacking different metal films, such as Ti / Au or Ti / Al. The method for forming the second electrode 30 is also not particularly limited, and known methods such as vacuum evaporation and sputtering can be employed.

[0099] In this embodiment, the atomic nitrogen treatment layer 40 is provided on the gallium oxide epitaxial layer 20 to increase the Schottky barrier height. In this embodiment, the atomic nitrogen treatment layer can be continuous or discontinuous. Thus, after the first electrode 50 is formed, the Schottky barrier height formed by the first electrode 50 and the atomic nitrogen treatment layer 40 is significantly increased compared to the Schottky barrier height formed by the first electrode 50 and the gallium oxide epitaxial layer 20. This is because the atomic nitrogen treatment layer 40 provided in this embodiment is formed by subjecting the gallium oxide epitaxial layer 20 to radio frequency atomic nitrogen treatment. The atomic nitrogen treatment promotes the formation of Ga-ON compounds on the Schottky interface and optimizes the distribution of the interface state density, thereby significantly increasing the Schottky barrier height of the formed atomic nitrogen treatment layer, and significantly increasing the breakdown voltage and reducing the leakage current while slightly increasing the turn-on voltage.

[0100] Furthermore, the process parameters of the atomic nitrogen treatment include but are not limited to a nitrogen flow rate of 4 sccm; a radio frequency power of 200-400 W, wherein the power increase rate is 50 W / 5 min; and a treatment time of 30-120 min.

[0101] The following characteristic peaks exist in the X-ray photoelectron spectrum of the atomic nitrogen treatment layer: two characteristic peaks appear in the 1s electron energy spectrum of nitrogen, that is, the 1s electron energy spectrum of nitrogen has characteristic peaks corresponding to Ga-ON bonds and N-O bonds, respectively; three characteristic peaks appear in the 1s electron energy spectrum of oxygen, that is, the 1s electron energy spectrum of oxygen has characteristic peaks corresponding to Ga-O bonds, oxygen vacancies (VO) and GaO-N bonds, respectively; three characteristic peaks appear in the 3d electron energy spectrum of gallium, that is, the 3d electron energy spectrum of gallium has characteristic peaks corresponding to Ga-Ga bonds, Ga-O bonds and Ga-ON bonds, respectively.

[0102] Furthermore, the oxygen vacancy concentration of the atomic nitrogen treated layer of this embodiment is lower than that of the gallium oxide epitaxial layer. This embodiment forms the GaOH layer by using the atomic nitrogen treatment method, thereby significantly improving the breakdown voltage performance of the gallium oxide Schottky barrier diode.

[0103] In this embodiment, the first electrode 50 is disposed on the gallium oxide epitaxial layer 20; the first electrode 50 is not particularly limited as long as it can be used as an electrode, and can be a well-known electrode, a conductive inorganic material, or a conductive organic material. In this embodiment, the first electrode 50 is preferably a metal material, and can be selected from at least one metal in Groups 4 to 11 of the periodic table, such as molybdenum (Mo), platinum (Pt), nickel (Ni), palladium (Pd), or gold (Au). The first electrode 50 can be a multilayer structure of different metal films stacked together, for example, Mo / Au, Ni / Au, Pt / Au, Pd / Au, Pt / Ti / Au, or Ni / Ti / Au.

[0104] The present invention provides a comparative example of the first embodiment, which provides a gallium oxide Schottky diode. The difference between the comparative example and the first embodiment is that the comparative example does not contain an atomic nitrogen treatment layer, that is, the gallium oxide epitaxial layer is not subjected to atomic nitrogen treatment.

[0105] Figure 2 Shown are semi-logarithmic plots of the forward IV characteristics of treated and untreated SBDs; Figure 2 At 1A / cm 2 The turn-on voltages of the untreated and nitrogen-treated SBDs were 0.50 V and 0.65 V, respectively, at a current density of 1.5 GHz.

[0106] Figure 3 (a) Comparison of the forward IV characteristics of treated and untreated β-Ga2O3 SBDs as a function of temperature (T). Compared with the untreated device, the treated device has a lower current density and V on This indicates an increase in Schottky barrier height (SBH). Although the treated devices show V on increases and the current density decreases, but V on The change with temperature is small, which indicates that the treated device has higher stability. This forward IV data is in good agreement with the pyroelectric model of the thermal example, as shown in Figure 2. Figure 3 As shown in (b), the nitrogen-treated SBD has a higher SBH (0.95 eV) compared to 0.80 eV of the untreated SBD.

[0107] like Figure 4 (a) shows the frequency versus conductance-voltage (G / ω-V) of the studied SBD. As the frequency increases, the conductance decreases, indicating the existence of interface states with different response times. ss -f features such as Figure 4 (b) shows that the N ssThe maximum N extracted by the untreated device at 800kHz is always higher than that of the untreated device. ss 1.3×10 12 eV -1 cm -2 , while the treated device increases to 1.8×10 12 eV -1 cm -2 Therefore, the change of SBH may be the result of the redistribution of the interface state density on the Schottky surface. ss will increase, leading to I r However, unlike previous studies, although the observed N ss higher, but the SBD treated with atomic nitrogen significantly reduced I r At the same time, it also improves V br This phenomenon is related to the formation of a unique Ga-ON compound at the interface. Although the introduction of Ga-ON compounds leads to the formation of N ss , but it not only maintains the integrity of the Schottky interface but also effectively passivates the interface, thereby improving the overall performance of the SBD.

[0108] Please refer to Figure 5 The second embodiment of the present invention provides a gallium oxide Schottky diode, comprising: a second electrode 30, a substrate 10, a gallium oxide epitaxial layer 20, an atomic nitrogen treated layer 40, a first electrode 50, an insulating dielectric layer 60 and a trench 70;

[0109] In this embodiment, the substrate 10 has a first surface 10a and a second surface 10b relative to each other; the second electrode 30 is arranged on the second surface 10b of the substrate 10; the gallium oxide epitaxial layer 20 is arranged on the first surface 10a of the substrate 10; the groove 70 is arranged in the gallium oxide epitaxial layer 20 and opens at the upper surface of the gallium oxide epitaxial layer 20; the atomic nitrogen treatment layer 40 is arranged in the groove 70 to passivate oxygen vacancies and surface defects induced by the etching process; specifically, it is deposited on the inner surface of the groove by radio frequency atomic nitrogen source technology to passivate sidewall damage introduced by inductively coupled plasma (ICP) etching process; the first electrode 50 is arranged on the gallium oxide epitaxial layer 20; the insulating dielectric layer 60 is arranged on the atomic nitrogen treatment layer 30 to electrically insulate the first electrode 50 from the atomic nitrogen treatment layer 40.

[0110] In this second embodiment, atomic nitrogen treatment is performed on the gallium oxide epitaxial layer at the trench interface after ICP etching, introducing Ga-ON compounds. This effectively passivates oxygen vacancies on the gallium oxide epitaxial layer's surface, reducing surface leakage current. Simultaneously, the fixed positive charge density at the Al2O3 / Ga2O3 interface is increased, thereby expanding the depletion region and improving the device's withstand voltage and reliability.

[0111] In some preferred embodiments, the width of the groove 70 in the first direction decreases linearly along the second direction; the first direction is a direction perpendicular to the thickness of the gallium oxide epitaxial layer 20, and the second direction is a direction in which the gallium oxide epitaxial layer 20 points to the substrate 10; for example, the cross-section of the groove 70 is an inverted trapezoidal shape; in this way, the use of a trapezoidal groove structure can effectively disperse the distribution of the peak electric field of the Schottky interface under breakdown conditions, reduce edge field aggregation, and improve the breakdown characteristics of the device. At the same time, the groove structure can increase the current density per unit area, so that the device performs better under high power conditions; further, the first width of the top of the groove in the first direction ranges from 2μm to 10μm, and the first width can specifically be 2μm, 3μm, 4μm, etc. μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc., but are not limited to the listed values, and other unlisted values within the numerical range are also applicable. The top of the groove is away from the substrate; the second width of the bottom of the groove in the first direction ranges from 1μm to 7μm, and the first width can specifically be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, etc., but are not limited to the listed values, and other unlisted values within the numerical range are also applicable; the thickness of the groove in the second direction ranges from 1μm to 5μm, and the thickness can specifically be 1μm, 2μm, 3μm, 4μm, 5μm, etc., but are not limited to the listed values, and other unlisted values within the numerical range are also applicable. Furthermore, the spacing between the tops of two adjacent grooves in the plurality of grooves ranges from 1 μm to 10 μm, and the spacing can specifically be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc., but is not limited to the listed values. Other unlisted values within the numerical range are also applicable, that is, through the geometric features of narrower bottom and wider top, to ensure complete coverage and dispersed electric field distribution formed by the deposition of the insulating dielectric layer and the Schottky metal contact.

[0112] In this embodiment, the insulating dielectric layer 60 is arranged on the atomic nitrogen treated layer 30 to electrically insulate the first electrode 50 from the atomic nitrogen treated layer 40; the insulating dielectric layer is selected from a dielectric material with a dielectric constant in the range of 10-25; thus, using an insulating dielectric layer with a high dielectric constant as a dielectric layer can improve the uniformity of the electric field and increase the breakdown voltage; in some preferred embodiments, the insulating dielectric layer is selected from any one of Al2O3, Gd2O3, HfO2 or a combination of at least two; more preferably, the insulating dielectric layer is selected from Al2O3 or Gd2O3 to be more compatible with the gallium oxide substrate process.

[0113] This embodiment provides a gallium oxide trench-type gallium oxide Schottky diode based on atomic nitrogen treatment, which can reduce oxygen vacancies, promote the formation of Ga-ON compounds on the interface, passivate surface defects induced by ICP etching, and fill the trench with an insulating dielectric layer with a high dielectric constant to further suppress the electric field concentration at the bottom of the trench, thereby effectively improving the breakdown voltage of the device.

[0114] Please refer to Figure 6 The present invention provides a second embodiment of a method for manufacturing a gallium oxide Schottky diode, comprising the following steps:

[0115] Step 1: Provide a substrate having a first surface and a second surface opposite to each other; in this embodiment, the substrate is an N-type β-Ga2O3 substrate with a doping concentration of 5×10 18 cm -3 , with a thickness of 570μm.

[0116] Step 2: Form a gallium oxide epitaxial layer on the first surface of the substrate; specifically, an N-type gallium oxide epitaxial layer is obtained by epitaxial growth on the first surface of the β-Ga2O3 substrate. The epitaxial growth method can be chemical vapor deposition (CVD), physical vapor deposition (PVD) or molecular beam epitaxy (MBE), and N-type conductivity is achieved by Si or Sn doping; please refer to Figure 7 In this embodiment, an N-type β-Ga2O3 epitaxial layer is obtained by epitaxy, and its doping concentration is 2×10 16 cm -3 , with a thickness of 10μm.

[0117] Step 3: RCA cleaning, acetone, alcohol and deionized water cleaning are performed on the β-Ga2O3 substrate and the gallium oxide epitaxial layer to remove surface organic matter.

[0118] Step 4: forming a second electrode on the second surface of the substrate; specifically, using electron beam evaporation to deposit the second electrode on the second surface of the β-Ga2O3 substrate, and then using a rapid annealing process to obtain an ohmic contact. Figure 8In this embodiment, a Ti / Au metal stack is deposited on the second surface of the N-type β-Ga2O3 substrate by electron beam evaporation as the second electrode. The thickness of the metal stack is 50 nm and 100 nm respectively, and then an ohmic contact is obtained by a rapid annealing process.

[0119] Step 5: Forming a groove on the gallium oxide epitaxial layer; specifically, photolithography is performed to form a mask for trench etching, and ICP etching is performed using BCl3 / Ar gas in an inductively coupled plasma etcher to form the gallium oxide groove. Figure 9 In this embodiment, a groove is formed on the upper surface of the N-type β-Ga2O3 epitaxial layer by photolithography and ICP BCl3 / Ar gas etching. The bottom width of the groove is 6 μm, the height is 3 μm, the top width is 9 μm, and the spacing between adjacent grooves is 12 μm.

[0120] Step 6: Perform atomic nitrogen treatment on at least a portion of the gallium oxide in the trench to form an atomic nitrogen treatment layer to passivate the surface damage caused by the trench formation. In other words, the inner surface of the trench is treated with a radio frequency atomic nitrogen source technology to passivate the sidewall damage introduced by the inductively coupled plasma (ICP) etching process. Specifically, a mask treated with atomic nitrogen is formed by photolithography, and the gallium oxide trench is subjected to atomic nitrogen treatment using a radio frequency atomic nitrogen source to form the atomic nitrogen treatment layer. Figure 10 In this embodiment, the upper surface of the N-type β-Ga2O3 epitaxial layer is photolithographically processed again, and the trench is subjected to atomic nitrogen treatment using a radio frequency atomic nitrogen source to form a corresponding atomic nitrogen treatment layer. The nitrogen flow rate is controlled at 4 sccm, and the radio frequency power is gradually increased to 300 W. The treatment time is 2 hours.

[0121] Step 7: forming an insulating dielectric layer on the atomic nitrogen treated layer; specifically, forming an insulating dielectric layer with a high dielectric constant on the atomic nitrogen treated layer by atomic layer deposition. Figure 11 In this embodiment, an Al2O3 insulating dielectric layer is deposited on the atomic nitrogen treatment layer by atomic layer deposition, and the thickness of the Al2O3 insulating dielectric layer is 100 nm.

[0122] Step 8: ICP is used to etch the insulating dielectric layer to form an opening for the subsequently deposited metal electrode to complete the Schottky contact with the epitaxial layer; see Figure 12 The top Schottky contact port is opened on the Al2O3 insulating dielectric layer by using ICP BCl3 / Ar gas etching.

[0123] Step 9: forming a first electrode on the gallium oxide epitaxial layer; specifically, depositing the first electrode on the Schottky contact opening by electron beam evaporation, thereby obtaining a Schottky contact. Figure 13 In this embodiment, a Ni / Au metal stack is deposited on the Schottky contact port by electron beam evaporation as the first electrode, and the thickness of the metal stack is 50 nm and 100 nm respectively.

[0124] In the second embodiment provided by the present invention, a method for regulating the Schottky interface of gallium oxide is provided by combining the device structure of the trench, the electric field regulation of the high dielectric constant insulating layer, and the radio frequency atomic nitrogen treatment; the peak electric field is transferred by the device structure of the trench, the distribution of the electric field is optimized, and the breakdown characteristics of the device are ultimately improved; due to the geometric characteristics of the trench structure, the electric field concentration is easily formed at the bottom of the trench, resulting in an increased risk of local breakdown. By introducing a high dielectric constant insulating layer in the trench, the electric field at the bottom of the trench can be redistributed, thereby alleviating the electric field concentration and improving the breakdown voltage of the device; by using radio frequency atomic nitrogen treatment, Ga-ON compounds are formed at the gallium oxide trench interface, which passivates the damage caused by ICP etching while introducing more fixed charges, further regulating the electric field distribution of the device, thereby further improving the breakdown characteristics of the device. At the same time, the introduction of the Ga-ON compound optimizes the Schottky interface state, which can effectively reduce the problem of excessive leakage current caused by material defects or Schottky interface unevenness, and reduce device loss.

[0125] The present invention provides a comparative example of the second embodiment, which provides a gallium oxide Schottky diode. The difference between the comparative example and the second embodiment is that the comparative example does not contain an atomic nitrogen treatment layer, that is, the gallium oxide epitaxial layer is not subjected to atomic nitrogen treatment.

[0126] like Figure 14 As shown in (a), the atomically nitrided TSBD (trench Schottky barrier diode) has a breakdown voltage of 1200 V, while that of the untreated TSBD is 832 V. Under a reverse bias of 400 V, the leakage current of the atomically nitrided TSBD also decreases, and even at the maximum breakdown voltage of 1200 V, the leakage current is still lower than that of the untreated TSBD. These results clearly demonstrate that atomic nitrogen treatment of the Ga2O3 trench sidewalls can significantly improve the breakdown voltage of the TSBD. Figure 14 (b) Reveals the performance upper limit of different materials and the R corresponding to the reverse breakdown voltage of the reported β-Ga2O3 SBD. on,sp Benchmark graph highlighting the superior electrical performance of atomic nitrogen treated Ga2O3 TSBD.

[0127] Chemical bond analysis was performed using X-ray photoelectron spectroscopy (XPS). Figure 15(a) shows the XPS survey scan and element identification of the nitrogen-treated sample. Figure 15 In (b), the nitrogen 1s spectrum shows characteristic peaks at 397.34 eV and 398.36 eV, corresponding to the Ga-ON bond and the N-O bond, respectively. Figure 15 (c) shows the oxygen 1s spectrum of the untreated sample, which has two main peaks at 530.40eV and 531.41eV, which are related to the O-Ga bond and oxygen vacancies (VO), respectively. It is worth noting that the treated sample has a peak at 530.43eV ( Figure 15 An additional peak appears at (d), attributed to the formation of Ga-ON bonds. This new feature confirms the presence of ternary Ga-ON compounds on the Ga2O3 surface and suggests that atomic nitrogen treatment facilitates nitrogen integration into the Ga2O3 lattice, forming stable Ga-ON bonds at the interface. Nitrogen's high electronegativity reduces the electron cloud density around oxygen atoms, increasing the effective nuclear charge and raising the binding energy of the oxygen 1s electron from 530.40 eV to 531.02 eV.

[0128] Quantitative analysis shows that the oxygen vacancy concentration is significantly reduced from 26.47% to 19.48% after nitrogen treatment, which indicates that the oxygen vacancies are effectively passivated and the surface quality of β-Ga2O3 is improved. Figure 15 (e) shows the gallium 3d spectrum, with characteristic peaks at 18.94eV (Ga-Ga bond) and 19.76eV (Ga-O bond). Figure 15 (f) shows an additional peak at 20.81 eV, further confirming the formation of Ga-ON bonds. These results collectively indicate that atomic nitrogen treatment reduces oxygen vacancies and stabilizes the Ga2O3 surface through the formation of Ga-ON compounds. Therefore, the passivation of ICP-induced defects and the formation of Ga-ON bonds at the interface play a key role in reducing the leakage current and improving the breakdown performance of the TSBD.

[0129] Furthermore, the present invention provides two embodiments of metal-oxide-semiconductor capacitors (MOSCAPs), one of which is an untreated Al2O3 / Ga2O3 interface and the other is an atomic nitrogen treated interface, both of which have a 100 nm thick Al2O3 dielectric layer. Figure 16 (a) is a schematic diagram of a MOSCAP treated with atomic nitrogen. The treatment process is the same as the fabrication process of the aforementioned atomic nitrogen-treated Ga2O3TSBD, which is performed at a power of 300 W for 2 hours. Figure 16 (b) shows the high-frequency capacitance-voltage (CV) measurement results of MOSCAP. From the CV curve, it can be seen that the flat-band voltage (ΔV FB) has an obvious positive shift.

[0130] Figure 16 (c) and Figure 16 (d) shows the energy band diagram of the Al2O3 / Ga2O3 interface before and after atomic nitrogen treatment under reverse bias. When reverse bias is applied, the presence of Q1 causes the depletion region width to expand from L1 to L2, which further repels electrons around the interface and increases the contact barrier (Φbh) between Al2O3 and Ga2O3. As a result, electrons are less likely to cross the interface in the field concentration region, which increases the breakdown voltage and thus plays an important role in improving the breakdown performance of the Ga2O3 TSBD.

[0131] Furthermore, the present invention performs TCAD simulation on the electric field distribution in Ga2O3 TSBD, as shown in FIG. Figure 17 As shown in Figure 2, Sentaurus was used in the simulation. Since atomic nitrogen treatment cannot be directly implemented in TCAD simulation, Figure 17 The theoretical analysis in introduced fixed negative charges at the Al2O3 / Ga2O3 interface to simulate trench interface modification. Figure 17 (a) shows the simulated electric field profile of the baseline Ga2O3 TSBD (no fixed negative charge) with a peak field strength of 10.1 MV / cm. Figure 17 (b) shows the simulated electric field profile of the modified Ga2O3 TSBD with the introduction of fixed negative charges at the Al2O3 / Ga2O3 interface. The peak field intensity is reduced to 8.8 MV / cm, and the maximum field intensity of both configurations is concentrated at the bottom of the trench (point C). Figure 17 Schematic diagram of the groove structure in (c) and Figure 17 The corresponding field profile along the ABCD tangent in (d) reveals two key features: first, the trench design effectively alleviates field crowding on the Ga2O3 surface by shifting the peak field to the trench bottom; second, comparative analysis of the BC segment of the above simulation confirms that the additional fixed negative charge at the interface reduces the interface field strength by 12.9%. These simulation results provide conclusive evidence that atomic nitrogen treatment can enhance the withstand voltage capability of Ga2O3 TSBDs.

[0132] In conclusion, atomic nitrogen treatment of the Al2O3 / Ga2O3 interface in Ga2O3 TSBD devices can significantly improve device performance, increasing the breakdown voltage from 832 V to 1200 V while maintaining a low V on and R on,spAt the same time, XPS spectroscopy demonstrated that the treatment reduced oxygen vacancies and promoted the formation of Ga-ON compounds at the interface, which can passivate defects and reduce leakage current. In addition, CV measurements showed that the treatment increased the fixed charge density at the Al2O3 / Ga2O3 interface, thereby expanding the depletion region and further strengthening the contact barrier. TCAD simulations further confirmed that the introduction of fixed negative charges at the Al2O3 / Ga2O3 interface through atomic nitrogen treatment can effectively optimize the electric field distribution, thereby enhancing the breakdown capability of the device.

[0133] Please refer to Figure 18 The third embodiment of the present invention provides a gallium oxide Schottky diode, comprising: a second electrode 30, a substrate 10, a gallium oxide epitaxial layer 20, an atomic nitrogen treated layer 40, a first electrode 50 and a trench 70;

[0134] In this embodiment, the substrate 10 has a first surface 10a and a second surface 10b opposite to each other; the second electrode 30 is disposed on the second surface 10b of the substrate 10; the gallium oxide epitaxial layer 20 is disposed on the first surface 10a of the substrate 10; the trench 70 is disposed in the gallium oxide epitaxial layer 20 and opens at the upper surface of the gallium oxide epitaxial layer 20; the atomic nitrogen treatment layer 40 is disposed in the trench 70; and the first electrode 50 is disposed on the gallium oxide epitaxial layer 20.

[0135] In this way, on the one hand, the atomic nitrogen treatment promotes the formation of Ga-ON compounds on the Schottky interface and optimizes the distribution of the interface state density, so that the Schottky barrier height of the atomic nitrogen treated layer is significantly increased, and the turn-on voltage is slightly increased while the breakdown voltage is significantly increased and the leakage current is reduced; on the other hand, since the atomic nitrogen treatment is performed on the surface of the gallium oxide epitaxial layer in the trench after etching, the Ga-ON compound is introduced, thereby effectively passivating the oxygen vacancies on the surface of the gallium oxide epitaxial layer, reducing the surface leakage current, and further improving the reliability of the device.

[0136] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present invention may be improved in only one or several aspects, without having to simultaneously solve all the technical problems listed in the prior art or background art. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as limiting the claim.

[0137] Although terms such as substrate, first surface, second surface, gallium oxide epitaxial layer, second electrode, atomic nitrogen treated layer, first electrode, insulating dielectric layer, and trench are frequently used herein, the use of other terms is not excluded. These terms are used merely to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitations is contrary to the spirit of the present invention. The terms "first," "second," and the like (if any) in the description and claims of the embodiments of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gallium oxide Schottky diode, characterized in that: include: substrate; a gallium oxide epitaxial layer, disposed on the substrate; an atomic nitrogen treatment layer disposed on the gallium oxide epitaxial layer; A first electrode is disposed on the gallium oxide epitaxial layer; The second electrode is disposed under the gallium oxide substrate.

2. The gallium oxide Schottky diode according to claim 1, characterized in that: The substrate is formed of β-Ga2O3 and has a first predetermined crystal plane direction; Preferably, the first predetermined crystal plane direction includes one of the (100), (010) and (001) crystal plane directions; Optionally, the substrate is made of N-type heavily doped gallium oxide; Preferably, the doping element is selected from any one or at least two of Sn, Si, and Ge, and the doping concentration is 1×10 18 cm -3 above; Optionally, the gallium oxide epitaxial layer is made of N-type lightly doped gallium oxide; Preferably, the doping element is selected from any one or at least two of Sn, Si, and Ge, and the doping concentration is 1×10 17 cm -3 the following.

3. The gallium oxide Schottky diode according to claim 1, characterized in that: The following characteristic peaks are present in the X-ray photoelectron spectrum of the atomic nitrogen treated layer: Two characteristic peaks appear in the 1s electron spectrum of nitrogen; and / or Three characteristic peaks appear in the 1s electron spectrum of oxygen; and / or There are three characteristic peaks in the 3d electron energy spectrum of gallium.

4. The gallium oxide Schottky diode according to claim 1, characterized in that: The oxygen vacancy concentration of the atomic nitrogen treatment layer is less than the oxygen vacancy concentration of the gallium oxide epitaxial layer.

5. A gallium oxide Schottky diode, characterized in that: include: substrate; a gallium oxide epitaxial layer, disposed on the gallium oxide substrate; A groove is provided in the gallium oxide epitaxial layer and opens at the upper surface of the gallium oxide epitaxial layer; an atomic nitrogen treatment layer disposed in the trench to passivate oxygen vacancies and surface defects induced by the etching process; A first electrode is disposed on the gallium oxide epitaxial layer; a second electrode disposed under the gallium oxide substrate; The insulating dielectric layer is disposed on the atomic nitrogen treated layer and is used to electrically insulate the first electrode from the atomic nitrogen treated layer.

6. The gallium oxide Schottky diode according to claim 5, characterized in that: The insulating dielectric layer is selected from dielectric materials having a dielectric constant in the range of 10-25; Preferably, the insulating dielectric layer is selected from any one of Al2O3, Gd2O3, HfO2, or a combination of at least two thereof.

7. The gallium oxide Schottky diode according to claim 5, characterized in that: The width of the groove in the first direction decreases linearly along the second direction; The first direction is a direction perpendicular to the thickness of the gallium oxide epitaxial layer, and the second direction is a direction from the gallium oxide epitaxial layer to the substrate; Preferably, a first width of the top of the trench in the first direction is in a range of 2 μm to 10 μm; the top of the trench is away from the substrate; a second width of the bottom of the trench in the first direction is in a range of 1 μm to 7 μm; and a thickness of the trench in the second direction is in a range of 1 μm to 5 μm. Preferably, the distance between the tops of two adjacent grooves in the plurality of grooves ranges from 1 μm to 10 μm.

8. The gallium oxide Schottky diode according to claim 5, characterized in that: The following characteristic peaks are present in the X-ray photoelectron spectrum of the atomic nitrogen treated layer: Two characteristic peaks appear in the 1s electron spectrum of nitrogen; and / or Three characteristic peaks appear in the 1s electron spectrum of oxygen; and / or There are three characteristic peaks in the 3d electron energy spectrum of gallium.

9. The gallium oxide Schottky diode according to claim 5, characterized in that: The oxygen vacancy concentration of the atomic nitrogen treatment layer is less than the oxygen vacancy concentration of the gallium oxide epitaxial layer.

10. A method for manufacturing a gallium oxide Schottky diode, It is characterized in that The following steps are involved: providing a substrate comprising a first surface and a second surface that are opposed to each other; forming a gallium oxide epitaxial layer on the first surface of the substrate; forming a second electrode on the second surface of the substrate; forming a trench on the gallium oxide epitaxial layer; performing atomic nitrogen treatment on at least a portion of the gallium oxide in the trench to form an atomic nitrogen treated layer; forming an insulating dielectric layer on the atomic nitrogen treated layer; A first electrode is formed on the gallium oxide epitaxial layer.

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