A gallium oxide field termination power diode based on soG and a preparation method thereof

Abstract

The application discloses a gallium oxide field termination power diode based on SOG, which comprises a cathode metal electrode, a substrate layer and a drift layer arranged in sequence from bottom to top; a plurality of P-type SOG dielectric structures are arranged on the drift layer, and an anode metal electrode is arranged between the surface of the P-type SOG dielectric structure and the intervals of the plurality of P-type SOG dielectric structures. The application further provides a preparation method of the gallium oxide field termination power diode based on SOG. The P-type SOG dielectric structure formed by B-doped SOG is used as a field termination, the electric field distribution in the device channel can be modulated, the peak value of the edge electric field of the anode metal electrode is reduced, the breakdown voltage of the device is improved, and the reverse leakage current of the anode metal electrode can be greatly reduced. In addition, the P-type SOG dielectric structure is used to form a P-type dielectric in a physical spin-on SOG mode, damage caused by a glow introduced during equipment deposition is avoided, the preparation process is simple and easy to implement, and the manufacturing cost is effectively reduced.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics technology, specifically relating to a gallium oxide field-terminated power diode based on SOG and its fabrication method. Background Technology

[0002] Due to the ultra-wide bandgap and high breakdown field strength of β-Ga2O3 material, power devices made from β-Ga2O3 have the characteristics of high voltage resistance and high power, and have the potential for application in the field of power electronics. In recent years, many scholars have been attracted to study β-Ga2O3 crystal material and power devices. However, the breakdown field strength of the devices currently prepared is still far from the theoretical limit. At the same time, there is a problem of large thermal field emission current (TFE leakage current). Moreover, the deposition of P-type dielectric is not only complicated, but also prone to drift layer (30) damage, which affects device performance and has a high cost. Summary of the Invention

[0003] To address the aforementioned problems in the prior art, this invention provides a gallium oxide field-terminated power diode based on SOG and its fabrication method. The technical problem to be solved by this invention is achieved through the following technical solution:

[0004] A first aspect of the present invention provides a gallium oxide field-terminated power diode based on SOG, comprising: a cathode metal electrode, a substrate layer, and a drift layer arranged sequentially from bottom to top;

[0005] Both the substrate layer and the drift layer are Sn-doped β-Ga2O3 materials, and the doping concentration of the drift layer is lower than that of the substrate layer; the crystal orientation of the substrate is (001);

[0006] Multiple P-type SOG dielectric structures are disposed on the drift layer, and spacers are formed between the multiple P-type SOG dielectric structures; the P-type SOG dielectric structures are formed by spin-coating B-doped SOG.

[0007] An anode metal electrode is provided between the surface of the P-type SOG dielectric structure and the spacing between the plurality of P-type SOG dielectric structures.

[0008] In one embodiment of the present invention, the doping concentration of the P-type SOG dielectric structure is 1×10⁻⁶. 17 cm -3 ~1×10 19 cm -3 .

[0009] In one embodiment of the present invention, the P-type SOG dielectric structure is a block structure.

[0010] In one embodiment of the present invention, the P-type SOG dielectric structure is a ring structure;

[0011] Multiple P-type SOG dielectric structures form a nested ring structure, with the interval between two adjacent P-type SOG dielectric structures.

[0012] In one embodiment of the present invention, the interval is 1 μm to 11 μm.

[0013] In one embodiment of the present invention, the width of the P-type SOG dielectric structure is 1μm to 11μm and the thickness is 100nm to 500nm.

[0014] In one embodiment of the present invention, the cathode metal electrode is Ti and Au stacked sequentially from top to bottom; the anode metal electrode is Ni and Au stacked sequentially from bottom to top.

[0015] In one embodiment of the present invention, the doping concentration of the substrate layer is 1×10⁻⁶. 18 cm -3 ~1×10 20 cm -3 The doping concentration of the drift layer is 1×10⁻⁶. 17 cm -3 ~1×10 19 cm -3 .

[0016] A second aspect of this invention provides a method for fabricating a gallium oxide field-terminated power diode based on SOG, comprising the following steps:

[0017] Step 1: A drift layer is grown on the substrate; wherein both the substrate and the drift layer are Sn-doped β-Ga2O3 materials, and the doping concentration of the drift layer is lower than that of the substrate; the crystal orientation of the substrate is (001).

[0018] Step 2: Deposit metal on the surface of the substrate layer opposite to the drift layer, and form a cathode metal electrode after annealing;

[0019] Step 3: Spin-coat B-doped SOG over the drift layer. After spin-coating, heat-dry the coating to form a P-type SOG dielectric layer.

[0020] Step four: Etch the P-type SOG dielectric layer to form multiple P-type SOG dielectric structures; wherein, a gap is formed between the multiple P-type SOG dielectric structures;

[0021] Step 5: Deposit metal on the surface of the product prepared in step 4 to form an anode metal electrode, and the diode provided in the first aspect of the present invention is obtained after the preparation is completed.

[0022] The beneficial effects of this invention are:

[0023] This invention uses boron-doped SOG to form a p-type SOG dielectric structure as a field terminal, which can modulate the electric field distribution in the device channel. The p-type SOG dielectric structure can form a high-resistivity PN junction region at the edge of the device, reduce the peak electric field at the edge of the anode metal electrode, and thus improve the breakdown voltage of the device.

[0024] Meanwhile, the P-type SOG dielectric structure can form a heterojunction structure with Ga2O3, and its barrier height is greater than that of the Schottky junction structure, which can significantly reduce the reverse leakage current of the anode metal electrode.

[0025] Furthermore, the P-type SOG dielectric structure is formed by physically spin-coating SOG, which avoids damage caused by glow discharge during equipment deposition. The preparation process is simple and easy to implement, effectively reducing manufacturing costs.

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] Figure 1 This is a schematic cross-sectional view of a gallium oxide field-terminated power diode based on SOG provided in an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the fabrication process of a gallium oxide field-terminated power diode based on SOG provided in an embodiment of the present invention. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0030] Example 1

[0031] like Figure 1 As shown, a gallium oxide field-terminated power diode based on SOG includes: a cathode metal electrode 10, a substrate layer 20 and a drift layer 30 arranged sequentially from bottom to top;

[0032] Both substrate layer 20 and drift layer 30 are Sn-doped β-Ga2O3 materials, and the doping concentration of drift layer 30 is lower than that of substrate layer 20. The crystal orientation of the substrate is (001).

[0033] Multiple P-type SOG dielectric structures 40 are disposed on the drift layer 30, and gaps are formed between the multiple P-type SOG dielectric structures 40; the P-type SOG dielectric structures 40 are formed by spin-coating B-doped SOG.

[0034] An anode metal electrode 50 is provided between the surface of the P-type SOG dielectric structure 40 and the spacing between the plurality of P-type SOG dielectric structures 40.

[0035] Optionally, the doping concentration of the p-type SOG dielectric structure 40 is 1×10⁻⁶. 17 cm -3 ~1×10 19 cm -3 The doping concentration of substrate layer 20 is 1×10⁻⁶. 18 cm -3 ~1×10 20 cm -3 The doping concentration of drift layer 30 is 1×10⁻⁶. 17 cm -3 ~1×10 19 cm -3 The thickness of the drift layer 30 is 2–14 μm.

[0036] In one feasible implementation, the P-type SOG dielectric structure 40 is a block structure. The width W of the P-type SOG dielectric structure 40 is 1μm to 11μm, and the thickness is 100nm to 500nm. Multiple block-shaped P-type SOG dielectric structures 40 are arranged sequentially at intervals, with the interval between two adjacent block-shaped P-type SOG dielectric structures 40 being 1μm to 11μm.

[0037] In one feasible implementation, the P-type SOG dielectric structure 40 is a ring structure. Multiple P-type SOG dielectric structures 40 form a nested ring structure, with a gap between adjacent P-type SOG dielectric structures 40. The width W of each P-type SOG dielectric structure 40 is 1 μm to 11 μm, and its thickness is 100 nm to 500 nm. The gaps between adjacent ring-shaped P-type SOG dielectric structures 40 are 1 μm to 11 μm. The P-type SOG dielectric structures 40 have different radii, with the smaller-radius ring-shaped P-type SOG dielectric structure 40 nested within the larger-radius ring-shaped P-type SOG dielectric structure 40.

[0038] Optionally, the cathode metal electrode 10 is composed of Ti and Au stacked sequentially from top to bottom, with Ti / Au thicknesses of 20 / 200 nm. The anode metal electrode 50 is composed of Ni and Au stacked sequentially from bottom to top, with Ni / Au thicknesses of 45 / 400 nm.

[0039] In this embodiment, boron-doped SOG (spin-on-glass coating) forms a p-type SOG dielectric structure 40 as a field terminator, which can modulate the electric field distribution within the device channel. The p-type SOG dielectric structure 40 enables the formation of a high-resistivity PN junction region at the device edge, reducing the peak electric field at the edge of the anode metal electrode 50 and thus improving the device breakdown voltage. Simultaneously, the p-type SOG dielectric structure can form a heterojunction structure with Ga2O3, whose barrier height is greater than that of a Schottky junction structure, significantly reducing the reverse leakage current of the anode metal electrode 50. Furthermore, the p-type SOG dielectric structure 40 is formed by physically spin-coating SOG, avoiding damage introduced by glow discharge during device deposition. The fabrication process is simple and easy to implement, effectively reducing manufacturing costs.

[0040] Example 2

[0041] like Figure 2 As shown, a method for fabricating a gallium oxide field-terminated power diode based on SOG includes the following steps:

[0042] Step 1: A drift layer 30 is grown on the substrate layer 20; wherein the substrate layer 20 and the drift layer 30 are both Sn-doped β-Ga2O3 materials, and the doping concentration of the drift layer 30 is lower than that of the substrate layer 20; the crystal orientation of the substrate is (001).

[0043] The doping concentration of substrate layer 20 is 1×10⁻⁶. 18 cm -3 ~1×10 20 cm -3 The doping concentration of drift layer 30 is 1×10⁻⁶. 17 cm -3 ~1×10 19 cm -3 The thickness of the drift layer 30 is 2–14 μm.

[0044] Step 2: Deposit metal on the surface of the back drift layer 30 of the substrate layer 20, and form the cathode metal electrode 10 after annealing.

[0045] The cathode metal electrode 10 is composed of Ti and Au stacked sequentially from top to bottom, with the thicknesses of Ti and Au being 20 and 200 nm, respectively.

[0046] Step 3: Spin-coat B-doped SOG over the drift layer 30. After spin-coating, heat-dry to form a P-type SOG dielectric layer; the doping concentration of the P-type SOG dielectric layer is 1×10⁻⁶. 17 cm -3 ~1×10 19 cm -3 .

[0047] Step four: Etch a P-type SOG dielectric layer to form multiple P-type SOG dielectric structures 40; wherein, a spacer is formed between the multiple P-type SOG dielectric structures 40. The width W of the P-type SOG dielectric structure 40 is 1μm to 11μm, the thickness is 100nm to 500nm, and the spacing is 1μm to 11μm.

[0048] Step 5: Deposit metal on the surface of the product prepared in step 4 to form an anode metal electrode 50. After preparation, the diode of Example 1 is obtained.

[0049] The anode metal electrode 50 is composed of Ni and Au stacked sequentially from bottom to top, with Ni / Au thicknesses of 45 / 400 nm, respectively.

[0050] The preparation method of Example 2 will be described in detail below through three specific examples:

[0051] Example 3

[0052] Fabrication of a gallium oxide field-terminated power diode with a 2μm drift layer 30:

[0053] Step 31: Epitaxial growth of gallium oxide drift layer 30.

[0054] A lightly doped β-Ga2O3 layer is grown as a drift layer 30 above a Sn-doped (001) oriented β-Ga2O3 substrate 20. The drift layer 30 has a thickness of 2 μm and a doping concentration of 1 × 10⁻⁶. 15 cm -3 The substrate layer 20 has a doping concentration of 1×10⁻⁶. 18 cm -3 .

[0055] Step 32, Fabrication of the cathode electrode:

[0056] Step 32.1: Cathode metals Ti and Au are sputtered sequentially below the substrate layer 20, with thicknesses of 20 / 200 nm, respectively;

[0057] Step 32.2: Rapid thermal annealing is performed to alloy the cathode metal, completing the fabrication of the 10Ti / Au cathode metal electrode.

[0058] Step 33, fabricate the P-type SOG field terminal:

[0059] Step 33.1: Spin-coat B-doped SOG onto drift layer 30. The spin-coating thickness is 100 nm. The doping concentration of the B-doped SOG is 1 × 10⁻⁶. 17 cm -3 ,

[0060] Step 33.2: Heat and dry to form a P-type SOG dielectric layer;

[0061] Step 34: Selectively etch the dried SOG to a depth of 100 nm to form a P-type SOG dielectric structure 40 with a width W of 1 μm and a spacing of 1 μm.

[0062] During etching, multiple blocky structures or multiple ring structures with decreasing radii from the outside to the inside are formed.

[0063] Step 35: Fabricate the anode electrode.

[0064] The anode metal was evaporated on the surface of the product prepared in step 34 using an electron beam evaporation stage. Ni and Au were evaporated sequentially to form a Ni / Au metal stack with thicknesses of 45 / 400 nm, respectively. After evaporation, the metal was stripped to form the anode metal electrode 50. The gallium oxide field-terminated power diode of Example 1 was obtained.

[0065] Example 4

[0066] Fabrication of a gallium oxide field-terminated power diode with an 8 μm drift layer 30:

[0067] Step 41, epitaxial growth of gallium oxide drift layer 30.

[0068] A lightly doped β-Ga2O3 layer is grown as a drift layer 30 above a Sn-doped (001) oriented β-Ga2O3 substrate 20. The drift layer 30 has a thickness of 8 μm and a doping concentration of 1 × 10⁻⁶. 16 cm -3 The substrate layer 20 has a doping concentration of 1×10⁻⁶. 19 cm -3 .

[0069] Step 42, Fabrication of the cathode electrode:

[0070] Step 42.1: Cathode metals Ti and Au are sputtered sequentially below the substrate layer 20, with thicknesses of 20 / 200 nm, respectively;

[0071] Step 42.2: Rapid thermal annealing is performed to alloy the cathode metal, completing the fabrication of the 10Ti / Au cathode metal electrode.

[0072] Step 43, fabricate the P-type SOG field terminal:

[0073] Step 43.1: Spin-coat B-doped SOG onto drift layer 30. The spin-coating thickness is 300 nm. The doping concentration of the B-doped SOG is 1 × 10⁻⁶. 18 cm -3 ,

[0074] Step 43.2: Heat and dry to form a P-type SOG dielectric layer;

[0075] Step 44: Selectively etch the dried SOG to a depth of 300 nm to form a P-type SOG dielectric structure 40 with a width W of 6 μm and a spacing of 6 μm.

[0076] During etching, multiple blocky structures or multiple ring structures with decreasing radii from the outside to the inside are formed.

[0077] Step 45: Fabricate the anode electrode.

[0078] The anode metal was evaporated on the surface of the product prepared in step 44 using an electron beam evaporation stage. Ni and Au were evaporated sequentially to form a Ni / Au metal stack with thicknesses of 45 / 400 nm, respectively. After evaporation, the metal was stripped to form the anode metal electrode 50. The gallium oxide field-terminated power diode of Example 1 was obtained.

[0079] Example 5

[0080] Fabrication of a gallium oxide field-terminated power diode with a 14 μm drift layer 30:

[0081] Step 51: Epitaxial growth of gallium oxide drift layer 30.

[0082] A lightly Sn-doped β-Ga2O3 layer is grown as a drift layer 30 above a Sn-doped (001) oriented β-Ga2O3 substrate 20. The drift layer 30 has a thickness of 14 μm and a doping concentration of 1 × 10⁻⁶. 17 cm -3 The substrate layer 20 has a doping concentration of 1×10⁻⁶. 20 cm -3 .

[0083] Step 52, fabricate the cathode electrode:

[0084] Step 52.1: Cathode metals Ti and Au are sputtered sequentially below the substrate layer 20, with thicknesses of 20 / 200 nm, respectively;

[0085] Step 52.2: Rapid thermal annealing is performed to alloy the cathode metal, completing the fabrication of the 10Ti / Au cathode metal electrode.

[0086] Step 53, fabricate the P-type SOG field terminal:

[0087] Step 53.1: Spin-coat B-doped SOG onto drift layer 30. The spin-coating thickness is 500 nm. The doping concentration of the B-doped SOG is 1 × 10⁻⁶. 19 cm -3 ,

[0088] Step 53.2: Heat and dry to form a P-type SOG dielectric layer;

[0089] Step 54: Selectively etch the dried SOG to a depth of 500 nm to form a P-type SOG dielectric structure 40 with a width W of 11 μm and a spacing of 11 μm.

[0090] During etching, multiple blocky structures or multiple ring structures with decreasing radii from the outside to the inside are formed.

[0091] Step 55: Fabricate the anode electrode.

[0092] An electron beam evaporation stage is used to evaporate the anode metal on the surface of the product prepared in step 54. Ni and Au are evaporated sequentially to form a Ni / Au metal stack with thicknesses of 45 / 400 nm, respectively. After evaporation, the metal is stripped to form the anode metal electrode 50.

[0093] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0094] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0095] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0096] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0097] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0098] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A gallium oxide field-terminated power diode based on SOG, characterized in that, include: The cathode metal electrode (10), the substrate layer (20), and the drift layer (30) are arranged sequentially from bottom to top; Both the substrate layer (20) and the drift layer (30) are Sn-doped β-Ga2O3 materials, and the doping concentration of the drift layer (30) is lower than that of the substrate layer (20); the crystal orientation of the substrate is (001). Multiple P-type SOG dielectric structures (40) are disposed on the drift layer (30), and a gap is formed between the multiple P-type SOG dielectric structures (40); the P-type SOG dielectric structures (40) are formed by spin-coating B-doped SOG; the P-type SOG dielectric structures (40) and the drift layer (30) form a heterojunction structure; An anode metal electrode (50) is provided between the surface of the P-type SOG dielectric structure (40) and the spacing between the plurality of P-type SOG dielectric structures (40).

2. The gallium oxide field-terminated power diode based on SOG according to claim 1, characterized in that, The doping concentration of the P-type SOG dielectric structure (40) is 1×10⁻⁶. 17 cm -3 ~1×10 19 cm -3 .

3. A gallium oxide field-terminated power diode based on SOG according to claim 2, characterized in that, The P-type SOG dielectric structure (40) is a block structure.

4. A gallium oxide field-terminated power diode based on SOG according to claim 2, characterized in that, The P-type SOG dielectric structure (40) is a ring structure; Multiple P-type SOG dielectric structures (40) form a nested ring structure, with the interval between two adjacent P-type SOG dielectric structures (40).

5. A gallium oxide field-terminated power diode based on SOG according to claim 2, characterized in that, The interval is 1μm to 11μm.

6. A gallium oxide field-terminated power diode based on SOG according to claim 2, characterized in that, The width of the P-type SOG dielectric structure (40) is 1μm~11μm and the thickness is 100nm~500nm.

7. A gallium oxide field-terminated power diode based on SOG according to claim 2, characterized in that, The cathode metal electrode (10) is composed of Ti and Au stacked sequentially from top to bottom; the anode metal electrode (50) is composed of Ni and Au stacked sequentially from bottom to top.

8. A gallium oxide field-terminated power diode based on SOG according to claim 2, characterized in that, The doping concentration of the substrate layer (20) is 1×10⁻⁶. 18 cm -3 ~1×10 20 cm -3 The doping concentration of the drift layer (30) is 1×10⁻⁶. 17 cm -3 ~1×10 19 cm -3 .

9. A method for fabricating a gallium oxide field-terminated power diode based on SOG, characterized in that, Includes the following steps: Step 1: A drift layer (30) is grown on the substrate layer (20); wherein the substrate layer (20) and the drift layer (30) are both Sn-doped β-Ga2O3 materials, and the doping concentration of the drift layer (30) is lower than that of the substrate layer (20); the crystal orientation of the substrate is (001). Step 2: Deposit metal on the surface of the substrate layer (20) opposite to the drift layer (30), and form a cathode metal electrode (10) after annealing; Step 3: Spin-coat B-doped SOG over the drift layer (30). After spin-coating, heat-dry the coating to form a P-type SOG dielectric layer. Step 4: Etch the P-type SOG dielectric layer to form multiple P-type SOG dielectric structures (40); wherein, a gap is formed between the multiple P-type SOG dielectric structures (40); Step 5: Deposit metal on the surface of the product prepared in step 4 to form an anode metal electrode (50), and the diode as described in any one of claims 1-8 is obtained upon completion of the preparation.

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