Schottky barrier diode containing mixed anode and mixed cathode and preparation method and application thereof

Abstract

The invention discloses a Schottky barrier diode containing a mixed anode and a mixed cathode and a preparation method and application thereof. The Schottky barrier diode containing the mixed anode and the mixed cathode comprises a substrate, an AlN nucleating layer, a GaN buffer layer, a GaN channel layer, an AlGaN barrier layer and a passivation layer which are sequentially stacked, and further comprises a first cathode metal electrode, a first anode metal electrode, a GaN cap layer, an anode field plate, a second cathode metal electrode and a second anode metal electrode. The Schottky barrier diode is provided with the mixed anode structure and the mixed cathode structure, has the advantages of being large in inflection point voltage, small in turn-on voltage, high in reliability and the like, and is suitable for large-scale industrial production and application.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a Schottky barrier diode containing a mixed anode and a mixed cathode, and a preparation method and application thereof. Background Art

[0002] Schottky barrier diodes, also known as hot carrier diodes, are indispensable devices in most power electronic products. They need to have a low turn-on voltage, a specific on-resistance, a low reverse leakage current, and a high breakdown voltage to reduce power loss during use. Gallium nitride (GaN) has a large bandgap and high electron mobility, and is a semiconductor material with broad application prospects. Si / GaN-based Schottky barrier diodes have both good performance and low cost, and have great commercial potential, which has attracted widespread attention. However, existing Si / GaN-based Schottky barrier diodes generally have problems with low inflection point voltage and excessively high turn-on voltage, which leads to easy failure and insufficient power in many application scenarios, making it difficult to fully meet actual application requirements.

[0003] Therefore, it is of great significance to develop a Schottky barrier diode with a large inflection point voltage, a small turn-on voltage and high reliability. Summary of the invention

[0004] The object of the present invention is to provide a Schottky barrier diode containing a mixed anode and a mixed cathode, and a preparation method and application thereof.

[0005] The technical solution adopted by the present invention is:

[0006] A Schottky barrier diode containing a mixed anode and a mixed cathode, comprising a substrate, an AlN nucleation layer, a GaN buffer layer, a GaN channel layer, an AlGaN barrier layer and a passivation layer stacked in sequence, and also comprising a first cathode metal electrode, a first anode metal electrode, a GaN cap layer, an anode field plate, a second cathode metal electrode and a second anode metal electrode; the first cathode metal electrode is arranged on the side of the AlGaN barrier layer away from the GaN channel layer; the first anode metal electrode is arranged on the side of the GaN channel layer away from the GaN buffer layer, and is in contact with the AlGaN barrier layer, the GaN cap layer and the anode field plate; the GaN cap layer is arranged on the side of the AlGaN barrier layer away from the GaN channel layer, and is in contact with the passivation layer; the anode field plate is arranged on the side of the GaN cap layer away from the AlGaN barrier layer; the second cathode metal electrode is arranged inside the first anode metal electrode, and is in contact with the GaN channel layer; the second anode metal electrode is arranged on the side of the AlGaN barrier layer away from the GaN channel layer, and is in contact with the first cathode metal electrode and the passivation layer.

[0007] Preferably, the substrate is one of a Si substrate, a GaAs substrate and a sapphire substrate.

[0008] Preferably, the thickness of the AlN nucleation layer is 0.5 nm to 1.5 nm.

[0009] Preferably, the GaN buffer layer has a thickness of 200 nm to 400 nm.

[0010] Preferably, the GaN channel layer has a thickness of 100 nm to 300 nm.

[0011] Preferably, the AlGaN barrier layer has a thickness of 10 nm to 30 nm.

[0012] Preferably, the thickness of the passivation layer is 40 nm to 80 nm.

[0013] Preferably, the passivation layer comprises Si3N4.

[0014] Preferably, the width of the first cathode metal electrode is 3 μm to 6 μm.

[0015] Preferably, the first cathode metal electrode comprises components including Ti, Al, Ni and Au.

[0016] Preferably, the width of the first anode metal electrode is 5 μm to 8 μm.

[0017] Preferably, the first anode metal electrode comprises Ni and Au.

[0018] Preferably, the distance between the first cathode metal electrode and the first anode metal electrode (the distance between the left edge of the first cathode metal electrode and the right edge of the first anode metal electrode, ie the shortest distance between the two) is 15 μm to 25 μm.

[0019] Preferably, the GaN capping layer has a thickness of 10 nm to 30 nm.

[0020] Preferably, the thickness of the anode field plate is 30 nm to 50 nm.

[0021] Preferably, the anode field plate is composed of Ni and Au.

[0022] Preferably, the width of the second cathode metal electrode is 2 μm to 5 μm.

[0023] Preferably, the second cathode metal electrode comprises components including Ti, Al, Ni and Au.

[0024] Preferably, the width of the second anode metal electrode is 2 μm to 6 μm.

[0025] Preferably, the second anode metal electrode comprises Ni and Au.

[0026] A method for preparing a Schottky barrier diode containing a mixed anode and a mixed cathode as described above comprises the following steps:

[0027] 1) depositing an AlN nucleation layer, a GaN buffer layer, a GaN channel layer, an AlGaN barrier layer and a GaN cap layer on a substrate in sequence;

[0028] 2) Performing photolithography and CF4 etching source etching on the surface of the GaN cap layer to expose part of the AlGaN barrier layer;

[0029] 3) performing photolithography and CF4 etching source etching on the surface of the AlGaN barrier layer to form a first cathode metal electrode preparation area and a second cathode metal electrode preparation area, and then performing photoresist stripping and annealing after evaporating electrode metal to form a first cathode metal electrode and a second cathode metal electrode;

[0030] 4) performing photolithography and CF4 etching source etching on the surface of the AlGaN barrier layer to form a first anode metal electrode preparation region and a second anode metal electrode preparation region, and then performing photoresist stripping after evaporating electrode metal to form a first anode metal electrode and a second anode metal electrode;

[0031] 5) Evaporating electrode metal on the surface of the GaN cap layer to form an anode field plate;

[0032] 6) Photolithography is performed on the surface of the AlGaN barrier layer to form a passivation layer preparation area, and then a passivation layer material is deposited to form a passivation layer, thereby obtaining a Schottky barrier diode containing a mixed anode and a mixed cathode.

[0033] An electronic product comprises the Schottky barrier diode containing a mixed anode and a mixed cathode.

[0034] The beneficial effects of the present invention are as follows: the Schottky barrier diode of the present invention is provided with a mixed anode structure and a mixed cathode structure, which has the advantages of a large inflection point voltage, a small turn-on voltage, and high reliability, and is suitable for large-scale industrial production and application.

[0035] Specifically:

[0036] 1) The Schottky barrier diode of the present invention is provided with a hybrid anode structure. When the voltage is less than the threshold voltage of the Schottky barrier and greater than the threshold voltage of the ohmic contact of the cathode metal electrode in the hybrid anode structure, the device can be turned on, which greatly reduces the turn-on voltage of the device;

[0037] 2) The Schottky barrier diode of the present invention is provided with a mixed cathode structure. When forward conducting, the Schottky contact at the cathode can deplete electrons to a certain extent, playing a role in current regulation, thereby increasing the inflection point voltage of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the structure of the Schottky barrier diode containing a mixed anode and a mixed cathode in Example 1.

[0039] Figure 2 Schematic diagram of the structure of a Schottky barrier diode of a comparative example.

[0040] Explanation of the accompanying drawings: 10, Si substrate; 20, AlN nucleation layer; 30, GaN buffer layer; 40, GaN channel layer; 50, AlGaN barrier layer; 60, passivation layer; 70, first cathode metal electrode; 80, first anode metal electrode; 90, GaN capping layer; 100, anode field plate; 110, second cathode metal electrode; 120, second anode metal electrode.

[0041] Figure 3 The saturation current test results of the Schottky barrier diodes containing mixed anodes and mixed cathodes of Examples 1 to 3 and the Schottky barrier diode of the comparative example are shown.

[0042] Figure 4 The graph is a breakdown voltage test result diagram of the Schottky barrier diodes containing mixed anodes and mixed cathodes of Examples 1 to 3 and the Schottky barrier diode of the comparative example. DETAILED DESCRIPTION

[0043] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0044] Embodiment 1:

[0045] A Schottky barrier diode with a mixed anode and a mixed cathode (schematic diagram as shown in FIG. Figure 1 ), which consists of a Si substrate 10, an AlN nucleation layer 20, a GaN buffer layer 30, a GaN channel layer 40, an AlGaN barrier layer 50, a passivation layer 60, a first cathode metal electrode 70, a first anode metal electrode 80, a GaN cap layer 90, an anode field plate 100, a second cathode metal electrode 110 and a second anode metal electrode 120;

[0046] A Si substrate 10, an AlN nucleation layer 20, a GaN buffer layer 30, a GaN channel layer 40, an AlGaN barrier layer 50 and a passivation layer 60 are sequentially stacked;

[0047] The first cathode metal electrode 70 is disposed on the side of the AlGaN barrier layer 50 away from the GaN channel layer 40;

[0048] The first anode metal electrode 80 is disposed on the side of the GaN channel layer 40 away from the GaN buffer layer 30 and is in contact with the AlGaN barrier layer 50 , the GaN cap layer 90 and the anode field plate 100 ;

[0049] The GaN cap layer 90 is disposed on the side of the AlGaN barrier layer 50 away from the GaN channel layer 40 and is in contact with the passivation layer 60;

[0050] The anode field plate 100 is disposed on the side of the GaN cap layer 90 away from the AlGaN barrier layer 50 ;

[0051] The second cathode metal electrode 110 is disposed inside the first anode metal electrode 80 and is in contact with the GaN channel layer 40;

[0052] The second anode metal electrode 120 is disposed on a side of the AlGaN barrier layer 50 away from the GaN channel layer 40 , and is in contact with the first cathode metal electrode 70 and the passivation layer 60 .

[0053] The preparation method of the Schottky barrier diode containing a mixed anode and a mixed cathode is as follows:

[0054] 1) epitaxially growing an AlN nucleation layer with a thickness of 1 nm, a GaN buffer layer with a thickness of 300 nm, a GaN channel layer with a thickness of 200 nm, an AlGaN barrier layer with a thickness of 20 nm, and a GaN capping layer with a thickness of 20 nm on a Si substrate by a metal organic chemical vapor deposition (MOCVD) method;

[0055] 2) Performing photolithography and CF4 etching source etching on the surface of the GaN cap layer to expose part of the AlGaN barrier layer;

[0056] 3) Photolithography and CF4 etching source etching are performed on the surface of the AlGaN barrier layer to form a first cathode metal electrode preparation area and a second cathode metal electrode preparation area, and then Ti-Al-Ni-Au alloy is evaporated by electron beam evaporation, with an electron beam energy of 3 kV and a vacuum degree of P≤10 -3 Pa, then stripping the photoresist with acetone and annealing in a nitrogen atmosphere to form a first cathode metal electrode with a width of 3 μm and a second cathode metal electrode with a width of 3 μm;

[0057] 4) Photolithography and CF4 etching source etching are performed on the surface of the AlGaN barrier layer to form a first anode metal electrode preparation area and a second anode metal electrode preparation area, and then Ni-Au alloy is evaporated by electron beam evaporation, with an electron beam energy of 3kV and a vacuum degree of P≤10-3 Pa, and then using acetone to strip the photoresist to form a first anode metal electrode with a width of 8 μm and a distance of 20 μm from the first cathode metal electrode, and a second anode metal electrode with a width of 2 μm;

[0058] 5) Ni-Au alloy is deposited on the surface of the GaN cap layer by electron beam evaporation, with an electron beam energy of 3 kV and a vacuum degree of P ≤ 10 -3 Pa, forming an anode field plate with a thickness of 40 nm;

[0059] 6) Photolithography is performed on the surface of the AlGaN barrier layer to form a passivation layer preparation area, and then a Si3N4 layer with a thickness of 60 nm is deposited by low-pressure chemical vapor deposition to form a passivation layer, thereby obtaining a Schottky barrier diode containing a mixed anode and a mixed cathode.

[0060] Embodiment 2:

[0061] A Schottky barrier diode containing a mixed anode and a mixed cathode is completely the same as the Schottky barrier diode containing a mixed anode and a mixed cathode in Example 1 except that the width of the second cathode metal electrode is adjusted from "3μm" to "5μm".

[0062] Embodiment 3:

[0063] A Schottky barrier diode containing a mixed anode and a mixed cathode is completely the same as the Schottky barrier diode containing a mixed anode and a mixed cathode in Example 1 except that the width of the second cathode metal electrode is adjusted from "3μm" to "4μm".

[0064] Comparative Example: (without mixed anode structure and mixed cathode structure)

[0065] A Schottky barrier diode (schematic diagram as shown in FIG. Figure 2 ), which consists of a Si substrate 10, an AlN nucleation layer 20, a GaN buffer layer 30, a GaN channel layer 40, an AlGaN barrier layer 50, a passivation layer 60, a first cathode metal electrode 70, a first anode metal electrode 80, a GaN capping layer 90 and an anode field plate 100;

[0066] A Si substrate 10, an AlN nucleation layer 20, a GaN buffer layer 30, a GaN channel layer 40, an AlGaN barrier layer 50 and a passivation layer 60 are sequentially stacked;

[0067] The first cathode metal electrode 70 is disposed on the side of the AlGaN barrier layer 50 away from the GaN channel layer 40 and in contact with the passivation layer 60;

[0068] The first anode metal electrode 80 is disposed on the side of the GaN channel layer 40 away from the GaN buffer layer 30 and is in contact with the AlGaN barrier layer 50 , the GaN cap layer 90 and the anode field plate 100 ;

[0069] The GaN cap layer 90 is disposed on the side of the AlGaN barrier layer 50 away from the GaN channel layer 40 and is in contact with the passivation layer 60;

[0070] The anode field plate 100 is disposed on the side of the GaN cap layer 90 away from the AlGaN barrier layer 50 .

[0071] The preparation method of the above-mentioned Schottky barrier diode is as follows:

[0072] 1) epitaxially growing an AlN nucleation layer with a thickness of 1 nm, a GaN buffer layer with a thickness of 300 nm, a GaN channel layer with a thickness of 200 nm, an AlGaN barrier layer with a thickness of 20 nm, and a GaN capping layer with a thickness of 20 nm on a Si substrate by a metal organic chemical vapor deposition (MOCVD) method;

[0073] 2) Performing photolithography and CF4 etching source etching on the surface of the GaN cap layer to expose part of the AlGaN barrier layer;

[0074] 3) Photolithography and CF4 etching source etching are performed on the surface of the AlGaN barrier layer to form the first cathode metal electrode preparation area, and then Ti-Al-Ni-Au alloy is evaporated by electron beam evaporation. The electron beam energy is 3kV and the vacuum degree P≤10 - 3 Pa, then stripping the photoresist with acetone and annealing in a nitrogen atmosphere to form a first cathode metal electrode with a width of 3 μm;

[0075] 4) Photolithography and CF4 etching source etching are performed on the surface of the AlGaN barrier layer to form the first anode metal electrode preparation area, and then Ni-Au alloy is evaporated by electron beam evaporation, the electron beam energy is 3kV, and the vacuum degree P≤10 -3 Pa, and then using acetone to strip the photoresist to form a first anode metal electrode with a width of 8 μm and a distance of 20 μm from the first cathode metal electrode;

[0076] 5) Ni-Au alloy is deposited on the surface of the GaN cap layer by electron beam evaporation, with an electron beam energy of 3 kV and a vacuum degree of P ≤ 10 -3 Pa, forming an anode field plate with a thickness of 40 nm;

[0077] 6) Photolithography is performed on the surface of the AlGaN barrier layer to form a passivation layer preparation area, and then a Si3N4 layer with a thickness of 60 nm is deposited by low-pressure chemical vapor deposition to form a passivation layer, thereby obtaining a Schottky barrier diode.

[0078] Performance Test:

[0079] The saturation current test results of the Schottky barrier diodes containing mixed anodes and mixed cathodes in Examples 1 to 3 and the Schottky barrier diodes in the comparative example are as follows: Figure 3 The breakdown voltage test results are shown in Figure 4 shown.

[0080] Depend on Figure 3 It can be seen that the inflection point voltages of the Schottky barrier diodes containing mixed anodes and mixed cathodes in Examples 1 to 3 are 1.2V, 1.4V and 1.1V respectively, while the inflection point voltage of the Schottky barrier diode in the comparative example (without mixed anode structure and mixed cathode structure) is 0.8V. The breakdown voltage of the Schottky barrier diode containing mixed anodes and mixed cathodes in Example 1 is increased by up to 50% compared with the Schottky barrier diode in the comparative example, indicating that setting a mixed anode structure and a mixed cathode structure can indeed significantly increase the inflection point voltage of the Schottky barrier diode device.

[0081] Depend on Figure 4 It can be seen that the turn-on voltages of the Schottky barrier diodes containing a mixed anode and a mixed cathode in Examples 1 to 3 are 0.35V, 0.40V and 0.30V respectively, while the turn-on voltage of the Schottky barrier diode in the comparative example (without a mixed anode structure and a mixed cathode structure) is 0.60V. The turn-on voltage of the Schottky barrier diode containing a mixed anode and a mixed cathode in Example 1 is reduced by as much as 42% compared with the Schottky barrier diode in the comparative example, indicating that setting a mixed anode structure and a mixed cathode structure can indeed significantly reduce the turn-on voltage of the Schottky barrier diode device.

[0082] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A Schottky barrier diode comprising a mixed anode and a mixed cathode, characterized in that: The composition includes a substrate, an AlN nucleation layer, a GaN buffer layer, a GaN channel layer, an AlGaN barrier layer and a passivation layer which are stacked in sequence, and also includes a first cathode metal electrode, a first anode metal electrode, a GaN cap layer, an anode field plate, a second cathode metal electrode and a second anode metal electrode; the first cathode metal electrode is arranged on the side of the AlGaN barrier layer away from the GaN channel layer; the first anode metal electrode is arranged on the side of the GaN channel layer away from the GaN buffer layer, and is in contact with the AlGaN barrier layer, the GaN cap layer and the anode field plate; the GaN cap layer is arranged on the side of the AlGaN barrier layer away from the GaN channel layer, and is in contact with the passivation layer; The anode field plate is arranged on the side of the GaN cap layer away from the AlGaN barrier layer; the second cathode metal electrode is arranged inside the first anode metal electrode and in contact with the GaN channel layer; the second anode metal electrode is arranged on the side of the AlGaN barrier layer away from the GaN channel layer, and in contact with the first cathode metal electrode and the passivation layer.

2. The Schottky barrier diode comprising a mixed anode and a mixed cathode according to claim 1, characterized in that: The thickness of the AlN nucleation layer is 0.5nm-1.5nm; the thickness of the GaN buffer layer is 200nm-400nm; the thickness of the GaN channel layer is 100nm-300nm; and the thickness of the AlGaN barrier layer is 10nm-30nm.

3. The Schottky barrier diode containing a mixed anode and a mixed cathode according to claim 1 or 2, characterized in that: The thickness of the passivation layer is 40nm-80nm.

4. The Schottky barrier diode containing a mixed anode and a mixed cathode according to claim 1 or 2, characterized in that: The passivation layer comprises Si3N4.

5. The Schottky barrier diode containing a mixed anode and a mixed cathode according to claim 1 or 2, characterized in that: The thickness of the GaN capping layer is 10nm-30nm.

6. The Schottky barrier diode containing a mixed anode and a mixed cathode according to claim 1 or 2, characterized in that: The width of the first cathode metal electrode is 3μm to 6μm; the width of the first anode metal electrode is 5μm to 8μm; the thickness of the anode field plate is 30nm to 50nm; the width of the second cathode metal electrode is 2μm to 5μm; the width of the second anode metal electrode is 2μm to 6μm; the distance between the first cathode metal electrode and the first anode metal electrode is 15μm to 25μm.

7. The Schottky barrier diode containing a mixed anode and a mixed cathode according to claim 1 or 2, characterized in that: The components of the first cathode metal electrode include Ti, Al, Ni and Au; the components of the first anode metal electrode include Ni and Au; the components of the anode field plate include Ni and Au; the components of the second cathode metal electrode include Ti, Al, Ni and Au; the components of the second anode metal electrode include Ni and Au.

8. The Schottky barrier diode containing a mixed anode and a mixed cathode according to claim 1 or 2, characterized in that: The substrate is one of a Si substrate, a GaAs substrate and a sapphire substrate.

9. A method for preparing a Schottky barrier diode containing a mixed anode and a mixed cathode as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: 1) depositing an AlN nucleation layer, a GaN buffer layer, a GaN channel layer, an AlGaN barrier layer and a GaN cap layer on a substrate in sequence; 2) Performing photolithography and CF4 etching source etching on the surface of the GaN cap layer to expose part of the AlGaN barrier layer; 3) performing photolithography and CF4 etching source etching on the surface of the AlGaN barrier layer to form a first cathode metal electrode preparation area and a second cathode metal electrode preparation area, and then performing photoresist stripping and annealing after evaporating electrode metal to form a first cathode metal electrode and a second cathode metal electrode; 4) performing photolithography and CF4 etching source etching on the surface of the AlGaN barrier layer to form a first anode metal electrode preparation region and a second anode metal electrode preparation region, and then performing photoresist stripping after evaporating electrode metal to form a first anode metal electrode and a second anode metal electrode; 5) Evaporating electrode metal on the surface of the GaN cap layer to form an anode field plate; 6) Photolithography is performed on the surface of the AlGaN barrier layer to form a passivation layer preparation area, and then a passivation layer material is deposited to form a passivation layer, thereby obtaining a Schottky barrier diode containing a mixed anode and a mixed cathode.

10. An electronic product, characterized in that: A Schottky barrier diode comprising a mixed anode and a mixed cathode as claimed in any one of claims 1 to 8.

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