A schottky barrier diode with multi-channel and mixed cathode and its preparation method and application

Abstract

The application discloses a Schottky barrier diode containing multiple channels and a mixed cathode as well as a preparation method and application thereof. The Schottky barrier diode comprises a substrate, an AlN nucleation layer, a GaN buffer layer, a first GaN channel layer, a first InAlGaN barrier layer, a second GaN channel layer, a second InAlGaN barrier layer, a third GaN channel layer, a third InAlGaN barrier layer, a fourth GaN channel layer, a fourth InAlGaN barrier layer, a fifth GaN channel layer, a fifth InAlGaN barrier layer, a GaN cap layer and a passivation layer which are sequentially arranged in layers, and further comprises a cathode metal electrode, a first anode metal electrode and a second anode metal electrode. The Schottky barrier diode has the advantages of high power and high current, stable current, high reliability and the like, and is suitable for large-scale industrial production and application.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to a Schottky barrier diode with multiple channels and a hybrid cathode, its fabrication method, and its application. Background Technology

[0002] Schottky barrier diodes, also known as hot-carrier diodes, are indispensable components in most power electronic products. They require low turn-on voltage, specific on-resistance, low reverse leakage current, and high breakdown voltage to reduce power loss during operation. Gallium nitride (GaN) has a large bandgap and high electron mobility, making it a promising semiconductor material with broad application prospects. Si / GaN-based Schottky barrier diodes combine good performance with low cost, showing great commercial potential and attracting widespread attention. However, existing Si / GaN-based Schottky barrier diodes generally suffer from low saturation current and are prone to current collapse at high voltages, leading to a risk of failure in some high-power applications and failing to fully meet practical application requirements.

[0003] Therefore, developing a high-power, high-current, stable, and highly reliable Schottky barrier diode is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a Schottky barrier diode with multiple channels and a hybrid cathode, its fabrication method, and its application.

[0005] The technical solution adopted in this invention is:

[0006] A Schottky barrier diode comprising multiple channels and a hybrid cathode includes, in sequence, a substrate, an AlN nucleation layer, a GaN buffer layer, a first GaN channel layer, a first InAlGaN barrier layer, a second GaN channel layer, a second InAlGaN barrier layer, a third GaN channel layer, a third InAlGaN barrier layer, a fourth GaN channel layer, a fourth InAlGaN barrier layer, a fifth GaN channel layer, a fifth InAlGaN barrier layer, a GaN capping layer, and a passivation layer. It also includes a cathode metal electrode, a first anode metal electrode, and a second anode metal electrode; the cathode metal electrode is disposed far from the GaN capping layer. The side away from the fifth InAlGaN barrier layer; the first anode metal electrode is disposed on the side of the GaN capping layer away from the fifth InAlGaN barrier layer and is in contact with the cathode metal electrode and the passivation layer; one side of the second anode metal electrode is stepped; one side of the structure composed of the second InAlGaN barrier layer, the third GaN channel layer, the third InAlGaN barrier layer, the fourth GaN channel layer, the fourth InAlGaN barrier layer, the fifth GaN channel layer, the fifth InAlGaN barrier layer, the GaN capping layer and the passivation layer is stepped, and this side matches and contacts the stepped side of the second anode metal electrode.

[0007] Preferably, the width of the third GaN channel layer and the third InAlGaN barrier layer are the same, and the width is smaller than that of the second InAlGaN barrier layer.

[0008] Preferably, the fourth GaN channel layer and the fourth InAlGaN barrier layer have the same width, and the width is smaller than that of the third InAlGaN barrier layer.

[0009] Preferably, the width of the fifth GaN channel layer is smaller than that of the fourth InAlGaN barrier layer.

[0010] Preferably, the fifth InAlGaN barrier layer and the GaN capping layer have the same width, and the width is smaller than that of the fifth GaN channel layer.

[0011] Preferably, the passivation layer has a width smaller than the GaN capping layer, and the side furthest from the first anode metal electrode is aligned with the GaN capping layer.

[0012] Preferably, the substrate is one of a Si substrate, a GaAs substrate, or a sapphire substrate.

[0013] Preferably, the thickness of the AlN nucleation layer is 0.5 nm to 1.5 nm.

[0014] Preferably, the thickness of the GaN buffer layer is 200nm to 400nm.

[0015] Preferably, the thicknesses of the first GaN channel layer, the second GaN channel layer, the third GaN channel layer, the fourth GaN channel layer, and the fifth GaN channel layer are all independently 100 nm to 300 nm.

[0016] Preferably, the thicknesses of the first InAlGaN barrier layer, the second InAlGaN barrier layer, the third InAlGaN barrier layer, the fourth InAlGaN barrier layer, and the fifth InAlGaN barrier layer are all independently 10 nm to 30 nm.

[0017] Preferably, the thickness of the GaN capping layer is 10 nm to 30 nm.

[0018] Preferably, the passivation layer is composed of Si3N4.

[0019] Preferably, the thickness of the passivation layer is 40 nm to 80 nm.

[0020] Preferably, the cathode metal electrode comprises Ti, Al, Ni, and Au.

[0021] Preferably, the width of the cathode metal electrode is 2μm to 4μm.

[0022] Preferably, the first anode metal electrode comprises Ni and Au.

[0023] Preferably, the width of the first anode metal electrode is 2μm to 4μm.

[0024] Preferably, the second anode metal electrode comprises Ni and Au.

[0025] Preferably, the width of the second anode metal electrode is 7 μm to 11 μm.

[0026] Preferably, the distance between the cathode metal electrode and the second anode metal electrode (the distance between the right edge of the cathode metal electrode and the leftmost edge of the second anode metal electrode, i.e., the minimum distance between the two) is 15μm to 25μm.

[0027] A method for fabricating a Schottky barrier diode with multiple channels and a hybrid cathode as described above includes the following steps:

[0028] 1) An AlN nucleation layer, a GaN buffer layer, a first GaN channel layer, a first InAlGaN barrier layer, a second GaN channel layer, a second InAlGaN barrier layer, a third GaN channel layer, a third InAlGaN barrier layer, a fourth GaN channel layer, a fourth InAlGaN barrier layer, a fifth GaN channel layer, a fifth InAlGaN barrier layer, and a GaN capping layer are epitaxially grown sequentially on the substrate surface.

[0029] 2) The surface of the GaN capping layer is etched to form the cathode metal electrode preparation area, the first anode metal electrode preparation area and the second anode metal electrode preparation area, and then the electrode metal is deposited by vapor deposition to form the cathode metal electrode, the first anode metal electrode and the second anode metal electrode;

[0030] 3) The surface of the GaN capping layer is etched to form a passivation layer preparation area, and then passivation layer material is deposited to form a passivation layer, thus obtaining a Schottky barrier diode with multiple channels and a hybrid cathode.

[0031] An electronic product comprising the aforementioned Schottky barrier diode with multiple channels and a hybrid cathode.

[0032] The beneficial effects of the present invention are: the Schottky barrier diode of the present invention is provided with a multi-channel structure and a hybrid cathode structure, which has the advantages of high power and high current, stable current and high reliability, and is suitable for large-scale industrial production and application.

[0033] Specifically:

[0034] 1) The Schottky barrier diode of the present invention is provided with a multi-channel structure consisting of multiple GaN channel layers and multiple InAlGaN barrier layers, which can reduce the thin-film resistance without increasing tensile strain. Tensile strain is unavoidable in AlGaN. By adding In to the AlGaN layer, strain can be reduced even in the case of high Al content, thereby achieving both high carrier density and high electron mobility.

[0035] 2) The Schottky barrier diode of the present invention is provided with a hybrid cathode structure. The Schottky junction in the cathode is reverse biased. As the forward bias increases, the 2DEG channel under the Schottky contact will gradually be depleted. Therefore, the output current will first increase with the application of the anode voltage and then gradually reach saturation. Under these circumstances, a stable output current can be obtained and the current collapse effect can be effectively suppressed. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a Schottky barrier diode with multiple channels and a hybrid cathode, as shown in the embodiment.

[0037] Figure 2 This is a schematic diagram of the Schottky barrier diode in Comparative Example 2.

[0038] Figure labeling: 10, Si substrate; 20, AlN nucleation layer; 30, GaN buffer layer; 40, first GaN channel layer; 50, first InAlGaN barrier layer; 60, second GaN channel layer; 70, second InAlGaN barrier layer; 80, third GaN channel layer; 90, third InAlGaN barrier layer; 100, fourth GaN channel layer; 110, fourth InAlGaN barrier layer; 120, fifth GaN channel layer; 130, fifth InAlGaN barrier layer; 140, GaN capping layer; 150, passivation layer; 160, cathode metal electrode; 170, first anode metal electrode; 180, second anode metal electrode.

[0039] Figure 3 The diagram shows the IV test results of the Schottky barrier diode with multi-channel and hybrid cathode in the embodiment, the Schottky barrier diode of Comparative Example 1, and the Schottky barrier diode of Comparative Example 2.

[0040] Figure 4 The figure shows the forward maximum voltage test results of the Schottky barrier diode with multi-channel and hybrid cathode in the embodiment, the Schottky barrier diode of Comparative Example 1, and the Schottky barrier diode of Comparative Example 2. Detailed Implementation

[0041] The present invention will be further explained and described below with reference to specific embodiments.

[0042] Example:

[0043] A Schottky barrier diode with multiple channels and a hybrid cathode (structural schematic shown in figure) Figure 1 As shown, it consists of a Si substrate 10, an AlN nucleation layer 20, a GaN buffer layer 30, a first GaN channel layer 40, a first InAlGaN barrier layer 50, a second GaN channel layer 60, a second InAlGaN barrier layer 70, a third GaN channel layer 80, a third InAlGaN barrier layer 90, a fourth GaN channel layer 100, a fourth InAlGaN barrier layer 110, a fifth GaN channel layer 120, a fifth InAlGaN barrier layer 130, a GaN capping layer 140, a passivation layer 150, a cathode metal electrode 160, a first anode metal electrode 170, and a second anode metal electrode 180.

[0044] A Si substrate 10, an AlN nucleation layer 20, a GaN buffer layer 30, a first GaN channel layer 40, a first InAlGaN barrier layer 50, a second GaN channel layer 60, a second InAlGaN barrier layer 70, a third GaN channel layer 80, a third InAlGaN barrier layer 90, a fourth GaN channel layer 100, a fourth InAlGaN barrier layer 110, a fifth GaN channel layer 120, a fifth InAlGaN barrier layer 130, a GaN capping layer 140, and a passivation layer 150 are stacked sequentially.

[0045] The cathode metal electrode 160 is disposed on the side of the GaN capping layer 140 that is away from the fifth InAlGaN barrier layer 130;

[0046] The first anode metal electrode 170 is disposed on the side of the GaN capping layer 140 away from the fifth InAlGaN barrier layer 130, and is in contact with the cathode metal electrode 160 and the passivation layer 150.

[0047] One side of the second anode metal electrode 180 is stepped;

[0048] The structure consisting of the second InAlGaN barrier layer 70, the third GaN channel layer 80, the third InAlGaN barrier layer 90, the fourth GaN channel layer 100, the fourth InAlGaN barrier layer 110, the fifth GaN channel layer 120, the fifth InAlGaN barrier layer 130, the GaN capping layer 140, and the passivation layer 150 has a stepped shape on one side, and this side matches and contacts the stepped side of the second anode metal electrode 180.

[0049] The third GaN channel layer 80 and the third InAlGaN barrier layer 90 have the same width, and their widths are smaller than those of the second InAlGaN barrier layer 70.

[0050] The fourth GaN channel layer 100 and the fourth InAlGaN barrier layer 110 have the same width, and the width is smaller than that of the third InAlGaN barrier layer 90.

[0051] The width of the fifth GaN channel layer 120 is smaller than that of the fourth InAlGaN barrier layer 110;

[0052] The fifth InAlGaN barrier layer 130 and the GaN capping layer 140 have the same width, but the width is smaller than that of the fifth GaN channel layer 120.

[0053] The passivation layer 150 is narrower than the GaN capping layer 140, and the side furthest from the first anode metal electrode 170 is aligned with the GaN capping layer 140.

[0054] The fabrication method of the Schottky barrier diode with multi-channel and hybrid cathode described above is as follows:

[0055] 1) Metal-organic chemical vapor deposition (MOCVD) was used to epitaxially grow the following layers sequentially on one surface of a Si substrate: an AlN nucleation layer with a thickness of 1 nm, a GaN buffer layer with a thickness of 300 nm, a first GaN channel layer with a thickness of 200 nm, a first InAlGaN barrier layer with a thickness of 20 nm, a second GaN channel layer with a thickness of 200 nm, a second InAlGaN barrier layer with a thickness of 20 nm, a third GaN channel layer with a thickness of 200 nm, a third InAlGaN barrier layer with a thickness of 20 nm, a fourth GaN channel layer with a thickness of 200 nm, a fourth InAlGaN barrier layer with a thickness of 20 nm, a fifth GaN channel layer with a thickness of 200 nm, a fifth InAlGaN barrier layer with a thickness of 20 nm, and a GaN capping layer with a thickness of 20 nm.

[0056] 2) The cathode metal electrode fabrication area is formed by photolithography on the surface of the GaN capping layer, and then Ti-Al-Ni-Au alloy is deposited by electron beam evaporation with an electron beam energy of 3kV and a vacuum degree P≤10. -3 Pa, then acetone is used for photoresist stripping and annealing in an N2 atmosphere to form a 3μm wide cathode metal electrode. Next, photolithography and controlled CF4 etching are performed on the GaN capping layer surface to form the first and second anode metal electrode fabrication areas. Finally, Ni-Au alloy deposition is performed using electron beam evaporation at an electron beam energy of 3kV and a vacuum degree P≤10. -3 Pa, then acetone is used to remove the photoresist to obtain a first anode metal electrode with a width of 2μm and a second anode metal electrode with a width of 7μm and a distance of 20μm from the cathode metal electrode;

[0057] 3) Photolithography is performed on the surface of the GaN capping layer to form a passivation layer preparation area. Then, a Si3N4 thin film with a thickness of 60nm is deposited by low-pressure chemical vapor deposition to form a passivation layer, thus obtaining a Schottky barrier diode with multiple channels and a hybrid cathode.

[0058] Comparative Example 1: (AlGaN barrier layer without In)

[0059] A Schottky barrier diode is identical to the Schottky barrier diode with multi-channel and hybrid cathode of Example 1, except that the first InAlGaN barrier layer, the second InAlGaN barrier layer, the third InAlGaN barrier layer, the fourth InAlGaN barrier layer, and the fifth InAlGaN barrier layer are replaced with the first AlGaN barrier layer, the second AlGaN barrier layer, the third AlGaN barrier layer, the fourth AlGaN barrier layer, and the fifth AlGaN barrier layer, respectively.

[0060] Comparative Example 2: (without hybrid cathode structure)

[0061] A Schottky barrier diode (structural schematic shown) Figure 2 As shown, except that the first anode metal electrode is replaced with a cathode metal electrode of the same size, it is completely identical to the Schottky barrier diode with multi-channel and hybrid cathode of Example 1.

[0062] Performance testing:

[0063] 1) The IV test results of the Schottky barrier diode with multi-channel and hybrid cathode in the embodiments, the Schottky barrier diode of Comparative Example 1 (AlGaN barrier layer without In), and the Schottky barrier diode of Comparative Example 2 (without hybrid cathode structure) are as follows: Figure 3 As shown.

[0064] Depend on Figure 3 It can be seen that the Schottky barrier diode in Comparative Example 1 has a current of 0.16A at a voltage of 6V, the Schottky barrier diode in Comparative Example 2 has a current of 0.15A at a voltage of 6V, while the Schottky barrier diode in the embodiment with multiple channels and a hybrid cathode reaches a current of 0.25A at a voltage of 6V. By comparing the embodiment and Comparative Example 1, it can be seen that the InAlGaN heterojunction significantly improves the saturation current of the Schottky barrier diode device.

[0065] 2) The forward maximum voltage (current collapse effect) test results of the Schottky barrier diode with multi-channel and hybrid cathode in the embodiments, the Schottky barrier diode of Comparative Example 1 (AlGaN barrier layer without In), and the Schottky barrier diode of Comparative Example 2 (without hybrid cathode structure) are as follows: Figure 4 As shown.

[0066] Depend on Figure 4 It can be seen that the maximum voltage of the Schottky barrier diode in Comparative Example 1 is 17V, the maximum voltage of the Schottky barrier diode in Comparative Example 2 is 10V, and the maximum voltage of the Schottky barrier diode with multi-channel and hybrid cathode in the embodiment reaches 19V. By comparing the embodiment and Comparative Example 2, it can be seen that the hybrid cathode structure significantly improves the maximum forward voltage of the Schottky barrier diode device.

[0067] In summary, the Schottky barrier diode with multi-channel and hybrid cathode of the present invention has the advantages of high power and high current, stable current and high reliability, and is suitable for large-scale industrial production and application.

[0068] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A Schottky barrier diode comprising a plurality of channels and a mixed cathode, characterized in that, It comprises a substrate, an AlN nucleation layer, a GaN buffer layer, a first GaN channel layer, a first InAlGaN barrier layer, a second GaN channel layer, a second InAlGaN barrier layer, a third GaN channel layer, a third InAlGaN barrier layer, a fourth GaN channel layer, a fourth InAlGaN barrier layer, a fifth GaN channel layer, a fifth InAlGaN barrier layer, a GaN capping layer, and a passivation layer, as well as a cathode metal electrode, a first anode metal electrode, and a second anode metal electrode, arranged sequentially. The cathode metal electrode is disposed on the GaN capping layer away from the fifth InAlGaN barrier layer. The first anode metal electrode is disposed on the side of the GaN capping layer away from the fifth InAlGaN barrier layer and is in contact with the cathode metal electrode and the passivation layer; one side of the second anode metal electrode is stepped; one side of the structure consisting of the second InAlGaN barrier layer, the third GaN channel layer, the third InAlGaN barrier layer, the fourth GaN channel layer, the fourth InAlGaN barrier layer, the fifth GaN channel layer, the fifth InAlGaN barrier layer, the GaN capping layer and the passivation layer is stepped, and this side matches and contacts the stepped side of the second anode metal electrode.

2. The multi-channel and mixed cathode containing Schottky barrier diode according to claim 1, wherein: The third GaN channel layer and the third InAlGaN barrier layer have the same width, and the width is smaller than that of the second InAlGaN barrier layer; the fourth GaN channel layer and the fourth InAlGaN barrier layer have the same width, and the width is smaller than that of the third InAlGaN barrier layer; the fifth GaN channel layer has a smaller width than the fourth InAlGaN barrier layer; the fifth InAlGaN barrier layer and the GaN capping layer have the same width, and the width is smaller than that of the fifth GaN channel layer; the passivation layer has a smaller width than the GaN capping layer, and the side furthest from the first anode metal electrode is aligned with the GaN capping layer.

3. The Schottky barrier diode with multiple channels and a mixed cathode according to claim 1 or 2, characterized in that: The thickness of the AlN nucleation layer is 0.5 nm to 1.5 nm; the thickness of the GaN buffer layer is 200 nm to 400 nm.

4. The Schottky barrier diode with multi-channel and hybrid cathode according to claim 1 or 2, characterized in that: The thicknesses of the first GaN channel layer, the second GaN channel layer, the third GaN channel layer, the fourth GaN channel layer, and the fifth GaN channel layer are all independently 100 nm to 300 nm; the thicknesses of the first InAlGaN barrier layer, the second InAlGaN barrier layer, the third InAlGaN barrier layer, the fourth InAlGaN barrier layer, and the fifth InAlGaN barrier layer are all independently 10 nm to 30 nm; and the thickness of the GaN capping layer is 10 nm to 30 nm.

5. The Schottky barrier diode with multi-channel and hybrid cathode according to claim 1 or 2, characterized in that: The passivation layer is composed of Si3N4.

6. The Schottky barrier diode with multi-channel and hybrid cathode according to claim 1 or 2, characterized in that: The thickness of the passivation layer is 40 nm to 80 nm.

7. The Schottky barrier diode with multi-channel and hybrid cathode according to claim 1 or 2, characterized in that: The cathode metal electrode is composed of Ti, Al, Ni and Au; the first anode metal electrode is composed of Ni and Au; and the second anode metal electrode is composed of Ni and Au.

8. The Schottky barrier diode with multi-channel and hybrid cathode according to claim 1 or 2, characterized in that: The width of the cathode metal electrode is 2μm to 4μm; the width of the first anode metal electrode is 2μm to 4μm; the width of the second anode metal electrode is 7μm to 11μm; and the distance between the cathode metal electrode and the second anode metal electrode is 15μm to 25μm.

9. A method for fabricating a Schottky barrier diode containing multiple channels and a hybrid cathode as described in any one of claims 1 to 8, characterized in that, Includes the following steps: 1) An AlN nucleation layer, a GaN buffer layer, a first GaN channel layer, a first InAlGaN barrier layer, a second GaN channel layer, a second InAlGaN barrier layer, a third GaN channel layer, a third InAlGaN barrier layer, a fourth GaN channel layer, a fourth InAlGaN barrier layer, a fifth GaN channel layer, a fifth InAlGaN barrier layer, and a GaN capping layer are epitaxially grown sequentially on the substrate surface. 2) The surface of the GaN capping layer is etched to form the cathode metal electrode preparation area, the first anode metal electrode preparation area and the second anode metal electrode preparation area, and then the electrode metal is deposited by vapor deposition to form the cathode metal electrode, the first anode metal electrode and the second anode metal electrode; 3) The surface of the GaN capping layer is etched to form a passivation layer preparation area, and then passivation layer material is deposited to form a passivation layer, thus obtaining a Schottky barrier diode with multiple channels and a hybrid cathode.

10. An electronic product, characterized in that, The Schottky barrier diode comprising any one of claims 1 to 8, having a multi-channel and hybrid cathode.

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