Schottky barrier diode containing multiple channels and mixed cathode and preparation method and application thereof

Abstract

The invention discloses a Schottky barrier diode containing multiple channels and a mixed cathode and a preparation method and application of the Schottky barrier diode. The Schottky barrier diode comprises a substrate, an AlN nucleating 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 a stacked mode. The device further comprises a cathode metal electrode, a first anode metal electrode and a second anode metal electrode. A multi-channel structure and a mixed cathode structure are arranged in the Schottky barrier diode, so that the Schottky barrier diode has the advantages of high power, high current, stable current, high 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 multiple channels 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 such as small saturation current and easy current collapse at high voltage, which leads to the risk of easy failure when used in some high-power application scenarios, and cannot fully meet the actual application requirements.

[0003] Therefore, it is of great significance to develop a Schottky barrier diode with high power, high current, stable current and high reliability. Summary of the invention

[0004] The object of the present invention is to provide a Schottky barrier diode containing multiple channels 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 with multiple channels and a mixed cathode, comprising 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 stacked in sequence, and also comprising a cathode metal electrode, a first anode metal electrode and a second anode metal electrode; the cathode metal electrode is arranged at a distance from the GaN cap layer. The first anode metal electrode is arranged on the side of the GaN cap 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 cap layer and the passivation layer is stepped, and the side matches and contacts with the stepped side of the second anode metal electrode.

[0007] Preferably, 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.

[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 fifth GaN channel layer has a width smaller than that of the fourth InAlGaN barrier layer.

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

[0011] Preferably, the width of the passivation layer is smaller than that of the GaN capping layer, and the side of the passivation layer away 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 and a sapphire substrate.

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

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

[0015] Preferably, the thickness 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 independently 100 nm to 300 nm.

[0016] Preferably, the thickness 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 independently 10 nm to 30 nm.

[0017] Preferably, the GaN capping layer has a thickness of 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 2 μm to 4 μm.

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

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

[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, ie, the shortest distance between the two) is 15 μm to 25 μm.

[0027] A method for preparing the Schottky barrier diode with multiple channels and mixed cathode as described above comprises the following steps:

[0028] 1) epitaxially growing 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 cap layer in sequence on the surface of the substrate;

[0029] 2) etching the surface of the GaN cap layer to form a cathode metal electrode preparation region, a first anode metal electrode preparation region, and a second anode metal electrode preparation region, and then evaporating electrode metal to form a cathode metal electrode, a first anode metal electrode, and a second anode metal electrode;

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

[0031] An electronic product comprises the Schottky barrier diode with multiple channels and a mixed cathode.

[0032] The beneficial effects of the present invention are as follows: the Schottky barrier diode of the present invention is provided with a multi-channel structure and a mixed cathode structure, and has the advantages of high power, high current, stable current, high reliability, etc., 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 a multi-layer GaN channel layer and a multi-layer InAlGaN barrier layer, which can reduce the sheet resistance without increasing the tensile strain, while the tensile strain is inevitable for AlGaN. By adding In to the AlGaN layer, the strain can be reduced even in the case of a high Al content, thereby achieving high carrier density and high electron mobility at the same time;

[0035] 2) The Schottky barrier diode of the present invention is provided with a hybrid cathode structure, and the Schottky junction in the cathode is reverse biased. As the forward bias increases, the 2DEG channel under the Schottky contact will gradually be exhausted. Therefore, the output current will first increase with the application of the anode voltage, and then gradually reach saturation. In this case, a stable output current can be obtained and the current collapse effect can be effectively suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the structure of a Schottky barrier diode with multiple channels and a mixed cathode according to an embodiment.

[0037] Figure 2 Schematic diagram of the structure of the Schottky barrier diode of comparative example 2.

[0038] Explanation of the accompanying drawings: 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 It is a graph showing IV test results of the Schottky barrier diode with multiple channels and mixed cathodes of the embodiment, the Schottky barrier diode of comparative example 1, and the Schottky barrier diode of comparative example 2.

[0040] Figure 4 It is a graph showing the maximum forward voltage test results of the Schottky barrier diode with multiple channels and a mixed cathode of the embodiment, the Schottky barrier diode of comparative example 1, and the Schottky barrier diode of comparative example 2. DETAILED DESCRIPTION

[0041] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0042] Example:

[0043] A Schottky barrier diode with multiple channels 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 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 cap 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 cap layer 140 and a passivation layer 150 are sequentially stacked;

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

[0046] The first anode metal electrode 170 is disposed on the side of the GaN cap 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 in a stepped shape;

[0048] One side of the structure composed 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 cap layer 140 and the passivation layer 150 is stepped, and the 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 the width is smaller than that 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 fifth GaN channel layer 120 has a width smaller than that of the fourth InAlGaN barrier layer 110 ;

[0052] The fifth InAlGaN barrier layer 130 has the same width as the GaN cap layer 140 , and is smaller in width than the fifth GaN channel layer 120 ;

[0053] The width of the passivation layer 150 is smaller than that of the GaN capping layer 140 , and the side of the passivation layer 150 away from the first anode metal electrode 170 is aligned with the GaN capping layer 140 .

[0054] The preparation method of the Schottky barrier diode containing multiple channels and mixed cathode is as follows:

[0055] 1) epitaxially growing 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 cap layer with a thickness of 20 nm on one surface of a Si substrate by a metal organic chemical vapor deposition (MOCVD) method;

[0056] 2) The surface of the GaN cap layer is photolithographically formed into a 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 acetone is used to strip the photoresist and annealing is performed in N2 atmosphere to form a cathode metal electrode with a width of 3μm, and then the surface of the GaN cap layer is photolithographically etched and etched by a controllable CF4 etching source to form a first anode metal electrode preparation area and a second anode metal electrode preparation area, and then electron beam evaporation is used to evaporate Ni-Au alloy, the electron beam energy is 3kV, and the vacuum degree P≤10 -3 Pa, and then using acetone to strip the photoresist to obtain a first anode metal electrode with a width of 2 μm and a second anode metal electrode with a width of 7 μm and a distance of 20 μm from the cathode metal electrode;

[0057] 3) The surface of the GaN cap layer is photolithographically formed into a passivation layer preparation area, and then a Si3N4 film 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 multiple channels and a mixed cathode.

[0058] Comparative Example 1: (AlGaN barrier layer does not contain In)

[0059] A Schottky barrier diode is identical to the Schottky barrier diode with multiple channels and a mixed cathode in Embodiment 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 by 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 mixed cathode structure)

[0061] A Schottky barrier diode (schematic diagram as shown in FIG. Figure 2 ), except that the first anode metal electrode is replaced by a cathode metal electrode of the same size, the rest is exactly the same as the Schottky barrier diode with multiple channels and a mixed cathode in Example 1.

[0062] Performance Test:

[0063] 1) The IV test results of the Schottky barrier diode with multi-channel and mixed cathode of the embodiment, the Schottky barrier diode of comparative example 1 (the AlGaN barrier layer does not contain In), and the Schottky barrier diode of comparative example 2 (without mixed cathode structure) are as follows: Figure 3 shown.

[0064] Depend on Figure 3 It can be seen that the current of the Schottky barrier diode in comparative example 1 is 0.16A when the voltage is 6V, the current of the Schottky barrier diode in comparative example 2 is 0.15A when the voltage is 6V, and the current of the Schottky barrier diode containing multiple channels and mixed cathodes in the embodiment reaches 0.25A when the voltage is 6V. By comparing the embodiment and comparative example 1, it can be seen that the InAlGaN heterojunction greatly 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 multiple channels and mixed cathode of the embodiment, the Schottky barrier diode of comparative example 1 (the AlGaN barrier layer does not contain In), and the Schottky barrier diode of comparative example 2 (without mixed cathode structure) are as follows: Figure 4 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 containing multiple channels and a mixed cathode in the embodiment reaches 19V. By comparing the embodiment and comparative example 2, it can be seen that the mixed cathode structure greatly improves the forward maximum voltage of the Schottky barrier diode device.

[0067] In summary, the Schottky barrier diode with multiple channels and mixed cathodes of the present invention has the advantages of high power, high current, stable current, high reliability, etc., and is suitable for large-scale industrial production and application.

[0068] 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 with multiple channels and a mixed cathode, characterized in that: The composition includes 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 stacked in sequence, and also includes a cathode metal electrode, a first anode metal electrode and a second anode metal electrode; the cathode metal electrode is arranged on the GaN cap layer away from the fifth InAlGaN barrier layer. barrier layer; the first anode metal electrode is arranged on the side of the GaN cap 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 cap layer and the passivation layer is stepped, and the side matches and contacts with the stepped side of the second anode metal electrode.

2. The Schottky barrier diode with multiple channels and mixed cathode according to claim 1, characterized in that: The third GaN channel layer has the same width as the third InAlGaN barrier layer, and the width is smaller than the second InAlGaN barrier layer; the fourth GaN channel layer has the same width as the fourth InAlGaN barrier layer, and the width is smaller than 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 has the same width as the GaN cap layer, and the width is smaller than the fifth GaN channel layer; the passivation layer has a smaller width than the GaN cap layer, and the side away from the first anode metal electrode is aligned with the GaN cap layer.

3. The Schottky barrier diode with multiple channels and 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 multiple channels and mixed 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 independently 100nm to 300nm; 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 independently 10nm to 30nm; the thickness of the GaN cap layer is 10nm to 30nm.

5. The Schottky barrier diode with multiple channels and mixed cathode according to claim 1 or 2, characterized in that: The passivation layer is composed of Si3N4.

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

7. The Schottky barrier diode with multiple channels and mixed cathode according to claim 1 or 2, characterized in that: The cathode metal electrode comprises Ti, Al, Ni and Au; the first anode metal electrode comprises Ni and Au; and the second anode metal electrode comprises Ni and Au.

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

9. A method for preparing a Schottky barrier diode with multiple channels and a mixed cathode as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: 1) epitaxially growing 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 cap layer in sequence on the surface of the substrate; 2) etching the surface of the GaN cap layer to form a cathode metal electrode preparation region, a first anode metal electrode preparation region, and a second anode metal electrode preparation region, and then evaporating electrode metal to form a cathode metal electrode, a first anode metal electrode, and a second anode metal electrode; 3) The surface of the GaN cap layer is etched to form a passivation layer preparation area, and then the passivation layer material is deposited to form a passivation layer, thereby obtaining a Schottky barrier diode containing multiple channels and a mixed cathode.

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

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