Hydrogen terminal diamond MIS diode and preparation method thereof

Abstract

The invention discloses a hydrogen terminal diamond MIS diode and a preparation method thereof. The diode structure comprises a hydrogen terminal diamond substrate, an ohmic contact electrode, a dielectric layer, a cathode metal electrode, a passivation medium and a metal electrode, the material selection of each layer specifically comprises the following steps: the ohmic contact electrode adopts a metal combination of Ti / Al / Au and the like, the dielectric layer adopts oxides of Al2O3 / HfO2 and the like, and the passivation layer and the dielectric layer are matched with the same-series material. According to the preparation method, a multi-layer structure is realized through atomic layer deposition and evaporation stripping processes. Through the synergistic effect of the dielectric layer / passivation layer, the structure can effectively reduce the reverse leakage current, improves the voltage resistance of the device, and is especially suitable for the field of high-voltage and high-power electronic devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor device fabrication, and particularly relates to a hydrogen-terminated diamond MIS diode and a method for fabricating the same. Background Art

[0002] Diamond is an excellent ultra-wide bandgap semiconductor. It not only has a large bandgap width and a high breakdown field strength, but also has an extremely high thermal conductivity. It is an ideal semiconductor material for developing a new generation of high-performance power and radio frequency devices. Due to the high impurity activation energy of diamond, hydrogen-termination technology is generally used to develop various diamond devices at present. There is a two-dimensional hole gas conductive channel with a high concentration on the surface of hydrogen-terminated diamond, which can not only be used to fabricate field-effect transistors, but also be used to develop diodes. Different from the AlGaN / GaN heterojunction, the two-dimensional hole gas is located on the diamond surface. If a Schottky electrode is directly fabricated on the surface, due to the tunneling effect, the reverse leakage current of the Schottky junction is relatively large, resulting in relatively low rectification ratio and breakdown voltage of the device. Summary of the Invention

[0003] The purpose of the present invention is to provide a hydrogen-terminated diamond MIS diode and a method for fabricating the same, which can effectively increase the barrier height of the junction, suppress the reverse leakage current of the device, improve the rectification ratio, and increase the breakdown voltage.

[0004] To achieve the purpose of the present invention, on the one hand, the present invention provides a hydrogen-terminated diamond MIS diode, including a hydrogen-terminated diamond substrate, an ohmic contact electrode, a dielectric, a cathode metal electrode, a passivation dielectric, and a metal electrode;

[0005] The ohmic contact electrode and the dielectric are provided on the hydrogen-terminated diamond substrate;

[0006] The ohmic contact electrode is located on one side of the surface of the hydrogen-terminated diamond substrate;

[0007] The dielectric is located on the surface of the hydrogen-terminated diamond substrate and partially covers above the ohmic contact electrode;

[0008] The cathode metal electrode is located on one side of the surface of the dielectric;

[0009] The passivation dielectric is located above the dielectric and partially covers above the ohmic contact electrode;

[0010] The metal electrode is located above the ohmic contact electrode and the cathode metal electrode and partially covers above the ohmic contact electrode.

[0011] The hydrogen-terminated diamond substrate is single crystal or polycrystalline, and the ohmic contact electrode is one or a combination of more than one of Ti, Al, Au, Pt, Ni, Mo, Cu, Ag, Pd, W, Fe, and the thickness is 10 nm to 1 μm.

[0012] The medium is one or a combination of more than one of Al2O3, HfO2, TiO2, BN, ZrO2, Si3N4, SiO2, MoO3, V2O5, WO3, and the total thickness is between 1 nm and 20 nm.

[0013] The cathode metal electrode is a combination of one or more of Ti, Al, Au, Pt, Ni, Mo, Cu, Ag, Pd, W, Fe, and the thickness is 10 nm to 1 μm.

[0014] The passivation medium is one or a combination of more than one of Al2O3, HfO2, TiO2, BN, ZrO2, Si3N4, SiO2, MoO3, V2O5, WO3, and the total thickness is between 1 nm and 20 nm.

[0015] The metal electrode is a combination of one or more of Ti, Al, Au, Pt, Ni, Mo, Cu, Ag, Pd, W, Fe, and the thickness is 10 nm to 1 μm.

[0016] On the other hand, the present invention also provides a method for preparing a hydrogen-terminated diamond MIS diode, which specifically includes the following steps:

[0017] Step 1: Prepare an ohmic contact electrode on the hydrogen-terminated diamond substrate and perform an annealing treatment;

[0018] Step 2: Deposit a layer of medium on the surface of the hydrogen-terminated diamond substrate and the ohmic contact electrode;

[0019] Step 3: Prepare a cathode metal electrode on the medium by a conventional evaporation and stripping process;

[0020] Step 4: Deposit a layer of passivation medium on the surface of the hydrogen-terminated diamond substrate, the medium, and the cathode metal electrode;

[0021] Step 5: Using a photoresist as a mask, etch away the medium and the passivation medium on the ohmic contact electrode and the cathode metal electrode to expose part of the ohmic contact electrode and the cathode metal electrode;

[0022] Step 6: Deposit the metal electrode on the ohmic contact electrode, the cathode metal electrode, and part of the passivation medium by an evaporation and stripping method.

[0023] The annealing atmosphere in Step 1 is nitrogen or argon or hydrogen, and the annealing temperature is between room temperature and 800 °C; the deposition method in Step 2 is atomic layer deposition or thermal evaporation or electron beam evaporation or sputtering.

[0024] The deposition method of the passivation medium in step 4 is atomic layer deposition or PECVE or LPCVD or ICPCVD or thermal evaporation or electron beam evaporation or magnetron sputtering;

[0025] The etching methods of the medium and the passivation medium in step 5 are inductively coupled plasma or reactive ion etching or wet etching.

[0026] Compared with the prior art, the remarkable progress of the present invention lies in that the present invention effectively improves the barrier height of the junction, suppresses the reverse leakage of the device, and at the same time, by optimizing the thickness of the inserted medium, the tunneling effect can ensure that the device has good forward conduction characteristics. The developed device has the characteristics of low reverse leakage and high voltage of the device, effectively improves the barrier height of the junction, suppresses the reverse leakage of the device, increases the rectification ratio, increases the breakdown voltage, and can be applied to the research, development and production of diamond power and microwave diodes.

[0027] To more clearly illustrate the functional characteristics and structural parameters of the present invention, the following further describes in conjunction with the drawings and specific embodiments. Description of the Drawings

[0028] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0029] Figure 1 is a schematic structural diagram of the present invention;

[0030] Figure 2 (a)-(f) are the process flow charts of the preparation method of the present invention.

[0031] The reference numerals in the drawings are: 1 - hydrogen-terminated diamond substrate, 2 - ohmic contact electrode, 3 - medium, 4 - cathode metal electrode, 5 - passivation medium, 6 - metal electrode. Detailed Embodiments

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] Combined with Figure 1 , a hydrogen-terminated diamond MIS diode of the present invention includes a hydrogen-terminated diamond substrate 1, an ohmic contact electrode 2, a medium 3, a cathode metal electrode 4, a passivation medium 5, and a metal electrode 6;

[0034] The ohmic contact electrode 2 and the dielectric 3 are provided on the hydrogen-terminated diamond substrate 1;

[0035] The ohmic contact electrode 2 is located on one side of the surface of the hydrogen-terminated diamond substrate 1;

[0036] The dielectric 3 is located on the surface of the hydrogen-terminated diamond substrate 1 and partially covers above the ohmic contact electrode 2;

[0037] The cathode metal electrode 4 is located on one side of the surface of the dielectric 3;

[0038] The passivation dielectric 5 is located above the dielectric 3 and partially covers above the ohmic contact electrode 2;

[0039] The metal electrode 6 is located above the ohmic contact electrode 2 and the cathode metal electrode 4 and partially covers above the ohmic contact electrode 2.

[0040] The hydrogen-terminated diamond substrate 1 is single crystal or polycrystal, and the ohmic contact electrode 2 is a combination of one or more of Ti, Al, Au, Pt, Ni, Mo, Cu, Ag, Pd, W, Fe, and the thickness is 10 nm to 1 μm.

[0041] The dielectric 3 is a combination of one or more of Al2O3, HfO2, TiO2, BN, ZrO2, Si3N4, SiO2, MoO3, V2O5, WO3, and the total thickness is between 1 nm and 20 nm.

[0042] The cathode metal electrode 4 is a combination of one or more of Ti, Al, Au, Pt, Ni, Mo, Cu, Ag, Pd, W, Fe, and the thickness is 10 nm to 1 μm.

[0043] The passivation dielectric 5 is a combination of one or more of Al2O3, HfO2, TiO2, BN, ZrO2, Si3N4, SiO2, MoO3, V2O5, WO3, and the total thickness is between 1 nm and 20 nm.

[0044] The metal electrode 6 is a combination of one or more of Ti, Al, Au, Pt, Ni, Mo, Cu, Ag, Pd, W, Fe, and the thickness is 10 nm to 1 μm.

[0045] Combined Figure 2 , a preparation method of a hydrogen-terminated diamond MIS diode according to the present invention specifically includes the following steps:

[0046] Step 1, prepare the ohmic contact electrode 2 on the hydrogen-terminated diamond substrate 1 and perform annealing treatment;

[0047] Step 2: Deposit a layer of dielectric 3 on the surface of the hydrogen-terminated diamond substrate 1 and the ohmic contact electrode 2;

[0048] Step 3: Prepare the cathode metal electrode 4 on the dielectric 3 by conventional evaporation and lift-off process;

[0049] Step 4: Deposit a layer of passivation dielectric 5 on the surface of the hydrogen-terminated diamond substrate 1, the dielectric 3, and the cathode metal electrode 4;

[0050] Step 5: Using photoresist as a mask, etch away the dielectric 3 and the passivation dielectric 5 on the ohmic contact electrode 2 and the cathode metal electrode 4 to expose part of the ohmic contact electrode 2 and the cathode metal electrode 4;

[0051] Step 6: Deposit the metal electrode 6 on the ohmic contact electrode 2, the cathode metal electrode 4, and part of the passivation dielectric 5 by evaporation and lift-off method.

[0052] The annealing atmosphere in Step 1 is nitrogen or argon or hydrogen, and the annealing temperature is between room temperature and 800 °C; the deposition method in Step 2 is atomic layer deposition (ALD) or thermal evaporation or electron beam evaporation or sputtering.

[0053] The deposition method of the passivation dielectric 5 in Step 4 is atomic layer deposition (ALD) or PECVE or LPCVD or ICPCVD or thermal evaporation or electron beam evaporation or magnetron sputtering;

[0054] The etching methods of the dielectric 3 and the passivation dielectric 5 in Step 5 are inductively coupled plasma (ICP) or reactive ion etching (RIE) or wet etching.

[0055] Example

[0056] A preparation method of a hydrogen-terminated diamond MIS diode specifically includes the following steps:

[0057] Step 1: Electron beam evaporate Au with a thickness of 50 nm on the hydrogen-terminated single-crystal diamond substrate 1. Using photoresist as a mask, etch away the Au in the area without photoresist protection with KI / I2 solution to form the ohmic contact electrode 2;

[0058] Step 2: Deposit a layer of Al2O3 dielectric 3 with a thickness of 5 nm on the sample surface by ALD;

[0059] Step 3: Prepare a Ti / Au cathode metal electrode 4 with a thickness of 20 / 200 nm on the Al2O3 dielectric 3 by conventional evaporation and lift-off process;

[0060] Step 4: Deposit a layer of Al2O3 passivation dielectric 5 with a thickness of 200 nm on the sample surface by ALD;

[0061] Step 5: Using the photoresist as a mask, etch away the Al2O3 passivation medium 5 and the Al2O3 medium 3 on the ohmic contact electrode 2 and the Ti / Au cathode metal electrode 4, partially exposing the ohmic contact electrode 2 and the cathode metal electrode 4;

[0062] Step 6: Deposit a 20 / 300 nm thick Ti / Au metal electrode 6 on the ohmic contact electrode 2 and the Ti / Au cathode metal electrode 4 of the device by the lift-off method to thicken them, and simultaneously form a field plate structure above the Ti / Au cathode metal electrode 4.

[0063] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0064] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hydrogen-terminated diamond MIS diode, characterized in that, It includes a hydrogen-terminated diamond substrate (1), an ohmic contact electrode (2), a dielectric (3), a cathode metal electrode (4), a passivation dielectric (5), and a metal electrode (6); The ohmic contact electrode (2) and the dielectric 3 are provided on the hydrogen-terminated diamond substrate (1); The ohmic contact electrode (2) is located on one side of the surface of the hydrogen-terminated diamond substrate (1); The dielectric (3) is located on the surface of the hydrogen-terminated diamond substrate (1) and partially covers above the ohmic contact electrode (2); The cathode metal electrode (4) is located on one side of the surface of the dielectric (3); The passivation dielectric (5) is located above the dielectric (3) and partially covers above the ohmic contact electrode (2); The metal electrode (6) is located above the ohmic contact electrode (2) and the cathode metal electrode (4) and partially covers above the ohmic contact electrode (2).

2. The hydrogen-terminated diamond MIS diode according to claim 1, characterized in that, The hydrogen-terminated diamond substrate (1) is single crystal or polycrystalline, and the ohmic contact electrode (2) is one or a combination of more than one of Ti, Al, Au, Pt, Ni, Mo, Cu, Ag, Pd, W, Fe, with a thickness of 10 nm to 1 μm.

3. The hydrogen-terminated diamond MIS diode according to claim 1, characterized in that, The dielectric (3) is one or a combination of more than one of Al2O3, HfO2, TiO2, BN, ZrO2, Si3N4, SiO2, MoO3, V2O5, WO3, and the total thickness is between 1 nm and 20 nm.

4. The hydrogen-terminated diamond MIS diode according to claim 1, wherein The cathode metal electrode (4) is one or a combination of more than one of Ti, Al, Au, Pt, Ni, Mo, Cu, Ag, Pd, W, Fe, with a thickness of 10 nm to 1 μm.

5. The hydrogen-terminated diamond MIS diode according to claim 1, characterized in that, The passivation dielectric (5) is one or a combination of more than one of Al2O3, HfO2, TiO2, BN, ZrO2, Si3N4, SiO2, MoO3, V2O5, WO3, and the total thickness is between 1 nm and 20 nm.

6. The hydrogen-terminated diamond MIS diode according to claim 1, wherein The metal electrode (6) is one or a combination of more than one of Ti, Al, Au, Pt, Ni, Mo, Cu, Ag, Pd, W, Fe, with a thickness of 10 nm to 1 μm.

7. A method for preparing a hydrogen-terminated diamond MIS diode according to any one of claims 1-6, characterized in that, Specifically, it includes the following steps: Step 1: Prepare the ohmic contact electrode (2) on the hydrogen-terminated diamond substrate (1) and perform an annealing treatment; Step 2: Deposit a layer of dielectric (3) on the surfaces of the hydrogen-terminated diamond substrate (1) and the ohmic contact electrode (2); Step 3: Prepare the cathode metal electrode (4) on the dielectric (3) through a conventional evaporation and lift-off process; Step 4: Deposit a layer of passivation dielectric (5) on the surfaces of the hydrogen-terminated diamond substrate (1), the dielectric (3), and the cathode metal electrode (4); Step 5: Using a photoresist as a mask, etch away the dielectric 3 and the passivation dielectric (5) on the ohmic contact electrode (2) and the cathode metal electrode (4) to expose a part of the ohmic contact electrode (2) and the cathode metal electrode (4); Step 6: Deposit the metal electrode (6) on the ohmic contact electrode (2), the cathode metal electrode (4), and a part of the passivation dielectric (5) through an evaporation and lift-off method.

8. The preparation method of a hydrogen-terminated diamond MIS diode according to claim 7, characterized in that, The annealing atmosphere in step 1 is nitrogen or argon or hydrogen, and the annealing temperature is between room temperature and 800 °C; the deposition method in step 2 is atomic layer deposition or thermal evaporation or electron beam evaporation or sputtering.

9. The preparation method of a hydrogen-terminated diamond MIS diode according to claim 7, characterized in that, The deposition method of the passivation medium (5) in step 4 is atomic layer deposition or PECVE or LPCVD or ICPCVD or thermal evaporation or electron beam evaporation or magnetron sputtering.

10. The manufacturing method of a hydrogen-terminated diamond MIS diode according to claim 7, characterized in that, The etching method of the medium (3) and the passivation medium (5) in step 5 is inductively coupled plasma or reactive ion etching or wet etching.

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