Gallium nitride-based resonant tunneling diode with multi-region differential negative resistance characteristics and manufacturing method

Abstract

The present invention discloses a gallium nitride-based resonant tunneling diode with multi-region differential negative resistance characteristics and a manufacturing method thereof, which mainly solves the problems of the existing gallium nitride resonant tunneling diode in achieving multi-region differential negative resistance characteristics, low series integration and poor consistency of differential negative resistance characteristics. The diode comprises, from bottom to top, a substrate, a GaN epitaxial layer, an emitter ohmic contact layer, a multi-layer composite active region, a collector ohmic contact layer and a collector electrode; the multi-layer composite active region is composed of an N-layer active region and an N-1 layer n- + This composite structure consists of alternating GaN layers arranged in series. Each active region layer comprises, from bottom to top, an isolation layer, a barrier layer, a quantum well layer, a barrier layer, and an isolation layer. The barrier layers are all made of wide-bandgap semiconductor materials. This device exhibits a differential negative resistance effect with multiple peak currents, resulting in stable device performance, consistent differential negative resistance, high reliability, and high integration. It eliminates the metal interconnects of a planar series process and can be used in multi-valued logic digital circuits and memories.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a gallium nitride-based resonant tunneling diode that can be used in multi-valued logic digital circuits and memories. Background Art

[0002] A resonant tunneling diode (RTD) is a vertical quantum effect device characterized by differential negative resistance, low junction capacitance, short carrier transport time, and unipolar transport, capable of operating in the terahertz range. Oscillators fabricated from RTDs offer the advantages of high frequency and low power consumption, making them a promising approach to terahertz radiation sources. They have broad applications in security detection, spectral imaging, broadband wireless communications, and circuit design. Compared to GaAs, GaN offers advantages such as a wide bandgap, high saturation electron velocity, and high thermal stability. GaN RTDs can achieve higher frequencies and higher power outputs at room temperature. GaN materials possess diverse crystal structures, polarization properties, and a variety of crystal planes, offering greater freedom in device design. Studying the physical mechanisms associated with vertical transport in GaN RTDs is fundamental to the development of complex GaN quantum cascade lasers.

[0003] The high peak-to-valley current ratio differential negative resistance characteristic also provides support for GaN digital circuit design. The emergence of the differential negative resistance characteristic of the GaN resonant tunneling diode depends on the alignment of the discrete energy levels in the double-barrier single quantum well with the energy levels of the emitter two-dimensional electron gas. In theory, multiple alignment processes can be achieved, resulting in multi-region differential negative resistance characteristics. This provides a basis for the implementation of multi-valued logic digital circuits and can realize circuit functions with a relatively small number of devices. However, due to the strong polarization effect and energy band asymmetry of nitride materials, only a single differential negative resistance region can generally be present.

[0004] In order to realize the multi-region differential negative resistance characteristics of GaN resonant tunneling diodes, a multi-quantum well structure can be used. In the output characteristics of the device with this structure, the peak current and peak-to-valley current ratio of the differential negative resistance characteristics in different regions are too different, which makes it difficult to apply to the monolithic integration of digital logic circuits. In addition, the series integration of GaN resonant tunneling diodes on the same wafer can also be used to realize the multi-region differential negative resistance characteristics, but this places extremely high demands on the thickness uniformity and distribution volatility of the epitaxial material sheet, which poses technical challenges to the epitaxial growth and device manufacturing process. Conventional GaN resonant tunneling diode structures such as Figure 1 As shown, it includes substrate, GaN Epitaxial layer, n + GaN emitter ohmic contact layer, first GaN isolation layer, first AlGaN barrier layer, GaN quantum well layer, second AlGaN barrier layer, second GaN isolation layer, n +GaN collector ohmic contact layer and collector electrode, in n + A ring-shaped emitter electrode is provided on the GaN emitter ohmic contact layer. This device has the following disadvantages:

[0005] First, it is difficult to achieve a differential negative resistance characteristic with close peak current and peak-to-valley current ratios, and thus cannot be applied alone to multi-logic digital circuits;

[0006] Second, achieving multi-region differential negative resistance characteristics requires integrating on-chip devices in series. This not only places extremely high demands on on-chip device performance consistency, but also consumes a large amount of wafer area and requires metal interconnects, resulting in complex device processes and low fault tolerance.

[0007] Third, the multi-region differential negative resistance characteristics must be achieved through a multi-quantum well structure. However, the peak current and peak-to-valley current ratios of the device's differential negative resistance characteristics vary greatly, making it unsuitable for digital circuit design. Furthermore, the epitaxial growth of multi-quantum well materials can lead to large fluctuations in material thickness and uneven distribution.

[0008] Fourth, the differential negative resistance characteristic has a self-oscillation phenomenon, and the device output characteristic curve has a "chair-shaped" bulge, resulting in unstable device performance and low reliability. Summary of the Invention

[0009] The present invention aims to address the shortcomings of the above-mentioned existing technologies and propose a gallium nitride-based resonant tunneling diode with multi-region differential negative resistance characteristics and a manufacturing method. The purpose is to improve the device integration and reliability, reduce the requirements for thickness fluctuations of the multi-quantum well material, avoid the complex metal interconnection process required for on-chip device series connection and inconsistent device performance, and achieve a differential negative resistance effect with multiple peak currents and peak-to-valley current ratios close to the same.

[0010] The technical solution of the present invention is achieved as follows:

[0011] 1. A multi-region differential negative resistance gallium nitride-based resonant tunneling diode, comprising, from bottom to top, a substrate, a GaN epitaxial layer, an emitter ohmic contact layer, an active region, a collector ohmic contact layer, a collector electrode, and an annular emitter electrode on either side of the active region; a cylindrical mesa formed by etching from the active region to the collector electrode, the cylindrical mesa being coated with a passivation layer, characterized in that:

[0012] The active region is composed of N layers of active regions and N-1 layers of n + The composite structure consists of alternating GaN series layers, with a doping concentration of 1×10 19 cm -3 -5×10 20 cm -3 , thickness of 30nm-200nm n +The GaN layers are connected in series to achieve differential negative resistance characteristics with multiple peak currents and peak-to-valley current ratios that are close, where N ≥ 2.

[0013] Furthermore, each layer of the active region of the composite structure comprises, from bottom to top, a first isolation layer, a first barrier layer, a quantum well layer, a second barrier layer, and a second isolation layer;

[0014] The thickness of the first isolation layer and the second isolation layer are both 4nm-15nm GaN;

[0015] The first barrier layer and the second barrier layer have the same composition and thickness of 1nm-3nm;

[0016] The quantum well layer uses In with a composition v between 0% and 100%. v Ga 1-v N, its thickness is 1nm-3nm.

[0017] Furthermore, the first barrier layer and the second barrier layer are made of the same material, and both can be made of Sc x Al 1-x N, Y x Al 1-x N, B w Al y Ga z For any one of N, its component x is between 5% and 25%, its components w, y, and z are between 0% and 100%, and w+y+z=100%.

[0018] Furthermore, the collector ohmic contact layer has a doping concentration of 5×10 19 cm -3 -5×10 20 cm -3 , thickness of 50nm-200nm n + GaN; the emitter ohmic contact layer has a doping concentration of 5×10 19 cm -3 -5×10 20 cm -3 , thickness of 50nm-200nm n + GaN; the GaN epitaxial layer has a thickness of 500nm-5000nm;

[0019] Furthermore, the passivation layer is made of any one of SiN material, Al2O3 material, and HfO2 material; the substrate is made of any one of self-supporting gallium nitride single crystal material, self-supporting aluminum nitride single crystal material, sapphire material, silicon carbide material, silicon material, boron nitride material, and diamond material.

[0020] 2. A method for manufacturing a gallium nitride-based resonant tunneling diode with multiple differential negative resistance effects, characterized by comprising the following steps:

[0021] 1) epitaxially growing a GaN epitaxial layer of 500nm-5000nm on a substrate by molecular beam epitaxy or metal organic chemical vapor deposition;

[0022] 2) Using molecular beam epitaxy, n is grown on the GaN epitaxial layer. + The GaN emitter ohmic contact layer has a thickness of 50nm-200nm and a doping concentration of 5×10 19 cm -3 -5×10 20 cm -3 ;

[0023] 3) Using molecular beam epitaxy method, + The active area of ​​the multi-layer composite structure is alternately grown on the GaN emitter ohmic contact layer:

[0024] 3a) Growth of the first active region:

[0025] 3a1) in n + A GaN first isolation layer with a thickness of 4nm-15nm is grown on the GaN emitter ohmic contact layer;

[0026] 3a2) growing a Sc layer with a composition x between 5% and 25% and a thickness of 1 nm to 3 nm on the GaN first isolation layer. x Al 1-x N or Y x Al 1-x N; or B with components w, y, z ranging from 0% to 100%, w+y+z=100%, and a thickness of 1nm-3nm w Al y Ga z The first barrier layer of N;

[0027] 3a3) Growing an In layer with a composition v between 0% and 100% and a thickness of 1 nm to 3 nm on the first barrier layer v Ga 1-v N quantum well layer;

[0028] 3a4) growing a second barrier layer having the same composition and thickness as the first barrier layer on the quantum well layer;

[0029] 3a5) growing a GaN second isolation layer with a thickness of 4 nm to 15 nm on the second barrier layer to complete the growth of the first active region;

[0030] 3b) Using molecular beam epitaxy, a doping concentration of 1×10 19cm -3 -5×10 20 cm -3 , the first layer n is 30nm-200nm thick + GaN tandem layer;

[0031] 3c) In the first layer n + A second active region layer is grown on the GaN tandem layer according to the process flow of 3a), completing the growth of a composite active region structure of two active regions and one tandem layer. The growth is repeated cyclically to ultimately form an active region having a multilayer composite structure of N active regions and N-1 tandem layers.

[0032] 4) Using molecular beam epitaxy, n is grown on the active area of ​​the composite structure. + The GaN collector ohmic contact layer has a thickness of 50nm-200nm and a doping concentration of 5×10 19 cm -3 -5×10 20 cm -3 ;

[0033] 5) Using traditional optical lithography process, + On the GaN collector ohmic contact layer, a device mesa isolation pattern is formed. Using a photoresist as a mask, an inductively coupled plasma etching method is used, and a BCl3 / Cl2 gas source is used to etch the epitaxial material to form a mesa isolation with a depth of 650nm-1200nm;

[0034] 6) Using electron beam lithography, + On the GaN collector ohmic contact layer, a circular pattern with a diameter of 0.5μm-20μm is formed, and a photoresist is used as a mask and an electron beam evaporation method is used to form a circular pattern with a diameter of 0.5μm-20μm. + A Ti / Au / Ni metal layer is evaporated on the GaN collector ohmic contact layer to form a collector electrode. Then, the metal is used as a mask and an inductively coupled plasma etching method is used. A BCl3 / Cl2 gas source is used to etch to a depth of n + GaN emitter ohmic contact layer, forming a cylindrical mesa from the first active layer to the collector electrode;

[0035] 7) Using traditional optical lithography technology, + On the GaN emitter ohmic contact layer, a ring pattern with an inner circumference 3μm away from the cylindrical table is formed. Using photoresist as a mask, electron beam evaporation is used to form a GaN emitter ohmic contact layer. + A Ti / Au metal layer is evaporated on the GaN emitter ohmic contact layer (3) to form an emitter electrode;

[0036] 8) Using plasma enhanced chemical vapor deposition or atomic layer deposition process, +A passivation layer with a thickness of 50nm-200nm is deposited on the surface of the GaN emitter ohmic contact layer to the collector electrode;

[0037] 9) Using conventional optical lithography, the emitter electrode through-hole pattern is formed on the passivation layer. Using photoresist as a mask, reactive ion etching is performed using an SF6 gas source to form the emitter electrode through-hole;

[0038] 10) Using electron beam lithography, a circular pattern with a diameter of 200 nm to 18 μm is formed on the cylindrical mesa passivation layer. Using photoresist as a mask, reactive ion etching is performed using an SF6 gas source to form collector electrode through-holes.

[0039] 11) Using traditional optical lithography technology, emitter and collector pad patterns are formed on the device surface. Using photoresist as a mask, electron beam evaporation is used to evaporate the Ti / Au metal layer on the entire device surface to form emitter and collector pads, completing the device preparation.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] 1. The present invention is provided with an N-layer active area and an N-1 layer n + The multi-layer composite structure active area composed of GaN series layers can achieve multi-region differential negative resistance characteristics using a single device through the resonant tunneling phenomenon occurring in each active area. This not only avoids the on-chip series integration of multiple devices in the horizontal direction, saving wafer area and improving device integration, but also avoids the metal interconnection of the on-chip device integration process, simplifies the preparation process and improves the fault tolerance.

[0042] 2. The multi-layer composite structure active area of ​​the present invention ensures the consistency of epitaxial material thickness because each active area and series layer are realized in the epitaxial direction, avoids large deviations in on-chip device performance caused by material thickness fluctuations and uneven distribution, and improves device survival rate and reliability.

[0043] 3. The present invention adopts n + The GaN series layer connects multiple active regions in the vertical direction. It can not only effectively adjust the self-oscillation frequency of the differential negative resistance region of the resonant tunneling diode by changing the thickness and doping concentration of the series layer, eliminate the "chair-shaped" bump in the output characteristic curve, and improve the stability and reliability of the device, but also avoid the problem of too large difference in the peak current density and peak-to-valley current ratio of the multi-region differential negative resistance characteristics when multiple quantum wells are used in a single active region to realize the multi-region differential negative resistance characteristics, further improving the stability and reliability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1This is a structural diagram of an existing AlGaN / GaN double-barrier resonant tunneling diode;

[0045] Figure 2 This is a structural diagram of a gallium nitride-based resonant tunneling diode with multi-region differential negative resistance characteristics in the present invention;

[0046] Figure 3 This is a general flow chart of the present invention for fabricating a gallium nitride-based resonant tunneling diode with multi-region differential negative resistance characteristics;

[0047] Figure 4 The present invention is to make a 2-layer active area and 1 layer n + Schematic diagram of the process of the composite active region composed of alternating GaN series layers;

[0048] Figure 5 The present invention is to make a 4-layer active area and 3-layer n + Schematic diagram of the process of the composite active region composed of alternating GaN series layers;

[0049] Figure 6 The present invention is to produce a 6-layer active area and 5-layer n + Schematic diagram of the process of a 6-layer composite active region composed of alternating GaN series layers;

[0050] Figure 7 This is the IV DC characteristic curve test result of the first embodiment. DETAILED DESCRIPTION

[0051] The embodiments and effects of the present invention will be further described with reference to the accompanying drawings.

[0052] Reference Figure 2 The gallium nitride-based resonant tunneling diode with multi-characteristic differential negative resistance characteristics of the present invention includes, from bottom to top, a substrate 1, a GaN epitaxial layer 2, an emitter ohmic contact layer 3, a composite active region 4, a collector ohmic contact layer 5, a collector electrode 6, and an annular emitter electrode 8 on both sides of the active region; the active region 4 to the collector electrode 6 is a cylindrical table formed by etching, and the outside of the cylindrical table is wrapped with a passivation layer 7.

[0053] The composite active region 4 is composed of N layers of active regions and N-1 layers of n + The composite structure is composed of alternating GaN series layers, wherein the active region of each layer includes, from bottom to top, a first isolation layer 41, a first barrier layer 42, a quantum well layer 43, a second barrier layer 44, and a second isolation layer 45; each layer has a n + The GaN series layer has a doping concentration of 1×10 19 cm -3 -5×10 20 cm -3, thickness of 30nm-200nm n + GaN, where N ≥ 2.

[0054] The thickness of the first isolation layer 41 and the second isolation layer 45 are both 4nm-15nm GaN;

[0055] The first barrier layer 42 and the second barrier layer 44 have the same composition and thickness of 1 nm to 3 nm.

[0056] The quantum well layer 43 is made of In with a composition v between 0% and 100%. v Ga 1-v N, whose thickness is 1nm-3nm;

[0057] The first barrier layer 42 and the second barrier layer 44 are made of the same material. x Al 1-x N, Y x Al 1-x N, B w Al y Ga z For any of N, the component x is between 5% and 25%, the components w, y, and z are between 0% and 100%, and w+y+z=100%;

[0058] The collector ohmic contact layer 5 has a doping concentration of 5×10 19 cm -3 -5×10 20 cm -3 , thickness of 50nm-200nm n + GaN;

[0059] The emitter ohmic contact layer 3 has a doping concentration of 5×10 19 cm -3 -5×10 20 cm -3 , thickness of 50nm-200nm n + GaN;

[0060] The GaN epitaxial layer 2 has a thickness of 500nm-5000nm;

[0061] The passivation layer 7 is made of any one of SiN material, Al2O3 material, and HfO2 material;

[0062] The substrate 1 is made of any one of self-supporting gallium nitride single crystal material, self-supporting aluminum nitride single crystal material, sapphire material, silicon carbide material, silicon material, boron nitride material, and diamond material.

[0063] Reference Figure 3 The present invention provides the following six embodiments for fabricating a gallium nitride-based resonant tunneling diode with multi-region differential negative resistance characteristics.

[0064] Example 1: On a self-supporting gallium nitride single crystal substrate, Sc 0.18 Al 0.82 A gallium nitride-based resonant tunneling diode with differential negative resistance characteristics of the ScAlN / GaN two regions of the N barrier layer and GaN quantum well.

[0065] Step 1: growing a GaN epitaxial layer.

[0066] A GaN epitaxial layer with a thickness of 1500nm was grown on a self-supporting gallium nitride substrate using molecular beam epitaxy.

[0067] The process conditions for growing GaN epitaxial layers are: temperature of 700°C, equilibrium vapor pressure of gallium beam of 8.0×10 - 7 Torr, the nitrogen flow rate was 1.8 sccm, and the nitrogen plasma RF source power was 375 W.

[0068] Step 2: Grow n + GaN emitter ohmic contact layer.

[0069] The molecular beam epitaxy method was used to grow a GaN epitaxial layer with a thickness of 100nm and a doping concentration of 1×10 20 cm -3 n + GaN emitter ohmic contact layer.

[0070] Growth + The process conditions of the GaN emitter ohmic contact layer are: temperature 700℃, gallium beam equilibrium vapor pressure 8.0×10 -7 Torr, the equilibrium vapor pressure of silicon beam is 3.5×10 -8 Torr, the nitrogen flow rate was 2.3 sccm, and the nitrogen plasma RF source power was 375 W.

[0071] Step three: growing a composite active region.

[0072] Reference Figure 4 The specific implementation of this step is as follows

[0073] 3.1) Growth of the first active region:

[0074] 3.1.1) Using molecular beam epitaxy, + A first GaN isolation layer 41 is grown on the GaN emitter ohmic contact layer, with a thickness of 10 nm. Figure 4(a), the process conditions are: temperature 700℃, gallium beam equilibrium vapor pressure 8.0×10 - 7 Torr, the nitrogen flow rate was 2.3 sccm, and the nitrogen plasma RF source power was 375 W;

[0075] 3.1.2) Using molecular beam epitaxy, a first Sc layer with a thickness of 2 nm and a Sc content of 18% is grown on the first GaN isolation layer. 0.18 Al 0.82 N barrier layer 42, such as Figure 4 (b) The process conditions are: temperature of 700 °C, nitrogen flow rate of 2.3 sccm, and scandium beam equilibrium vapor pressure of 1.5×10 -8 Torr, the equilibrium vapor pressure of aluminum beam is 2.5×10 -7 Torr, the nitrogen plasma RF source power is 375W;

[0076] 3.1.3) Using molecular beam epitaxy, grow a GaN quantum well layer 43 with a thickness of 2 nm on the first ScAlN barrier layer, as shown in FIG. Figure 4 (c) The process conditions are: temperature of 700°C, equilibrium vapor pressure of gallium beam of 8.0×10 -7 Torr, the nitrogen flow rate was 2.3 sccm, and the nitrogen plasma RF source power was 375 W;

[0077] 3.1.4) Using molecular beam epitaxy, a second Sc layer with a thickness of 2 nm and a Sc content of 18% is grown on the GaN quantum well layer. 0.18 Al 0.82 N barrier layer 44, such as Figure 4 (d) The process conditions are: temperature 700 °C, nitrogen flow rate 2.3 sccm, scandium beam equilibrium vapor pressure 1.5×10 -8 Torr, the equilibrium vapor pressure of aluminum beam is 2.5×10 -7 Torr, the nitrogen plasma RF source power is 375W;

[0078] 3.1.5) Using molecular beam epitaxy, in the second Sc 0.18 Al 0.82 A second GaN isolation layer 45 is grown on the N barrier layer. Figure 4 (e) The process conditions are: temperature of 700°C, equilibrium vapor pressure of gallium beam of 8.0×10 -7 Torr, the nitrogen flow rate was 2.3 sccm, and the nitrogen plasma RF source power was 375 W;

[0079] 3.2) Using molecular beam epitaxy, a 30 nm thick layer with a doping concentration of 1×10 20cm -3 n + GaN tandem layers, such as Figure 4 (f) The process conditions are: temperature of 700°C, equilibrium vapor pressure of gallium beam of 8.0×10 - 7 Torr, the equilibrium vapor pressure of silicon beam is 3.5×10 -8 Torr, the nitrogen flow rate was 2.3 sccm, and the nitrogen plasma RF source power was 375 W.

[0080] 3.3) Growth of the second active region:

[0081] 3.3.1) Using molecular beam epitaxy, + A first GaN isolation layer 41 is grown on the GaN series layer with a thickness of 10 nm. Figure 4 (g), the process conditions are: temperature 700℃, gallium beam equilibrium vapor pressure 8.0×10 -7 Torr, the nitrogen flow rate was 2.3 sccm, and the nitrogen plasma RF source power was 375 W;

[0082] 3.3.2) Using molecular beam epitaxy, a first Sc layer with a thickness of 2 nm and a Sc content of 18% is grown on the first GaN isolation layer. 0.18 Al 0.82 N barrier layer 42, such as Figure 4 (h), the process conditions are: temperature 700 ° C, nitrogen flow rate 2.3 sccm, scandium beam equilibrium vapor pressure 1.5 × 10 -8 Torr, the equilibrium vapor pressure of aluminum beam is 2.5×10 -7 Torr, the nitrogen plasma RF source power is 375W;

[0083] 3.3.3) Using molecular beam epitaxy, grow a GaN quantum well layer 43 with a thickness of 2 nm on the first ScAlN barrier layer, as shown in FIG. Figure 4 (i) The process conditions are: temperature of 700°C, equilibrium vapor pressure of gallium beam of 8.0×10 -7 Torr, the nitrogen flow rate was 2.3 sccm, and the nitrogen plasma RF source power was 375 W;

[0084] 3.3.4) Using molecular beam epitaxy, a second Sc layer with a thickness of 2 nm and a Sc content of 18% is grown on the GaN quantum well layer. 0.18 Al 0.82 N barrier layer 44, such as Figure 4 (j), the process conditions are: temperature 700 °C, nitrogen flow rate 2.3 sccm, scandium beam equilibrium vapor pressure 1.5×10 -8Torr, the equilibrium vapor pressure of aluminum beam is 2.5×10 -7 Torr, the nitrogen plasma RF source power is 375W;

[0085] 3.3.5) Using molecular beam epitaxy, in the second Sc 0.18 Al 0.82 A second GaN isolation layer 45 is grown on the N barrier layer. Figure 4 (k), the process conditions are: temperature 700℃, gallium beam equilibrium vapor pressure 8.0×10 -7 Torr, the nitrogen flow rate was 2.3 sccm, and the nitrogen plasma RF source power was 375 W.

[0086] Step 4: Grow n + GaN collector ohmic contact layer, such as Figure 4 (l).

[0087] The molecular beam epitaxy method was used to grow a 100nm thick layer on the composite active area with a doping concentration of 1×10 20 cm -3 n + GaN collector ohmic contact layer.

[0088] Growth + The process conditions of the GaN collector ohmic contact layer are: temperature of 700°C, gallium beam equilibrium vapor pressure of 8.0×10 -7 Torr, the equilibrium vapor pressure of silicon beam is 3.5×10 -8 Torr, the nitrogen flow rate was 2.3 sccm, and the nitrogen plasma RF source power was 375 W.

[0089] Step 5, in n + The GaN collector ohmic contact layer is subjected to photolithography, development and etching to form a grid-like mesa isolation with a depth of 500 nm.

[0090] 5.1) Using photolithography to form mesa isolation patterns:

[0091] 5.1.1) Spin-coat AZ5214 photoresist at a speed of 500 rad / min and an acceleration of 1000 rad. 2 / min, and then spin-coated for 3s at a speed of 4000rad / min and an acceleration of 2000rad. 2 Spin coating was performed at 400 nm / min for 30 s and then cured at 95°C for 90 s.

[0092] 5.1.2) Using traditional optical lithography, + Exposure treatment of AZ5214 photoresist on the GaN collector ohmic contact layer;

[0093] 5.1.3) The exposed photoresist was developed using RZX-3038 developer for 45 seconds to form a grid-like mesa isolation pattern.

[0094] 5.2) Etching to form mesa isolation:

[0095] The inductively coupled plasma etching method is used, and a photoresist is used as a mask to etch a grid-like mesa isolation with a depth of 700 nm. The etching process conditions are: Cl2 gas flow rate is 10 sccm, BCl3 gas flow rate is 25 sccm, and etching time is 350 s.

[0096] Step 6, in n + The GaN collector ohmic contact layer is etched to n + A GaN emitter ohmic contact layer is formed, a cylindrical table with a diameter of 2μm is formed, and metal is deposited to form a collector electrode.

[0097] 6.1) Photolithography to form circular mesa patterns:

[0098] 6.1.1) In n + Spin-coat PMMA A4 photoresist on the InN collector ohmic contact layer: first spin at a speed of 500 rad / min and an acceleration of 1000 rad 2 / min, and then spin-coated for 3s at a speed of 4000rad / min and an acceleration of 2000rad. 2 Spin-coat for 30 seconds at a speed of 1000 nm / min and then bake at 180°C for 90 seconds.

[0099] 6.1.2) Expose PMMA A4 photoresist using electron beam lithography at an electron dose ratio of 750.

[0100] 6.1.3) Develop the exposed photoresist with a 3:1 solution of tetramethyl dipentyl ketone and isopropyl alcohol for 120 seconds, then fix with isopropyl alcohol for 30 seconds to form a circular mesa pattern with a diameter of 2 μm.

[0101] 6.2) Using electron beam evaporation method, on the circular table Ti / Au / Ni metals with thicknesses of 20 / 80 / 50 nm were evaporated at a rate of 100 nm and then soaked in acetone solution;

[0102] 6.3) Using metal as mask, use inductively coupled plasma etching method to etch n + GaN collector ohmic contact layer to n + The GaN emitter ohmic contact layer forms a cylindrical table with a diameter of 2μm. The etching process conditions are: Cl2 gas flow rate of 10sccm, BCl3 gas flow rate of 25sccm, and etching time of 150s.

[0103] Step 7, in n + A ring-shaped emitter electrode with an inner circumference 3 μm away from the cylindrical table is formed on the GaN emitter ohmic contact layer.

[0104] 7.1) Photolithography to form a ring-shaped emitter electrode pattern:

[0105] 7.1.1) In n + AZ5214 photoresist is spin-coated on the GaN emitter ohmic contact layer at a rotation speed of 500 rad / min and an acceleration of 1000 rad. 2 / min spin coating for 3s; then at a speed of 4000rad / min and an acceleration of 2000rad 2 Spin coating at 400 nm / min for 30 s, and then bake at 95°C for 90 s;

[0106] 7.1.2) Using traditional optical lithography, + Exposure treatment of AZ5214 photoresist on the GaN emitter ohmic contact layer;

[0107] 7.1.3) Develop the exposed photoresist with RZX-3038 developer for 45 seconds to form a ring-shaped emitter electrode pattern with an inner circumference 3 μm from the cylindrical mesa.

[0108] 7.2) Using electron beam evaporation method, + The GaN emitter ohmic contact layer is Ti / Au metal with a thickness of 20 / 80 nm was evaporated at a rate of 100 nm and then immersed in acetone solution to form an emitter electrode with an inner circumference 3 μm away from the cylindrical table.

[0109] Step eight, depositing a passivation layer.

[0110] A 200nm thick SiN passivation layer was deposited on the entire device surface using plasma-enhanced chemical vapor deposition (PECVD). The process conditions were: 60s, 2200mTorr, 350°C, 13.5sccm SiH4, 10sccm NH3, and 1000sccm N2.

[0111] Step nine: photolithography and etching are performed on the SiN passivation layer to form an emitter electrode through hole.

[0112] 9.1) Photolithography to form emitter electrode through-hole pattern:

[0113] 9.1.1) Spin-coat AZ5214 photoresist on the SiN passivation layer at a speed of 500 rad / min and an acceleration of 1000 rad. 2 / min for 3s; then spin-coat at a speed of 4000rad / min and an acceleration of 2000rad 2 / min, rotate up and down for 30s, and then bake at 95℃ for 90s;

[0114] 9.1.2) Expose the AZ5214 photoresist on the SiN passivation layer using conventional optical lithography.

[0115] 9.1.3) Develop the exposed photoresist with RZX-3038 developer for 45 seconds to form a circular pattern with an inner diameter slightly smaller than the emitter electrode.

[0116] 9.2) Use reactive ion etching (RIE) with a photoresist mask to etch the SiN passivation layer down to the emitter metal surface to form an emitter electrode through-hole. The process conditions are: pressure 1500 mTorr, power 200 W, SF6 flow rate 8 sccm, CHF3 flow rate 10 sccm, and He flow rate 150 sccm.

[0117] Step 10: Prepare a collector electrode through hole with a diameter of 1 μm on the SiN passivation layer.

[0118] 10.1) Photolithography to form collector electrode through-hole pattern:

[0119] 10.1a) Spin-coat PMMA A4 photoresist onto the SiN passivation layer at a rotation speed of 500 rad / min and an acceleration of 1000 rad. 2 / min for 3s; then spin-coat at a speed of 4000rad / min and an acceleration of 2000rad 2 Spin coating was performed at 400 nm / min for 30 s and then cured at 180°C for 90 s.

[0120] 10.1b) Expose PMMA A4 photoresist using electron beam lithography, setting the electron dose ratio to 750.

[0121] 10.1c) The exposed photoresist is first developed with a 3:1 solution of tetramethyl dipentyl ketone and isopropyl alcohol for 120 seconds, and then fixed with isopropyl alcohol for 30 seconds to form a collector electrode through-hole pattern.

[0122] 10.2) Using photoresist as a mask, use reactive ion etching to etch the SiN passivation layer to the collector electrode metal

[0123] surface,

[0124] The collector electrode through hole with a diameter of 1 μm is formed under the following process conditions: pressure of 1500 mTorr, power of 200 W, SF6 flow rate of 8 sccm, CHF3 of 10 sccm, and He flow rate of 150 sccm.

[0125] Step 11: Lead out the emitter electrode Pad and the collector electrode Pad on the emitter electrode through-hole and the collector electrode through-hole to complete the device manufacturing.

[0126] 11.1) Photolithography to form emitter and collector electrode metal pad patterns:

[0127] 11.1a) Spin-coat AZ5214 photoresist on the emitter and collector holes at a speed of 500 rad / min and an acceleration of 1000 rad. 2 / min for 3s; then spin-coat at a speed of 4000rad / min and an acceleration of 2000rad 2 Spin coating was performed at 400 nm / min for 30 s and then cured at 95°C for 90 s.

[0128] 11.1b) Expose AZ5214 photoresist using conventional optical lithography methods;

[0129] 11.1c) Develop the exposed photoresist with RZX-3038 developer for 45 seconds to form emitter and collector electrode metal pad patterns.

[0130] 11.2) Using electron beam evaporation, Ti / Au metal with a thickness of 20 / 80 nm is evaporated at a rate of , and then soaked in acetone to form an emitter electrode Pad and a collector electrode Pad interconnected with the emitter electrode and the collector electrode, completing the device fabrication.

[0131] Example 2: On a sapphire substrate, a Y 0.20 Al 0.80 Gallium nitride-based resonant tunneling diode with YAlN / InGaN four-region differential negative resistance characteristics of N barrier layer and InGaN quantum well.

[0132] Step 1: growing a GaN epitaxial layer.

[0133] Using molecular beam epitaxy, the temperature was 720 ° C and the equilibrium vapor pressure of the gallium beam was 8.5 × 10 -7 Under the process conditions of 0.575 GHz, 0.67 GHz, 1.3 GHz and 2.5 GHz nitrogen plasma RF source power, a GaN epitaxial layer with a thickness of 5000 nm was grown on a sapphire substrate.

[0134] Step 2, grow n +GaN emitter ohmic contact layer.

[0135] Using molecular beam epitaxy, the temperature was 720 ° C and the equilibrium vapor pressure of the gallium beam was 8.5 × 10 -7 Torr, the equilibrium vapor pressure of silicon beam is 3.2×10 -8 Torr, a nitrogen flow rate of 2.3 sccm, and a nitrogen plasma RF source power of 375 W were used to grow a GaN epitaxial layer with a thickness of 200 nm and a doping concentration of 8×10 19 cm -3 n + GaN emitter ohmic contact layer.

[0136] Step 3: Grow four active regions and three n + A composite active region with alternating GaN series layers.

[0137] Reference Figure 5 , this step is specifically implemented as follows

[0138] (3.1) Grow the first active region, such as Figure 5 (a):

[0139] (3.1.1) Molecular beam epitaxy was used, with a temperature of 720°C and a gallium beam equilibrium vapor pressure of 8.5×10 - 7 Torr, nitrogen flow rate of 2.3 sccm, nitrogen plasma RF source power of 375 W, in n + A first GaN isolation layer 41 with a thickness of 6 nm is grown on the GaN emitter ohmic contact layer;

[0140] (3.1.2) Using the molecular beam epitaxy method, set the temperature to 720°C, the nitrogen flow rate to 2.3 sccm, and the iridium beam equilibrium vapor pressure to 1.8×10 -8 Torr, the equilibrium vapor pressure of aluminum beam is 2.3×10 -7 Torr, the nitrogen plasma RF source power is 375W, and the first Y component with a thickness of 1.5nm and a Y content of 20% is grown on the GaN isolation layer. 0.2 Al 0.8 N barrier layer 42;

[0141] (3.1.3) Using the molecular beam epitaxy method, the temperature was set to 720°C and the equilibrium vapor pressure of the indium beam was set to 2.0×10 - 7 Torr, the equilibrium vapor pressure of gallium beam is 8.5×10 -7 Torr, nitrogen flow rate of 2.3 sccm, nitrogen plasma RF source power of 375W, in the first Y 0.2Al 0.8 An InGaN quantum well layer 43 with a thickness of 2.5 nm is grown on the N barrier layer;

[0142] (3.1.4) Using the molecular beam epitaxy method, set the temperature to 720°C, the nitrogen flow rate to 2.3 sccm, and the iridium beam equilibrium vapor pressure to 1.8×10 -8 Torr, the equilibrium vapor pressure of aluminum beam is 2.3×10 -7 Torr, under the process conditions of nitrogen plasma RF source power of 375W, a second Y-containing layer with a thickness of 1.5nm and a Y component of 20% was grown on the InGaN quantum well layer. 0.2 Al 0.8 N barrier layer 44;

[0143] (3.1.5) Molecular beam epitaxy was used, with a temperature of 720°C and a gallium beam equilibrium vapor pressure of 8.5×10 - 7 Torr, nitrogen flow rate of 2.3 sccm, nitrogen plasma RF source power of 375W, in the second Y 0.2 Al 0.8 A second GaN isolation layer 45 with a thickness of 6 nm is grown on the N barrier layer;

[0144] (3.2) Using the molecular beam epitaxy method, the temperature was set to 720 °C and the equilibrium vapor pressure of the gallium beam was 8.5×10 - 7 Torr, the equilibrium vapor pressure of silicon beam is 3.2×10 -8 Torr, nitrogen flow rate of 2.3 sccm, nitrogen plasma RF source power of 375 W, the thickness of the growth on the first active area is 50 nm, the doping concentration is 8×10 19 cm -3 The first layer n + GaN tandem layers, such as Figure 5 (b).

[0145] (3.3) In the first layer n + The second active region is grown on the GaN series layer, such as Figure 5 (c) The specific implementation of this step is the same as step (3.1);

[0146] (3.4) Grow the second layer n on the second active region + GaN tandem layers, such as Figure 5 (d) The specific implementation of this step is the same as step (3.2);

[0147] (3.5) In the second layer n + The third active region is grown on the GaN series layer, such as Figure 5(e) The specific implementation of this step is the same as step (3.1);

[0148] (3.6) Grow the third layer n on the third active region + GaN tandem layers, such as Figure 5 (f) The specific implementation of this step is the same as step (3.2);

[0149] (3.7) In the third layer n + The fourth active region is grown on the GaN series layer, such as Figure 5 (g) The specific implementation of this step is the same as step (3.1); complete the four-layer active area and three-layer n + Growth of a composite active region with alternating GaN tandem layers.

[0150] Step 4, grow n + GaN collector ohmic contact layer.

[0151] Using molecular beam epitaxy, the temperature was 720 ° C and the equilibrium vapor pressure of the gallium beam was 8.5 × 10 -7 Torr, the equilibrium vapor pressure of silicon beam is 3.2×10 -8 Torr, a nitrogen flow rate of 2.3 sccm, and a nitrogen plasma RF source power of 375 W were used to grow a GaN epitaxial layer with a thickness of 200 nm and a doping concentration of 8×10 19 cm -3 n + GaN collector ohmic contact layer.

[0152] Step 5, in n + The GaN collector ohmic contact layer is subjected to photolithography, development and etching to form a grid-like mesa isolation with a depth of 800 nm.

[0153] (5.1) Photolithography is used to form a mesa isolation pattern. The specific implementation of this step is the same as step 5.1) of Example 1.

[0154] (5.2) Using the inductively coupled plasma etching method, with the photoresist as the mask, the process conditions of Cl2 gas flow rate of 10 sccm and BCl3 gas flow rate of 25 sccm were adopted to etch n + The GaN collector ohmic contact layer is 400s, forming a grid-like mesa isolation with a depth of 800nm.

[0155] Step 6, in n + The GaN collector ohmic contact layer is etched to n + The GaN emitter ohmic contact layer is formed into a cylindrical table with a diameter of 1 μm, and metal is deposited to form the collector electrode.

[0156] (6.1) Photolithography to form circular mesa patterns:

[0157] (6.1.1) In n + PMMA A4 photoresist was spin-coated twice on the GaN collector ohmic contact layer: the first time at a speed of 500 rad / min and an acceleration of 1000 rad 2 The second spin coating was performed at a speed of 4000 rad / min and an acceleration of 2000 rad. 2 Spin-coat for 30 seconds at a speed of 1000 nm / min and then bake at 180°C for 90 seconds.

[0158] (6.1.2) Expose PMMA A4 photoresist using electron beam lithography with an electron dose ratio of 750.

[0159] (6.1.3) The exposed photoresist is first developed with a 3:1 solution of tetramethyl dipentyl ketone and isopropyl alcohol for 120 seconds, followed by fixing with isopropyl alcohol for 30 seconds to form a circular mesa pattern with a diameter of 1 μm.

[0160] (6.2) Using electron beam evaporation method, on the circular table pattern according to Ti / Au / Ni metals with thicknesses of 20 / 80 / 50 nm were evaporated at a rate of 100 nm and then soaked in acetone solution.

[0161] (6.3) Using metal as a mask, the circular mesa pattern is etched by inductively coupled plasma etching. The process conditions are set to 10 sccm of Cl2 gas flow, 25 sccm of BCl3 gas flow, and 150 s of etching time. + The GaN emitter ohmic contact layer forms a cylindrical mesa with a diameter of 1μm.

[0162] Step 7, in n + A ring-shaped emitter electrode with an inner circumference 3 μm away from the cylindrical table is formed on the GaN emitter ohmic contact layer.

[0163] The specific implementation of this step is the same as step seven of Example 1.

[0164] Step 8: Deposit a 50nm Al2O3 dielectric passivation layer.

[0165] An atomic layer deposition process was used with a setting time of 40s, a pressure of 2000mTorr, a temperature of 300°C, an Al(CH3)3 flow rate of 850sccm, a H2O flow rate of 350sccm, and a N2 flow rate of 1000sccm to deposit a 50nm thick Al2O3 dielectric passivation layer on the entire device surface.

[0166] Step 9: Photolithography and etching are performed on the Al2O3 dielectric passivation layer to form an emitter electrode through hole.

[0167] (9.1) Photolithography to form emitter electrode through-hole pattern:

[0168] The specific implementation of this step is the same as step 9.1) of Example 1.

[0169] (9.2) Using the photoresist as a mask, reactive ion etching is performed with the following process conditions: pressure of 1500 mTorr, power of 200 W, SF6 flow rate of 8 sccm, CHF3 of 10 sccm, and He flow rate of 150 sccm. The Al2O3 dielectric passivation layer is etched to the metal surface of the emitter electrode to form an emitter electrode through hole.

[0170] Step 10: Prepare a collector electrode through hole with a diameter of 500 nm on the Al2O3 dielectric passivation layer.

[0171] (10.1) Photolithography to form collector electrode through-hole pattern:

[0172] The specific implementation of this step is the same as step 10.1) of Example 1.

[0173] (10.2) Using photoresist as a mask, reactive ion etching is used to etch the Al2O3 dielectric passivation layer to the collector electrode metal surface under the process conditions of a pressure of 1500mTorr, a power of 200W, an SF6 flow rate of 8sccm, a CHF3 flow rate of 10sccm, and a He flow rate of 150sccm, forming a collector electrode through-hole with a diameter of 500nm.

[0174] Step 11: Lead out the emitter electrode Pad and the collector electrode Pad on the emitter electrode and the collector electrode through-holes to complete the device manufacturing.

[0175] The specific implementation of this step is the same as step 11 of embodiment 1.

[0176] In the third embodiment, a gallium nitride-based resonant tunneling diode with an AlN / GaN six-region differential negative resistance characteristic using an AlN barrier layer and a GaN quantum well is fabricated on a silicon substrate.

[0177] Step A: growing a GaN epitaxial layer.

[0178] Using molecular beam epitaxy, the temperature was 650 ° C and the equilibrium vapor pressure of the gallium beam was 4.5 × 10 -7 A GaN epitaxial layer with a thickness of 500 nm was grown on a silicon substrate under the process conditions of 0.5 GHz, a nitrogen flow rate of 1.2 sccm, and a nitrogen plasma RF source power of 375 W.

[0179] Step B, growing n+ GaN emitter ohmic contact layer.

[0180] The molecular beam epitaxy method was used, and the temperature was 650℃ and the equilibrium vapor pressure of the gallium beam was 7.5×10 -7 Torr, the silicon beam equilibrium vapor pressure is 3.0×10 -8 Under the process conditions of 100 Torr, nitrogen flow rate of 2.3 sccm, and nitrogen plasma RF source power of 375 W, a GaN epitaxial layer with a thickness of 300 nm and a doping concentration of 5×10 19 cm -3 n + GaN emitter ohmic contact layer.

[0181] Step C, growing six layers of active area and five layers of n + A composite active region with alternating GaN series layers.

[0182] Reference Figure 6 , the specific implementation of this step is as follows:

[0183] C.1) Grow the first active region, such as Figure 6 (a):

[0184] C.1.1) Using molecular beam epitaxy, the temperature was 650°C and the equilibrium vapor pressure of the gallium beam was 7.5×10 - 7 Under the process conditions of 1000 Torr, nitrogen flow rate of 2.3 sccm, and nitrogen plasma RF source power of 375W, the + A first GaN isolation layer 41 with a thickness of 4 nm is grown on the GaN emitter ohmic contact layer;

[0185] C.1.2) Using molecular beam epitaxy, the temperature was 650°C, the nitrogen flow rate was 2.3 sccm, and the gallium beam equilibrium vapor pressure was 7.5×10 -7 Torr, the equilibrium vapor pressure of aluminum beam is 2.8×10 -7 Under the process conditions of 0.6777 Å and 0.677 Å, a first AlN barrier layer 42 with a thickness of 3 nm was grown on the first GaN isolation layer 41 .

[0186] C.1.3) Using molecular beam epitaxy, the temperature was 680°C and the equivalent equilibrium vapor pressure of the gallium beam was 7.5×10 - 7 Under the process conditions of 0.0447 Å, 0.020 Å, 0.062 Å nitrogen flow rate of 2.3 sccm, and 375 W nitrogen plasma RF source power, a GaN quantum well layer 43 with a thickness of 3 nm was grown on the first AlN barrier layer 42 .

[0187] C.1.4) Using molecular beam epitaxy, the temperature was 650°C, the nitrogen flow rate was 2.3 sccm, and the gallium beam equilibrium vapor pressure was 7.5×10 -7 Torr, the equilibrium vapor pressure of aluminum beam is 2.8×10 -7 Under the process conditions of 0.0447 Å / min at 0.020 Å / min and a nitrogen plasma radio frequency source power of 375 W, a second AlN barrier layer 44 with a thickness of 3 nm was grown on the GaN quantum well layer 43 .

[0188] C.1.5) Using molecular beam epitaxy, the temperature was 530°C, the nitrogen flow rate was 2.3 sccm, and the gallium beam equilibrium vapor pressure was 7.5×10 -7 Under the process conditions of 0.175 Torr and a nitrogen plasma radio frequency source power of 375 W, a GaN isolation layer 45 with a thickness of 4 nm is grown on the second AlN barrier layer 44 .

[0189] C.2) Growth of the first layer n + GaN tandem layers, such as Figure 6 (b):

[0190] The molecular beam epitaxy method was used, and the temperature was 650℃ and the equilibrium vapor pressure of the gallium beam was 7.5×10 -7 Torr, the silicon beam equilibrium vapor pressure is 3.0×10 -8 Under the process conditions of 100 Torr, 2.3 sccm nitrogen flow rate and 375W nitrogen plasma RF source power, a GaN epitaxial layer with a thickness of 100 nm and a doping concentration of 5×10 19 cm -3 The first layer n + GaN tandem layer.

[0191] C.3) In the first layer n + The second active region is grown on the GaN series layer, such as Figure 6 (c) The specific implementation of this step is the same as step (C.1);

[0192] C.4) Grow the second layer n on the second active region + GaN tandem layers, such as Figure 6 (d) The specific implementation of this step is the same as step (C.2);

[0193] C.5) In the second layer n + The third active region is grown on the GaN series layer, such as Figure 6 (e) The specific implementation of this step is the same as step (C.1);

[0194] C.6) Grow the third layer n on the third active region + GaN tandem layers, such as Figure 6(f) The specific implementation of this step is the same as step (C.2);

[0195] C.7) In the third layer n + The fourth active region is grown on the GaN series layer, such as Figure 6 (g) The specific implementation of this step is the same as step (C.1);

[0196] C.8) Grow the fourth layer n on the fourth active region + GaN tandem layers, such as Figure 6 (h), the specific implementation of this step is the same as step (C.2).

[0197] C.9) At the fourth layer n + The fifth active region is grown on the GaN series layer, such as Figure 6 (i) The specific implementation of this step is the same as step (C.1).

[0198] C.6) Grow the fifth layer n on the fifth active region + GaN tandem layers, such as Figure 6 (j) The specific implementation of this step is the same as step (C.2).

[0199] C.7) On the fifth layer n + The sixth active region is grown on the GaN series layer, such as Figure 6 (k), the specific implementation of this step is the same as step (C.1); complete the six-layer active area and five-layer n + Growth of a composite active region with alternating GaN tandem layers.

[0200] Step D, growing n + GaN collector ohmic contact layer.

[0201] The molecular beam epitaxy method was used, and the temperature was 650℃, the nitrogen flow rate was 2.3sccm, and the gallium beam equilibrium vapor pressure was 7.5×10 -7 Torr, the silicon beam equilibrium vapor pressure is 3.0×10 -8 Under the process conditions of 375W of nitrogen plasma RF source power, a 300nm thick and 5×10 19 cm -3 n + GaN collector ohmic contact layer.

[0202] Step E, in n + The GaN collector ohmic contact layer is subjected to photolithography, development and etching to form a grid-like mesa isolation with a depth of 1000nm.

[0203] E.1) Using photolithography to form mesa isolation patterns:

[0204] The specific implementation of this step is the same as step 5.1) of Example 1.

[0205] E.2) Etching to form mesa isolation:

[0206] The photoresist was used as a mask and an inductively coupled plasma etching method was used. Under the process conditions of Cl2 gas flow rate of 10 sccm, BCl3 gas flow rate of 25 sccm and etching time of 500 s, the n + The GaN collector ohmic contact layer forms a grid-like mesa isolation with a depth of 1000nm.

[0207] Step F, in n + The GaN collector ohmic contact layer is etched to n + A GaN emitter ohmic contact layer is formed to form a cylindrical mesa with a diameter of 4 μm, and metal is deposited to form a collector electrode.

[0208] F.1) Photolithography to form circular mesa patterns:

[0209] F.1.1) In n + On the InN collector ohmic contact layer, spin-coat PMMA A4 photoresist: first spin at a speed of 500 rad / min and an acceleration of 1000 rad 2 / min spin coating for 3s; then at a speed of 4000rad / min and an acceleration of 2000rad 2 The film was spin-coated at 1000 nm / min for 30 s and then baked at 180°C for 90 s.

[0210] F.1.2) Expose PMMA A4 photoresist using electron beam lithography with an electron dose ratio of 750.

[0211] F.1.3) The exposed photoresist is first developed with a 3:1 solution of tetramethyl dipentyl ketone and isopropyl alcohol for 120 seconds, followed by fixing with isopropyl alcohol for 30 seconds to form a circular mesa pattern with a diameter of 4 μm.

[0212] F.2) Using electron beam evaporation method, on the circular table pattern according to Ti / Au / Ni metals with thicknesses of 20 / 80 / 50 nm were evaporated at a rate of 100 nm and then soaked in acetone solution;

[0213] F.3) Using metal as mask, adopt inductively coupled plasma etching method, set Cl2 gas flow rate to 10sccm, BCl3 gas flow rate to 25sccm, etching time to 150s, etching n + InN collector ohmic contact layer to n +The GaN emitter ohmic contact layer forms a cylindrical mesa with a diameter of 4μm.

[0214] Step G, in n + A ring-shaped emitter electrode with an inner circumference 3 μm away from the cylindrical table is formed on the GaN emitter ohmic contact layer.

[0215] The specific implementation of this step is the same as step seven of Example 1.

[0216] Step H, depositing a HfO2 dielectric passivation layer.

[0217] An atomic layer deposition process was used with a setting time of 70s, a temperature of 280°C, a flow rate of 1200sccm of hafnium ethylmethylamine, a flow rate of 110sccm of H2O, and a flow rate of 1000sccm of N2 to deposit a 100nm thick HfO2 dielectric passivation layer on the entire device surface.

[0218] Step I: photolithography and etching to form an emitter electrode through hole on the HfO2 dielectric passivation layer.

[0219] I.1) Photolithography is performed to form an emitter electrode through-hole pattern, the specific implementation of which is the same as step 9.1) of embodiment 1.

[0220] I.2) Using the photoresist as a mask, set the pressure to 1500 mTorr, the power to 200 W, the SF6 flow rate to 8 sccm, the CHF3 flow rate to 10 sccm, and the He flow rate to 150 sccm. Use reactive ion etching to etch the HfO2 dielectric passivation layer to the emitter electrode metal surface to form an emitter electrode through hole.

[0221] Step J: Prepare collector electrode through holes with a diameter of 3 μm on the HfO2 dielectric passivation layer, as shown in Figure 3 (l).

[0222] J.1) Photolithography is used to form a collector electrode through-hole pattern, which is specifically implemented in the same manner as step 10a) of the first embodiment.

[0223] J.2) Using a photoresist mask, set the process conditions to 1500 mTorr pressure, 200 W power, 8 sccm SF6 flow rate, 10 sccm CHF3, and 150 sccm He flow rate, and use reactive ion etching to etch the HfO2 dielectric passivation layer to the collector electrode metal surface to form a collector electrode through-hole with a diameter of 3 μm.

[0224] Step K, lead out the emitter and collector electrode Pad on the emitter and collector electrode through holes, such as Figure 3 (m).

[0225] The specific implementation of this step is the same as step 11 of embodiment 1.

[0226] In addition to using the molecular beam epitaxy method, the material epitaxial growth steps of the three embodiments described above can also be achieved by metal organic chemical vapor deposition technology. The following are three embodiments of growing GaN epitaxial layers using metal organic chemical vapor deposition technology; in addition, the subsequent other material epitaxial steps all use the molecular beam epitaxy method as in the three implementation cases described above.

[0227] Example 4: On a boron nitride substrate, Sc 0.18 Al 0.82 A gallium nitride-based resonant tunneling diode with differential negative resistance characteristics of the ScAlN / GaN two regions of the N barrier layer and GaN quantum well.

[0228] In the first step, a 500nm thick GaN epitaxial layer was grown on a boron nitride substrate using a metal organic chemical vapor deposition method with process conditions set at 1000°C, a pressure of 40 Torr, an ammonia flow rate of 1000sccm, a gallium source flow rate of 60sccm, and a hydrogen flow rate of 2000sccm.

[0229] The specific implementation of other subsequent steps is the same as the corresponding steps in Example 1.

[0230] Example 5: On a diamond substrate, a Y 0.20 Al 0.80 Gallium nitride-based resonant tunneling diode with YAlN / InGaN four-region differential negative resistance characteristics of N barrier layer and InGaN quantum well.

[0231] In the first step, a GaN epitaxial layer with a thickness of 5000nm was grown on a diamond substrate using a metal organic chemical vapor deposition method under the process conditions of a temperature of 1300°C, a pressure of 60Torr, an ammonia flow rate of 3000sccm, a gallium source flow rate of 120sccm, and a hydrogen flow rate of 5000sccm.

[0232] The specific implementation of other subsequent steps is the same as the corresponding steps in Example 2.

[0233] Example 6: On a self-supporting aluminum nitride single crystal substrate, a Y 0.20 Al 0.80 Gallium nitride-based resonant tunneling diode with YAlN / InGaN four-region differential negative resistance characteristics of N barrier layer and InGaN quantum well.

[0234] In step A, a 2000nm thick GaN epitaxial layer was grown on a self-supporting aluminum nitride single crystal substrate using a metal organic chemical vapor deposition method under the process conditions of a temperature of 1100°C, a pressure of 50 Torr, an ammonia flow rate of 2000sccm, a gallium source flow rate of 90sccm, and a hydrogen flow rate of 3000sccm.

[0235] The specific implementation of other subsequent steps is the same as the corresponding steps in Example 3.

[0236] The effect of the present invention can be further illustrated by the following test results:

[0237] The GaN-based resonant tunneling diode with two-region differential negative resistance characteristics on a self-supporting GaN substrate in Example 1 was measured to obtain its IV DC characteristic curve, as shown in FIG. Figure 7 shown.

[0238] from Figure 7 The following conclusions can be drawn:

[0239] First, this example consists of 2 layers of active area and 1 layer of n + The active region of the double-layer composite structure, composed of tandem GaN layers, can achieve differential negative resistance characteristics in two regions using a single device through the resonant tunneling phenomenon occurring in each active region. This saves wafer area, increases device integration, and avoids metal interconnects in the on-chip device integration process. This simplifies the fabrication process and improves fault tolerance.

[0240] Second, this example has two active regions and one n + The GaN series layers are all realized in the epitaxial direction, ensuring the consistency of the epitaxial material thickness, thereby improving the device survival rate and reliability;

[0241] Third, this example uses 1 layer n + The GaN series layer connects the two active regions in the vertical direction. By adjusting the thickness and doping concentration of the series layer, the self-oscillation frequency of the differential negative resistance region of the resonant tunneling diode can be changed, eliminating the "chair-shaped" bump in the output characteristic curve and improving the stability and reliability of the device.

[0242] From the above measurement results of the GaN-based resonant tunneling diode with two-region differential negative resistance characteristics, it can be seen that the GaN-based resonant tunneling diode with multiple-region differential negative resistance characteristics of a multi-layer composite active region structure with more than two active regions will have better performance than the embodiment 1.

Claims

1. A multi-region differential negative resistance effect gallium nitride-based resonant tunneling diode, comprising, from bottom to top, a substrate (1), a GaN epitaxial layer (2), an emitter ohmic contact layer (3), an active region (4), a collector ohmic contact layer (5), a collector electrode (6), and an annular emitter electrode (8) on both sides of the active region; a cylindrical mesa formed by etching from the active region (4) to the collector electrode (6), the cylindrical mesa being wrapped with a passivation layer (7), characterized in that: The active area (4) is composed of N layers of active areas and N-1 layers of n + The composite structure consists of alternating GaN series layers, with a doping concentration of 1×10 19 cm -3 -5×10 20 cm -3 , thickness of 30nm-200nm n + GaN layers are connected in series to achieve differential negative resistance characteristics with multiple peak currents and peak-to-valley current ratios close to each other, where N ≥ 2; The active region (4) of the composite structure comprises, from bottom to top, a first isolation layer (41), a first barrier layer (42), a quantum well layer (43), a second barrier layer (44), and a second isolation layer (45); The thickness of the first isolation layer (41) and the second isolation layer (45) are both 4nm-15nm of GaN; The first barrier layer (42) and the second barrier layer (44) have the same composition, and both have a thickness of 1 nm to 3 nm, and are the same thickness; The quantum well layer (43) uses In with a composition v between 0% and 100%. v Ga 1-v N, its thickness is 1nm-3nm.

2. The diode according to claim 1, wherein: The first barrier layer (42) and the second barrier layer (44) are made of the same material, both of which can be Sc x Al 1-x N, Y x Al 1-x N, B w Al y Ga z For any one of N, its component x is between 5% and 25%, its components w, y, and z are between 0% and 100%, and w+y+z=100%.

3. The diode according to claim 1, wherein: The collector ohmic contact layer (5) has a doping concentration of 5×10 19 cm -3 -5×10 20 cm -3 , thickness of 50nm-200nm n + GaN; The emitter ohmic contact layer (3) has a doping concentration of 5×10 19 cm -3 -5×10 20 cm -3 , thickness of 50nm-200nm n + GaN; The GaN epitaxial layer (2) has a thickness of 500nm-5000nm.

4. The diode according to claim 1, wherein: The passivation layer (7) is made of any one of SiN material, Al2O3 material, and HfO2 material; The substrate (1) is made of any one of self-supporting gallium nitride single crystal material, self-supporting aluminum nitride single crystal material, sapphire material, silicon carbide material, silicon material, boron nitride material, and diamond material.

5. A method for manufacturing a gallium nitride-based resonant tunneling diode with multiple differential negative resistance effects, characterized in that: The steps include: 1) epitaxially growing a GaN epitaxial layer (2) of 500 nm to 5000 nm on a substrate (1) by using a molecular beam epitaxy method or a metal organic chemical vapor deposition method; 2) Using molecular beam epitaxy, n is grown on the GaN epitaxial layer (2). + The GaN emitter ohmic contact layer (3) has a thickness of 50 nm to 200 nm and a doping concentration of 5×10 19 cm -3 -5×10 20 cm -3 ; 3) Using molecular beam epitaxy method, + An active region (4) of a multilayer composite structure is alternately grown on the GaN emitter ohmic contact layer (3): 3a) Growth of the first active region: 3a1) in n + A GaN first isolation layer (41) with a thickness of 4 nm to 15 nm is grown on the GaN emitter ohmic contact layer (3); 3a2) growing a Sc layer with a composition x between 5% and 25% and a thickness of 1 nm to 3 nm on the GaN first isolation layer (41). x Al 1-x N or Y x Al 1-x N; or B with components w, y, z ranging from 0% to 100%, w+y+z=100%, and a thickness of 1nm-3nm w Al y Ga z A first barrier layer (42) of N; 3a3) Growing an In layer with a composition v between 0% and 100% and a thickness of 1 nm to 3 nm on the first barrier layer (42) v Ga 1-v N quantum well layer (43); 3a4) growing a second barrier layer (44) having the same composition and thickness as the first barrier layer (42) on the quantum well layer (43); 3a5) growing a GaN second isolation layer (45) with a thickness of 4 nm to 15 nm on the second barrier layer (44) to complete the growth of the first active region; 3b) Using molecular beam epitaxy, a doping concentration of 1×10 19 cm -3 -5×10 20 cm -3 , the first layer n is 30nm-200nm thick + GaN tandem layer; 3c) In the first layer n + The second active region is generated on the GaN series layer according to the process flow of 3a), completing the growth of the composite structure active region of two active regions and one series layer; the growth is cyclically continued, and finally a structure with N layers of active regions and N-1 layers of n is formed. + An active region (4) of a multilayer composite structure of GaN series layers; 4) Using molecular beam epitaxy, n is grown on the active region (4) of the composite structure. + The GaN collector ohmic contact layer (5) has a thickness of 50 nm to 200 nm and a doping concentration of 5×10 19 cm -3 -5×10 20 cm -3 ; 5) Using optical lithography technology, + On the GaN collector ohmic contact layer (5), a device mesa isolation pattern is formed, and the epitaxial material is etched by an inductively coupled plasma etching method using a BCl3 / Cl2 gas source using a photoresist as a mask to form a mesa isolation with a depth of 650nm-1200nm; 6) Using electron beam lithography, + On the GaN collector ohmic contact layer (5), a circular pattern with a diameter of 0.5 μm-20 μm is formed, and a photoresist is used as a mask and an electron beam evaporation method is used to form a circular pattern with a diameter of 0.5 μm-20 μm. + A Ti / Au / Ni metal layer is evaporated on the GaN collector ohmic contact layer (5) to form a collector electrode (6), and then the metal is used as a mask and an inductively coupled plasma etching method is adopted using a BCl3 / Cl2 gas source to etch to a depth of n + A GaN emitter ohmic contact layer (3) is formed to form a cylindrical mesa from the first active layer to the collector electrode (6); 7) Using traditional optical lithography technology, + On the GaN emitter ohmic contact layer (3), a ring pattern with an inner circumference 3 μm away from the cylindrical table is formed, and an electron beam evaporation method is used to form a GaN emitter ohmic contact layer (3). + A Ti / Au metal layer is evaporated on the GaN emitter ohmic contact layer (3) to form an emitter electrode (8); 8) Using plasma enhanced chemical vapor deposition or atomic layer deposition process, + A passivation layer (7) with a thickness of 50 nm to 200 nm is deposited on the surface of the GaN emitter ohmic contact layer (3) to the collector electrode (6); 9) using an optical photolithography process to form an emitter electrode through-hole pattern on the passivation layer (7); using a photoresist as a mask, using a reactive ion etching method, and using an SF6 gas source to form the emitter electrode through-hole; 10) Using electron beam lithography, a circular pattern with a diameter of 200 nm to 18 μm is formed on the cylindrical mesa passivation layer; using photoresist as a mask, a reactive ion etching method and an SF6 gas source are used to form a collector electrode through hole; 11) Using optical lithography, emitter and collector pad patterns are formed on the device surface. Using photoresist as a mask, electron beam evaporation is used to evaporate a Ti / Au metal layer on the entire device surface to form emitter and collector pads, completing device fabrication.

6. The production method according to claim 5, wherein: The metal organic chemical vapor deposition method used in 1) has the following process conditions: The temperature is 1000℃-1300℃, the pressure is 40Torr-60Torr, the ammonia flow rate is 1000sccm-3000sccm, the gallium source flow rate is 60sccm-120sccm, and the hydrogen flow rate is 2000sccm-5000sccm; The molecular beam epitaxy method used in 1) has the following process conditions: temperature of 650°C-720°C, equilibrium vapor pressure of gallium beam of 4.5×10 -7 Torr-8.5×10 -7 Torr, the nitrogen flow rate is 1.2sccm-2.3sccm, and the nitrogen plasma RF source power is 375W.

7. The production method according to claim 5, wherein: The molecular beam epitaxy method in step 2) and step 4) has the following process conditions: temperature of 650°C-720°C, equilibrium vapor pressure of gallium beam of 4.5×10 -7 Torr-8.5×10 -7 Torr, the equilibrium vapor pressure of silicon beam is 2.5×10 -8 Torr-4.5×10 -8 Torr, nitrogen flow rate is 1.2sccm-2.3sccm, and nitrogen plasma RF source power is 375W; The molecular beam epitaxy method in step 3) has the following process conditions: temperature of 500°C-720°C, nitrogen flow rate of 1.2 sccm-2.3 sccm, and gallium beam equilibrium vapor pressure of 4.5×10 -7 Torr-8.5×10 -7 Torr, the equilibrium vapor pressure of aluminum beam is 1.4×10 -7 Torr-3.2×10 -7 Torr, the equilibrium vapor pressure of indium beam is 1.4×10 -7 Torr-3.2×10 -7 Torr, the equilibrium vapor pressure of the boron beam is 2.0×10 -7 Torr-4.0×10 -7 Torr, the equilibrium vapor pressure of scandium beam is 1.5×10 -8 Torr-1.8×10 -8 Torr, the equilibrium vapor pressure of the yttrium beam is 1.0×10 -8 Torr-2.0×10 -8 Torr, the equilibrium vapor pressure of silicon beam is 2.0×10 -8 Torr-4.5×10 -8 Torr, and the nitrogen plasma RF source power was 375W.

8. The production method according to claim 5, wherein: The conventional optical lithography process in step 5) is as follows: using AZ5214 photoresist, first at a rotation speed of 500 rad / min and an acceleration of 1000 rad 2 / min spin coating for 3s; then at a speed of 4000rad / min and an acceleration of 2000rad 2 Spin coating was performed at 400 nm / min for 30 seconds; the adhesive was baked for 90 seconds at a temperature of 95°C; the developer used was RZX-3038, and the developing time was 45 seconds; The plasma enhanced chemical vapor deposition method used in step 5) has the following process conditions: pressure of 2200 mTorr, temperature of 350°C, SiH4 flow rate of 13.5 sccm, NH3 flow rate of 10 sccm, N2 flow rate of 1000 sccm, and time of 30s-120s; The process conditions of the inductively coupled plasma etching method in step 5) are: Cl2 gas flow rate of 10 sccm, BCl3 gas flow rate of 25 sccm, and etching time of 300s-420s.

9. The production method according to claim 5, wherein: The electron beam lithography process used in step 6) has the following process conditions: PMMA A4 photoresist was used, the baking time was 90s, the temperature was 180°C, the electron dose ratio was 750, the diameter of the photolithographic circular pattern was 1μm-4μm, the developer was 3:1 tetramethyl dipentyl ketone and isopropyl alcohol, the developing time was 120s; the fixer was isopropyl alcohol, and the fixing time was 30s.

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