A non-reciprocal acoustoelectric amplifier, a preparation method and application thereof

Abstract

The application discloses a non-reciprocal acoustic-electric amplifier and a preparation method and application thereof. The non-reciprocal acoustic-electric amplifier comprises a substrate, an AlN / GaN nucleation layer, a GaN buffer layer, an AlN insertion layer, a ScAlN barrier layer, a ScAlN acoustic film, a source electrode, a drain electrode, a gate electrode, an interdigital transducer and a metal interconnection layer. The substrate of the non-reciprocal Lamb wave acoustic-electric amplifier is provided with an open cavity and a back electrode away from the side of the AlN / GaN nucleation layer. The non-reciprocal acoustic-electric amplifier can realize high-contrast and adjustable acoustic wave non-reciprocal transmission, has the advantages of small size, high isolation, good integrability, high stability, high reliability and the like, can be monolithically integrated with a ScAlN / GaN radio frequency front-end chip, can be used in radio frequency communication, acoustic wave processing, quantum computing and the like, and is suitable for large-scale industrial production and application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor devices, in particular to a non-reciprocal acoustoelectric amplifier and a preparation method and application thereof. BACKGROUND

[0002] Acoustoelectric effect refers to various physical effects caused by the interaction between acoustic waves (or high-frequency phonons) and free carriers in semiconductor materials, such as: attenuation or amplification of acoustic waves (absorption or emission of phonons), influence of ultrasound on voltage characteristics and current characteristics of semiconductors, etc. Acoustoelectric amplification effect refers to the scattering of carriers (such as electrons and holes) in the material caused by ultrasound, which produces additional current or voltage change, thereby realizing amplification of signals. Non-reciprocal transmission of acoustic waves refers to the asymmetry of the propagation direction of acoustic waves during propagation (i.e. acoustic waves exhibit different behavior characteristics when propagating in the forward and reverse directions), thereby introducing unidirectionality.

[0003] The non-reciprocal acoustoelectric amplifier is a semiconductor device capable of working in an extremely high frequency acoustic wave environment, and its core feature is its non-reciprocity, i.e. signals can only be transmitted in one direction and cannot be transmitted in the reverse direction. The non-reciprocal acoustoelectric amplifier can achieve net gain and low noise during continuous operation, and is particularly suitable for processing extremely high frequency acoustic waves, and has important applications in radio frequency electronic devices, which can improve performance while reducing device size. However, the existing non-reciprocal acoustoelectric amplifiers generally have problems such as large size, low isolation, poor integrability, poor stability, low reliability, etc., and cannot fully meet the requirements of actual applications.

[0004] Therefore, it is of great significance to develop a non-reciprocal acoustoelectric amplifier with small size, high isolation, good integrability, high stability and high reliability. SUMMARY

[0005] The present application relates to the technical field of semiconductor devices, in particular to a non-reciprocal acoustoelectric amplifier and a preparation method and application thereof.

[0006] The technical solution adopted by the present application is:

[0007] The application discloses a non-reciprocal acoustic-electric amplifier, which is divided into a non-reciprocal Rayleigh wave acoustic-electric amplifier and a non-reciprocal Lamb wave acoustic-electric amplifier; the non-reciprocal Rayleigh wave acoustic-electric amplifier and the non-reciprocal Lamb wave acoustic-electric amplifier are composed of a substrate, an AlN / GaN nucleation layer, a GaN buffer layer, an AlN insertion layer and a ScAlN barrier layer which are sequentially arranged in layers, and further composed of a ScAlN acoustic film, a source electrode, a drain electrode, a gate electrode, an interdigital transducer and a metal interconnection layer; the ScAlN acoustic film, the source electrode, the drain electrode and the gate electrode are arranged on the side of the ScAlN barrier layer away from the AlN insertion layer and are not in contact with each other; the interdigital transducer is arranged on the side of the ScAlN acoustic film away from the ScAlN barrier layer; the metal interconnection layer is arranged on the surfaces of the source electrode, the drain electrode, the gate electrode and the interdigital transducer; the substrate of the non-reciprocal Lamb wave acoustic-electric amplifier is further provided with an open cavity on the side away from the AlN / GaN nucleation layer, and the bottom surface of the open cavity is further provided with a back electrode.

[0008] Preferably, the substrate is one of a silicon substrate, a silicon carbide substrate, a sapphire substrate, a diamond substrate and a gallium nitride substrate.

[0009] Preferably, the thickness of the substrate is 200-1000 microns.

[0010] Preferably, the thickness of the AlN / GaN nucleation layer is 0.8-1.5 microns.

[0011] Preferably, the GaN buffer layer is composed of C and / or Fe-doped GaN.

[0012] Preferably, the thickness of the GaN buffer layer is 0.6-3 microns.

[0013] Preferably, the thickness of the AlN insertion layer is 1-2 nanometers.

[0014] Preferably, the mole fraction of Sc in the ScAlN barrier layer is 10-30%.

[0015] Preferably, the thickness of the ScAlN barrier layer is 15-30 nanometers.

[0016] Preferably, the mole fraction of Sc in the ScAlN acoustic film is 10-30%.

[0017] Preferably, the thickness of the ScAlN acoustic film is 0.8-1.1 microns.

[0018] Preferably, the source electrode comprises a Ti layer, an Al layer, a Ni layer and an Au layer arranged in sequence, the thickness of the Ti layer is 5-25 nm, the thickness of the Al layer is 90-160 nm, the thickness of the Ni layer is 45-65 nm, and the thickness of the Au layer is 50-120 nm.

[0019] Preferably, the width of the source electrode is 4-10 μm.

[0020] Preferably, the drain electrode comprises a Ti layer, an Al layer, a Ni layer and an Au layer arranged in sequence, the thickness of the Ti layer is 5-25 nm, the thickness of the Al layer is 90-160 nm, the thickness of the Ni layer is 45-65 nm, and the thickness of the Au layer is 50-120 nm.

[0021] Preferably, the width of the drain electrode is 4-10 μm.

[0022] Preferably, the gate electrode comprises a Ni layer and an Au layer arranged in sequence, the thickness of the Ni layer is 30-60 nm, and the thickness of the Au layer is 100-400 nm.

[0023] Preferably, the width of the gate electrode is 2-7 μm.

[0024] Preferably, the gate electrode is one of a planar structure, a multi-gate finger structure, a T-shaped structure and a field plate structure.

[0025] Preferably, the distance between the source electrode and the drain electrode is 15-40 μm.

[0026] Preferably, the distance between the source electrode and the gate electrode is 3-10 μm.

[0027] Preferably, the distance between the drain electrode and the gate electrode is 5-15 μm.

[0028] Preferably, a passivation material is filled between the source electrode and the gate electrode, and the passivation material is at least one of SiN x , diamond, Al2O3 and HfO2.

[0029] Preferably, a passivation material is filled between the drain electrode and the gate electrode, and the passivation material is at least one of SiN x , diamond, Al2O3 and HfO2.

[0030] Preferably, the interdigital transducer is made of at least one of aluminum, tungsten, nickel, copper, tantalum, molybdenum, silver and gold.

[0031] Preferably, the interdigital transducer comprises 15-35 pairs of interdigital fingers, the width of the interdigital fingers is 0.5-4 um, and the length of the interdigital fingers is 128-256 um.

[0032] Preferably, the metal interconnection layer comprises a Ni layer and an Au layer arranged in a stack, the thickness of the Ni layer is 30-60 nm, and the thickness of the Au layer is 100-300 nm.

[0033] Preferably, the back electrode is composed of at least one of aluminum, tungsten, nickel, copper, tantalum, molybdenum, silver, and gold.

[0034] A preparation method of the non-reciprocal acoustic electric amplifier comprises the following steps:

[0035] 1) sequentially epitaxially growing an AlN / GaN nucleation layer, a GaN buffer layer, an AlN insertion layer, and a ScAlN barrier layer on the surface of the substrate;

[0036] 2) epitaxially growing a ScAlN acoustic film on the surface of the ScAlN barrier layer;

[0037] 3) etching the surface of the ScAlN barrier layer to form a source electrode deposition area, a drain electrode deposition area, and a gate electrode deposition area, depositing electrode metal in the source electrode deposition area and the drain electrode deposition area to form source electrodes and drain electrodes, and depositing electrode metal in the gate electrode deposition area to form a gate electrode;

[0038] 4) etching the surface of the ScAlN acoustic film to form an interdigital transducer deposition area, and depositing electrode metal in the interdigital transducer deposition area to form an interdigital transducer;

[0039] 5) depositing electrode metal on the surfaces of the source electrodes, the drain electrodes, the gate electrode, and the interdigital transducer to form a metal interconnection layer, thereby obtaining a non-reciprocal Rayleigh wave acoustic electric amplifier;

[0040] 6) etching the back surface of the substrate to form an open cavity, depositing electrode metal on the bottom surface of the open cavity to form a back electrode, thereby obtaining a non-reciprocal Lamb wave acoustic electric amplifier.

[0041] Preferably, the epitaxial growth in step 1) is at least one of metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and magnetron sputtering.

[0042] Preferably, the ScAlN barrier layer in step 1) is grown by a magnetron sputtering method, and the process parameters of the magnetron sputtering method include: the target material is an Al / Sc target material, the argon (Ar) gas flow rate is 25-35 sccm, the nitrogen (N2) gas flow rate is 25-35 sccm, the vacuum pressure is 2.6-3.1 mTorr, the substrate temperature is 180-220℃, and the sputtering power is 950-1100 W.

[0043] Preferably, the epitaxial growth in step 2) is performed by a magnetron sputtering method, and the process parameters of the magnetron sputtering method include: the target material is an Al / Sc target material, the argon (Ar) gas flow rate is 25-35 sccm, the nitrogen (N2) gas flow rate is 25-35 sccm, the vacuum pressure is 2.6-3.1 mTorr, the substrate temperature is 180-220℃, and the sputtering power is 950-1100 W.

[0044] Preferably, the annealing in step 3) is performed at a temperature of 800-900℃, and the annealing time is 30-60 s.

[0045] A radio frequency communication device comprising the above-mentioned non-reciprocal acoustoelectric amplifier.

[0046] The non-reciprocal acoustoelectric amplifier of the present application has the advantages of small size, high isolation, good integrability, high stability, high reliability, etc., and can be monolithically integrated with a ScAlN / GaN radio frequency front-end chip, and can be used in the fields of radio frequency communication, acoustic wave processing, quantum computing, etc., and is suitable for large-scale industrial production and application.

[0047] Specifically:

[0048] 1) The non-reciprocal acoustoelectric amplifier of the present application can adjust the acoustoelectric amplification effect by adjusting the two-dimensional electron gas concentration in the ScAlN / GaN heterojunction channel, and the non-reciprocal acoustoelectric amplifier has adjustable performance, and when the two-dimensional electron gas concentration in the ScAlN / GaN heterojunction channel is between 1×10 9 cm -2 and 1×10 10 cm -2 , the acoustoelectric amplification effect has the best performance, so that the non-reciprocal acoustoelectric amplifier has high contrast;

[0049] 2) The non-reciprocal Rayleigh wave acoustic electric amplifier of the application has good integrability, high stability and high reliability, the device can realize monolithic microwave integrated circuit with ScAlN / GaN high-power and high-frequency chips, and based on the ScAlN / GaN heterojunction, the device can work stably for a long time under high voltage and high temperature conditions. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 Structure diagram of the non-reciprocal Rayleigh wave acoustic electric amplifier of Example 1.

[0051] Figure 2 Structure diagram of the non-reciprocal Lamb wave acoustic electric amplifier of Example 2.

[0052] The figure mark is explained as follows: 10, substrate; 20, AlN / GaN nucleation layer; 30, GaN buffer layer; 40, AlN insertion layer; 50, ScAlN barrier layer; 60, ScAlN acoustic film; 70, source electrode; 80, drain electrode; 90, gate electrode; 100, interdigital transducer; 110, metal interconnection layer; 120, back electrode. DETAILED DESCRIPTION

[0053] The application will be further explained and described in combination with specific embodiments.

[0054] Example 1:

[0055] A non-reciprocal Rayleigh wave acoustic electric amplifier (structure diagram as shown in Figure 1 The non-reciprocal Rayleigh wave acoustic electric amplifier is composed of a substrate 10, an AlN / GaN nucleation layer 20, a GaN buffer layer 30, an AlN insertion layer 40, a ScAlN barrier layer 50, a ScAlN acoustic film 60, a source electrode 70, a drain electrode 80, a gate electrode 90, an interdigital transducer 100 and a metal interconnection layer 110; the substrate 10, the AlN / GaN nucleation layer 20, the GaN buffer layer 30, the AlN insertion layer 40 and the ScAlN barrier layer 50 are sequentially stacked from bottom to top; the ScAlN acoustic film 60, the source electrode 70, the drain electrode 80 and the gate electrode 90 are all arranged on the side of the ScAlN barrier layer 50 away from the AlN insertion layer 40, and are not in contact with each other; the interdigital transducer 100 is arranged on the side of the ScAlN acoustic film 60 away from the ScAlN barrier layer 50; and the metal interconnection layer 110 is arranged on the surface of the source electrode 70, the drain electrode 80, the gate electrode 90 and the interdigital transducer 100.

[0056] The preparation method of the above-mentioned non-reciprocal Rayleigh wave acoustic electric amplifier is as follows:

[0057] 1) A MOCVD method or an MBE method is used to epitaxially grow, on the surface of a high-resistance silicon substrate (625 μm in thickness), an AlN / GaN nucleation layer with a thickness of 1.2 μm, a GaN buffer layer with a thickness of 0.8 μm, and an AlN insertion layer with a thickness of 1 nm; a magnetron sputtering method is used to deposit, on the surface of the AlN insertion layer, a ScAlN barrier layer with a thickness of 22 nm (20% of Sc in mole fraction); the process parameters of the magnetron sputtering method include: the target is an Al / Sc target, the argon (Ar) gas flow rate is 25-35 sccm, the nitrogen (N2) gas flow rate is 25-35 sccm, the vacuum pressure is 2.6-3.1 mTorr, the substrate temperature is 180-220°C, and the sputtering power is 950-1100 W;

[0058] 2) A magnetron sputtering method is used to deposit, on the surface of the ScAlN barrier layer, a ScAlN acoustic film with a thickness of 1 μm (20% of Sc in mole fraction); the process parameters of the magnetron sputtering method include: the target is an Al / Sc target, the argon (Ar) gas flow rate is 25-35 sccm, the nitrogen (N2) gas flow rate is 25-35 sccm, the vacuum pressure is 2.6-3.1 mTorr, the substrate temperature is 180-220°C, and the sputtering power is 950-1100 W;

[0059] 3) An inductively coupled plasma (ICP) etching method is used to etch the surface of the ScAlN barrier layer to form a source electrode deposition area, a drain electrode deposition area, and a gate electrode deposition area; a Ti layer with a thickness of 20 nm, an Al layer with a thickness of 160 nm, a Ni layer with a thickness of 55 nm, and an Au layer with a thickness of 50 nm are sequentially deposited on the source electrode deposition area and the drain electrode deposition area; rapid thermal annealing is performed to form a source electrode (7 μm in width and 256 μm in length) and a drain electrode (7 μm in width and 256 μm in length); the annealing is performed at a temperature of 800-900°C for 30-60 s; a Ni layer with a thickness of 45 nm and an Au layer with a thickness of 400 nm are sequentially deposited on the gate electrode deposition area to form a gate electrode (5 μm in width and 256 μm in length; the distance between the source electrode and the drain electrode is 17 μm; the distance between the source electrode and the gate electrode is 6 μm; and the distance between the drain electrode and the gate electrode is 6 μm);

[0060] 4) An inductively coupled plasma (ICP) etching method is used to etch the surface of the ScAlN acoustic film to form an interdigital transducer deposition area; a Mo layer with a thickness of 100 nm is deposited on the interdigital transducer deposition area to form an interdigital transducer; the interdigital transducer includes 20 pairs of interdigital transducers, and each interdigital transducer is 2 μm in width and 256 μm in length;

[0061] 5) Depositing a 50 nm-thick Ni layer and a 200 nm-thick Au layer on the surface of the source electrode, the drain electrode, the gate electrode and the interdigital transducer in sequence to form a metal interconnection layer, thereby obtaining the non-reciprocal Rayleigh wave sound-electric amplifier.

[0062] Example 2:

[0063] A non-reciprocal Lamb wave sound-electric amplifier (a structural schematic diagram is shown in Figure 2 The non-reciprocal Lamb wave sound-electric amplifier is completely identical to the non-reciprocal Rayleigh wave sound-electric amplifier of Example 1 except that an open cavity is additionally arranged on the side of the substrate 10 far from the AlN / GaN nucleation layer 20, and a back electrode 120 (composed of Mo, 100 nm in thickness, identical in shape to the interdigital transducer 100 and corresponding in position to the interdigital transducer 100) is additionally arranged on the bottom surface of the open cavity.

[0064] The preparation method of the non-reciprocal Lamb wave sound-electric amplifier is as follows:

[0065] The ICP (inductive coupled plasma) etching method is used to etch the side of the high-resistance silicon substrate of the non-reciprocal Rayleigh wave sound-electric amplifier of Example 1 far from the AlN / GaN nucleation layer to form an open cavity, the DRIE (deep reactive ion etching) process is used to etch the bottom surface of the open cavity to form a back electrode deposition area, and a 100 nm-thick Mo layer is deposited on the back electrode deposition area to form a back electrode, thereby obtaining the non-reciprocal Lamb wave sound-electric amplifier.

[0066] The working principles of the non-reciprocal Rayleigh wave sound-electric amplifier and the non-reciprocal Lamb wave sound-electric amplifier are as follows:

[0067] The interdigital transducer in the non-reciprocal Rayleigh wave sound-electric amplifier is powered to generate a sound wave based on the piezoelectric effect, the transmission direction of the sound wave is identical to the electron migration direction in the ScAlN / GaN high electron mobility transistor, when the sound wave is transmitted in the channel, the phonon and the electron interact in energy, the phonon energy is improved, thereby amplifying the sound wave; the interdigital transducer in the non-reciprocal Lamb wave sound-electric amplifier is powered to generate a sound wave based on the piezoelectric effect, the transmission direction of the sound wave is opposite to the electron migration direction in the ScAlN / GaN high electron mobility transistor, when the sound wave is transmitted in the channel, the phonon and the electron interact in reverse energy, the phonon energy is weakened, thereby attenuating the sound wave; the combination of the non-reciprocal Rayleigh wave sound-electric amplifier and the non-reciprocal Lamb wave sound-electric amplifier can realize acoustic non-reciprocal transmission.

[0068] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A non-reciprocal acousto-electric amplifier, characterized in that: The invention is divided into two types: non-reciprocal Rayleigh wave acoustoelectric amplifier and non-reciprocal Lamb wave acoustoelectric amplifier; the components of the non-reciprocal Rayleigh wave acoustoelectric amplifier and the non-reciprocal Lamb wave acoustoelectric amplifier include a substrate, an AlN / GaN nucleation layer, a GaN buffer layer, an AlN insertion layer and a ScAlN barrier layer stacked in sequence, and also include a ScAlN acoustic film, a source electrode, a drain electrode, a gate electrode, an interdigital transducer and a metal interconnection layer; the ScAlN acoustic film, the source electrode, the drain electrode and the gate electrode are all arranged on the side of the ScAlN barrier layer away from the AlN insertion layer, and there is no contact between them. touch; the interdigital transducer is arranged on the side of the ScAlN acoustic film away from the ScAlN barrier layer; the metal interconnection layer is arranged on the surfaces of the source electrode, the drain electrode, the gate electrode and the interdigital transducer; the substrate of the non-reciprocal Lamb wave acousto-electric amplifier is further provided with an open cavity on the side away from the AlN / GaN nucleation layer, and the bottom surface of the open cavity is further provided with a back electrode; the ScAlN acoustic film is divided into two parts, which are respectively arranged at the two ends of the side of the ScAlN barrier layer away from the AlN insertion layer; the thickness of the ScAlN acoustic film is 0.8μm to 1.1μm.

2. The non-reciprocal acousto-electric amplifier according to claim 1, wherein: The substrate is one of a silicon substrate, a silicon carbide substrate, a sapphire substrate, a diamond substrate, and a gallium nitride substrate.

3. The non-reciprocal acousto-electric amplifier according to claim 1, wherein: The mole fraction of Sc in the ScAlN barrier layer is 10% to 30%.

4. The non-reciprocal acousto-electric amplifier according to claim 1, wherein: The mole fraction of Sc in the ScAlN acoustic film is 10% to 30%.

5. The non-reciprocal acousto-electric amplifier according to any one of claims 1 to 4, characterized in that: The thickness of the AlN / GaN nucleation layer is 0.8 μm to 1.5 μm; the thickness of the GaN buffer layer is 0.6 μm to 3 μm; and the thickness of the AlN insertion layer is 1 nm to 2 nm.

6. The non-reciprocal acousto-electric amplifier according to any one of claims 1 to 4, characterized in that: The thickness of the ScAlN barrier layer is 15 nm to 30 nm.

7. The non-reciprocal acousto-electric amplifier according to any one of claims 1 to 4, characterized in that: The interdigital transducer comprises 15 to 35 pairs of interdigital fingers, each of which has a width of 0.5 μm to 4 μm and a length of 128 μm to 256 μm.

8. A method for preparing a non-reciprocal acoustoelectric amplifier according to any one of claims 1 to 7, characterized in that: The following steps are involved: 1) Epitaxially growing an AlN / GaN nucleation layer, a GaN buffer layer, an AlN insertion layer, and a ScAlN barrier layer on the surface of the substrate; 2) epitaxially growing a ScAlN acoustic film on the surface of the ScAlN barrier layer; 3) Etching the surface of the ScAlN barrier layer to form a source electrode deposition region, a drain electrode deposition region, and a gate electrode deposition region, then depositing electrode metal in the source electrode deposition region and the drain electrode deposition region and annealing to form a source electrode and a drain electrode, and then depositing electrode metal in the gate electrode deposition region to form a gate electrode; 4) Etching the surface of the ScAlN acoustic film to form an IDT deposition area, and then depositing electrode metal on the IDT deposition area to form an IDT; 5) depositing electrode metal on the surface of the source electrode, drain electrode, gate electrode and interdigital transducer to form a metal interconnect layer to obtain a non-reciprocal Rayleigh wave acoustoelectric amplifier; 6) Etching the back side of the substrate to form an open cavity, and then depositing electrode metal on the bottom surface of the open cavity to form a back electrode, thereby obtaining a non-reciprocal Lamb wave acoustoelectric amplifier.

9. A radio frequency communication device, characterized in that: A non-reciprocal acoustoelectric amplifier comprising the non-reciprocal acoustoelectric amplifier according to any one of claims 1 to 7.

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