Light guide microwave device for synchronously triggering non-coplanar electrode parallel structure and manufacturing method

Abstract

The invention discloses a light guide microwave device for synchronously triggering a non-coplanar electrode parallel structure and a preparation method, which mainly solve the problem of low output power of the existing light guide device at high frequency, and comprises a light guide device (10), an anode connecting electrode (7) and a cathode connecting electrode (1). The photoconductive device is formed by vertically stacking two substrates (3, 8), and one end of the photoconductive device is provided with a groove; one end of the anode connecting electrode is connected with the two ohmic contact anodes (5 and 6) in the groove, and the other end of the anode connecting electrode is connected with an external circuit; the cathode connecting electrode is provided with three ports, the upper port and the lower port of the cathode connecting electrode are connected with the two ohmic contact cathodes (2 and 4) on the photoconductive device respectively, and the whole exterior of the cathode connecting electrode is packaged through an insulating shell (9). The two substrates can be conducted at the same time under irradiation of the same laser beam, the conduction delay after device cascading is reduced, the light energy utilization rate of the light guide device is improved, high-power output under high frequency is achieved, and the light guide device can be used for high-power systems such as accelerators, radars and high-power microwave sources.

Description

Technical Field

[0001] The present invention belongs to the field of microelectronic technology, and particularly relates to an optical waveguide microwave device and a manufacturing method thereof, which can be used in high-power systems and ultrafast technologies such as accelerators, radars, and high-power microwave sources. Background Art

[0002] In recent years, solid-state electronic devices have been increasingly used as microwave sources in frequency-agile microwave generation systems. Compared with other electronic devices, the photoconductive switch PCSS, which can be used as an optical waveguide microwave device, has the characteristics of small time jitter, fast response speed, tunable output signal, and small volume. It is widely used in high-power systems and ultrafast technologies such as accelerators, radars, and high-power microwave sources. The photoconductive switch mainly consists of a semiconductor wafer and electrodes. Wide-bandgap semiconductor materials represented by SiC and GaN are conducive to realizing high-power and fast-response photoconductive switches due to their high breakdown field strength and high mobility. When the photoconductive switch is irradiated by a laser, carriers are generated in the body, and the photo-generated carriers drift and diffuse between the two electrodes to form a current. When the laser disappears, the photo-generated carriers gradually recombine, and the semiconductor wafer returns to the insulating state. The recovery time depends on the carrier lifetime.

[0003] In the actual use process, the existence of the inter-stage capacitance of the device affects the charge and discharge process, which will slow down the recovery time of the photoconductive switch and lead to a slower frequency response. Therefore, in high-frequency applications, the photoconductive switch mainly adopts the form of coplanar electrodes. In order to improve the withstand voltage ability, the inclined coplanar electrode structure in the bulk structure is further adopted. Its capacitance value can be made to the 500 fF level, but compared with the facing electrode structure, its output power decreases significantly. Therefore, it is urgent to solve the problem of low output power and improve the output power of the inclined coplanar photoconductive switch.

[0004] The patent document with the application number CN201510098787.4 discloses a silicon carbide embedded electrode coplanar photoconductive switch and a manufacturing method thereof. It adopts a coplanar facing electrode structure, deposits a dense insulating oxide layer on the surface of the silicon carbide substrate and sets grooves at corresponding positions, so that the ohmic contact electrodes of the device are embedded in the groove area, effectively alleviating the breakdown phenomenon at the electrode edge. Although this structure can increase the output current, due to its facing electrode structure, it will inevitably introduce a large inter-stage capacitance, affecting the response of the device to high-frequency lasers, and unable to achieve high-power applications in the C band. At the same time, since the device uses front laser incidence, the light utilization rate is low, and it is not conducive to cascading multiple devices to improve the output power of the module.

[0005] The patent document with the application number 202410268297.3 discloses a cascade structure photoconductive switch for improving microwave generation efficiency and its preparation method. It adopts a facing electrode structure device and cascades two devices. The cathode and anode of each device both use transparent electrodes. The two devices are spaced a certain distance in the vertical direction, and a hollow cylindrical electrode is used to electrically connect the two devices, so that the laser passes through the first device and the second device from the front in sequence, realizing the series connection between the two devices. This solution can reduce the interelectrode capacitance value of the facing electrode photoconductive device, improve problems such as the deterioration of the modulation degree of the output waveform and the low microwave conversion efficiency of the current facing electrode photoconductive switch at high frequencies, and increase the operating frequency of the system. However, due to the use of a series structure in this solution, the device resistance will double, greatly increasing the power loss in the circuit; at the same time, due to the conduction delay caused by the sequential conduction problem between the two devices, it will lead to its inapplicability in higher frequency bands such as the X band. Summary of the Invention

[0006] The object of the present invention is to propose a photoconductive microwave device with a synchronous trigger face-to-face electrode parallel structure and its preparation method in view of the above-mentioned deficiencies of the prior art, so as to improve the light energy utilization rate of the face-to-face electrode structure device, reduce the power loss and conduction delay after device cascading, and achieve high-power output of the photoconductive device at high frequencies.

[0007] The key technology to achieve the object of the present invention is: by designing a single-sided deep groove etched substrate structure, realizing the close stacking and parallel connection of two substrates, and reserving space for placing external connection electrodes at the groove position, thereby realizing the synchronous trigger of the device conduction, reducing the conduction delay and power loss, and increasing the output current of the entire module.

[0008] According to the above idea, the technical solution of the present invention is realized as follows:

[0009] 1. A photoconductive microwave device with a synchronous trigger face-to-face electrode parallel structure, comprising a photoconductive device 10, a cathode connection electrode 1, an anode connection electrode 7, and an insulating encapsulation housing 9, characterized in that:

[0010] The photoconductive device 10 includes two first substrates 3 and second substrates 8 with a notch at one end. The upper surface of the first substrate 3 is provided with a first ohmic contact cathode 2, and a first ohmic contact anode 5 is arranged in the notch; the upper surface of the second substrate 8 is provided with a second ohmic contact cathode 4, and a second ohmic contact anode 6 is arranged in the notch;

[0011] The first substrate 3 and the second substrate 8 are closely attached to form a rectangular integral structure with a groove at one end;

[0012] The cathode connection electrode 1 is a non-enclosed rectangular three-port structure, the upper and lower ports are respectively connected to the first ohmic contact cathode 2 and the second ohmic contact cathode 4, and the middle port is used to connect to an external circuit;

[0013] The anode connection electrode 7 is located in the groove of the photoconductive device 10 , and is connected to the first ohmic contact anode 5 and the second ohmic contact anode 6 , and both are conductive at the same time, forming a parallel connection structure of the first substrate 3 and the second substrate 8 .

[0014] Furthermore, the insulating packaging shell 9 is entirely wrapped around the photoconductive device 10 and part of the cathode connecting electrode 1 and the anode connecting electrode 7 , and another part of the cathode connecting electrode 1 and the anode connecting electrode 7 is outside the insulating packaging shell 9 .

[0015] Furthermore, the first substrate 3 and the second substrate 8 are both made of any one of semiconductor semi-insulating materials such as silicon carbide, gallium nitride, gallium arsenide, gallium oxide, diamond, etc.; the substrate is in a rectangular structure with a thickness of 0.3mm-1.5mm and a side length of 5mm-15mm.

[0016] Furthermore, the first ohmic contact anode 5, the first ohmic contact cathode 2, the second ohmic contact anode 6, and the second ohmic contact cathode 4 are made of any one or a combination of metal materials selected from titanium, silver, gold, aluminum, tungsten, nickel, and platinum, and the total thickness of each ohmic contact electrode is 200nm-500nm; their shapes are all rectangular shapes with rounded edges of the same size, with a length of 4mm-8mm, a width of 2mm-4mm, and a rounded radius of 0.5mm-2mm.

[0017] Furthermore, the groove at one end of the optical waveguide device 10 is a rectangular structure with a length of 4 mm to 8 mm, a width of 2 mm to 5 mm, and a height of 100 um to 600 um.

[0018] Furthermore, the cathode connecting electrode 1 adopts a non-closed rectangular three-port structure, the upper and lower ports of which are 2mm-6mm long and 2mm-8mm wide, the upper and lower ports are 0.6mm-3mm apart, and the middle port is 5mm-10mm long and 2mm-8mm wide; the anode connecting electrode 7 is a rectangular body structure, 5mm-12mm long and 2mm-8mm wide.

[0019] Furthermore, the anode connecting electrode 7 and the cathode connecting electrode 1 are made of any one of platinum, palladium, silver and copper, and have a thickness of 0.1 mm to 0.5 mm.

[0020] 2. A method for manufacturing a photoconductive microwave device with a synchronously triggered parallel structure of electrodes on different surfaces, characterized in that it comprises the following steps:

[0021] S1) Select a semi-insulating wafer material as the first substrate 3 and the second substrate 8, and perform pre-treatment of cleaning and drying on them;

[0022] S2) Perform notch lithography, etching and cleaning at one end of the first substrate 3 and the second substrate 8 on the front side of the pre-treated semi-insulating wafer;

[0023] S3) Apply photoresist on the front side of the semi-insulating wafer, remove the excess photoresist after exposure and development to form an ohmic contact electrode region on the front side;

[0024] S4) Evaporate and sputter metal on the front side of the semi-insulating wafer to form a metal layer, and strip and remove the metal outside the ohmic contact electrode region to form a front-side metal electrode;

[0025] S5) Apply photoresist on the back side of the semi-insulating wafer, remove the excess photoresist after exposure and development to form an ohmic contact electrode region on the back side;

[0026] S6) Evaporate and sputter metal on the back side of the semi-insulating wafer to form a metal layer, and strip and remove the metal outside the ohmic contact electrode region to form a back-side metal electrode;

[0027] S7) Place the semi-insulating wafer with metal electrodes on both the upper and lower surfaces in an Ar or N2 gas atmosphere for a first annealing to form a first ohmic contact anode 5 and a second ohmic contact anode 6 on the upper surface, and a first ohmic contact cathode 2 and a second ohmic contact cathode 4 on the lower surface;

[0028] S8) Use a brass substrate to make an anode connection electrode 7 and a cathode connection electrode 1 by bending and slicing processes, and gold-plate their surfaces;

[0029] S9) Dice and separate the first substrate 3 and the second substrate 8 on the semi-insulating wafer, then vertically bond them so that their notches are opposite to each other to form an optical waveguide device 10 with a groove at one end, and connect the first ohmic contact anode 5 and the second ohmic contact anode 6 in the groove of the optical waveguide device 10 through the anode connection electrode 7;

[0030] S10) At the other end of the optical waveguide device 10, connect the upper right port and the lower right port of the cathode connection electrode 1 to the first ohmic contact cathode 2 and the second ohmic contact cathode 4 respectively;

[0031] S11) Wrap an insulating glue around the anode connection electrode 7, the cathode connection electrode 1 and the optical waveguide device 10 to form an insulating encapsulation shell 9, completing the device preparation.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1) The present invention vertically and tightly fits two substrates with notches so that their notches are relatively combined to form a photoconductive device with a groove at one end, and an external anode connection electrode is embedded in the groove, so that electrical connection can be achieved from the inside of the photoconductive device, so that the laser can be directly irradiated on the sides of the two substrates, thereby improving the utilization rate of light energy.

[0034] 2) Since the present invention realizes the parallel connection of two substrates, the entire photoconductive device can have two or even more current paths inside, thereby increasing the module output current, which is beneficial to alleviate the pinching effect under a single current path, and the system is highly compact, which is conducive to practical application.

[0035] 3) The present invention simplifies the process steps and is simple to manufacture because the front and back sides of the semi-insulating wafer are annealed at one time. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The structure diagram of the photoconductive microwave device of the present invention with parallel structure of electrodes on different surfaces;

[0037] Figure 2 for Figure 1 A cross-sectional view of a substrate with a notch;

[0038] Figure 3 for Figure 1 Top view of the notched substrate;

[0039] Figure 4 A schematic diagram of the process of manufacturing a photoconductive microwave device with parallel structure of electrodes on different surfaces according to the present invention;

[0040] Figure 5 A comparison diagram of the single pulse response output waveforms of the photoconductive microwave device with the parallel structure of electrodes on different surfaces of the present invention and the existing single-layer photoconductive device;

[0041] Figure 6 The figure is a normalized comparison diagram of the single pulse response output waveforms of the photoconductive microwave device with the parallel structure of electrodes on different surfaces of the present invention and the existing single-layer photoconductive device. DETAILED DESCRIPTION

[0042] The specific examples of the present invention are described in detail below with reference to the accompanying drawings.

[0043] Reference Figure 1 The photoconductive microwave device of the synchronously triggered eccentric electrode parallel structure of the present invention comprises a cathode connection electrode 1, a first ohmic contact cathode 2, a first substrate 3, a second ohmic contact cathode 4, a first ohmic contact anode 5, a second ohmic contact anode 6, an anode connection electrode 7, a second substrate 8, an insulating packaging shell 9 and a photoconductive device 10.

[0044] Both the first substrate 3 and the second substrate 8 are made of any one of semiconductor semi-insulating materials such as silicon carbide, gallium nitride, gallium arsenide, gallium oxide, and diamond. The substrate is in a rectangular structure with a thickness of 0.3 mm - 1.5 mm and a side length of 5 mm - 15 mm. One end of each of them is provided with a notch, and the notch is a rectangular body structure with a length of 4 mm - 8 mm, a width of 2 mm - 5 mm, and a height of 100 μm - 600 μm.

[0045] The first ohmic contact cathode 2 and the second ohmic contact cathode 4 are respectively arranged on the upper surfaces of the first substrate 3 and the second substrate 8.

[0046] The first ohmic contact anode 5 and the second ohmic contact anode 6 are respectively arranged in the notches of the first substrate 3 and the second substrate 8.

[0047] The first ohmic contact anode 5, the first ohmic contact cathode 2, the second ohmic contact anode 6, and the second ohmic contact cathode 4 are made of any one or several metal materials superimposed among silver, copper, gold, aluminum, tungsten, nickel, iron, and platinum. The total thickness of each ohmic contact electrode is 200 nm - 500 nm, and their shapes are all rectangular with rounded edges of the same size, with a length of 4 mm - 8 mm, a width of 2 mm - 4 mm, and a rounded corner radius of 0.5 mm - 2 mm.

[0048] The photoconductive device 10 is a rectangular integrated structure with one end being a groove formed by closely fitting the first substrate 3 and the second substrate 8. The groove is a rectangular body with a length of 4 mm - 8 mm, a width of 2 mm - 5 mm, and a height of 100 μm - 600 μm.

[0049] The cathode connection electrode 1 adopts a non-closed rectangular three-port structure and is made of any one of platinum, palladium, silver, and copper. Its thickness is 0.1 mm - 0.5 mm. The upper and lower ports have a length of 2 mm - 6 mm and a width of 2 mm - 8 mm, and the distance between the upper and lower ports is 0.6 mm - 3 mm. The middle port has a length of 5 mm - 10 mm and a width of 2 mm - 8 mm. The upper and lower two ports are respectively connected to the first ohmic contact cathode 2 and the second ohmic contact cathode 4, and the middle port is used to connect to an external circuit.

[0050] The anode connection electrode 7 is a rectangular body structure and is made of any one of platinum, palladium, silver, and copper. Its thickness is 0.1 mm - 1 mm, its length is 5 mm - 12 mm, and its width is 2 mm - 8 mm. It is located in the groove of the photoconductive device 10. One end of it is connected to the first ohmic contact anode 5 and the second ohmic contact anode 6, and the other end is connected to an external circuit.

[0051] The insulating packaging shell 9 is a rectangular structure with a length of 10mm-14mm, a width of 10mm-12mm, and a height of 2mm-4mm. It is made of insulating plastic material and is entirely wrapped around the photoconductive device 10 and part of the cathode connecting electrode 1 and the anode connecting electrode 7.

[0052] When the laser is irradiated from the side onto the first substrate 3 and the second substrate 8, the substrate generates photogenerated carriers, and the two substrates simultaneously change from a high resistance state to a low resistance state. A DC voltage is applied to the anode connection electrode 7, and a voltage difference is formed between the first ohmic contact anode 5 and the first ohmic contact cathode 2, the second ohmic contact anode 6 and the second ohmic contact cathode 4. Under the action of the bias voltage, the photogenerated carriers in the photoconductive device 10 move in a directional manner to form a current, and the generated current is output from the cathode connection electrode 1 connected to the first ohmic contact cathode 2 and the second ohmic contact cathode 4 to the external circuit.

[0053] Reference Figure 4 The present invention provides three embodiments of preparing a photoconductive microwave device with a synchronously triggered parallel structure of electrodes on different surfaces:

[0054] Embodiment 1, the two substrates in the photoconductive device 10 are 10 mm long, 10 mm wide, and 0.5 mm thick, and the material is vanadium-doped semi-insulating silicon carbide. The groove is 6 mm long, 4 mm wide, and 300 um high. The electrodes on each substrate are a four-layer metal composite structure of nickel, titanium, platinum, and gold, and the thicknesses are 50 nm, 150 nm, 200 nm, and 100 nm, respectively, and the shape is a rectangular photoconductive microwave device with rounded edges.

[0055] Step 1, select a semi-insulating substrate material and clean it, such as Figure 4 (a).

[0056] A vanadium-doped semi-insulating silicon carbide wafer with a thickness of 500 um was selected, and ultrasonically cleaned in acetone, isopropanol, and deionized water for 600 s, 180 s, and 180 s, respectively, and then dried in a nitrogen atmosphere.

[0057] Step 2, performing notch etching on the front side of the silicon carbide wafer.

[0058] (2.1) Evenly apply photoresist on the front of the cleaned silicon carbide wafer, use a photolithography machine with a photomask to expose and develop the silicon carbide wafer coated with photoresist, and then remove part of the photoresist to expose the gap area, such as Figure 4 (b);

[0059] (2.2) Use an etcher to perform precise deep groove etching on the notch area, with an etching depth of 150um, and then clean it. Figure 4 (c).

[0060] Step 3, fabricate metal electrodes on the front side of the silicon carbide wafer.

[0061] (3.1) Spin-coat photoresist on the front side of the silicon carbide wafer after etching. After performing overlay exposure through a mask aligner with a photomask in the rounded-rectangle ohmic contact electrode area within the front-side notch, perform exposure and development in sequence to remove the excess photoresist, exposing the front-side ohmic contact electrode area. After cleaning, evaporate and sputter metal on the entire front side of the wafer to form a metal layer, as shown in Figure 4 (d);

[0062] (3.2) Immerse the silicon carbide wafer with the metal layer in acetone solution for 10 hours and sonicate for 5 minutes. Then, immerse it in the stripping solution for 30 minutes, and then put it into acetone solution and sonicate for 5 minutes to completely strip and remove the metal outside the front-side electrode area, followed by cleaning to form the front-side rounded-rectangle metal electrode, as shown in Figure 4 (e).

[0063] Step 4, fabricate metal electrodes on the back side of the silicon carbide wafer.

[0064] (4.1) Evenly apply photoresist on the back side of the cleaned silicon carbide wafer. Use a mask aligner with a photomask to perform overlay exposure in the rounded-rectangle ohmic contact electrode area on the back side of the silicon carbide wafer coated with photoresist, and then perform exposure and development in sequence to remove the excess photoresist and expose the back-side ohmic contact electrode area. After cleaning, evaporate and sputter metal on the entire back side of the wafer to form a metal layer, as shown in Figure 4 (f);

[0065] (4.2) Immerse the silicon carbide wafer with the metal layer in acetone solution for 10 hours and sonicate for 5 minutes. Then, immerse it in the stripping solution for 30 minutes, and then put it into acetone solution and sonicate for 5 minutes to completely strip and remove the metal outside the back-side electrode area, followed by cleaning to form the back-side rounded-rectangle metal electrode, as shown in Figure 4 (g).

[0066] Step 5, anneal the metal electrodes on both the front and back sides of the silicon carbide wafer to form ohmic contacts, as shown in Figure 4 (h).

[0067] Place the silicon carbide wafer with metal electrodes on both the upper and lower surfaces into a rapid thermal annealing furnace. Set the annealing conditions of an annealing temperature of 1050 °C and an annealing time of 120 s in an Ar gas atmosphere to complete rapid annealing at one time, so as to form ohmic contact electrodes on the upper and lower surfaces of the wafer respectively, as shown in Figure 2 , where:

[0068] Form a first ohmic contact anode 5 and a second ohmic contact anode 6 on the upper surface,

[0069] Form a first ohmic contact cathode 2 and a second ohmic contact cathode 4 on the lower surface.

[0070] The shape of each ohmic contact electrode is a rectangular with rounded edges, with a length of 6 mm, a width of 3 mm, and a chamfer radius of 1 mm, as Figure 3 .

[0071] Step 6: Fabricate an anode connection electrode 7 and a cathode connection electrode 1.

[0072] Select a brass substrate, and use a slicing process to make it into two rectangular bodies with a thickness of 0.3 mm. Gold plating is performed on the surfaces of both. One rectangular body has a length of 10 mm and a width of 5 mm as the anode connection electrode 7, and the other rectangular body is folded into an unclosed rectangular three-port structure as the cathode connection electrode 1 through a bending process, where:

[0073] The upper and lower ports of the cathode connection electrode 1 have a length of 3 mm and a width of 3 mm, and the distance between the upper and lower ports is 1 mm.

[0074] The middle port has a length of 7 mm and a width of 3 mm.

[0075] Step 7: Separate the first substrate 3 and the second substrate 8 and make their notches fit tightly against each other.

[0076] (7.1) Separate the silicon carbide wafer that has completed the above steps through mechanical dicing to obtain the first substrate 3 and the second substrate 8, as Figure 4 (i);

[0077] (7.2) Vertically bond the two substrates so that their notches are opposite to each other to form an optical waveguide device 10 with a groove at one end. The upper and lower surfaces inside the groove are provided with the first ohmic contact anode 5 and the second ohmic contact anode 6 generated in the above steps, as Figure 4 (j).

[0078] Step 8: Connect the external electrodes to the optical waveguide device 10, as Figure 4 (k).

[0079] (8.1) Connect the first ohmic contact anode 5 and the second ohmic contact anode 6 in the groove of the optical waveguide device 10 through one end of the anode connection electrode 7, so that the anode connection electrode 7 is embedded between the first substrate 3 and the second substrate 8, and there is almost no gap between the two stacks; the other end of the anode connection electrode 7 is used to connect to an external circuit;

[0080] (8.2) Connect the upper right port and the lower right port of the cathode connection electrode 1 to the first ohmic contact cathode 2 and the second ohmic contact cathode 4 on the surface of the optical waveguide device 10 respectively, and the middle port is used to connect to an external circuit.

[0081] Step 9, perform insulation encapsulation on the optical waveguide device 10, such as Figure 4 (l).

[0082] Wrap the anode connection electrode 7, the cathode connection electrode 1, and the outside of the optical waveguide device 10 with epoxy resin to form an insulation encapsulation shell 9, completing the device preparation.

[0083] Example 2, fabricate two substrates in the optical waveguide device 10 with a length of 5 mm, a width of 5 mm, a thickness of 0.3 mm, and a material of semi-insulating gallium nitride. The groove has a length of 4 mm, a width of 2 mm, and a height of 100 um; the electrodes on each substrate are a four-layer metal composite structure of titanium, aluminum, nickel, and gold, with thicknesses of 20 nm, 100 nm, 30 nm, and 50 nm respectively, and the shape is a rectangular optical waveguide microwave device with rounded edges.

[0084] Step 1, select a semi-insulating substrate material and perform cleaning, such as Figure 4 (a).

[0085] Select a semi-insulating gallium nitride wafer with a thickness of 300 um, place it in acetone, isopropyl alcohol, and deionized water respectively for ultrasonic cleaning for 600 s, 180 s, and 180 s, and then dry it in a nitrogen atmosphere.

[0086] Step 2, perform notch etching on the front side of the gallium nitride wafer.

[0087] Evenly apply photoresist on the front side of the cleaned gallium nitride wafer, use a photolithography machine with a photomask to expose and develop the gallium nitride wafer coated with photoresist, and then remove part of the photoresist to expose the notch area, such as Figure 4 (b);

[0088] Then use an etching machine to perform precise deep groove etching with a depth of 50 um on the notch area and then clean it, such as Figure 4 (c).

[0089] Step 3, fabricate metal electrodes on the front side of the gallium nitride wafer, such as Figure 4 (e).

[0090] The specific implementation of this step is the same as step 3 of Example 1.

[0091] Step 4, fabricate metal electrodes on the back side of the gallium nitride wafer, such as Figure 4 (g).

[0092] The specific implementation of this step is the same as step 4 of Example 1.

[0093] Step 5, anneal the metal electrodes on both the front and back sides of the gallium nitride wafer to form an ohmic contact, such as Figure 4 (h).

[0094] Place a gallium nitride wafer with metal electrodes on its upper and lower surfaces into a rapid annealing furnace, and perform a single rapid annealing under annealing conditions where the gas atmosphere is N2, the annealing temperature is 850 °C, and the annealing time is 60 s, so as to form a first ohmic contact anode 5 and a second ohmic contact anode 6 on the upper surface of the wafer respectively, and form a first ohmic contact cathode 2 and a second ohmic contact cathode 4 on the lower surface, as Figure 2 , and the shape of each ohmic contact electrode is a rectangular with rounded edges having a length of 4 mm, a width of 2 mm, and a chamfer radius of 0.5 mm, as Figure 3 .

[0095] Step six, fabricate an anode connection electrode 7 and a cathode connection electrode 1.

[0096] Select a silver metal substrate, and fabricate it into two rectangular bodies with a thickness of 0.1 mm through a slicing process, and perform gold plating treatment on the surfaces of the two, where:

[0097] One rectangular body has a length of 10 mm and a width of 5 mm as the anode connection electrode 7;

[0098] Fold the other rectangular body into a non-closed rectangular three-port structure through a bending process as the cathode connection electrode 1. The upper and lower ports of the cathode connection electrode 1 have a length of 2 mm and a width of 2 mm, the distance between the upper and lower ports is 0.6 mm, and the middle port has a length of 5 mm and a width of 2 mm.

[0099] Step seven, separate the gallium nitride wafer to fabricate the optical waveguide device 10, as Figure 4 (i).

[0100] The specific implementation of this step is the same as step 7 of embodiment 1.

[0101] Step eight, perform external electrode connection on the optical waveguide device 10, as Figure 4 (k).

[0102] The specific implementation of this step is the same as step 8 of embodiment 1.

[0103] Step nine, perform insulation packaging on the optical waveguide device 10, as Figure 4 (l).

[0104] The specific implementation of this step is the same as step 9 of embodiment 1.

[0105] In embodiment 3, two substrates in the optical waveguide device 10 have a length of 15 mm, a width of 15 mm, a thickness of 1.5 mm, are made of semi-insulating gallium oxide, the grooves have a length of 8 mm, a width of 5 mm, and a height of 600 um; the electrodes on each substrate are a two-layer metal composite structure of titanium and gold, with thicknesses of 50 nm and 200 nm respectively, and the shape is a rectangular with rounded edges for the optical waveguide microwave device.

[0106] Step A, select a semi-insulating substrate material and perform cleaning, such as Figure 4 (a).

[0107] Select a semi-insulating gallium oxide wafer with a thickness of 1.5 mm, place it in acetone, isopropyl alcohol, and deionized water respectively for ultrasonic cleaning for 600 s, 180 s, and 180 s, and then dry it in a nitrogen atmosphere.

[0108] Step B, perform notch etching on the front side of the gallium oxide wafer.

[0109] B1) Uniformly apply photoresist on the front side of the cleaned gallium oxide wafer, use a lithography machine with a photomask to expose and develop the gallium oxide wafer coated with photoresist, and then remove part of the photoresist to expose the notch area, such as Figure 4 (b);

[0110] B2) Use an etching machine to etch a deep groove in the notch area and then clean it. The etching depth is 300 um, such as Figure 4 (c).

[0111] Step C, fabricate metal electrodes on the front side of the gallium oxide wafer, such as Figure 4 (e).

[0112] The specific implementation of this step is the same as that of step 3 in Embodiment 1.

[0113] Step D, fabricate metal electrodes on the back side of the gallium oxide wafer, such as Figure 4 (g).

[0114] The specific implementation of this step is the same as that of step 4 in Embodiment 1.

[0115] Step E, anneal the metal electrodes on both the front and back sides of the gallium oxide wafer to form ohmic contacts, such as Figure 4 (h).

[0116] Place the gallium oxide wafer with metal electrodes on both the upper and lower surfaces into a rapid annealing furnace. Under the annealing conditions of a gas atmosphere of N2, a temperature of 450 °C, and a time of 30 s, perform rapid annealing once to form a first ohmic contact anode 5 and a second ohmic contact anode 6 on the upper surface of the wafer, and a first ohmic contact cathode 2 and a second ohmic contact cathode 4 on the lower surface, such as Figure 2 , each ohmic contact electrode has a length of 8 mm, a width of 4 mm, and a chamfer radius of 2 mm, such as Figure 3 .

[0117] Step F, fabricate an anode connection electrode 7 and a cathode connection electrode 1.

[0118] Select a platinum substrate and make it into two rectangular bodies with a thickness of 0.5 mm through a slicing process, and perform gold plating on the surfaces of both, which are used as the anode connection electrode 7 and the cathode connection electrode 1 respectively. Among them:

[0119] The rectangular body serving as the anode connection electrode 7 has a length of 12 mm and a width of 8 mm;

[0120] The rectangular body serving as the cathode connection electrode 1 is further folded into a non-closed rectangular three-port structure through a bending process. The lengths of the upper and lower ports are both 6 mm, the widths are both 8 mm, the distance between the upper and lower ports is 3 mm, and the length of the middle port is 10 mm and the width is 8 mm.

[0121] Step G, separate the gallium oxide wafer to fabricate the photoconductive device 10, as shown in Figure 4 (j).

[0122] The specific implementation of this step is the same as step 7 of embodiment 1.

[0123] Step H, perform external electrode connection on the photoconductive device 10, as shown in Figure 4 (k).

[0124] The specific implementation of this step is the same as step 8 of embodiment 1.

[0125] Step I, perform insulation encapsulation on the photoconductive device 10, as shown in Figure 4 (l), and complete the device preparation.

[0126] The specific implementation of this step is the same as step 9 of embodiment 1.

[0127] The effects of the present invention can be further illustrated by the following simulation results.

[0128] First, simulation conditions

[0129] Parameter settings: The dielectric constant of the silicon carbide substrate is 10.03, the magnetic permeability is 1 H / m, the vanadium doping concentration is set to 1.2x10 17 cm -3 , the nitrogen doping concentration is 3x10 16 cm -3 , the laser optical power density is 3x10 8 W / cm 2 , the laser pulse full width at half maximum is about 300 ps, and the applied voltage is 2 kV.

[0130] The silicon carbide semiconductor physical model includes: energy band model, mobility model, generation-recombination model, optical recombination model, etc.

[0131] Comparison devices: existing device models and embodiment 1 of the present invention, among which:

[0132] The existing device model structure is a rectangle with a thickness of 1 mm and a side length of 10 mm. The ohmic contact anode is on its upper surface, and the ohmic contact cathode is on its lower surface. Each ohmic contact electrode is a rectangular with rounded edges with a length of 6 mm, a width of 3 mm, and a chamfer radius of 1 mm, and a thickness of 500 nm. The distance between the two electrodes is 1 mm.

[0133] In Example 1 of the present invention, the thickness of the photoconductive device is 1 mm, the side length is 10 mm, the groove length is 6 mm, the width is 4 mm, and the height is 0.3 mm. Each ohmic contact electrode is a rectangular with rounded edges with a length of 6 mm, a width of 3 mm, and a chamfer radius of 1 mm, and a thickness of 500 nm. The distance between the ohmic contact anode and the ohmic contact cathode is 1 mm.

[0134] Simulation software: Silvaco TCAD, Ansys Maxwell.

[0135] II. Simulation Contents and Results

[0136] Simulation 1: Under the above conditions, the single-pulse output characteristics of the device fabricated in Example 1 of the present invention and the existing single-layer device are respectively simulated. The results are as Figure 5 . From Figure 5 it can be seen that the peak output current of the stacked parallel structure photoconductive device of the present invention is 184 A, which is about 91% higher than 96 A of the existing single-layer device. Through substrate stacking, device parallel connection is realized, the module output current is increased, and the device output power can be effectively improved.

[0137] Simulation 2: Under the above conditions, the frequency response characteristics of the device fabricated in Example 1 of the present invention and the existing single-layer device are respectively simulated. The results are as Figure 6 . From Figure 6 it can be seen that the full width at half maximum of both is almost the same, indicating that both the parallel structure device of the present invention and the existing device can achieve optoelectronic response at a frequency of 2.5 GHz, but the device of the present invention can achieve high-power output at high frequencies.

[0138] Simulation 3: Using Ansys Maxwell software to simulate the capacitance value C of the device of the present invention and the existing single-layer device, and calculating the cut-off frequency f of the device through the cut-off frequency formula f = 1 / (2πR load C), where R load is a 50 Ω load in the circuit. The results are shown in Table 1 below.

[0139] Table 1 Data table of simulated capacitance value C and cut-off frequency f of the device of the present invention and the existing device

[0140]

[0141] As can be seen from Table 1, the cut-off frequencies f of both can meet the working frequency requirements of the C band, and are basically close to the upper limit of the optoelectronic response frequency of the silicon carbide material, which is 6 GHz, further indicating that the parallel-structured photoconductive device of the present invention has good frequency response characteristics.

[0142] The above description is only several specific examples of the present invention and does not constitute any limitation to the present invention. Obviously, for professionals in the field, after understanding the content and principle of the present invention, various modifications and changes in form and details may be made without departing from the principle and structure of the present invention. For example, in addition to silicon carbide, gallium nitride, and gallium oxide used in the above examples, the substrate material mentioned in the above embodiments may also use gallium arsenide and diamond materials; in addition to titanium, aluminum, nickel, platinum, and gold used in the above examples, the ohmic contact electrode material may also use silver and tungsten; in addition to platinum, silver, and copper used in the above examples, the cathode connection electrode and anode connection electrode materials may also use palladium materials. However, these corrections and changes based on the idea of the present invention are still within the protection scope of the claims of the present invention.

Claims

1. A photoconductive microwave device with a synchronously triggered parallel structure of electrodes on different surfaces, comprising a photoconductive device (10), a cathode connecting electrode (1), an anode connecting electrode (7) and an insulating packaging shell (9), characterized in that: The photoconductive device (10) comprises a first substrate (3) and a second substrate (8) each having a notch at one end; a first ohmic contact cathode (2) is provided on the upper surface of the first substrate (3), and a first ohmic contact anode (5) is provided in the notch; a second ohmic contact cathode (4) is provided on the upper surface of the second substrate (8), and a second ohmic contact anode (6) is provided in the notch; The first substrate (3) and the second substrate (8) are tightly fitted together to form a rectangular integrated structure with a groove at one end; The cathode connection electrode (1) is a non-enclosed rectangular three-port structure, wherein the upper and lower ports are respectively connected to the first ohmic contact cathode (2) and the second ohmic contact cathode (4), and the middle port is used to connect to an external circuit; The anode connection electrode (7) is located in the groove of the photoconductive device (10), and is connected to the first ohmic contact anode (5) and the second ohmic contact anode (6), and both are conductive at the same time, forming a parallel connection structure of the first substrate (3) and the second substrate (8).

2. The device according to claim 1, characterized in that The insulating packaging shell (9) is entirely wrapped around the photoconductive device (10) and part of the cathode connecting electrode (1) and the anode connecting electrode (7), and the other part of the cathode connecting electrode (1) and the anode connecting electrode (7) is outside the insulating packaging shell (9).

3. The device according to claim 1, characterized in that The first substrate (3) and the second substrate (8) are both made of any one of semiconductor semi-insulating materials such as silicon carbide, gallium nitride, gallium arsenide, gallium oxide, diamond, etc.; the substrate is in a rectangular structure with a thickness of 0.3 mm to 1.5 mm and a side length of 5 mm to 15 mm.

4. The device according to claim 1, characterized in that The first ohmic contact anode (5), the first ohmic contact cathode (2), the second ohmic contact anode (6), and the second ohmic contact cathode (4) are all made of any one or a combination of several metal materials selected from titanium, silver, gold, aluminum, tungsten, nickel, and platinum, and the total thickness of each ohmic contact electrode is 200 nm to 500 nm; The shapes are all rectangular with rounded edges of the same size, with a length of 4mm-8mm, a width of 2mm-4mm, and a rounded radius of 0.5mm-2mm.

5. The device according to claim 1, characterized in that The groove at one end of the optical guide device (10) is a rectangular structure with a length of 4mm-8mm, a width of 2mm-5mm and a height of 100um-600um.

6. The device according to claim 1, characterized in that: The cathode connecting electrode (1) adopts a non-enclosed rectangular three-port structure, wherein the upper and lower ports are 2mm-6mm long and 2mm-8mm wide, the distance between the upper and lower ports is 0.6mm-3mm, and the middle port is 5mm-10mm long and 2mm-8mm wide; The anode connecting electrode (7) is a rectangular structure with a length of 5 mm to 12 mm and a width of 2 mm to 8 mm.

7. The device according to claim 1, characterized in that The anode connecting electrode (7) and the cathode connecting electrode (1) are made of any one of platinum, palladium, silver and copper, and have a thickness of 0.1 mm to 0.5 mm.

8. A method for manufacturing a photoconductive microwave device with synchronously triggered parallel structure of electrodes on different surfaces, characterized in that: The following steps are involved: S1) selecting a semi-insulating wafer material as a first substrate (3) and a second substrate (8), and performing pre-treatment of cleaning and drying the wafers; S2) performing notch photolithography, etching and cleaning on the first substrate (3) and one end of the second substrate (8) on the front side of the pre-treated semi-insulating wafer; S3) applying photoresist on the front side of the semi-insulating wafer, removing excess photoresist after exposure and development, and forming an ohmic contact electrode region on the front side; S4) evaporating and sputtering metal on the front side of the semi-insulating wafer to form a metal layer, and stripping and removing the metal outside the ohmic contact electrode area to form a front metal electrode; S5) applying photoresist on the back side of the semi-insulating wafer, removing excess photoresist after exposure and development, and forming an ohmic contact electrode region on the back side; S6) evaporating and sputtering metal on the back side of the semi-insulating wafer to form a metal layer, and stripping and removing the metal outside the ohmic contact electrode area to form a back side metal electrode; S7) placing the semi-insulating wafer having metal electrodes on the upper and lower surfaces in an Ar or N2 gas atmosphere for annealing, forming a first ohmic contact anode (5) and a second ohmic contact anode (6) on the upper surface, and forming a first ohmic contact cathode (2) and a second ohmic contact cathode (4) on the lower surface; S8) using a brass substrate through a bending and slicing process to form an anode connecting electrode (7) and a cathode connecting electrode (1), and performing gold plating on the surface thereof; S9) separating the first substrate (3) and the second substrate (8) on the semi-insulating wafer by dicing, and then vertically attaching the two substrates so that their notches are opposite to each other to form a photoconductive device (10) with a groove at one end, and connecting the first ohmic contact anode (5) and the second ohmic contact anode (6) in the groove of the photoconductive device (10) through an anode connecting electrode (7); S10) at the other end of the photoconductive device (10), connecting the right upper port and the right lower port of the cathode connecting electrode (1) to the first ohmic contact cathode (2) and the second ohmic contact cathode (4) respectively; S11) Wrapping the anode connecting electrode (7), the cathode connecting electrode (1) and the photoconductive device (10) with insulating glue to form an insulating packaging shell (9), thereby completing the device preparation.

9. The method according to claim 8, characterized in that: In the step S1), the semi-insulating substrate wafer is pre-treated by first ultrasonically cleaning in acetone, isopropanol, and deionized water for 600 s, 180 s, and 180 s, respectively, and then drying in a nitrogen atmosphere.

10. The method according to claim 8, characterized in that: In the step S2), the notch is etched by deep groove etching in an SF6 and O2 atmosphere, and the etching depth is 50um-300um; The one-time annealing in step S7) is to place the semi-insulating wafer into a rapid annealing furnace, set the annealing temperature to 450°C-1050°C in an Ar or N2 gas atmosphere, and the annealing time to 30s-120s, so as to complete the rapid annealing in one time.

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