A nitride micromechanical radar pot and a method of making the same

Abstract

The application relates to the technical field of nanometer acoustic wave manipulation, and discloses a nitride micro-mechanical radar pot design and a preparation method thereof, which comprises a silicon substrate layer and a nitride layer arranged on the upper portion of the silicon substrate layer, the center of the nitride layer is supported by the top of the silicon substrate layer, and the remaining part is in a suspended state; the radar pot can realize the change of the swing scanning direction through the acoustic wave frequency; a suspended micro-mechanical radar pot is prepared on the epitaxial wafer nitride layer of the silicon substrate layer by using a photoetching, ICP dry etching and silicon wet etching process. The radar pot of the application is deformed under a certain frequency of acoustic wave, and the detection direction can be controlled.

Description

Technical Field

[0001] This invention relates to the field of nanoacoustic wave manipulation technology, specifically to a sound-controlled nitride micromechanical radar dish and its preparation method. Background Technology

[0002] Radar is a high-tech system that utilizes the reflection or scattering of electromagnetic waves by targets to detect, locate, track, image, and identify them. It is a culmination of modern electronic science and technology achievements. It has been successfully applied to ground-based (including vehicle-mounted), shipborne, airborne, and spaceborne applications. These radars are currently performing and are performing various military and civilian tasks. Based on their operating frequency band, radars can be categorized into over-the-horizon radar, microwave radar, millimeter-wave radar, lidar, and optical phased array radar, among others. In particular, current lidar chips and optical phased array radars operate in the near-infrared band with a wavelength of 1550nm, achieving beam scanning through phase changes.

[0003] Radar beam or electromagnetic wave oscillation can be divided into two types: one is beam oscillation based on phase change, such as chip-level optical phased array radar, and the other is radar with mechanically controlled oscillation, such as millimeter-wave radar. However, the size of this type of radar is usually relatively large, making it difficult to achieve a chip-sized size. Against this background, we propose a micrometer-level micromechanical radar dish based on acoustic wave-controlled direction. This structure is expected to be used in radar components for terahertz and underwater blue-green light communication. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for fabricating a nitride-based, acoustically controllable micromechanical radar dish structure. The method controls the swing direction of the radar dish by using the frequency of sound waves, thereby controlling the sweeping of the light beam.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In a first aspect, the present invention proposes a nitride micromechanical radar dish, comprising a silicon substrate layer serving as the base of the radar dish and a nitride layer disposed on the upper part of the silicon substrate layer, wherein the center of the nitride layer is supported by the top of the silicon substrate layer and the rest is suspended; the radar dish can change its sweeping direction by means of sound wave frequency.

[0007] Furthermore, the thickness of the nitride layer is 200-500 nm, preferably 300 nm; if the thickness is too thin (below 300 nm), the nitride layer is easily shattered by the sound wave frequency, and if the thickness is too thick (greater than 500 nm), the sound wave frequency cannot vibrate the nitride layer, resulting in poor radar dish oscillation effect.

[0008] Furthermore, the diameter of the radar dish is 40-60 μm, preferably 50 μm, and the thickness is 200-500 nm, preferably 300 nm.

[0009] Furthermore, the silicon substrate layer is a silicon-based material.

[0010] Furthermore, the nitride is one of gallium nitride, aluminum nitride, and silicon nitride.

[0011] Secondly, the present invention proposes a method for preparing a nitride micromechanical radar dish, comprising the following steps:

[0012] Step 1: Epitaxially grow a nitride layer on a silicon substrate to obtain a nitride epitaxial wafer. Alternatively, you can directly purchase a nitride epitaxial wafer.

[0013] Step 2: Spin-coat photoresist onto the upper surface of the nitride epitaxial wafer to obtain a photoresist layer;

[0014] Step 3: Define the radar dish described above on the spin-coated photoresist layer using optical lithography technology;

[0015] Step four: ICP etching technology (inductively coupled plasma etching technology) is used to etch the nitride layer downwards until the upper surface of the silicon substrate layer is reached, thereby transferring the patterned structure defined in the first step downwards into the nitride layer; the patterned structure of the radar dish is a disk microcavity structure;

[0016] Step 5: Remove residual photoresist with acetone solution;

[0017] Step six: Utilizing isotropy, wet etching technology is used to etch the silicon substrate layer, forming silicon pillars supporting the disk in the silicon substrate layer, thereby obtaining a completely suspended micromechanical structure.

[0018] In conjunction with the second aspect, the specific method of step two is as follows: After the nitride epitaxial wafer is ultrasonically cleaned once with acetone, anhydrous ethanol and deionized water, it is dried with a nitrogen gun. A spin coater is then used to spin-coat photoresist onto the upper surface of the nitride layer at a speed of 3000-4500 rpm. The photoresist is preferably AZ5214. The spin-coating time is 40-50 seconds, and the photoresist thickness is 1-1.5 micrometers. If the photoresist coating is too thick or too thin, it will directly affect the photolithography results, leading to the failure of the fabrication of the nitride micromechanical radar dish.

[0019] In conjunction with the second aspect, further, the etching solution of the wet etching technology in step six is ​​a mixed solution of hydrofluoric acid and dilute nitric acid in a ratio of 1:1 to 1:10. This mixed solution can unilaterally etch the silicon substrate without etching the nitride material, thereby enabling the radar dish structure to achieve a suspended effect; preferably, the etching solution is a mixed solution of hydrofluoric acid and dilute nitric acid in a ratio of 1:1.

[0020] Compared with the prior art, the present invention provides a sound-controlled nitride micromechanical radar dish and its preparation method, which has the following beneficial effects:

[0021] (1) Since sound has energy, sound waves of a certain frequency can cause micro- and nano-devices to vibrate, thereby changing their initial shape. The radar dish of this invention is based on the field of acoustic manipulation. The nitride radar dish changes its initial shape under the action of sound waves of different frequencies, resulting in a concave-convex shape change, thus achieving a change in the radar dish's sweeping direction. Therefore, the radar dish of this invention can control the swinging direction of the radar dish through the sound wave frequency, thereby controlling the sweeping of the beam. That is, under the control of sound waves of different frequencies, the detection direction of the radar dish can be rapidly changed. It is simple to operate, highly responsive, and easy to control.

[0022] (2) The radar dish of the present invention is made of nitride material. As a representative of group III nitride wide bandgap semiconductors, nitride has significant performance advantages compared with the previous two generations of semiconductors. It has properties such as wide direct bandgap, strong atomic bond, high thermal conductivity, good chemical stability (almost not corroded by any acid) and strong radiation resistance. Attached Figure Description

[0023] Figure 1 This is a side view of the nitride micromechanical radar dish of the present invention.

[0024] Figure 2 This is a top view of the nitride micromechanical radar dish of the present invention;

[0025] Figure 3 This is a process flow diagram of the method for preparing the nitride micromechanical radar dish of the present invention;

[0026] Figure 4 This is a simulation model diagram of the sound field when the incident sound wave direction of the gallium nitride micromechanical radar dish array is tilted at 45 degrees at the bottom in an embodiment of the present invention.

[0027] Figure 5 This is a simulation result diagram of Comsol software when the incident acoustic wave direction of the gallium nitride micromechanical radar dish array is tilted at 45 degrees at the bottom in an embodiment of the present invention;

[0028] Figure 6 This is a diagram showing the array deformation curve when the incident acoustic wave direction of the gallium nitride micromechanical radar dish is at a 45-degree angle at the bottom, according to an embodiment of the present invention.

[0029] Figure 7 This is a Comsol simulation diagram of the gallium nitride micromechanical radar dish in this embodiment of the invention, where the incident sound wave direction is vertical from the bottom and the incident sound wave frequency is 100KHz.

[0030] Figure 8This is a Comsol simulation diagram of a gallium nitride micromechanical radar dish in an embodiment of the present invention, where the incident sound wave direction is vertical from the bottom and the incident sound wave frequency is 800KHz.

[0031] The meanings of the reference numerals in the figure are as follows:

[0032] 1-Silicon substrate, 2-Nitride layer. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may include different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0035] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the present invention.

[0036] like Figure 1 and Figure 2 As shown, the present invention proposes a nitride micromechanical radar dish, including a silicon substrate layer 1 serving as the base of the radar dish and a nitride layer 2 disposed on the upper part of the silicon substrate layer 1. The center of the nitride layer 2 is supported by the top of the silicon substrate layer 1, and the rest is suspended. The radar dish can change its sweeping direction by means of the sound wave frequency.

[0037] In one specific embodiment of this example, the thickness of the nitride layer 2 is 200-500 nm, preferably 300 nm. If the thickness is too thin (below 300 nm), the nitride layer 2 is easily shattered by the sound wave frequency. If the thickness is too thick (greater than 500 nm), the sound wave frequency cannot vibrate the nitride layer 2, and the radar dish swing effect is poor.

[0038] In one specific embodiment of this example, the diameter of the radar dish is 40-60 μm, preferably 50 μm, and the thickness is 200-500 nm, preferably 300 nm.

[0039] In one specific embodiment of this example, the silicon substrate layer 1 is a silicon-based material.

[0040] In one specific embodiment of this example, the nitride is one of gallium nitride, aluminum nitride, and silicon nitride.

[0041] like Figure 3 As shown, this invention also proposes a method for preparing a nitride micromechanical radar dish, comprising the following steps:

[0042] Step 1: An epitaxial growth of a nitride layer 2 is performed on a silicon substrate 1 to obtain a nitride epitaxial wafer. Alternatively, a nitride epitaxial wafer can be purchased directly.

[0043] Step 2: Spin-coat photoresist onto the upper surface of the nitride epitaxial wafer to obtain a photoresist layer.

[0044] After ultrasonic cleaning with acetone, anhydrous ethanol, and deionized water, the nitride epitaxial wafer is dried with a nitrogen gun. Photoresist is then spin-coated onto the upper surface of nitride layer 2 using a spin coater at a speed of 3000–4500 rpm. AZ5214 is preferred as the photoresist. The spin-coating time is 40–50 seconds, and the photoresist thickness is 1–1.5 micrometers. If the photoresist coating is too thick or too thin, it will directly affect the photolithography results, leading to the failure of nitride micromechanical radar dish fabrication.

[0045] Step 3: Define the radar dish described above on the spin-coated photoresist layer using optical lithography technology;

[0046] Step 4: ICP etching technology (inductively coupled plasma etching technology) is used to etch the nitride layer 2 downwards until the upper surface of the silicon substrate layer 1 is reached, thereby transferring the patterned structure defined in the first step downwards into the nitride layer 2; the patterned structure of the radar dish is a disk microcavity structure.

[0047] Step 5: Remove residual photoresist with acetone solution;

[0048] Step 6: Using isotropic wet etching technology, the silicon substrate 1 is etched to form silicon pillars supporting the disk in the silicon substrate 1, thereby obtaining a completely suspended micromechanical structure.

[0049] In step six, the etching solution for the wet etching technique is a 1:1 mixture of hydrofluoric acid and dilute nitric acid. This mixture can unilaterally etch the silicon substrate without etching the nitride material, thus enabling the radar dish structure to achieve a suspended effect.

[0050] Figure 4 The four unit structures form a gallium nitride radar dish array, with the cylinders simulating the sound field. Figure 4 The sound waves are incident on the gallium nitride radar array from a 45-degree angle at the bottom.

[0051] Figure 5 With the sound wave incident at a 45-degree angle from the bottom, when the incident sound wave frequency is 210kHz, the gallium nitride radar array undergoes a significant change, achieving a swivel sweep effect.

[0052] Figure 6 The deformation curves of the gallium nitride radar dish after being incident on different acoustic frequencies from a 45-degree angle at the bottom, processed by Origin software, are shown on the horizontal axis. Figure 5 The diameter of the radar dish in the horizontal direction along the X-axis, with the ordinate as... Figure 5 The deformation along the Z-axis. (From...) Figure 6 As can be seen, the deformation of the gallium nitride (GaN) radar dish increases with the increase of the incident sound wave frequency. When the incident sound wave frequency is greater than 600 kHz, the deformation curve shows irregular changes, suggesting that the GaN radar dish is damaged due to the excessively high sound wave frequency. The figure also shows that when the incident sound wave angle is 45 degrees at the bottom and the sound wave frequency is 500 kHz, the deflection angle of the GaN radar dish array can almost reach 45 degrees. As the incident sound wave frequency decreases, the deflection angle also decreases.

[0053] Simulation results show that as the acoustic wave frequency increases, the deformation of the gallium nitride (GaN) radar dish also increases, and its detection angle changes dynamically. When the acoustic wave frequency is too high (above 600 kHz), the simulation results become incorrect because the high frequency damages the GaN radar dish. When the acoustic wave frequency is too low (below 0.2 kHz), the GaN radar dish shows almost no change and cannot achieve the desired scanning effect.

[0054] Figure 7 and Figure 8The results were obtained using Comsol software simulation. As can be seen from the two figures, the gallium nitride micromechanical radar dish of the present invention underwent different degrees of deformation under the action of 100KHz and 800KHz sound waves. Under the 100KHz sound wave, the structure of the gallium nitride micromechanical radar dish of the array tilted around the center point of the array. Under the 800KHz sound wave, the tilt angle of the structure of the gallium nitride micromechanical radar dish of the array was greater, and the shape of the radar dish changed from a disc shape to a pot shape.

[0055] Since all members of the nitride family possess properties such as wide direct band gaps, strong atomic bonds, high thermal conductivity, good chemical stability (almost unaffected by any acid corrosion), and strong radiation resistance, their mechanical properties are the same. Therefore, simulation data and simulation diagrams of micromechanical radar dishes for other nitride members have been omitted.

[0056] Therefore, this invention utilizes this characteristic to enable the nitride micromechanical radar pan structure to rapidly and freely change the detection direction. It is simple to operate, highly responsive, and easy to control, allowing the radar to scan and capture targets more quickly and accurately.

[0057] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A nitride micromechanical radar dish, characterized in that: The device includes a silicon substrate and a nitride layer disposed on top of the silicon substrate. The center of the nitride layer is supported by the top of the silicon substrate, and the rest is suspended. The radar dish can change its sweeping direction by means of sound wave frequency. The silicon substrate is a silicon-based material. The nitride is one of gallium nitride, aluminum nitride, and silicon nitride.

2. The nitride micromechanical radar dish according to claim 1, characterized in that: The thickness of the nitride layer is 200–500 nm.

3. The nitride micromechanical radar dish according to claim 1, characterized in that: The radar dish has a diameter of 40–60 μm and a thickness of 200–500 nm.

4. A method for preparing a nitride micromechanical radar dish, characterized in that, Includes the following steps: Step 1: A nitride layer is epitaxially grown on a silicon substrate to obtain a nitride epitaxial wafer; Step 2: Spin-coat photoresist onto the upper surface of the nitride epitaxial wafer to obtain a photoresist layer; Step 3: Define the radar dish as described in any one of claims 1 to 3 on the spin-coated photoresist layer using optical lithography technology; Step 4: Use ICP etching technology to etch the nitride layer downwards until the upper surface of the silicon substrate, thereby transferring the defined pattern structure downwards into the nitride layer; Step 5: Remove residual photoresist with acetone solution; Step six: Utilizing isotropy, wet etching technology is used to etch the silicon substrate layer, forming silicon pillars supporting the disk in the silicon substrate layer, thereby obtaining a completely suspended micromechanical structure.

5. The method for preparing a nitride micromechanical radar dish according to claim 4, characterized in that, The specific method of step two is as follows: after the nitride epitaxial wafer is ultrasonically cleaned once with acetone, anhydrous ethanol and deionized water, it is dried with a nitrogen gun, and photoresist is spin-coated on the upper surface of the nitride layer at a speed of 3000 to 4500 rpm for 40 to 50 seconds, with a photoresist thickness of 1 to 1.5 micrometers.

6. The method for preparing a nitride micromechanical radar dish according to claim 4, characterized in that, The etching solution in step six, using wet etching technology, is a mixed solution of hydrofluoric acid and dilute nitric acid in a ratio of 1:1 to 1:10.

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