A resonant InGaN quantum well integrated micro-opto-mechanical accelerometer device and a preparation method thereof

Abstract

The application discloses a resonant InGaN quantum well integrated micro-optical-mechanical-electrical accelerometer device and a preparation method thereof. A silicon-based nitride wafer is used as a carrier, and a structure from bottom to top is sequentially arranged as a silicon substrate layer, an aluminum nitride layer, a u-shaped gallium nitride layer, an n-type gallium nitride layer, an InGaN quantum well layer and a p-type gallium nitride layer. A p-type electrode is arranged above the p-type gallium nitride layer, and an n-type electrode is arranged above the edge of the n-type gallium nitride layer. In the application, two resonant beam detectors with different shapes and a crescent-shaped LED are prepared on the nitride material on the silicon substrate by using a photoetching etching process and an ICP etching process. Light emitted by the crescent-shaped LED is converged to the high-sensitivity resonant beam, under the acceleration load, the photoelectric current received by the resonant beam periodically changes, and the corresponding acceleration size can be deduced through the periodic resonance frequency, so that the detection device with the high-sensitivity long straight resonant beam is made to oscillate, a periodically changed current is generated, and the acceleration size is sensed.

Description

Technical Field

[0001] The present invention belongs to the fields of quantum electronics and optomechanical technology, and in particular relates to a resonant InGaN quantum well integrated micro-optomechanical accelerometer device and a preparation method thereof. Background Art

[0002] Currently, most semiconductor materials have relatively simple functions, and are basically aimed at realizing a single function. Most LEDs on the market have relatively simple functions and cannot perform the above two actions at the same time. Therefore, in the present invention, the light-emitting function of the InGaN quantum well LED is integrated with the photoelectric detection function of the resonant beam detector, and the light source and detection components are combined to prepare a resonant InGaN quantum well integrated micro-photoelectromechanical accelerometer system. The present invention prepares two LEDs and detectors of different shapes. In order to meet people's requirements for miniaturization, low cost and high sensitivity of acceleration sensors, the research on optical accelerometers has become a new hotspot. Optical acceleration sensors have the dual advantages of optical measurement and silicon-based micromachining. Based on optical principles, the displacement of the sensitive mass block under the action of acceleration will cause changes in optical properties such as interference and diffraction, and acceleration measurement is achieved by monitoring optical indicators. Since optical means have high displacement measurement accuracy and are immune to circuit noise, optical accelerometers have extremely high sensitivity and resolution.

[0003] Therefore, the following technical problems exist:

[0004] 1. When designing the overall beam structure of the LED, it is necessary to consider whether the length and width of the resonant beam can produce obvious oscillations, whether the length of the beam of the light-emitting device can illuminate the resonant beam of the detection device, and the feasibility of actual processing and application.

[0005] 2. Wet etching is a very important technique after device processing. When mixing hydrofluoric acid and dilute nitric acid to wet-etch silicon, make sure the beam is suspended.

[0006] 3. When designing the circuit connection of the device, it is necessary to ensure that the wiring position and wiring will not cause any interference with the normal operation of the device.

[0007] 4. The spacing between electrodes and the width of electrodes should be reasonable to prevent short circuits. Summary of the Invention

[0008] To solve the above problems, the application discloses a resonant InGaN quantum well integrated micro-opto-mechanical accelerometer device and a preparation method thereof, two LEDs and a detector with different shapes are prepared, in order to meet the requirements of miniaturization, low cost and high sensitivity of an acceleration sensor, research on an optical accelerometer has become a new hotspot.

[0009] The resonant InGaN quantum well micro-opto-mechanical integrated accelerometer device comprises an LED beam light emitting device and an LED beam detecting device; wherein the LED beam detecting device comprises an oblong beam and two discs connected to the oblong beam, and the LED beam light emitting device comprises a crescent beam and two discs connected to the crescent beam; the length of the oblong beam is greater than the length of the crescent beam; the left and right ends of the crescent beam and the oblong beam are connected to the middle parts of the two discs adjacent to the two sides, respectively; the disc on the left side is a p-type electrode, and the disc on the right side is an n-type electrode.

[0010] Further, the length ratio of the oblong beam to the crescent beam is 1.8:1.

[0011] The preparation method of the resonant InGaN quantum well micro-opto-mechanical integrated accelerometer device comprises the following steps: a silicon-based nitride wafer is used as a carrier, and the structure of the device is sequentially arranged from bottom to top as a silicon substrate layer, an aluminum nitride layer, a u-shaped gallium nitride layer, an n-type gallium nitride layer, an InGaN quantum well layer and a p-type gallium nitride layer; a p-type electrode is arranged above the p-type gallium nitride layer, and an n-type electrode is arranged above the edge of the n-type gallium nitride layer; the structure above the exposed silicon substrate layer is etched, a stepped mesa is etched at the edge of the n-type gallium nitride layer, the lower mesa of the stepped mesa is exposed, the n-type electrode is deposited on the lower mesa, and the n-type gallium nitride layer and the n-type electrode are exposed in a circular ring shape on the surface.

[0012] The specific steps are as follows:

[0013] First step: spin a layer of photoresist on the surface of the p-type gallium nitride layer of the silicon-based gallium nitride wafer, then define two pairs of discs on the spin-coated photoresist by using optical lithography technology, and the two pairs of discs are connected by a long and thin oblong beam and a crescent beam, respectively,

[0014] Step 2: Depositing a 300nm thick layer of nickel on the upper surface of the pattern defined in Step 1 by electron beam evaporation technology; then placing the wafer in an acetone solution and ultrasonically treating it; after treatment, the wafer is sequentially cleaned in ultrapure water, anhydrous ethanol, and then rinsed again in ultrapure water; finally, removing the remaining photoresist, thereby obtaining a nickel mask pattern;

[0015] Step 3: Using ICP etching technology, the pattern defined in the first step is successfully transferred to the n-type GaN layer on the silicon-based nitride wafer at the edge of the silicon-based nitride wafer, resulting in the desired LED single resonant beam structures, namely a rectangular beam and a crescent-shaped beam.

[0016] Step 4: After completing the third step, use dilute nitric acid to remove the metallic nickel deposited on the surface of the wafer, and then immediately put the wafer into ultrapure water for cleaning;

[0017] Step 5: Spin-coat photoresist on the surface of each single resonant beam structure LED to prevent the beam structure from being etched away during the etching process, thus playing a protective role.

[0018] Step 6: Using electron beam evaporation technology, a 300nm thick layer of nickel is deposited on the defined pattern. Afterwards, the epitaxial wafer is sequentially cleaned in acetone solution, anhydrous ethanol, and ultrapure water. Finally, the remaining photoresist is removed, thus obtaining a nickel mask pattern.

[0019] Step 7: Using ICP etching technology, the pattern obtained in the sixth step is etched from the n-type gallium nitride layer down to the surface of the silicon substrate layer, thereby transferring the pattern to the silicon substrate layer, and finally cleaning the remaining photoresist;

[0020] Step 8: Using electron beam evaporation technology, a positive electrode is deposited on the p-type electrode pattern on the p-type gallium nitride layer, and a negative electrode is deposited on the n-type electrode pattern on the n-type gallium nitride layer. The remaining photoresist is then cleaned to obtain the p-type and n-type electrodes, both of which are disc-shaped.

[0021] Step 9: Mix hydrofluoric acid and dilute nitric acid in a ratio of 1:10 and perform wet silicon etching to carve the silicon substrate layer into two silicon pillars and a bottom surface for supporting the structure, forming two suspended LED single beam structures.

[0022] Furthermore, the p-type electrode and the n-type electrode are both formed by Au / Ni evaporation.

[0023] Furthermore, the p-type electrode is deposited on the upper surface of the p-type gallium nitride layer.

[0024] In the present invention, when the LED with a crescent-shaped beam emits light, the light will converge on the highly sensitive resonant beam. Under the acceleration load, the photocurrent received by the resonant beam will change periodically. Therefore, the corresponding acceleration magnitude can be inferred from the periodic resonant frequency, causing the detection device with a long straight resonant beam with high sensitivity to oscillate, generating a periodically changing current and sensing the magnitude of the acceleration.

[0025] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0026] 1. The present invention integrates the two functions of luminescence and detection into the same chip, without the need for other chips. It has high practicality and simple structure. It can directly receive electrical signals and infer the corresponding acceleration size. It has high sensitivity and good conversion effect.

[0027] 2. The short crescent-shaped beam design facilitates the convergence of light onto the resonant beam that performs the detection function, effectively improving detection accuracy and sensitivity. The slender shape of the highly sensitive long straight resonant beam is designed to produce a more pronounced oscillation effect and to receive light from the crescent-shaped LED light-emitting device, obtaining a periodic resonant frequency and sensing the magnitude of acceleration. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 : Schematic diagram of the structure of a resonant InGaN quantum well micro-opto-electromechanical integrated accelerometer (the upper part is the front view, the lower part is the top view).

[0029] Figure 2 、 One Process flow chart of a single LED in a resonant InGaN quantum well micro-opto-electromechanical integrated accelerometer device.

[0030] Figure 3 、 One Light intensity diagram of a resonant InGaN quantum well micro-opto-electromechanical integrated accelerometer device based on COMSOL simulation software;

[0031] Figure 4 :Far-field diagram of a resonant InGaN quantum well micro-opto-electromechanical integrated accelerometer device based on COMSOL simulation software.

[0032] The figure marks are: 1-silicon substrate layer, 2-aluminum nitride layer, 3-u-type gallium nitride layer, 4-n-type gallium nitride layer, 5-InGaN quantum well layer, 6-p-type gallium nitride layer, 7-p-type electrode, 8-n-type electrode; 9-rectangular beam; 10-crescent-shaped beam. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inward" and "outward" refer to directions toward or away from the geometric center of a particular component, respectively.

[0034] like Figure 1 As shown, a resonant InGaN quantum well micro-opto-electromechanical integrated accelerometer device of this embodiment includes an LED beam light-emitting device and an LED beam detection device; wherein the LED beam detection device includes a rectangular beam 9 and two disks connected thereto, and the LED beam light-emitting device is a crescent-shaped beam 10 and two disks connected thereto; wherein the length of the rectangular beam 9 is greater than the length of the crescent-shaped beam 10, wherein the left and right ends of the crescent-shaped beam 10 and the rectangular beam 9 are respectively connected to the middle of the disks adjacent to them on both sides, wherein the disk on the left is a p-type electrode 7, and the disk on the right is an n-type electrode 8.

[0035] The length ratio of the rectangular beam 9 to the crescent-shaped beam 10 is 1.8:1.

[0036] The structure above the silicon substrate layer, exposed in the top view, is completely etched away, leaving only the disks and the portion below the beam connecting them. The exposed structure consists of two parts: one is two identical disks and a rectangular resonant beam connected to them, and the other is two identical disks and a shorter, crescent-shaped beam connected to them.

[0037] The exposed silicon substrate structure is completely etched away, leaving only the disk and the portion below the beam connecting it. The exposed structure consists of two parts: one consisting of two disks and a rectangular resonant beam, and the other consisting of two disks and a shorter, crescent-shaped beam. The highly sensitive straight resonant beam is 6μm wide and 400μm long in the side view; the shorter crescent-shaped beam is 20 to 30μm wide and 250μm long in the side view. The p-type electrode covering the p-type gallium nitride layer and the n-type electrode covering the n-type gallium nitride layer both have a radius of 30μm, and the thickness of both electrodes is 120nm.

[0038] Taking the preparation of a disk with a radius of 30 μm, a highly sensitive rectangular resonant beam with a width of 6 μm and a length of 400 μm in the side view, and a shorter crescent-shaped beam with a width of 20 to 30 μm and a length of 250 μm in the side view as an example, the preparation process is as follows:

[0039] First step: The silicon-based nitride wafer is cleaned with acetone solution, anhydrous ethanol and ultrapure water for five minutes by ultrasonic cleaning, and then the silicon substrate gallium nitride wafer is blown dry with nitrogen. Then the spin coater is used to spin the photoresist AZ-5214 on the surface of the silicon-based nitride wafer at a speed of 4000 rpm for 40 seconds, and the thickness of the photoresist is 1.5 μm. Then, an optical lithography technology is used to define a long and thin single-beam two-disc LED pattern and a shorter crescent-shaped single-beam two-disc LED pattern on the spin-coated photoresist layer. The model of the used photoetching machine is MA6.

[0040] Second step: A 300 nm thick layer of metal nickel is deposited on the p-type gallium nitride layer by electron beam evaporation technology. Then it is cleaned and the remaining photoresist is removed to form a mask pattern of nickel.

[0041] Third step: By ICP etching technology, the pattern defined in the first step is successfully transferred to the n-type gallium nitride on the silicon-based nitride wafer by etching down to the middle of the n-type gallium nitride layer, and the desired LED single-beam structure is obtained.

[0042] After the third step is completed, the deposited metal nickel on the surface is removed with dilute nitric acid, and then the wafer is immediately placed in ultrapure water for cleaning.

[0043] Fourth step: The spin coater is used to spin the photoresist AZ-5214 on the surface of the single-beam structure at a speed of 4000 rpm for 40 seconds, and the thickness of the photoresist is 1.5 μm.

[0044] Fifth step: A 300 nm thick layer of metal nickel is deposited on the n-type gallium nitride layer by electron beam evaporation technology. Then it is cleaned and the remaining photoresist is removed.

[0045] Sixth step: The pattern obtained in the fifth step is etched down from the n-type gallium nitride layer to the surface of the silicon substrate layer by ICP etching technology, so that the pattern is transferred to the silicon substrate layer, and finally the remaining photoresist is cleaned.

[0046] Seventh step: The positive and negative electrodes are evaporated on the p-type electrode area and n-type electrode area patterns on the p-type gallium nitride layer and n-type gallium nitride layer respectively by electron beam evaporation technology, and then the remaining photoresist is cleaned, so that the p-type electrode and n-type electrode are obtained.

[0047] Eighth step: Hydrofluoric acid and dilute nitric acid are mixed at a ratio of one to ten to etch silicon by wet etching, and the silicon substrate layer is etched into two silicon pillars and a bottom surface for supporting the structure, forming two suspended LED single-beam structures. The HF and HNO3 mixture is used as etching gas for 1 minute, and then the remaining photoresist is removed.

[0048] As Figure 3 and Figure 4 shown, the light intensity is mainly concentrated in the concave surface of the crescent-shaped resonant beam, and is gathered inward, so that the use of long and straight resonant beam as the receiving end can maximize the possibility of receiving the sending end, can improve the detection efficiency, better and more accurately perceive the size of acceleration.

Claims

1. A method for preparing a resonant InGaN quantum well micro-opto-electromechanical integrated accelerometer device, characterized in that: The invention comprises an LED beam light-emitting device and an LED beam detection device; wherein the LED beam detection device comprises a rectangular beam (9) and two circular disks connected thereto, and the LED beam light-emitting device comprises a crescent-shaped beam (10) and two circular disks connected thereto; wherein the length of the rectangular beam (9) is greater than the length of the crescent-shaped beam (10), wherein the left and right ends of the crescent-shaped beam (10) and the rectangular beam (9) are respectively connected to the middle of the circular disks adjacent to them on both sides, wherein the circular disk on the left is a p-type electrode (7), and the circular disk on the right is an n-type electrode (8); The length ratio of the rectangular beam (9) to the crescent-shaped beam (10) is 1.8:1; the device uses a silicon-based nitride wafer as a carrier, and its structure from bottom to top is a silicon substrate layer (1), an aluminum nitride layer (2), a u-type gallium nitride layer (3), an n-type gallium nitride layer (4), an InGaN quantum well layer (5), and a p-type gallium nitride layer (6); a p-type electrode (7) is provided above the p-type gallium nitride layer (6), and an n-type electrode (8) is provided above the edge of the n-type gallium nitride layer (4); wherein the structure above the exposed silicon substrate layer (1) is completely etched away, a stepped table is etched at the edge of the n-type gallium nitride layer (4), the lower table of the stepped table is exposed, the n-type electrode (8) is deposited on the lower table, and the n-type gallium nitride layer (4) and the n-type electrode (8) are exposed on the surface in a circular shape; The specific steps are as follows: The first step is to spin-coat a layer of photoresist on the surface of the p-type gallium nitride layer (6) of the silicon-based gallium nitride wafer. Then, optical lithography is used to define two pairs of disks on the spin-coated photoresist, each of which is connected by a long, thin, straight rectangular beam (9) and a crescent-shaped beam (10). Step 2: Depositing a 300nm thick layer of nickel on the upper surface of the pattern defined in Step 1 by electron beam evaporation technology; then placing the wafer in an acetone solution and ultrasonically treating it; after treatment, the wafer is sequentially cleaned in ultrapure water, anhydrous ethanol, and then rinsed again in ultrapure water; finally, removing the remaining photoresist, thereby obtaining a nickel mask pattern; Step 3: At the edge of the silicon-based nitride wafer, etching is performed downward to the middle of the n-type gallium nitride layer (4) by using the ICP etching technology, thereby successfully transferring the pattern defined in the first step to the n-type gallium nitride layer (4) of the silicon-based nitride wafer, thereby obtaining the desired LED single resonant beam structure, which is a rectangular beam (9) and a crescent-shaped beam (10); Step 4: After completing the third step, use dilute nitric acid to remove the metallic nickel deposited on the surface of the wafer, and then immediately put the wafer into ultrapure water for cleaning; Step 5: Spin-coat photoresist on the surface of each single resonant beam structure LED to prevent the beam structure from being etched away during the etching process, thus playing a protective role. Step 6: Using electron beam evaporation technology, a 300nm thick layer of nickel is deposited on the defined pattern. After that, the epitaxial wafer is sequentially placed in acetone solution, anhydrous ethanol, and ultrapure water for cleaning. Finally, the remaining photoresist is removed, thus obtaining a nickel mask pattern. Step 7: Using ICP etching technology, the pattern obtained in the sixth step is etched downward from the n-type gallium nitride layer (4) to the surface of the silicon substrate layer (1), thereby transferring the pattern to the silicon substrate layer (1), and finally cleaning the remaining photoresist; Step 8: Using electron beam evaporation technology, a positive electrode is evaporated on the p-type electrode (7) region pattern on the p-type gallium nitride layer (6), and a negative electrode is evaporated on the n-type electrode (8) region pattern on the n-type gallium nitride layer (4). Then, the residual photoresist is cleaned to obtain a p-type electrode (7) and an n-type electrode (8), both of which are disc-shaped. Step 9: Mix hydrofluoric acid and dilute nitric acid in a ratio of 1:10 and perform wet silicon etching to carve the silicon substrate layer into two silicon pillars and a bottom surface for supporting the structure, forming two suspended LED single beam structures.

2. The method for preparing a resonant InGaN quantum well micro-opto-electromechanical integrated accelerometer device according to claim 1, characterized in that: The p-type electrode (7) and the n-type electrode (8) are both formed by Au / Ni vapor deposition.

3. The method for preparing a resonant InGaN quantum well micro-opto-electromechanical integrated accelerometer device according to claim 2, characterized in that: The p-type electrode (7) is deposited on the upper surface of the p-type gallium nitride layer (6).

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