Indium gallium nitride difference frequency accelerometer based on quantum confined stark effect and preparation method thereof

Abstract

The application discloses a quantum limited Stark effect indium gallium nitride frequency difference accelerometer, a beam laser diode takes a silicon base nitride epitaxial sheet as a carrier, and comprises a silicon substrate layer, an aluminum nitride buffer layer, an n-type gallium nitride layer, a quantum well layer, a p-type gallium nitride layer and a SiO2 layer which are sequentially arranged from bottom to top, a p-type electrode arranged on the p-type gallium nitride layer and an n-type electrode arranged at the edge of the n-type gallium nitride layer. The nitride material on the silicon substrate utilizes a photoetching and ICP etching process to prepare a micro beam stress sensitive area LD light emission, and laser LD is obtained at the stress sensitive area of the beam after electrification. Under the electrification condition, the frequency wavelength of the laser will change due to the quantum limited Stark effect before and after acceleration load, and the size of the acceleration can be perceived through the frequency difference.

Description

Technical Field

[0001] This invention belongs to the fields of electronics and opto-mechatronics, specifically relating to an indium gallium nitride difference frequency accelerometer with quantum-confined Stark effect and its fabrication method. Background Technology

[0002] Background Technology: Accelerometers are crucial components of inertial navigation systems. Optical accelerometers are a relatively new type of accelerometer, offering advantages such as miniaturization, low cost, high sensitivity, resistance to electromagnetic interference, and shock resistance. However, current optical accelerometers utilize passive materials such as Si and SiN, meaning the sensing components themselves do not emit light, necessitating the integration of an external light source, which limits high-density optoelectronic integration. The existing technology faces the following challenges:

[0003] I. The design of the beam plus mass block for the overall accelerometer must take into account the influence of the beam length on light emission, the realization of the quantum-confined Stark effect, and the feasibility of implementation in actual manufacturing.

[0004] 2. When wiring components, the location of the wiring should not affect the normal operation of the components.

[0005] III. The influence of device slit width and slit spacing on device sensitivity. Summary of the Invention

[0006] To achieve the above objectives, this invention discloses a quantum-confined Stark effect indium gallium nitride differential frequency accelerometer, which uses a silicon-based nitride epitaxial wafer as a carrier and includes, from bottom to top, a silicon substrate layer, an aluminum nitride buffer layer, an n-type gallium nitride layer, a quantum well layer, a p-type gallium nitride layer, and a SiO2 layer, a p-type electrode disposed on the p-type gallium nitride layer, and an n-type electrode disposed on the edge of the n-type gallium nitride layer. The silicon substrate layer (1) is completely etched away around the disk-shaped mass block and the cantilever beam to present the shape of the beam and the mass block. The n-type electrode is disposed on the exposed n-type gallium nitride layer.

[0007] Furthermore, the accelerometer of the present invention includes a cantilever beam with a mass block at the edge.

[0008] Furthermore, in the accelerometer of the present invention, when powered on, the frequency wavelength of the laser changes before and after the acceleration load due to the quantum confinement Stark effect, and the magnitude of the acceleration is sensed through the difference frequency.

[0009] This invention utilizes optical lithography and ICP etching processes to fabricate a cantilever beam accelerometer. The designed process steps include etching the shape of the template to obtain a cantilever beam with smooth edges supported by a single-sided column and consisting of a disk-shaped mass block.

[0010] The present invention provides a method for fabricating an indium gallium nitride quantum well opto-electro-mechanical microcavity accelerometer based on the quantum confinement Stark effect, comprising the following steps:

[0011] Step 1: Spin-coat photoresist on the p-type gallium nitride (5) surface of the silicon-based gallium nitride epitaxial wafer, and then use optical lithography to define a pattern on the spin-coated photoresist layer consisting of a rectangle connecting a cantilever beam and a disk;

[0012] Step 2: Electron beam evaporation is used to deposit 300-500nm thick nickel on the defined pattern surface. Then, the epitaxial wafer is placed in an acetone solution for ultrasonic treatment. After that, the epitaxial wafer is cleaned in ultrapure water, and then cleaned in anhydrous ethanol and ultrapure water in sequence. Finally, the residual photoresist is removed to obtain a nickel mask pattern.

[0013] Step 3: ICP etching technology is used to etch down 2μm-2.5μm to the middle of the n-type gallium nitride layer (3), thereby transferring the pattern defined in the first step to the n-type gallium nitride layer (3) of the silicon-based nitride epitaxial wafer, and obtaining the accelerometer height and low shape structure as well as the prototype of the cantilever beam and mass block;

[0014] Step 4: Remove metallic nickel with dilute nitric acid, then immediately rinse thoroughly with ultrapure water;

[0015] Step 5: Deposit a SiO2 layer on the exposed p-type gallium nitride layer of the accelerometer, but do not deposit a SiO2 layer in the two regions on the cantilever beam that are 1 / 4 of the length from both ends.

[0016] Step 6: Spin-coat photoresist onto the accelerometer cantilever beam and the disk mass block to ensure that the beam structure and mass block will not be etched away during the etching process, thus providing protection.

[0017] Step 7: Electron beam evaporation is used to deposit a 300-500nm thick layer of metallic nickel on the defined pattern surface. Then, the epitaxial wafer is placed in an acetone solution for ultrasonic cleaning, followed by cleaning in anhydrous ethanol and ultrapure water. Finally, the residual photoresist is removed to obtain a mask pattern of nickel.

[0018] Step 8: Using ICP etching technology, the pattern is etched downwards until the center is hollowed out, and finally the residual photoresist is cleaned.

[0019] Step 9: Electron beam evaporation is used to deposit a positive electrode on the surface of the p-type electrode pattern and a negative electrode on the surface of the n-type electrode pattern, so that positive and negative electrodes are deposited on the p-type gallium nitride layer (5) and the n-type gallium nitride layer (3) respectively. Finally, the residual photoresist is removed to obtain the p-type electrode (7) and the n-type electrode (8).

[0020] Step 10: Wet etching of silicon is performed using a mixture of hydrofluoric acid and dilute nitric acid until the bottom of the silicon substrate layer (1) is reached, forming a cantilever beam plus mass block structure.

[0021] Furthermore, in the method of the present invention, both the positive electrode and the negative electrode are Au / Ni vapor-deposited.

[0022] Compared to existing technologies, the advantages of this invention are as follows: This invention uses a single epitaxial wafer, eliminating the need to grow different materials, resulting in a simple structure, small size, and easy integration. Compared to current optical accelerometers made with passive materials such as Si and SiN, it offers advantages in high resolution, high integration, and ultra-high sensitivity. Furthermore, its difference frequency transmission characteristics provide extremely high anti-interference capability. This invention provides a pathway for high-resolution, high-sensitivity, and low-mode-volume optomechanical sensors with dual functions of emission and sensing. Attached Figure Description

[0023] Figure 1 Side view of an indium gallium nitrogen difference frequency accelerometer based on the quantum-confined Stark effect;

[0024] Figure 2 Top view of an indium gallium nitrogen difference frequency accelerometer based on the quantum-confined Stark effect;

[0025] Figure 3 Flowchart of the process for an indium gallium nitride differential frequency accelerometer based on the quantum-confined Stark effect.

[0026] The diagram shows: 1. Silicon substrate layer; 2. Aluminum nitride buffer layer; 3. n-type gallium nitride layer; 4. Quantum well layer; 5. p-type gallium nitride layer; 6. SiO2 layer; 7. p-type electrode; and 8. n-type electrode. Detailed Implementation

[0027] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0028] Example: Figures 1 to 3 As shown:

[0029] This invention uses a silicon-based nitride epitaxial wafer as a carrier. From bottom to top, the wafer comprises a silicon substrate, an aluminum nitride buffer layer, an n-type gallium nitride layer, a quantum well layer, a p-type gallium nitride layer, a SiO2 layer, a p-type electrode disposed on the p-type gallium nitride layer, and an n-type electrode disposed at the edge of the n-type gallium nitride layer. The entire silicon substrate is etched away, leaving only the cantilever beam and mass block portion. The n-type electrodes are disposed on the exposed n-type gallium nitride layer. The accelerometer incorporates a cantilever beam with a mass block. The beam width is 20 mm. The p-type electrode, covering the p-type gallium nitride layer, consists of a beam and a square electrode. The beam is 100 mm long and 10 mm wide, the disk diameter is 50 mm, and the electrode thickness is 120 nm.

[0030] The method for fabricating an indium gallium nitride quantum well opto-electro-mechanical microcavity accelerometer based on the quantum confinement Stark effect of the present invention is as follows:

[0031] Step 1: Clean the purchased commercial silicon substrate gallium nitride epitaxial wafer with acetone, anhydrous ethanol and ultrapure water by ultrasonication (5 min) in sequence, and then dry it with nitrogen gas; use a spin coater to spin coat the photoresist AZ-5214 on the front side of the epitaxial wafer (the upper surface of the p-type nitride layer (5)) at a speed of 4000 rpm for 40 seconds (the photoresist thickness is 1.5 micrometers).

[0032] Optical lithography is used to define a rectangular pattern connecting the cantilever beam and the disk on the spin-coated photoresist layer. The lithography machine model is MA6.

[0033] Step 2: Electron beam evaporation is used to deposit 700 nm of metallic nickel on the surface of the p-type gallium nitride layer, and then the residual photoresist is removed.

[0034] Step 3: ICP etching technology is used to etch the nitride layer down to the n-type gallium nitride layer (3), thereby transferring the pattern defined in the first step to the n-type gallium nitride layer (3) of the silicon-based nitride epitaxial wafer, and obtaining the accelerometer height and low shape structure and the prototype of the cantilever beam and mass block;

[0035] Then the epitaxial wafer was placed in a dilute nitric acid solution to remove residual metallic nickel, and then rinsed in anhydrous ethanol and ultrapure water in sequence.

[0036] Step 4: Deposit a SiO2 layer on the exposed p-type gallium nitride layer of the accelerometer, but do not deposit a SiO2 layer in the two regions on the cantilever beam that are 1 / 4 of the length from both ends.

[0037] Step 5: Use a spin coater to spin coat the photoresist AZ-5214 on the front side of the epitaxial wafer (the cantilever beam structure surface and the disk mass block surface) at a speed of 4000 rpm for 40 seconds (photoresist thickness is 1.5 micrometers).

[0038] Step 6: Electron beam evaporation is used to deposit 700 nm of metallic nickel on the surface of the n-type gallium nitride layer (3), and then the residual photoresist is removed.

[0039] Step 7: Using ICP etching technology, the pattern is etched downwards into the n-type gallium nitride layer (3) until the surface of the Si layer (1), thereby transferring the pattern onto the Si layer (1);

[0040] Then the epitaxial wafer was placed in a dilute nitric acid solution to remove residual metallic nickel, and then rinsed in anhydrous ethanol and ultrapure water in sequence.

[0041] Step 8: Wet etching of silicon is performed using a mixture of hydrofluoric acid and dilute nitric acid until the bottom of the silicon substrate (1) is reached, so that the cantilever beam structure and the disk mass block are fully suspended. The etching gas is a mixture of HF and HNO3, and the etching time is 1 minute. Finally, the residual photoresist is removed.

[0042] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A method for fabricating an indium gallium nitride difference frequency accelerometer with quantum-confined Stark effect, characterized in that, The accelerometer uses a silicon-based nitride epitaxial wafer as a carrier and includes, from bottom to top, a silicon substrate layer (1), an aluminum nitride buffer layer (2), an n-type gallium nitride layer (3), a quantum well layer (4), a p-type gallium nitride layer (5), and a SiO2 layer (6). A p-type electrode (7) is disposed on the p-type gallium nitride layer (5), and an n-type electrode (8) is disposed at the edge of the n-type gallium nitride layer (3). The silicon substrate layer (1) is completely etched away at the cantilever beam and mass block locations, fully suspending the cantilever beam and mass block. A SiO2 layer (6) is deposited outside two regions on the cantilever beam at a distance of 1 / 4 of the length from both ends, while a p-type electrode (7) is deposited on the upper surface of the SiO2 layer (6) on the middle beam and on the disk mass block; The n-type electrode (8) is disposed at the edge of the n-type gallium nitride layer (3) and is a square electrode; the p-type electrode (7) is disposed on the p-type gallium nitride layer (5); When powered on, only two areas on the cantilever beam, one-quarter of the way from both ends, will emit laser LDs; Includes the following steps: Step 1, First step: Spin-coat photoresist on the p-type gallium nitride layer (5) of the silicon-based gallium nitride epitaxial wafer, and then use optical lithography to define a rectangular connecting cantilever beam and disk pattern on the spin-coated photoresist layer; Step 2: Electron beam evaporation is used to deposit a 300-500 nm thick layer of metallic nickel on the defined pattern surface. Then, the epitaxial wafer is placed in an acetone solution for ultrasonic treatment. After that, the epitaxial wafer is cleaned in ultrapure water, and then cleaned in anhydrous ethanol and ultrapure water in sequence. Finally, the residual photoresist is removed to obtain a nickel mask pattern. Step 3: ICP etching technology is used to etch down 2 mm - 2.5 mm to the n-type gallium nitride layer (3), thereby transferring the pattern defined in the first step to the n-type gallium nitride layer (3) of the silicon-based nitride epitaxial wafer, to obtain the accelerometer height and low shape structure and the prototype of the cantilever beam and mass block; Step 4: Remove metallic nickel with dilute nitric acid, then immediately rinse thoroughly with ultrapure water; Step 5: Deposit SiO2 layers on the middle beam and the disk mass block of the accelerometer, but do not deposit SiO2 layers on the two areas on the cantilever beam that are 1 / 4 of the length from both ends. Step 6: Spin-coat photoresist onto the beam and disk-shaped mass block of the accelerometer to ensure that the beam structure and mass block are not etched away during the etching process. Step 7: Electron beam evaporation is used to deposit a 300-500 nm thick layer of metallic nickel on the defined pattern surface. Then, the epitaxial wafer is placed in an acetone solution for ultrasonic cleaning, followed by cleaning in anhydrous ethanol and ultrapure water. Finally, the residual photoresist is removed to obtain a mask pattern of nickel. Step 8: Using ICP etching technology, the pattern is etched downwards until the center is hollowed out, and finally the residual photoresist is cleaned. Step 9: Electron beam evaporation is used to deposit a positive electrode on the surface of the p-type electrode pattern and a negative electrode on the surface of the n-type electrode pattern, so that positive and negative electrodes are deposited on the p-type gallium nitride layer (5) and the n-type gallium nitride layer (3) respectively. Finally, the residual photoresist is removed to obtain the p-type electrode (7) and the n-type electrode (8). Step 10: Wet etching of silicon is performed using a mixture of hydrofluoric acid and dilute nitric acid until the bottom of the silicon substrate (1) is reached, so that silicon pillars and bottom surfaces supporting this structure are formed in the silicon substrate (1), forming a suspended beam structure.

2. The method for fabricating a quantum-confined Stark effect indium gallium nitride difference frequency accelerometer according to claim 1, characterized in that, The cantilever beam carries a mass block, and two regions on the cantilever beam with a distance of 1 / 4 of its length from both ends are not coated with SiO2 layers. Before and after acceleration load, due to the quantum confinement Stark effect, the frequency wavelength of the laser will change, and the magnitude of acceleration can be sensed through the difference frequency.

3. The method for fabricating a quantum-confined Stark effect indium gallium nitride difference frequency accelerometer according to claim 1, characterized in that, Both the positive and negative electrodes are vapor-deposited Au / Ni.

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