A bidirectional drive FP filter device structure and its preparation method

Abstract

The present invention relates to the field of spectral technology and specifically provides a bidirectionally driven F-P filter device structure and a preparation method thereof, comprising: a first static electrode and a second static electrode, a movable electrode located between the first static electrode and the second static electrode, a first insulating support member provided between the movable electrode and the first static electrode, a second insulating support member provided between the movable electrode and the second static electrode, a first dielectric layer reflector provided on the movable electrode, and a second dielectric layer reflector provided on the second static electrode, the first static electrode having a light through hole, and the light through hole sharing an optical axis with the first dielectric layer reflector and the second dielectric layer reflector. By utilizing the bidirectional drive structure, a bidirectional drive range can be achieved, thereby improving the stability and robustness of the device.

Description

Technical Field

[0001] The present invention relates to the field of optical spectrum technology, and specifically provides a bidirectional driving FP filter device structure and a preparation method thereof. Background Art

[0002] Spectroscopic detection equipment is currently widely used in various fields, including medicine, agriculture, scientific research, and aerospace, as a non-contact, real-time, in-situ, and multi-dimensional method for detecting the composition of substances. The structural principle of a spectrometer is to interpret spectra using dispersive elements, narrowband filters, or computational spectroscopy. With the advancement of technology, spectrometers are currently developing towards high precision, wide spectral bandwidth, small size, and low power consumption. The design and fabrication of high-performance core spectroscopic components are of paramount importance in spectrometer development.

[0003] Currently, different spectral spectrometers have different advantages. Spectrometers implemented with dispersive elements primarily utilize reflection-transmission gratings and waveguides to disperse incident light, thereby achieving spectral separation and detection. Their advantages lie in their mature technology and simple structure, but due to the limitations of their principles, they are currently unable to miniaturize the device. Computational spectroscopy, as an emerging spectral spectrometry method, can achieve spectral analysis within a microscopic size, but its disadvantages lie in the large amount of post-processing calculations and the immaturity of the technology. Narrowband filtering, on the other hand, uses filter arrays or tunable array FP filters as filtering elements and employs the principle of multi-beam interference to achieve spectral splitting and analysis. This method can achieve stable light output within a microscopic scale, and its back-end detection is relatively easy. Therefore, this method is currently one of the main development trends in spectrometer components for miniature spectrometers.

[0004] Currently, there are two main device structures for narrowband filtering: filter arrays or tunable FP filters. Tunable FP filters, compared to filter arrays, offer smaller planar dimensions, a wider range of detection spectrums, and the ability to achieve continuous, high-precision detection, making them a current research focus. Current research utilizes a single-phase drive approach, leveraging electrostatic attraction to change the FP filter cavity length and thus the output wavelength for spectrum separation. However, this approach is limited by attraction instability and half-wave bandwidth, restricting its performance.

[0005] Currently available tunable FP filter modules primarily utilize a unidirectional electrode drive mode, leveraging the electrostatic attraction effect to change the cavity length and, therefore, the output wavelength. However, this unidirectional electrode drive mode can cause attraction instability. Exceeding the critical tuning point results in a "pull-in effect," causing the upper and lower electrodes to align, significantly limiting the tuning accuracy of the FP filter. Furthermore, the unidirectional drive mode can only tune the device in a single direction, which, due to the stress limit of the movable electrode, significantly restricts the device's operating range. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a bidirectional drive FP filter device structure and a preparation method thereof, which can achieve a bidirectional drive range and improve the stability and robustness of the device.

[0007] The present invention provides a bidirectionally driven FP filter device structure, comprising: a first static electrode and a second static electrode, a movable electrode located between the first static electrode and the second static electrode, a first insulating support member provided between the movable electrode and the first static electrode, a second insulating support member provided between the movable electrode and the second static electrode, a first dielectric layer reflector provided on the movable electrode, a second dielectric layer reflector provided on the second static electrode, the first static electrode having a light through hole, the light through hole being coaxial with the first dielectric layer reflector and the second dielectric layer reflector;

[0008] In the working state, high potential is alternately applied to the first static electrode and the second static electrode, and low potential is applied to the movable electrode in the middle, so that the first static electrode and the second static electrode respectively form an electrostatic attraction effect with the movable electrode. By controlling the voltage of the first static electrode and the second static electrode, the electrostatic force applied to the movable electrode is changed, so that the movable electrode can achieve up and down displacement and reciprocating motion. The movable electrode drives the position of the first dielectric layer reflector to move, so that the distance between the first dielectric layer reflector and the second dielectric layer reflector changes. The wavelength of the output light is adjusted based on the change to complete dynamic filtering.

[0009] As a preferred solution, the movable electrode is made of gold, and the first insulating support member and the second insulating support member are made of silicon nitride.

[0010] As a preferred solution, the movable electrode adopts a tic-tac-toe structure, which includes a frame, a fixed frame for mounting the first dielectric layer reflector, and multiple cantilevers for connecting the frame and the fixed frame, and the multiple cantilevers are evenly distributed between the fixed frame and the frame.

[0011] As a preferred solution, the first insulating support member and the second insulating support member are provided with four notches for passing the wires in orthogonal directions.

[0012] As a preferred solution, the first dielectric layer reflector and the second dielectric layer reflector are both designed with a DBR reflector structure. The film structure is determined to be (HL) by simulation using TFCalc model simulation software. 4H, where H is the high refractive index material niobium pentoxide, L is the low refractive index material silicon dioxide, and both have an optical thickness of λ / 4.

[0013] As a preferred solution, the light-through hole is located at the geometric center of the first static electrode.

[0014] The present invention also provides a method for preparing a bidirectional drive FP filter device structure, comprising:

[0015] A second dielectric layer reflector of a second static electrode is sputtered on a fused silica substrate using a dielectric magnetron device;

[0016] preparing a photoresist mask for the second static electrode using a photolithography mask technique;

[0017] Using a double-gun electron beam evaporation station, chromium material is used as an adhesion layer, and gold is used as an electrode material to prepare the electrode of the second static electrode;

[0018] performing metal lift-off to form a pattern of the second static electrode using a metal lift-off process;

[0019] A second insulating support member is prepared using a dielectric magnetron device and silicon nitride material;

[0020] patterning the second insulating support member using a photolithography mask technique and a dry etching technique;

[0021] Amorphous silicon is prepared using a sacrificial layer technology and a dielectric magnetron device to fill the second cavity of the second insulating support member, where the second cavity provides a processing platform for preparing the movable electrode;

[0022] Using photolithography mask technology, preparing the movable electrode and the first dielectric layer reflector;

[0023] Using a dielectric magnetron device and silicon nitride material to continue preparing a first insulating support member on the movable electrode;

[0024] patterning the first insulating support member using a photolithography mask technique and a dry etching technique;

[0025] Amorphous silicon is prepared by using a sacrificial layer technology and a dielectric magnetron device to fill the first cavity of the first insulating support member;

[0026] preparing a first static electrode;

[0027] A xenon fluoride etcher is used to release the sacrificial layer of the device structure to complete the preparation of the overall device structure.

[0028] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0029] An embodiment of the present invention provides a bidirectionally driven FP filter device structure and a preparation method thereof, including: a first static electrode and a second static electrode, a movable electrode located between the first static electrode and the second static electrode, a first insulating support member provided between the movable electrode and the first static electrode, a second insulating support member provided between the movable electrode and the second static electrode, a first dielectric layer reflector provided on the movable electrode, and a second dielectric layer reflector provided on the second static electrode. The first static electrode has a light-through hole, and the light-through hole shares an optical axis with the first dielectric layer reflector and the second dielectric layer reflector. By utilizing a bidirectional driving structure, a bidirectional driving range can be achieved, thereby improving the stability and robustness of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 2 is a schematic structural diagram of a bidirectional driving FP filter device structure according to an embodiment of the present invention;

[0031] Figure 2 1 is a schematic diagram of a membrane layer simulation result of a TFCalc software in a bidirectional drive FP filter device structure according to an embodiment of the present invention;

[0032] Figure 3 The present invention provides a schematic diagram of a manufacturing process flow of a method for manufacturing a bidirectional drive FP filter device structure according to an embodiment of the present invention.

[0033] Reference numerals include:

[0034] A first static electrode 1 , a first insulating support 2 , a movable electrode 3 , a first dielectric layer reflector 4 , a second insulating support 5 , a second static electrode 6 , a second dielectric layer reflector 7 , and a cantilever 8 . DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, identical modules are denoted by identical reference numerals. In the case of identical reference numerals, their names and functions are also identical. Therefore, their detailed description will not be repeated.

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0037] Combine Figure 1As shown, an embodiment of the present invention provides a bidirectional drive FP filter device structure, comprising: a first static electrode 1 and a second static electrode 6, a movable electrode 3 located between the first static electrode 1 and the second static electrode 6, a first insulating support member 2 is provided between the movable electrode 3 and the first static electrode 1, a second insulating support member 5 is provided between the movable electrode 3 and the second static electrode 6, a first dielectric layer reflector 4 is provided on the movable electrode 3, and a second dielectric layer reflector 7 is further provided on the second static electrode 6, the first static electrode 1 has a light hole, and the light hole and the first dielectric layer reflector 4 and the second dielectric layer reflector 7 share an optical axis to facilitate emission of output light from the device structure;

[0038] In the working state, high potential is applied alternately to the first static electrode 1 and the second static electrode 6, and low potential is applied to the movable electrode in the middle. The first static electrode 1 and the second static electrode 6 respectively form an electrostatic attraction effect with the movable electrode. By controlling the voltage of the first static electrode 1 and the second static electrode 6 respectively, the electrostatic force applied to the movable electrode 3 is changed, so that the movable electrode 3 can achieve up and down displacement and reciprocating motion. The movable electrode 3 drives the first dielectric layer reflector 4 to move the position so that the distance between the first dielectric layer reflector 4 and the second dielectric layer reflector 7 changes. The change in the distance between the two reflectors can regulate the wavelength of the output light, thereby realizing the adjustment of the output light wavelength based on the distance change and completing dynamic filtering.

[0039] As for the method of generating the electrostatic attraction effect, specifically, the first static electrode 1 and the second static electrode 6 can be respectively connected to an external power supply, the movable electrode 3 can be grounded, and direct current can be applied to the first static electrode 1 and the second static electrode 6 respectively. The first static electrode 1 and the second static electrode 6 form an electrostatic attraction effect so that the movable electrode 3 is driven and tuned, and the movable electrode 3 drives the first dielectric layer reflector 4 to move the position so that the distance between the first dielectric layer reflector 4 and the second dielectric layer reflector 7 changes.

[0040] An embodiment of the present invention provides a bidirectionally driven FP filter device structure, including: a first static electrode 1 and a second static electrode 6, a movable electrode 3 located between the first static electrode 1 and the second static electrode 6, a first insulating support member 2 is provided between the movable electrode 3 and the first static electrode 1, a second insulating support member 5 is provided between the movable electrode 3 and the second static electrode 6, a first dielectric layer reflector 4 is provided on the movable electrode 3, and a second dielectric layer reflector 7 is also provided on the second static electrode 6. The first static electrode 1 has a light hole, and the light hole and the first dielectric layer reflector 4 and the second dielectric layer reflector 7 share an optical axis. By utilizing the bidirectional driving structure, a bidirectional driving range can be achieved, thereby improving the stability and robustness of the device.

[0041] In this embodiment, a three-electrode structure consisting of two upper and lower fixed electrodes and a movable electrode 3 is used. The upper and lower electrodes can independently control the structure of the movable electrode 3, effectively suppressing the pull-in effect. Furthermore, the use of a bidirectional structure significantly improves the tuning modes and tuning range of the tunable FP filter. Compared to a unidirectional tunable FP filter structure, the bidirectional tunable filter structure of the present invention achieves a driven displacement that is 216.7% of the original structure.

[0042] In some embodiments, the movable electrode 3 adopts a tic-tac-toe structure, and the tic-tac-toe structure includes a frame (not shown in the figure), a fixed frame for mounting the first dielectric layer reflector 4 (not shown in the figure) and a plurality of cantilevers 8 for connecting the frame and the fixed frame. The plurality of cantilevers 8 are evenly distributed between the fixed frame and the frame. The structure of the cantilever 8 can adopt a plurality of bending parts, and a tic-tac-toe structure is adopted as the structure of the movable electrode 3. After simulation verification, the folding structure of the cantilever 8 will be able to achieve a larger displacement under the same voltage conditions and generate less stress at the same time compared with a single straight arm structure. Therefore, the tic-tac-toe structure is adopted as the structure of the movable electrode 3 in this embodiment.

[0043] When the first static electrode 1 and the second static electrode 6 are energized at the same time, an attractive force can be applied to the movable electrode 3 at the same time. This method, as a solution to the pull-in effect, will be able to improve the tuning stability when the dynamic electrode is close to the static electrode and increase the tuning range. In order to facilitate understanding of the technical solution of the present invention, it is explained below in combination with the working principle.

[0044] 1. Filtering principle of FP filter

[0045] The filtering of the FP filter is based on the principle of multi-beam interference, as shown in formula (1):

[0046] 2nd=mλ (1)

[0047] in:

[0048] n—refractive index, which is 1 under the conditions of the present invention;

[0049] d—the cavity length between the two mirrors of the filter;

[0050] m—is a positive integer, and in the present invention, m is 1.

[0051] λ—is the emission wavelength.

[0052] Therefore, the above formula can be simplified to λ = 2d. Therefore, by changing the parameter value of d, the output wavelength can be easily changed. Based on this principle, the present invention innovates to change the cavity length. By leveraging the advantages of a bidirectional driver, it can increase the drive range of the movable electrode 3, thereby expanding the wavelength range of the filter.

[0053] 2. Driving principle of FP filter

[0054] When the cantilever 8 is energized, an electrostatic attraction force is generated between the cantilever 8 and the ground electrode, and the attraction voltage is shown in formula (2):

[0055]

[0056] in:

[0057] V PI — Stable tuning voltage threshold (pull-in voltage);

[0058] k—spring constant;

[0059] —Planck constant;

[0060] c—is the speed of light;

[0061] ε—dielectric constant

[0062] H—cantilever 8 thickness;

[0063] W—width of cantilever 8;

[0064] L—cantilever 8 length;

[0065] d0—initial gap;

[0066] d PI — critical gap;

[0067] As can be seen from formula (2), the pull-in voltage at which the pull-in is unstable is positively correlated with the cavity length. When this value is exceeded, the movable electrode 3 will rapidly pull in with the static electrode, resulting in tuning instability and even irreversible damage to the microbridge structure and the reflective mirror. In the present invention, by adopting a bidirectional drive scheme, the electrode in the opposite direction of the pull-in voltage can be driven in the reverse direction according to the pull-in voltage value, so that it can still be stably tuned even when the pull-in voltage threshold is exceeded, thereby expanding the tuning range of the cavity length and ultimately achieving high-precision, wide-band filtering functions.

[0068] Combine Figure 2As shown, in some embodiments, in the near infrared band (950nm-1300nm), the first dielectric layer reflector 4 and the second dielectric layer reflector 7 are both designed with a DBR reflector structure, and the TFCalc model simulation software is used for simulation. Figure 2 As shown in the figure, the film structure is determined to be (HL) 4 H, where H is niobium pentoxide, a high-refractive-index material, and L is silicon dioxide, a low-refractive-index material, and their optical thicknesses are both λ / 4. This allows the first dielectric layer reflector 4 and the second dielectric layer reflector 7 to achieve high reflection within the 950nm-1300nm band. After simulation and actual measurement, this structure can achieve 80% broadband high reflectivity within the band, with a reflectivity of 94% at a central wavelength of 1000nm, meeting device requirements.

[0069] In some embodiments, the movable electrode 3 is made of gold, and the first insulating support member 2 and the second insulating support member 5 are made of silicon nitride. Those skilled in the art can flexibly choose and there is no limitation on this.

[0070] In some embodiments, the first insulating support 2 and the second insulating support 5 are provided with four gaps in orthogonal directions for passing the wires. The gaps can be prepared for introducing wires into the electrodes later. Ordinary technicians in this field can flexibly choose and there is no limitation on this.

[0071] In some embodiments, the light-through hole is located at the geometric center of the first static electrode 1 , and the cross-section of the entire device structure is a square structure. Those skilled in the art can flexibly select this structure and there is no limitation thereto.

[0072] The simulation results in the embodiment of the present invention show that the method is practical and effective. The invention content has been verified in many aspects by using TFCalc film layer design software, Comsol multi-physics field simulation software and FDTD Solution electromagnetic field simulation software. The design is feasible and the results can meet the requirements of use.

[0073] Combine Figure 3 As shown, accordingly, an embodiment of the present invention further provides a method for preparing a bidirectional driving FP filter device structure, comprising:

[0074] S301 , using a dielectric magnetron device to sputter a second dielectric layer reflector of a second static electrode on a fused silica substrate.

[0075] S302: Prepare a photoresist mask for the second static electrode using a photolithography mask technology.

[0076] S303 , using a double-gun electron beam evaporation table, adopting chromium material as an adhesion layer and gold as an electrode material to prepare the electrode of the second static electrode.

[0077] S304 , performing metal lift-off to form a pattern of the second static electrode by using a metal lift-off process.

[0078] S305 , using a dielectric magnetron device and silicon nitride material to prepare a second insulating support member.

[0079] S306 , patterning the second insulating support member using a photolithography mask technique and a dry etching technique.

[0080] S307 , using a sacrificial layer technology and a dielectric magnetron device to prepare amorphous silicon to fill the second cavity of the second insulating support member, where the second cavity provides a processing platform for preparing the movable electrode.

[0081] S308, using photolithography mask technology to prepare the movable electrode and the first dielectric layer reflector;

[0082] S309 , using a dielectric magnetron device and silicon nitride material to continue preparing a first insulating support member on the movable electrode.

[0083] S310 , patterning the first insulating support member using a photolithography mask technology and a dry etching technology.

[0084] S311. Use sacrificial layer technology and a dielectric magnetron device to prepare amorphous silicon to fill the first cavity of the first insulating support member.

[0085] S312, preparing a first static electrode.

[0086] S313. Use a xenon fluoride etcher to release the sacrificial layer of the device structure to complete the preparation of the overall device structure.

[0087] In S312, specifically, a photolithography mask technology is used to prepare a photoresist mask for the first static electrode, a dual-gun electron beam evaporation table is used, a chromium material is used as an adhesion layer, and gold is used as an electrode material to prepare the electrode of the first static electrode, and a metal stripping process is used to perform metal stripping to form a pattern of the first static electrode.

[0088] An embodiment of the present invention provides a method for preparing a bidirectionally driven FP filter device structure, and the bidirectionally driven FP filter device structure is prepared. By utilizing the bidirectional driving structure, a bidirectional driving range can be achieved, thereby improving the stability and robustness of the device.

[0089] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0090] The above specific embodiments of the present invention do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A bidirectional drive FP filter device structure, characterized in that: include: a first static electrode and a second static electrode, a movable electrode located between the first static electrode and the second static electrode, a first insulating support member provided between the movable electrode and the first static electrode, a second insulating support member provided between the movable electrode and the second static electrode, a first dielectric layer reflector provided on the movable electrode, a second dielectric layer reflector provided on the second static electrode, the first static electrode having a light through hole, the light through hole being coaxial with the first dielectric layer reflector and the second dielectric layer reflector; In a working state, a high potential is alternately applied to the first static electrode and the second static electrode, and a low potential is applied to the movable electrode in the middle, so that the first static electrode and the second static electrode respectively form an electrostatic attraction effect with the movable electrode. By controlling the voltages of the first static electrode and the second static electrode, the electrostatic force applied to the movable electrode is changed, so that the movable electrode achieves up and down displacement and reciprocating motion. The movable electrode drives the first dielectric layer reflector to move, so that the distance between the first dielectric layer reflector and the second dielectric layer reflector changes. The wavelength of the output light is adjusted based on the change in the distance between the first dielectric layer reflector and the second dielectric layer reflector, thereby completing dynamic filtering; The movable electrode adopts a tic-tac-toe structure, which includes a frame, a fixed frame for mounting the first dielectric layer reflector, and a plurality of cantilevers for connecting the frame and the fixed frame, wherein the plurality of cantilevers are evenly distributed between the fixed frame and the frame; The first dielectric layer reflector and the second dielectric layer reflector are both designed with a DBR reflector structure. The film structure is determined to be (HL) by simulation using TFCalc model simulation software. 4 H, wherein H is the high refractive index material niobium pentoxide, L is the low refractive index material silicon dioxide, and the optical thicknesses of the high refractive index material niobium pentoxide and the low refractive index material silicon dioxide are both λ / 4.

2. The bidirectional drive FP filter device structure according to claim 1, characterized in that: The movable electrode is made of gold, and the first insulating support member and the second insulating support member are made of silicon nitride.

3. The bidirectional drive FP filter device structure according to claim 1 or 2, characterized in that: The first insulating support member and the second insulating support member are provided with four notches for passing the wires in orthogonal directions.

4. The bidirectional drive FP filter device structure according to claim 1, characterized in that: The light-through hole is located at the geometric center of the first static electrode.

5. A method for preparing a bidirectional drive FP filter device structure, characterized in that: include: A second dielectric layer reflector of a second static electrode is sputtered on a fused silica substrate using a dielectric magnetron device; preparing a photoresist mask for the second static electrode using a photolithography mask technique; Using a double-gun electron beam evaporation station, chromium material is used as an adhesion layer, and gold is used as an electrode material to prepare the electrode of the second static electrode; performing metal lift-off to form a pattern of the second static electrode using a metal lift-off process; A second insulating support member is prepared using a dielectric magnetron device and silicon nitride material; patterning the second insulating support member using a photolithography mask technique and a dry etching technique; Amorphous silicon is prepared using a sacrificial layer technology and a dielectric magnetron device to fill the second cavity of the second insulating support member, where the second cavity provides a processing platform for preparing the movable electrode; Using photolithography mask technology, preparing the movable electrode and the first dielectric layer reflector; Using a dielectric magnetron device and silicon nitride material to continue preparing a first insulating support member on the movable electrode; patterning the first insulating support member using a photolithography mask technique and a dry etching technique; Amorphous silicon is prepared by using a sacrificial layer technology and a dielectric magnetron device to fill the first cavity of the first insulating support member; preparing a first static electrode; Use a xenon fluoride etcher to release the sacrificial layer of the device structure and complete the preparation of the overall device structure; The movable electrode adopts a tic-tac-toe structure, which includes a frame, a fixed frame for mounting the first dielectric layer reflector, and a plurality of cantilevers for connecting the frame and the fixed frame, wherein the plurality of cantilevers are evenly distributed between the fixed frame and the frame; The first dielectric layer reflector and the second dielectric layer reflector are both designed with a DBR reflector structure. The film structure is determined to be (HL) by simulation using TFCalc model simulation software. 4 H, wherein H is the high refractive index material niobium pentoxide, L is the low refractive index material silicon dioxide, and the optical thicknesses of the high refractive index material niobium pentoxide and the low refractive index material silicon dioxide are both λ / 4.

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