Tunable optical filter and preparation method thereof

Abstract

The invention provides a tunable optical filter and a preparation method thereof. The tunable optical filter comprises a static mirror surface part and a movable mirror surface part, the static mirror surface part comprises a first mirror surface structure and a braking groove; the movable mirror surface part comprises a movable cantilever structure, a piezoelectric driving structure and a second mirror surface structure; wherein the first end of the movable cantilever structure is connected with the second mirror surface structure, and the second end is connected with the piezoelectric driving structure; the first semiconductor substrate is bonded with the second semiconductor substrate, so that the first mirror surface structure is opposite to the second mirror surface structure; a cavity is further formed between the first mirror surface structure and the second mirror surface structure to serve as a Fabry-Perot cavity, and the first end of the movable cantilever structure is regulated and controlled to move based on the piezoelectric driving structure so as to regulate and control the cavity length of the Fabry-Perot cavity. The piezoelectric driving structure is directly arranged on the movable cantilever structure, high integration of the piezoelectric driving structure and the movable mirror surface component is achieved, and therefore miniaturization consistency and batch manufacturing are achieved.

Description

Technical Field

[0001] The present invention relates to the field of optical devices, and in particular to a tunable optical filter and a preparation method thereof. Background Art

[0002] Tunable optical filters play an important role in many fields, including fiber-optic communications and fiber-optic sensing. They can be used in wavelength multiplexing equipment, dispersion compensators, optical add-drop multiplexing equipment, optical cross-connects, wavelength converters, and wavelength selectors. With the rapid development of fiber-optic sensing technology, they have also become key components for wavelength demodulation in sensors such as fiber Bragg gratings and Fabry-Perot (FP). Using tunable optical filters for wavelength scanning enables real-time acquisition of spectral information and output of resonant wavelengths. Furthermore, by integrating them with broadband light sources, miniaturized spectrometers can be constructed for applications in areas such as material detection and spectral sensing. These applications have made tunable optical filters a hot topic for researchers and the optoelectronics industry worldwide.

[0003] Among traditional tunable optical filtering solutions, the most common is the combination of a dispersive element and a nano-moving platform. However, due to the precision and movement speed of the nano-moving platform, the filtering linewidth of this solution is usually in the nanometer range and the scanning speed is in the millisecond range. In order to achieve a smaller linewidth, it is usually necessary to increase the optical path, so the equipment of this filtering solution is not compatible with high performance and small size requirements. Therefore, tunable filters based on the FP interference principle (Fabry-Pérot, FP for short) have attracted more and more attention. Tunable filtering is achieved by adjusting the cavity length of the Fabry-Perot cavity or the refractive index of the medium in the cavity. This solution can meet the application requirements of fast, high precision and miniaturization. However, the existing tunable filters based on the FP interference principle still have problems such as being extremely susceptible to external vibrations, too low utilization of the Fabry-Perot cavity length, and lack of batch consistency production capabilities in actual production.

[0004] It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a tunable optical filter and a preparation method thereof, which are used to solve the problems of the existing FP interference principle tunable filter being extremely susceptible to external vibrations, the low utilization rate of the Fabry-Perot cavity length, and the lack of batch production consistency in actual production.

[0006] To achieve the above-mentioned and other related objects, the present invention provides a tunable optical filter, comprising: a stationary mirror component and a movable mirror component;

[0007] The stationary mirror component includes a first mirror structure and a braking groove provided on a first surface of a first semiconductor substrate; wherein the braking groove is provided around the first mirror structure;

[0008] The movable mirror component includes a movable cantilever structure, a piezoelectric drive structure, and a second mirror structure; wherein the movable cantilever structure and the piezoelectric drive structure are disposed on the first surface of the second semiconductor substrate; the second mirror structure is disposed on the first surface or the second surface of the second semiconductor substrate; the first end of the movable cantilever structure is connected to the second mirror structure, and the second end is connected to the piezoelectric drive structure;

[0009] The first semiconductor substrate is bonded to the second semiconductor substrate, the first mirror structure and the second mirror structure are arranged opposite to each other, and the braking groove corresponds to accommodate the movable cantilever structure to provide a translational space for the second mirror structure; a cavity is also set between the first mirror structure and the second mirror structure as a Fabry-Perot cavity, and the movement of the first end of the movable cantilever structure is regulated based on the piezoelectric drive structure to regulate the cavity length of the Fabry-Perot cavity.

[0010] Optionally, the tunable optical filter further includes an electrode lead-out structure, which is disposed above the piezoelectric drive structure and is used to electrically lead out the piezoelectric drive structure.

[0011] Optionally, the first semiconductor substrate includes a silicon substrate or an SOI substrate; the second semiconductor substrate includes an SOI substrate; and the SOI substrate is stacked with a bottom single crystal silicon layer, a buried oxide layer and a top single crystal silicon layer in sequence from bottom to top.

[0012] Optionally, when the second mirror structure is arranged on the first surface of the second semiconductor substrate, a first bonding structure and an electrode bonding structure are also arranged on the first surface of the first semiconductor substrate; the first bonding structure and the electrode bonding structure are both arranged along the periphery of the braking groove, and the distance between the first bonding structure and the first mirror structure is greater than the distance between the electrode bonding structure and the first mirror structure; a second bonding structure is also arranged on the first surface of the second semiconductor substrate; the second bonding structure is arranged around the periphery of the piezoelectric driving structure; wherein, the first bonding structure and the second bonding structure are correspondingly bonded; the electrode bonding structure is correspondingly bonded to the piezoelectric driving component.

[0013] Optionally, when the second mirror structure is arranged on the second surface of the second semiconductor substrate, a third bonding structure is also arranged on the first surface of the first semiconductor substrate; the third bonding structure is arranged along the periphery of the braking groove; a fourth bonding structure is also arranged on the second surface of the second semiconductor substrate; the fourth bonding structure is arranged around the second mirror structure; wherein the third bonding structure and the fourth bonding structure are bonded correspondingly.

[0014] Optionally, the tunable optical filter further includes a first fiber collimator and a second fiber collimator; the first fiber collimator is arranged above the second surface of the first semiconductor substrate; and the second fiber collimator is arranged above another surface opposite to the surface on which the second mirror structure is arranged.

[0015] To achieve the above-mentioned and other related objectives, the present invention provides a method for preparing a tunable optical filter, comprising:

[0016] Providing a first semiconductor substrate, and preparing a stationary mirror component on a first surface of the first semiconductor substrate; the stationary mirror component includes a first mirror structure and a braking groove; the braking groove is arranged around the first mirror structure;

[0017] A second semiconductor substrate is provided, and a movable mirror component is prepared on the second semiconductor substrate; the movable mirror component includes a movable cantilever structure, a piezoelectric drive structure, and a second mirror structure; wherein the movable cantilever structure and the piezoelectric drive structure are disposed on the first surface of the second semiconductor substrate; the second mirror structure is disposed on the first surface or the second surface of the second semiconductor substrate; the first end of the movable cantilever structure is connected to the second mirror structure, and the second end is connected to the piezoelectric drive structure;

[0018] The first semiconductor substrate and the second semiconductor substrate are bonded to each other so that the first mirror structure and the second mirror structure are arranged opposite to each other and the braking groove corresponds to accommodating the second mirror structure; wherein a cavity is further formed between the first mirror structure and the second mirror structure as a Fabry-Perot cavity.

[0019] Optionally, the step of forming the stationary mirror component specifically includes:

[0020] A first device region is defined on the first surface of the first semiconductor substrate; the first device region is patterned and etched to obtain a boss and the braking groove arranged around the boss, and a dielectric film is patterned and deposited on the boss to obtain the first mirror structure.

[0021] Optionally, the step of forming the stationary mirror component specifically includes:

[0022] A first device region is defined on the first surface of the first semiconductor substrate; the first device region is patterned etched to obtain the braking groove; and a patterned dielectric film is patterned deposited on the braking groove to obtain the first mirror structure.

[0023] Optionally, the step of forming the movable mirror component specifically includes:

[0024] A second device area is defined on the first surface of the second semiconductor substrate; the second device area is divided into a piezoelectric drive area and a cantilever area, and the piezoelectric drive area is subjected to metallization deposition and patterned etching to form the piezoelectric drive structure; the cantilever area is patterned etched to obtain an etched groove and the movable cantilever structure arranged around the etched groove; a dielectric film is patterned deposited on the etched groove to obtain the second mirror structure.

[0025] Optionally, the step of forming the movable mirror component specifically includes:

[0026] A third device region is defined on the first surface of the second semiconductor substrate; the third device region is divided into a piezoelectric drive region and a cantilever region, and the piezoelectric drive region is subjected to metallization deposition and patterned etching to form the piezoelectric drive structure; the cantilever region is patterned etched to obtain etched grooves and the movable cantilever structure arranged around the etched grooves; a fourth device region is defined on the second surface of the second semiconductor substrate; the fourth device region is arranged at a position corresponding to the etched grooves; a dielectric thin film is patterned deposited on the fourth device region to obtain the second mirror structure.

[0027] Optionally, the step of bonding the first semiconductor substrate to the second semiconductor substrate specifically includes:

[0028] When the second mirror structure is provided on the first surface of the second semiconductor substrate, a first oxide layer and a first metal layer are sequentially formed on the first surface of the first semiconductor substrate from bottom to top, and the surface of the first metal layer is divided into a first bonding area and a first device area; the first bonding area is provided around the first device area; the first bonding area is patterned and etched to form a first bonding structure and an electrode bonding structure; the first bonding structure is provided around the periphery of the electrode bonding structure;

[0029] Depositing a second metal layer, a piezoelectric thin film material layer, and a third metal layer on the first surface of the second semiconductor substrate in order from bottom to top, and dividing the surface of the third metal layer into a second bonding area and a second device area; the second bonding area is arranged around the second device area; and patterning and etching the second bonding area to obtain the second bonding structure;

[0030] The first bonding structure and the second bonding structure are bonded correspondingly; and the electrode bonding structure and the piezoelectric driving structure are bonded correspondingly.

[0031] Optionally, the step of bonding the first semiconductor substrate to the second semiconductor substrate specifically includes:

[0032] When the second mirror structure is provided on the second surface of the second semiconductor substrate, a second oxide layer and a second metal layer are sequentially formed on the first surface of the first semiconductor substrate from bottom to top, and the surface of the second metal layer is divided into a third bonding area and the third device area; the third bonding area is provided around the third device area; the third bonding area is patterned and etched to form a third bonding structure; the third bonding structure is provided around the periphery of the braking groove;

[0033] forming a third oxide layer and a third metal layer in sequence from bottom to top on the second surface of the second semiconductor substrate, and dividing the surface of the third metal layer into the fourth bonding area; the fourth bonding area is arranged around the second mirror structure;

[0034] The third bonding structure and the fourth bonding structure are bonded and arranged correspondingly.

[0035] Optionally, the preparation method further includes the step of preparing an electrode lead structure, specifically comprising:

[0036] When the second mirror structure is disposed on the first surface of the second semiconductor substrate, after forming the second bonding structure and the piezoelectric driving structure, a passivation layer is deposited on the first surface of the second semiconductor substrate, and the passivation layer is etched to expose a portion of the piezoelectric driving structure to form an electrode hole;

[0037] At least performing metallization deposition and pattern etching on the electrode hole to obtain an electrode lead-out structure to electrically lead out the piezoelectric drive structure corresponding to the electrode hole;

[0038] While patterning and etching the cantilever region to obtain the movable cantilever structure and the etching groove, a side wall of the second semiconductor substrate is also etched to obtain a pad exposure region;

[0039] While the first bonding structure is correspondingly bonded to the second bonding structure, the electrode lead-out structure is led out to the pad exposed area.

[0040] Optionally, the preparation method further includes the step of preparing an electrode lead structure, specifically comprising:

[0041] When the second mirror structure is arranged on the second surface of the second semiconductor substrate, after the piezoelectric driving structure is formed, the passivation layer is etched on the first surface of the second semiconductor substrate and a portion of the piezoelectric driving structure is exposed to form an electrode hole; at least the electrode hole is metallized and patterned and etched to obtain an electrode lead-out structure.

[0042] Optionally, the preparation method further includes the step of welding the first optical fiber collimator and the second optical fiber collimator, specifically comprising:

[0043] Providing a first optical fiber collimator and a second optical fiber collimator, and coupling the first optical fiber collimator to the second surface of the first semiconductor substrate by gluing or welding;

[0044] The second optical fiber collimator is coupled to another surface opposite to the surface where the second mirror structure is provided by gluing or welding.

[0045] As described above, the tunable optical filter and the preparation method thereof of the present invention have the following beneficial effects:

[0046] The piezoelectric drive structure of the present invention is directly arranged on the movable cantilever structure, which realizes the high integration of the piezoelectric drive structure and the movable mirror, and realizes miniaturization consistency and batch production. At the same time, the piezoelectric drive structure of the present invention ensures the parallelism of the two mirrors of the Fabry-Perot cavity and the precise control of the cavity length of the Fabry-Perot cavity by arranging the piezoelectric drive structure between the two mirrors and directly bonding them, thereby improving the spectral filtering bandwidth, and there is no attraction effect, nonlinear phenomenon and the limitation of the external permanent magnet on the filter size and filtering performance of the Fabry-Perot cavity, which can realize high-frequency, narrow linewidth and large bandwidth filtering. In addition, the preparation method of the present invention is simple, low-cost, and the prepared structure is small in volume, which is conducive to industrial production and manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Shown is a schematic structural diagram of the first tunable optical filter of the present invention.

[0048] Figure 2 Shown is a schematic diagram of the positions of various structures in the stationary mirror component of the present invention.

[0049] Figure 3 It is a schematic diagram showing the positions of various structures in the movable mirror member of the present invention.

[0050] Figure 4 Shown is a cross-sectional view of a stationary mirror component of the present invention.

[0051] Figure 5 A cross-sectional view of the movable mirror member of the present invention is shown.

[0052] Figure 6 It shows the filtering principle curve diagram of the Fabry-Perot cavity of the present invention.

[0053] Figure 7 Shown is a graph showing the relationship between line width and reflectivity in the tunable optical filter of the present invention.

[0054] Figure 8 Shown is a pictorial diagram of the tunable optical filter of the present invention.

[0055] Figure 9 Shown is a transmission spectrum diagram of the tunable optical filter of the present invention.

[0056] Figure 10 Shown is a frequency sweep diagram of the tunable optical filter of the present invention.

[0057] Figure 11 Shown is a schematic diagram of the steps of the method for preparing the tunable optical filter of the present invention.

[0058] Figure 12 Shown is a flow chart for preparing the stationary mirror component of the present invention.

[0059] Figure 13 The following is a flow chart showing the preparation process of the movable mirror member of the present invention.

[0060] Figure 14 A flow chart showing the preparation process for bonding the stationary mirror member and the movable mirror member of the present invention.

[0061] Figure 15 Shown is a schematic structural diagram of a second tunable optical filter of the present invention.

[0062] Component number description

[0063] 1 Stationary mirror component

[0064] 10. First semiconductor substrate

[0065] 11 First mirror structure

[0066] 12 braking grooves

[0067] 121 Boss

[0068] 13 First bonding structure

[0069] 131 First Oxide Layer

[0070] 132 First Metal Layer

[0071] 14 Electrode bonding structure

[0072] 15. The first high-transmittance film

[0073] 16 Pad lead-out area

[0074] 17 Third bonding structure

[0075] 171 Second Oxide Layer

[0076] 172 Second Metal Layer

[0077] 2 Movable mirror parts

[0078] 20 second semiconductor substrate

[0079] 201 bottom single crystal silicon layer

[0080] 202 buried oxide layer

[0081] 203 top single crystal silicon layer

[0082] 204 electrical isolation layer

[0083] 21 Movable cantilever structure

[0084] 211 Cantilever Space

[0085] 22 Piezoelectric drive structure

[0086] 221 Piezoelectric Drive Substructure

[0087] 23 Second mirror structure

[0088] 230 Faber cavity

[0089] 24 Second bonding structure

[0090] 240 lower metal layer

[0091] 241 piezoelectric film material layer

[0092] 242 Upper Metal Layer

[0093] 243 passivation layer

[0094] 244 electrode lead structure

[0095] 25 Second Highest Transmittance Film

[0096] 26 Electrical lead area

[0097] 261 Pad exposed area

[0098] 27 Fourth bonding structure

[0099] 271 Third Oxide Layer

[0100] 272 Fourth Metal Layer

[0101] 3. First fiber collimator

[0102] 30 third semiconductor substrate

[0103] 31 The third highest transmittance film

[0104] 4 Second fiber collimator

[0105] 40 fourth semiconductor substrate

[0106] 41 Fourth Highest Transmittance Film DETAILED DESCRIPTION

[0107] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0108] See also Figures 1 to 15 It should be noted that the diagrams provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Therefore, the diagrams only show components relevant to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be arbitrarily changed, and the component layout may also be more complex.

[0109] Currently, there are two types of tunable optical filters with FP cavities: one is an FP structure based on all-fiber; the other is an FP structure based on MEMS technology.

[0110] The all-fiber FP structure forms an FP cavity through the fiber end face and uses piezoelectric ceramics to drive the axial tension of the fiber. This is applied to the fiber through mechanical structures such as springs to change the distance between the fibers, thereby achieving optical filtering. In these structures, the fiber end face is polished to form a concave Fabry-Perot cavity, which helps reduce insertion loss and improve the quality factor. However, because components such as piezoelectric ceramics and optical fibers are integrated through gluing and assembly, the axial alignment accuracy of the fiber end face is unstable and is easily affected by external vibrations or external vibrations, causing the Fabry-Perot cavity structure to lose its resonant state.

[0111] The development of MEMS technology has driven the development of tunable optical filters toward miniaturization, integration, mass production, and low cost. Based on the tuning method, mainstream MEMS tunable optical filters can be divided into electrostatically driven filters and piezoelectrically driven filters. Electrostatically driven filters primarily achieve filtering by driving a mirror in a Fabry-Perot cavity through the electrostatic force between planar electrodes. However, due to the pull-in effect, electrostatic drive only utilizes one-third of the cavity length. Further increasing the tuning voltage can cause the device to pull in and fail, thus limiting the optical filtering bandwidth. Furthermore, electrostatic drive introduces nonlinear effects, complicating the data processing system. Furthermore, since the fiber collimator is fixed with optical resin, it cannot meet the requirements for mass production and consistency, and the aging of the resin can affect filtering performance. Piezoelectrically driven filters utilize the properties of piezoelectric materials to achieve mechanical motion. However, current piezoelectric drive fabrication suffers from issues such as insufficient parallelism between the two mirrors, complex device manufacturing processes, and inaccurate control of the Fabry-Perot cavity length. Consequently, they are not suitable for mass production and consistency in practice. Furthermore, the limited elasticity of the movable components makes actuation difficult. In addition to electrostatically driven filters and piezoelectrically driven filters, MEMS tunable optical filters also have electromagnetically driven filters. Although electromagnetically driven filters can achieve a large diameter light-transmitting area, the driving linearity is only about 95%, and non-MEMS processes are required to assemble permanent magnets. The cost and volume are limited, and they cannot meet the requirements of mass production and consistency manufacturing.

[0112] Example 1

[0113] In order to solve the above problems, this embodiment proposes a new tunable optical filter, such as Figure 1 As shown, the tunable optical filter of this embodiment includes a stationary mirror component 1 and a movable mirror component 2 .

[0114] like Figure 1 and Figure 2 As shown, the stationary mirror component 1 includes a first mirror structure 11 and a braking groove 12 provided on a first surface of a first semiconductor substrate 10 ; wherein the braking groove 12 is provided around the first mirror structure 11 , and the first mirror structure 11 is provided as a stationary mirror.

[0115] Specifically, in this embodiment, Figure 2As shown, the first mirror structure 11 is set as a high reflectivity dielectric film, which has a high reflectivity and can adjust the line width of the narrow-band light source input and output between the light and the area where the first mirror structure 11 is located, and can improve the fineness of the Fabry-Perot cavity. It is set in the mirror area of ​​the first semiconductor substrate 10. The braking groove 12 is realized by performing a deep silicon etching process on the first semiconductor substrate 10. The cross section of the first mirror structure 11 is set to be circular; the braking groove 12 is set along the circumference of the first mirror structure 11, as shown in FIG. Figure 1 As shown, the braking groove 12 is recessed into the interior of the first semiconductor substrate 10, and the braking groove 12 provides a translational space for the resonant cavity to move. It should be noted that the shape and structure of the first mirror structure 11 are not limited to this embodiment.

[0116] In this embodiment, the first semiconductor substrate 10 includes but is not limited to a silicon substrate, a glass substrate, and an SOI substrate.

[0117] As an example, when the second mirror structure is arranged on the first surface of the second semiconductor substrate, the first surface of the first semiconductor substrate 10 is also provided with a first bonding structure 13 and an electrode bonding structure 14; the first bonding structure 13 and the electrode bonding structure 14 are both arranged along the periphery of the braking groove 12, and the distance between the first bonding structure 13 and the first mirror structure 11 is greater than the distance between the electrode bonding structure 14 and the first mirror structure 11.

[0118] In this embodiment, combined with Figure 1 and Figure 4 Note that electrode bonding structures 14 are provided on opposite sides of the first semiconductor substrate 10, with the left side being provided with an upper electrode pad (corresponding to the subsequent extraction of the upper metal layer 240), and the right side being provided with a lower electrode pad (corresponding to the subsequent extraction of the lower metal layer 242). The number of electrode pads in the actual electrode bonding structure 14 is not limited by this embodiment; as long as the upper and lower electrode pads in the electrode bonding structure 14 are ensured to appear in pairs and the upper and lower metal layers of the subsequent piezoelectric driving structure 22 can be correspondingly extracted, the configuration is within the scope of protection of this embodiment.

[0119] In this embodiment, the electrode bonding structure 14 is bonded to the subsequent piezoelectric drive structure. The first bonding structure 13 is used to encapsulate and bond the entire structure, and is therefore arranged at the outermost periphery of the tunable optical filter. In addition, in order to ensure the stability of the bonding, the first bonding structure 13 must be symmetrically arranged at least along the central axis of the first mirror structure 11. Specifically, the first bonding structure 13 needs to be arranged on at least two opposite sides of the first semiconductor substrate 10. In this embodiment, the top view of the first semiconductor substrate 10 is rectangular, and the first bonding structure 13 is arranged along three sides of the first semiconductor substrate 10.

[0120] In this embodiment, the first bonding structure 13 and the electrode bonding structure 14 each include a first oxide layer 131 and a first metal layer 132. The first oxide layer 131 and the first metal layer 132 are sequentially disposed on the first surface of the first semiconductor substrate 10, and the first oxide layer 131 and the first metal layer 132 are patterned and etched to simultaneously form the first bonding structure 13 and the electrode bonding structure 14.

[0121] In this embodiment, if Figure 4 As shown, a pad lead-out region 16 is further provided on the first semiconductor substrate 10 for leading out the electrode bonding structure 14 after electrode pad bonding with the subsequent piezoelectric driving structure 14. The electrode bonding structure 14 includes at least an upper electrode pad and a lower electrode pad, which are arranged at positions corresponding to the upper electrode (lower metal layer 242) and the lower electrode (upper metal layer 240), for subsequently leading out the upper and lower electrodes, respectively.

[0122] It should be noted that the actual shape and arrangement position of the bonding structure can also be set accordingly based on needs and are not limited to this embodiment.

[0123] Specifically, a first high-transmittance film 15 is disposed on the second surface of the first semiconductor substrate 10; the first high-transmittance film 15 covers at least the area where the first mirror structure 11 is located. The high-transmittance film is a high-transmittance dielectric film with high transmittance. In this embodiment, the first high-transmittance film 15 and the first mirror structure 11 have the same cross-sectional shape and are coaxially arranged. The area of ​​the first high-transmittance film 15 covers the cross-sectional area of ​​the first mirror structure, ensuring that the light spot diameter is smaller than the area of ​​the first high-transmittance film 15.

[0124] like Figure 1 and Figure 3 As shown, the movable mirror component 2 includes a movable cantilever structure 21, a piezoelectric drive structure 22 and a second mirror structure 23 arranged on the first surface of the second semiconductor substrate 20; wherein the first end of the movable cantilever structure 21 is connected to the second mirror structure 23, and the second end is connected to the piezoelectric drive structure 22.

[0125] Specifically, the second semiconductor substrate 20 is configured as an SOI substrate, which includes, from bottom to top, a bottom single crystal silicon layer 201, a buried oxide layer 202, and a top single crystal silicon layer 203. In this embodiment, a movable cantilever structure 21, a piezoelectric drive structure 22, and a second mirror structure 23 are provided on the first surface of the top single crystal silicon layer 210.

[0126] As an example, the tunable optical filter further includes an electrical isolation layer 204 disposed on the top single crystal silicon layer; the electrical isolation layer 204 is used to isolate the piezoelectric driving structure 22 from the second semiconductor substrate 20 .

[0127] Specifically, the movable cantilever structure 21 is prepared and released on the second semiconductor substrate 20 using a deep silicon process, ensuring that it has good elastic deformation ability and is more sensitive to changes in driving voltage, which is beneficial to improving the sensitivity of the mirror reaction, reducing the driving difficulty, and improving the application prospects.

[0128] It should be noted that, in this embodiment, the movable cantilever structure 21 is configured to include but not limited to an elastic structure such as a flat plate or a sudden change beam.

[0129] Specifically, the piezoelectric drive structure 22 includes at least an upper metal layer 240, a piezoelectric thin film material layer 241, and a lower metal layer 242 stacked in sequence on the second semiconductor substrate 20. Different voltages are set for the upper metal layer 240 and the lower metal layer 242. The voltage difference causes the piezoelectric thin film material layer 241 to deform, forcing the movable cantilever structure 21 to move in a translational manner. The second mirror structure 23 simultaneously changes its position during the movement of the movable cantilever structure 21, thereby changing the cavity length of the Fabry-Perot cavity 230 between the first mirror structure 11 and the second mirror structure 23. In this embodiment, the piezoelectric thin film material layer 241 includes at least one material selected from aluminum nitride or PZT piezoelectric film. In fact, the material of the piezoelectric thin film material layer 241 is not limited to this embodiment.

[0130] More specifically, if Figure 5 As shown, the piezoelectric driving structure 22 includes four piezoelectric driving substructures 221, wherein the first ends of the four piezoelectric driving substructures 221 are connected to the electrode lead structure 244 (electrode pad) to receive voltage, and the second ends are connected to the piezoelectric driving structure 22. The four piezoelectric driving substructures 221 are arranged along the center of the second mirror structure 23 to ensure the stability of the movable cantilever structure 21 driving the second mirror structure 23 to move.

[0131] As an example, the tunable optical filter further includes an electrode lead-out structure 244, which is disposed above the piezoelectric drive structure 22 and is used to electrically lead the piezoelectric drive structure 22. In this embodiment, the electrode lead-out structure 244 is configured as an electrode pad, which is electrically connected to the upper electrode (lower metal layer 242) and the lower electrode (upper metal layer 240) of the piezoelectric drive substructure 221, respectively, to facilitate the subsequent provision of a voltage across the piezoelectric drive substructure 221.

[0132] In this embodiment, an electrical lead-out region 26 is further provided on the second semiconductor substrate 20 for exposing the electrode lead-out structure 244 to the outside.

[0133] It should be noted that, by bonding the electrodes between the two mirror components and leading them out to the electrical lead-out area 26 , cross-layer distribution of the electrodes can be achieved.

[0134] It should be further explained that the four piezoelectric driver structures 221 are driven individually, and the same voltage may be applied, or different bias voltages may be applied to the four drivers 221 according to the settings so that the four axes move at the same distance.

[0135] Specifically, the second mirror structure 23 includes a high reflectivity dielectric film. In this embodiment, the shape and size of the second mirror structure 23 are the same as those of the first mirror structure 11 , and the second mirror structure 23 and the first mirror structure 11 are coaxial.

[0136] Specifically, Figure 3 As shown, a second bonding structure 24 is further provided on the first surface of the second semiconductor substrate 20 ; the second bonding structure 24 is provided around the periphery of the piezoelectric driving structure 22 .

[0137] In this embodiment, the second bonding structure 24 is arranged corresponding to the first bonding structure 13, and is arranged on three sides of the second semiconductor substrate 20. The second bonding structure 24 and the piezoelectric driving structure 22 have the same structure as each layer, and both include an upper metal layer 240, a piezoelectric film material layer 241, and a lower metal layer 242 stacked in sequence.

[0138] Specifically, a second high-transmittance film 25 is disposed on the second surface of the second semiconductor substrate 20; the second high-transmittance film 25 covers the area where the second mirror structure 23 is located. In this embodiment, the second high-transmittance film 25 and the second mirror structure 23 have identical cross-sectional shapes and are coaxially disposed with each other, thereby enabling control of the linewidth of the narrowband light source transmitted and received between the area where the second mirror structure 23 is located.

[0139] It should be noted that in this embodiment, the piezoelectric drive structure 22 and the membrane island structure (movable cantilever structure 21 and second mirror structure 23) are integrated on the wafer, which helps improve the consistency of device manufacturing, meet the requirements of large-scale production, and improve the integration level. In addition, the membrane island structure ensures that the movable mirror will not warp due to coating stress during coating, thereby destroying the FP resonance.

[0140] like Figure 1 As shown, the first semiconductor substrate 10 is bonded to the second semiconductor substrate 20 to arrange the first mirror structure 11 and the second mirror structure 23 relative to each other, and the braking groove 12 is correspondingly accommodated in the movable cantilever structure 21 to provide a translation space for the second mirror structure and ensure the moving gap of the movable mirror component; a cavity is further provided between the first mirror structure 11 and the second mirror structure 23 as a Fabry-Perot cavity 230, and the movement of the first end of the movable cantilever structure 21 is regulated based on the piezoelectric driving structure 22 to regulate the cavity length of the Fabry-Perot cavity 230, thereby realizing the tunability of the optical filter, as shown in FIG. Figure 6As shown, by changing the driving voltage, the wavelength of light processed by the optical filter can be effectively controlled.

[0141] Specifically, in this embodiment, when the first surface of the first semiconductor substrate 10 further includes a first bonding structure 13 and an electrode bonding structure 14 and the first surface of the second semiconductor substrate 20 further includes a second bonding structure 24, the first bonding structure 13 and the second bonding structure 24 are bonded correspondingly; the electrode bonding structure 14 and the piezoelectric driving component 22 are bonded correspondingly.

[0142] More specifically, the bonding structure is conducive to ensuring the controllable cavity length of the Fabry-Perot cavity 230 and the relative parallelism between the movable mirror component 2 and the stationary mirror component 1 at high frequencies.

[0143] In this embodiment, the main performance of the tunable optical filter with a Fabry-Perot cavity includes filtering bandwidth, filtering linewidth and scanning frequency. The filtering bandwidth depends on the cavity length and driving voltage of the Fabry-Perot cavity. In this embodiment, the cavity length of the Fabry-Perot cavity depends on the difference between the total thickness of the first oxide layer 131, the first metal layer 132, the electrode lead structure 244, the passivation layer 243, the upper metal layer 240, the piezoelectric thin film material layer 241, the lower metal layer 242, the electrical isolation layer 204, the buried oxide layer 202 and the top single crystal silicon layer 203 and the first mirror structure 11 and the second mirror structure 23, that is:

[0144] h fp =h 131 +h 132 +h 244+ h 243+ h 242+ h 241+ h 240+ h 204+ h 203+ h 202 -h 11 -h 23 (1)

[0145] Among them, when h FP is the length of the Fabry-Perot cavity, h 131 、h 132 、h 244 、h 243 、h 242 、h 241 、h 240 、h 204 、h 203 、h 202 、h 11 、h 23They are respectively the thickness of the first oxide layer 131, the first metal layer 132, the electrode lead structure 244, the passivation layer 243, the lower metal layer 242, the piezoelectric thin film material layer 241, the upper metal layer 240, the electrical isolation layer 204, the top single crystal silicon layer 203, the buried oxide layer 202, the first mirror structure 11 and the second mirror structure 23.

[0146] The movement of the cavity length of the Fabry-Perot cavity and the frequency shift of the resonance peak also depend on the m coefficient, which can be determined using formula (2):

[0147]

[0148] Where λ0 is the center wavelength of the dielectric film.

[0149] When there is a voltage difference between the upper metal layer 240 and the lower metal layer 242 in the piezoelectric driving structure 22 on the movable cantilever structure 21, the piezoelectric thin film material layer 241 deforms, forcing the membrane island structure composed of the movable cantilever structure 21 and the second mirror structure 23 to produce translational motion. V , we can get the filtering bandwidth to satisfy:

[0150]

[0151] Wherein, λv is the filter bandwidth. The filter line width is the half-maximum width of the resonance peak of the formed Fabry-Perot cavity, and the half-maximum width depends on the reflectivity of the dielectric films 206 and 310. When h FP =3.1um, the m coefficient is 2. Under a driving voltage of 90V, the moving distance of the movable mirror is 1260nm through finite element simulation, so the filter bandwidth λ V =630nm. Therefore, different filtering bandwidths can be achieved by changing the cavity length and driving voltage of the Fabry-Perot cavity. FP =3.1um and the reflectivity is 99.6%, the filter line width is 0.3nm. The filter line width decreases with the increase of reflectivity, such as Figure 7 As shown, the Fabry-Perot cavity length is reduced, shifting the resonant peak wavelength of the transmitted light, thus achieving filtering. In this embodiment, the scanning frequency is determined by the eigenfrequency of the movable mirror. Under certain driving voltage conditions, to minimize the impact of the scanning frequency on the filtering bandwidth, the operating frequency should be kept as far away from the eigenfrequency of the movable mirror as possible.

[0152] like Figure 8 The figure shows a tunable optical filter. The movable mirror component 2 is supported by three movable cantilever structures 21 and driven by the electric drive structure 22 connected to the movable cantilever structures 21. The movable mirror component 2 and the stationary mirror component 1 are integrated by BCB bonding process, and the transmission spectrum is as follows: Figure 9 As shown. The FSR of the bonded Fabry-Perot cavity is 24nm, corresponding to a cavity length of 50μm. In this example, both the movable mirror component 2 and the stationary mirror component 1 are deposited with a 93% reflective film (mirror structure), and the filter linewidth is 1.2nm. This example achieves a spectral filter bandwidth of 19nm from 1535.6nm to 1554.6nm under a ±90V driving voltage, as shown in the figure. Figure 10 shown.

[0153] like Figure 1 As shown, the tunable optical filter also includes a first fiber collimator 3 and a second fiber collimator 4; the first fiber collimator 3 is arranged above the second surface of the first semiconductor substrate 30; the second fiber collimator 4 is arranged above another surface opposite to the surface on which the second mirror structure is arranged, which is above the second surface of the second semiconductor substrate 20 in this embodiment.

[0154] Specifically, as an example, when a first high-transmittance film 15 is provided on the second surface of the first semiconductor substrate 10, a second high-transmittance film 25 is provided on the second surface of the second semiconductor substrate 20, and the tunable optical filter further includes a first fiber collimator and a second fiber collimator, the first surface of the first fiber collimator 3 includes a third high-transmittance film 31; the first surface of the second fiber collimator 4 includes a fourth high-transmittance film 41; the third high-transmittance film 31 is disposed opposite the first high-transmittance film 15; and the fourth high-transmittance film 41 is disposed opposite the second high-transmittance film 25. In this embodiment, the first high-transmittance film 15, the second high-transmittance film 25, the third high-transmittance film 31, and the fourth high-transmittance film 41 are coaxially disposed to facilitate control of the light source linewidth. At the same time, the high-transmittance films are all configured as composite dielectric films, which include but are not limited to multiple layers of alternating silicon oxide and tantalum oxide, multiple layers of alternating silicon oxide and titanium oxide, and multiple layers of alternating silicon oxide and nitrogen oxide.

[0155] like Figure 11 As shown, this embodiment also provides a method for preparing a tunable optical filter, comprising:

[0156] like Figure 11 As shown, in step S1 , a first semiconductor substrate 10 is provided, and a stationary mirror component 1 is prepared on a first surface of the first semiconductor substrate 10 ; the stationary mirror component 1 includes a first mirror structure 11 and a braking groove 12 ; the braking groove 12 is arranged around the first mirror structure 11 .

[0157] Specifically, if Figure 12 As shown, the steps of forming the stationary mirror component 1 specifically include:

[0158] A first device region is defined on the first surface of the first semiconductor substrate 10; the first device region is patterned and etched to obtain a boss and a braking groove 12 (such as Figure 12(c)), and perform dielectric film patterning deposition on the boss 121 (as shown in FIG. Figure 12 (d)), a first mirror structure 11 is obtained.

[0159] It should be noted that, in this embodiment, the dielectric thin film patterning deposition of the first mirror structure 11 adopts methods including but not limited to a lift-off process, a dry etching process, and a shadow mask process.

[0160] like Figure 11 As shown, step S2, providing a second semiconductor substrate 20, and preparing a movable mirror component 2 on the first surface of the second semiconductor substrate 20; the movable mirror component 2 includes a movable cantilever structure 21, a piezoelectric drive structure 22 and a second mirror structure 23; wherein, the first end of the movable cantilever structure 21 is connected to the second mirror structure 23, and the second end is connected to the piezoelectric drive structure 22.

[0161] Specifically, the second semiconductor substrate 20 includes an SOI substrate, and the SOI substrate includes a bottom single crystal silicon layer 201 , a buried oxide layer 202 , and a top single crystal silicon layer 203 stacked in sequence.

[0162] Specifically, if Figure 13 As shown, the steps of forming the movable mirror component 2 specifically include:

[0163] A second device region is defined on the upper surface of the second semiconductor substrate 20; the second device region is divided into a piezoelectric drive region and a cantilever region, and the piezoelectric drive region is subjected to metallization deposition and patterned etching to form a piezoelectric drive structure 22, and the cantilever region is patterned etched to obtain an etched groove and a movable cantilever structure 21 arranged around the etched groove; a dielectric film is patterned deposited on the etched groove to obtain a second mirror structure 23.

[0164] In this embodiment, cantilever grooves 231 are etched between the movable cantilever structures 21 to allow the movable cantilever structures 21 and the second mirror structure 23 to function as a membrane island structure for translation. In this embodiment, the second surface of the second semiconductor substrate 20 is subsequently etched to release the movable cantilever structures 21 and ensure their ability to translate vertically.

[0165] In this embodiment, the preparation method further includes the step of pre-treating the second semiconductor substrate 20, specifically comprising: forming an electrical isolation layer 204 on the first surface of the second semiconductor substrate 20; the electrical isolation layer 204 is used to isolate the movable mirror component 2 from the second semiconductor substrate 20. In this embodiment, a silicon dioxide layer is obtained by oxidizing the second semiconductor substrate 20 to serve as the electrical isolation layer.

[0166] like Figure 11As shown, in step S3, the first semiconductor substrate 10 is bonded to the second semiconductor substrate 20, so that the first mirror structure 11 and the second mirror structure 23 are arranged relative to each other and the braking groove 22 corresponds to accommodate the movable cantilever structure 21; wherein, a cavity is also formed between the first mirror structure 11 and the second mirror structure 23 as a Fabry-Perot cavity 230.

[0167] Specifically, if Figure 14 As shown, the step of bonding the first semiconductor substrate 10 to the second semiconductor substrate 20 specifically includes:

[0168] Step S31, forming a first oxide layer 131 and a first metal layer 132 in sequence from bottom to top on the first surface of the first semiconductor substrate 10, and dividing the surface of the first metal layer 132 into a first bonding area and a first device area; the first bonding area is arranged around the first device area; the first bonding area is graphically etched to form a first bonding structure 13 and an electrode bonding structure 14; the first bonding structure 13 is arranged around the periphery of the electrode bonding structure 14.

[0169] In this embodiment, the first bonding structure 13 and the electrode bonding structure 14 are prepared before preparing the stationary mirror component 1 .

[0170] Combine Figure 12 To illustrate: A first oxide layer 131 is formed by oxidation on the first surface of the first semiconductor substrate 10, and then a first metal layer 132 is deposited on the first oxide layer 131. Using a MEMS etching process, the first oxide layer 131 and the first metal layer 132 in the first bonding region are sequentially etched to form a first bonding structure 13 and an electrode bonding structure 14. Next, a deep silicon etching process is used to etch the first device region to form a braking groove 12, and a first mirror structure 11 is deposited on the boss 121.

[0171] Step S32, depositing a lower metal layer 240, a piezoelectric thin film material layer 241 and an upper second metal layer 242 in sequence from bottom to top on the first surface of the second semiconductor substrate 20; and dividing the surface of the lower metal layer 242 into a second bonding area and a second device area; the second bonding area is arranged around the second device area; and the second bonding area is graphically etched to obtain a second bonding structure 24.

[0172] In this embodiment, the cantilever region is patterned and etched to obtain the movable cantilever structure 21 and the grooves. The pad exposed region 261 is also etched simultaneously to serve as the subsequent electrical lead-out region 26. Simultaneously, in this embodiment, the piezoelectric drive structure 22 is prepared while the second bonding structure is prepared.

[0173] Combine Figure 13 To illustrate: On the second conductive substrate 20 (eg Figure 13 (a)) is oxidized to form an electrical isolation layer 204 (as shown in FIG. Figure 13 (b)); then depositing the upper metal layer 240, the piezoelectric film material layer 241 and the lower metal layer 242 on the electrical isolation layer 204 in sequence (as shown in FIG. Figure 13 (c)); the piezoelectric film material layer 241, the upper metal layer 240, and the lower metal layer 242 are patterned and etched by an etching process to obtain a second bonding structure 24 and a piezoelectric driving structure 22 in the second bonding area (as shown in FIG. Figure 13 (d)). Then, silicon dioxide is deposited as a passivation layer 243, and the passivation layer 243 and the electrical isolation layer 204 in the second device region are dry-etched; and the bottom single crystal silicon layer 201 and the buried oxide layer 202 in the second device region are etched again to obtain the movable cantilever structure 21 and the etched groove (as shown in FIG. Figure 13 (e)). The dielectric film is patterned and deposited on the etched groove to obtain the second mirror structure 23 (as shown in FIG. Figure 13 (f) shown.

[0174] Step S33: Bond the first bonding structure 13 to the second bonding structure 24, and bond the electrode bonding structure 14 to the piezoelectric drive structure 22. At this time, the first mirror structure 11 and the second mirror structure 23 are arranged opposite to each other, and the braking groove 12 corresponds to the movable cantilever structure 21.

[0175] Specifically, in this embodiment, bonding is achieved using processes including but not limited to metal bonding processes and BCB bonding processes.

[0176] More specifically, combined Figures 12 to 14 To illustrate, the preparation method also includes the step of preparing an electrode lead structure, specifically including:

[0177] After forming the second bonding structure and the piezoelectric drive structure, a passivation layer 243 is deposited on the first surface of the second semiconductor substrate and etched to expose a portion of the piezoelectric drive structure 22 to form an electrode hole. At least the electrode hole is metallized and patterned to form an electrode lead-out structure 244, thereby electrically leading the piezoelectric drive structure 22 corresponding to the electrode hole. While patterning the cantilever region to form the movable cantilever structure 21 and etching the groove, a sidewall of the second semiconductor substrate 20 is also etched to form a pad exposure region 261 (corresponding to the pad lead-out region 16 provided on the first semiconductor substrate 10), facilitating the placement of the lead-out end of the electrode lead-out structure 244 in the same pad exposure region 261 for lead-out to form an electrical lead-out region 26. While the first bonding structure and the second bonding structure are bonded to each other, the electrode lead-out structure 244 is attached to the pad exposure region 261.

[0178] In this embodiment, while bonding the first semiconductor substrate 10 and the second semiconductor substrate 20, the second surface of the second semiconductor substrate 20 is also etched to release the cantilever space 211 under the cantilever to form an elastic structure to improve the elastic deformation capability.

[0179] like Figure 14 As shown, the preparation method also includes the steps of patterning and depositing a first high-transmittance film 15 on the second surface of the first semiconductor substrate 10; and patterning and depositing a second high-transmittance film 25 on the second surface of the second semiconductor substrate 20; wherein the first high-transmittance film 15 covers the area where the first mirror structure 11 is located; and the first high-transmittance film 25 covers the area where the second mirror structure 23 is located.

[0180] like Figure 1 As shown, the preparation method further includes the step of welding the first optical fiber collimator 3 and the second optical fiber collimator 4, specifically including:

[0181] A first fiber collimator 3 and a second fiber collimator 4 are provided. The first fiber collimator 3 is coupled to the second surface of the first semiconductor substrate 10 by gluing or welding; the second fiber collimator 4 is coupled to the second surface of the second semiconductor substrate 20 by gluing or welding.

[0182] In this embodiment, the first fiber collimator 3 and the second fiber collimator 4 are integrated on the same wafer by fusion, gluing, or welding to form the final device. This allows for the input of a broadband light source and the output of a narrowband light source, thus achieving filtering. By combining the advantages of MEMS technology and piezoelectric drive, a tunable optical filter with a large linear filtering range, narrow filter linewidth, and high scanning speed can be realized.

[0183] In this embodiment, if Figure 1 As shown, in order to achieve low-loss transmission of the light source, a third high-transmittance film 31 and a fourth high-transmittance film 41 are deposited on the first surface of the third semiconductor substrate 30 where the first optical fiber collimator 3 is located and the first surface of the fourth semiconductor substrate 40 where the second optical fiber collimator 4 is located, respectively. The third high-transmittance film 31 is opposite to the first high-transmittance film 15, and the fourth high-transmittance film 41 is opposite to the second high-transmittance film 25.

[0184] Example 2

[0185] This embodiment is basically the same as the first embodiment, except that the second mirror structure is located at a different position. Figure 14 As shown, in this embodiment, the second mirror structure 23 is disposed on the second surface of the second semiconductor substrate 20 .

[0186] Specifically, when the second mirror structure 23 is arranged on the second surface of the second semiconductor substrate, a third bonding structure 17 is also arranged on the first surface of the first semiconductor substrate 10; the third bonding structure 17 is arranged along the periphery of the braking groove 12; a fourth bonding structure 27 is also arranged on the second surface of the second semiconductor substrate 20; the fourth bonding structure 27 is arranged around the second mirror structure 23; wherein, the third bonding structure 17 and the fourth bonding structure 27 are bonded correspondingly.

[0187] In this embodiment, the first semiconductor substrate 10 is configured as an SOI substrate, which is stacked with a bottom single crystal silicon layer, a buried oxide layer, and a top single crystal silicon layer in sequence from bottom to top. In this embodiment, the steps of forming the first mirror structure include: defining a first device region on the first surface of the first semiconductor substrate 10; patterning the first device region to obtain a braking groove, and patterning a dielectric film deposition in the braking groove to obtain a first mirror structure 11. That is, in this embodiment, the SOI substrate is directly etched to obtain the braking groove, and the center position of the braking groove is patterned and deposited to obtain the first mirror structure 11 at the center position. In fact, the provision of a concave platform can be used to adjust the cavity length of the initial Fabry-Perot cavity. The provision of a convex platform of different heights or no convex platform can be based on different needs, all of which are within the scope of protection of this embodiment.

[0188] It should be noted that the position of the bonding structure in this embodiment varies depending on the position of the second mirror structure, as long as the first and second mirror structures are positioned relative to each other and the cavity between them can form a Fabry-Perot cavity. Furthermore, the electrode lead-out structure in this embodiment is still provided on the piezoelectric drive structure, for electrically leading the upper and lower electrodes therein.

[0189] It should be further explained that the setting position of the high-transmittance film and the optical fiber collimator in this embodiment can be set with reference to the principle of Example 1. As long as the two optical fiber collimators are respectively located outside the overall structure bonded to the movable mirror component 2 and the stationary mirror component 1, so as to facilitate the penetration of the light beam into the Fabry-Perot cavity, they are all within the protection scope of this embodiment.

[0190] This embodiment also provides a method for preparing a tunable optical filter, which is basically the same as that of the first embodiment, except that the steps for preparing the movable mirror component are different.

[0191] Specifically, the steps of forming the movable mirror component include: defining a third device region on the first surface of the second semiconductor substrate 20; dividing the third device region into a piezoelectric drive region and a cantilever region, and performing metallization deposition and patterned etching on the piezoelectric drive region to form a piezoelectric drive structure 22; patterned etching on the cantilever region to obtain an etched groove and a movable cantilever structure 21 disposed around the etched groove; defining a fourth device region on the second surface of the second semiconductor substrate 20; disposing the fourth device region at a position corresponding to the etched groove; and patterned deposition of a dielectric film on the fourth device region to obtain a second mirror structure 23. In this embodiment, the steps of forming the movable mirror component are substantially the same as those in the first embodiment, except that the second mirror structure 23 is formed at a different location. The specific principles and configurations have been described above and will not be repeated here.

[0192] The method for preparing the tunable optical filter of this embodiment is different from that of the first embodiment in that the steps of bonding the movable mirror component 2 and the stationary mirror component 1 are different, specifically including:

[0193] As an example, in this embodiment, when the second mirror structure 23 is disposed on the second surface of the second semiconductor substrate 20, a second oxide layer 171 and a second metal layer 172 are sequentially formed on the first surface of the first semiconductor substrate 10 from bottom to top. The surface of the second metal layer 172 is divided into a third bonding region and a third device region. The third bonding region is disposed around the third device region. The third bonding region is patterned and etched to form a third bonding structure 17. The third bonding structure is disposed around the periphery of the braking groove 12. The specific principles and steps for the third bonding structure 17 are substantially the same as those for the first bonding structure and have been described above, so they will not be repeated here.

[0194] As an example, in this embodiment, a third oxide layer 271 and a third metal layer 272 are sequentially formed on the second surface of the second semiconductor substrate 20 from bottom to top, and the surface of the third metal layer 271 is divided into a fourth bonding region; the fourth bonding region is arranged around the second mirror structure 23. The specific principles and steps of the fourth bonding structure 27 are basically the same as those of the first bonding structure, and the corresponding configuration can be referred to above.

[0195] In this embodiment, the third bonding structure and the fourth bonding structure are bonded to each other to ensure device bonding.

[0196] The method for preparing the tunable optical filter of this embodiment differs from that of the first embodiment in that the steps for preparing the electrode lead structure are different, specifically including:

[0197] When the second mirror structure 23 is disposed on the second surface of the second semiconductor substrate 20, after the piezoelectric driving structure 22 is formed, the passivation layer is etched on the first surface of the second semiconductor substrate 20 to expose a portion of the piezoelectric driving structure 22 to form an electrode hole; at least the electrode hole is metallized and patterned and etched to obtain an electrode lead structure.

[0198] In this embodiment, the piezoelectric drive structure 22 and the fourth bonding structure are not disposed on the same surface, allowing subsequent electrical leads to be directly connected to the upper surface of the piezoelectric drive structure 22, eliminating the need for an additional electrical lead-out area. In fact, the electrical lead-out method is not limited to this embodiment; any method that can ensure the piezoelectric drive structure 22 is within the scope of this embodiment.

[0199] It should be noted that the high-transmittance film setting and the setting steps of the optical fiber collimator in this embodiment can also refer to the principle setting of Example 1. As long as the setting ensures that the light beam penetrates into the Fabry-Perot cavity, it is within the protection scope of this embodiment.

[0200] In summary, the present invention provides a tunable optical filter and a method for preparing the same, wherein the tunable optical filter comprises: a stationary mirror component and a movable mirror component; the stationary mirror component comprises a first mirror structure and a braking groove; the movable mirror component comprises a movable cantilever structure, a piezoelectric drive structure, and a second mirror structure; wherein the first end of the movable cantilever structure is connected to the second mirror structure, and the second end is connected to the piezoelectric drive structure; the first semiconductor substrate and the second semiconductor substrate are bonded to position the first mirror structure relative to the second mirror structure; a cavity is further provided between the first mirror structure and the second mirror structure as a Fabry-Perot cavity, and the movement of the first end of the movable cantilever structure is controlled based on the piezoelectric drive structure to control the cavity length of the Fabry-Perot cavity. The piezoelectric drive structure of the present invention is directly provided on the movable cantilever structure, achieving a high degree of integration of the piezoelectric drive structure and the movable mirror component, thereby achieving miniaturization consistency and mass production, and can be applied in the fields of optical fiber signal demodulation and spectral analysis. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0201] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A tunable optical filter, characterized in that: The tunable optical filter comprises at least: a stationary mirror component and a movable mirror component; The stationary mirror component includes a first mirror structure and a braking groove provided on a first surface of a first semiconductor substrate; wherein the braking groove is provided around the first mirror structure; The movable mirror component includes a movable cantilever structure, a piezoelectric drive structure, and a second mirror structure; wherein the movable cantilever structure and the piezoelectric drive structure are disposed on the first surface of the second semiconductor substrate; the second mirror structure is disposed on the first surface or the second surface of the second semiconductor substrate; the first end of the movable cantilever structure is connected to the second mirror structure, and the second end is connected to the piezoelectric drive structure; The first semiconductor substrate is bonded to the second semiconductor substrate, the first mirror structure and the second mirror structure are arranged opposite to each other, and the braking groove corresponds to accommodate the movable cantilever structure to provide a translational space for the second mirror structure; a cavity is also set between the first mirror structure and the second mirror structure as a Fabry-Perot cavity, and the movement of the first end of the movable cantilever structure is regulated based on the piezoelectric drive structure to regulate the cavity length of the Fabry-Perot cavity.

2. The tunable optical filter according to claim 1, wherein: The tunable optical filter further includes an electrode lead-out structure, which is disposed above the piezoelectric drive structure and is used to electrically lead out the piezoelectric drive structure.

3. The tunable optical filter according to claim 1, wherein: The first semiconductor substrate includes a silicon substrate or an SOI substrate; the second semiconductor substrate includes an SOI substrate; the SOI substrate is stacked with a bottom single crystal silicon layer, a buried oxide layer and a top single crystal silicon layer in sequence from bottom to top.

4. The tunable optical filter according to claim 1, wherein: When the second mirror structure is provided on the first surface of the second semiconductor substrate, a first bonding structure and an electrode bonding structure are also provided on the first surface of the first semiconductor substrate; the first bonding structure and the electrode bonding structure are both provided along the periphery of the braking groove, and the distance between the first bonding structure and the first mirror structure is greater than the distance between the electrode bonding structure and the first mirror structure; A second bonding structure is further provided on the first surface of the second semiconductor substrate; the second bonding structure is provided around the periphery of the piezoelectric driving structure; Wherein, the first bonding structure and the second bonding structure are bonded correspondingly; the electrode bonding structure and the piezoelectric driving component are bonded correspondingly; Alternatively, when the second mirror structure is provided on the second surface of the second semiconductor substrate, a third bonding structure is further provided on the first surface of the first semiconductor substrate; the third bonding structure is provided along the periphery of the braking groove; A fourth bonding structure is further provided on the second surface of the second semiconductor substrate; the fourth bonding structure is provided around the second mirror structure; Wherein, the third bonding structure and the fourth bonding structure are bonded correspondingly.

5. The tunable optical filter according to claim 1, wherein: The tunable optical filter further includes a first fiber collimator and a second fiber collimator; the first fiber collimator is disposed above the second surface of the first semiconductor substrate; The second optical fiber collimator is disposed above another surface opposite to the surface on which the second mirror structure is disposed.

6. A method for preparing a tunable optical filter, characterized in that: The preparation method at least comprises: Providing a first semiconductor substrate, and preparing a stationary mirror component on a first surface of the first semiconductor substrate; the stationary mirror component includes a first mirror structure and a braking groove; the braking groove is arranged around the first mirror structure; A second semiconductor substrate is provided, and a movable mirror component is prepared on the second semiconductor substrate; the movable mirror component includes a movable cantilever structure, a piezoelectric drive structure, and a second mirror structure; wherein the movable cantilever structure and the piezoelectric drive structure are disposed on the first surface of the second semiconductor substrate; the second mirror structure is disposed on the first surface or the second surface of the second semiconductor substrate; the first end of the movable cantilever structure is connected to the second mirror structure, and the second end is connected to the piezoelectric drive structure; The first semiconductor substrate and the second semiconductor substrate are bonded to each other so that the first mirror structure and the second mirror structure are arranged opposite to each other and the braking groove corresponds to accommodating the second mirror structure; wherein a cavity is further formed between the first mirror structure and the second mirror structure as a Fabry-Perot cavity.

7. The method for preparing a tunable optical filter according to claim 6, wherein: The steps of forming the stationary mirror component specifically include: A first device region is defined on the first surface of the first semiconductor substrate; the first device region is patterned and etched to obtain a boss and the braking groove provided around the boss, and a dielectric film is patterned and deposited on the boss to obtain the first mirror structure; or a first device region is defined on the first surface of the first semiconductor substrate; the first device region is patterned and etched to obtain the braking groove, and a dielectric film is patterned and deposited on the braking groove to obtain the first mirror structure; The steps of forming the movable mirror component specifically include: A second device region is defined on the first surface of the second semiconductor substrate; the second device region is divided into a piezoelectric drive region and a cantilever region, and the piezoelectric drive region is subjected to metallization deposition and patterned etching to form the piezoelectric drive structure; the cantilever region is patterned etched to obtain an etched groove and the movable cantilever structure disposed around the etched groove; a dielectric film is patterned deposited on the etched groove to obtain the second mirror structure; Alternatively, a third device area is defined on the first surface of the second semiconductor substrate; the third device area is divided into a piezoelectric drive area and a cantilever area, and the piezoelectric drive area is subjected to metallization deposition and patterned etching to form the piezoelectric drive structure; the cantilever area is patterned etched to obtain etched grooves and the movable cantilever structure arranged around the etched grooves; a fourth device area is defined on the second surface of the second semiconductor substrate; the fourth device area is arranged at a position corresponding to the etched grooves; a dielectric thin film is patterned deposited on the fourth device area to obtain the second mirror structure.

8. The method for preparing a tunable optical filter according to claim 7, wherein: The step of bonding the first semiconductor substrate to the second semiconductor substrate specifically includes: When the second mirror structure is provided on the first surface of the second semiconductor substrate, a first oxide layer and a first metal layer are sequentially formed on the first surface of the first semiconductor substrate from bottom to top, and the surface of the first metal layer is divided into a first bonding area and a first device area; the first bonding area is provided around the first device area; the first bonding area is patterned and etched to form a first bonding structure and an electrode bonding structure; the first bonding structure is provided around the periphery of the electrode bonding structure; Depositing a second metal layer, a piezoelectric thin film material layer, and a third metal layer on the first surface of the second semiconductor substrate in order from bottom to top, and dividing the surface of the third metal layer into a second bonding area and a second device area; the second bonding area is arranged around the second device area; and patterning and etching the second bonding area to obtain the second bonding structure; Bonding the first bonding structure to the second bonding structure correspondingly; bonding the electrode bonding structure to the piezoelectric driving structure correspondingly; Alternatively, when the second mirror structure is provided on the second surface of the second semiconductor substrate, a second oxide layer and a second metal layer are sequentially formed on the first surface of the first semiconductor substrate from bottom to top, and the surface of the second metal layer is divided into a third bonding area and the third device area; the third bonding area is provided around the third device area; the third bonding area is patterned and etched to form a third bonding structure; and the third bonding structure is provided around the periphery of the braking groove; forming a third oxide layer and a third metal layer in sequence from bottom to top on the second surface of the second semiconductor substrate, and dividing the surface of the third metal layer into the fourth bonding area; the fourth bonding area is arranged around the second mirror structure; The third bonding structure and the fourth bonding structure are bonded and arranged correspondingly.

9. The method for preparing a tunable optical filter according to claim 8, wherein: The preparation method further includes the step of preparing an electrode lead-out structure, specifically comprising: When the second mirror structure is disposed on the first surface of the second semiconductor substrate, after forming the second bonding structure and the piezoelectric driving structure, a passivation layer is deposited on the first surface of the second semiconductor substrate, and the passivation layer is etched to expose a portion of the piezoelectric driving structure to form an electrode hole; At least performing metallization deposition and pattern etching on the electrode hole to obtain an electrode lead-out structure to electrically lead out the piezoelectric drive structure corresponding to the electrode hole; While patterning and etching the cantilever region to obtain the movable cantilever structure and the etching groove, a side wall of the second semiconductor substrate is also etched to obtain a pad exposure region; While correspondingly bonding the first bonding structure to the second bonding structure, the electrode lead-out structure is led out to the pad exposed area; Alternatively, when the second mirror structure is arranged on the second surface of the second semiconductor substrate, after the piezoelectric driving structure is formed, the passivation layer is etched on the first surface of the second semiconductor substrate and a portion of the piezoelectric driving structure is exposed to form an electrode hole; at least the electrode hole is metallized and patterned and etched to obtain an electrode lead-out structure.

10. The method for preparing a tunable optical filter according to claim 6, wherein: The preparation method further includes the step of welding the first optical fiber collimator and the second optical fiber collimator, specifically comprising: Providing a first optical fiber collimator and a second optical fiber collimator, and coupling the first optical fiber collimator to the second surface of the first semiconductor substrate by gluing or welding; The second optical fiber collimator is coupled to another surface opposite to the surface where the second mirror structure is provided by gluing or welding.

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