Tunable fabry-perot cavity device with movable mirror and method of manufacturing the same

Abstract

An adjustable Fabry-Perot cavity device with a movable mirror, the movable mirror is arranged opposite to another mirror, the movable mirror and the other mirror are bonded at the periphery to form a Fabry-Perot cavity between the mirrors, the movable mirror comprises a silicon thin film (10) inlaid with glass (12), the middle region of the silicon thin film is inlaid with glass to form a light transmission region, and the surface of the light transmission region facing the cavity is formed with a mirror material, and the transition region between the bonded peripheral region of the silicon thin film and the middle region is inlaid with glass to form an elastic structure. Since the Young's modulus of silicon is much higher than that of glass, the silicon thin film inlaid with glass can have good mechanical strength and stable elastic coefficient, and is not affected by stress, so that the movable mirror has good controllability and stability, and the inlaid combination of glass and silicon can increase the flexibility of device design.

Description

Technical Field

[0001] This invention relates to the field of semiconductor devices, and more particularly to an adjustable Fabry-Perot cavity device with a movable mirror and a method for manufacturing the same. Background Technology

[0002] Tunable filter devices (FPIs) based on Fabry-Perot interferometry can be used to fabricate miniature spectrometers and small or even miniature hyperspectral cameras. Fabry-Perot cavity devices in the visible-near-infrared range typically use optical glass (such as synthetic quartz glass) as a substrate, forming mirror chips through optical and semiconductor processing. Two mirror chips are then assembled with an external piezo actuator to form a Fabry-Perot cavity module. However, this results in a large Fabry-Perot cavity module with high driving voltage, making it unsuitable for applications in space-constrained devices, such as handheld hyperspectral cameras.

[0003] On the other hand, Fabry-Perot cavity devices formed by micromachining are mainly bulk and surface-machining types. Surface-machining devices form movable mirrors from suspended thin films; bulk-machining devices form movable mirrors from substrates with cantilever beam structures.

[0004] Since Fabry-Perot cavity devices in the visible-near-infrared range typically use optical glass (such as synthetic quartz glass) as substrates, several challenges arise. First, glass can only be etched with chemical solvents (such as hydrofluoric acid), but the etching rate is very slow (less than 1 micrometer / minute), making substrate fabrication extremely difficult. Furthermore, the achievable line dimensions are limited by the substrate thickness (typically 400 to 700 micrometers), hindering fine machining. Second, fabricating cantilever beams on the substrate increases the complexity of device design and fabrication, thus increasing costs. Third, in bulk fabrication devices, the elastic structure (spring) and the mirror are provided by the same substrate, resulting in the mirror being subject to stress and deformation due to the influence of the elastic structure. Finally, the cantilever beam structure occupies a large chip area, which also limits the size of the mirror itself. Summary of the Invention

[0005] To address the issues of controllability, stability, and design flexibility of movable mirrors in existing Fabry-Perot cavity devices, this invention proposes an adjustable Fabry-Perot cavity device with movable mirrors and its manufacturing method, aiming to resolve these problems.

[0006] This invention proposes an adjustable Fabry-Perot cavity device with a movable mirror. The movable mirror is positioned opposite another mirror and is bonded to each other on its periphery to form a Fabry-Perot cavity between the mirrors. The movable mirror includes a silicon thin film embedded with glass. The central region of the silicon thin film is embedded with glass to form a light-transmitting region, and a mirror material is formed on the surface of the light-transmitting region facing the cavity. The transition region between the bonded peripheral region and the central region of the silicon thin film is embedded with glass to form an elastic structure. Since silicon has a much higher Young's modulus than glass, the silicon thin film embedded with glass can possess good mechanical strength and a stable elastic coefficient, and is unaffected by stress. This results in good controllability and stability for the movable mirror. Furthermore, the combination of glass and silicon increases the flexibility of device design. By adjusting the design of the embedded structure, the same device structure can be applied to devices of different sizes. Additionally, the conductivity of silicon can be adjusted through doping, so the movable mirror can also form an electrode structure for the electrodes of the external leads of the adjustable Fabry-Perot cavity device.

[0007] In a preferred embodiment, a silicon layer remaining between the transition region and the central region of the silicon thin film forms a ring-shaped support structure. This ring-shaped support structure formed by the silicon layer enhances the mechanical flatness of the movable mirror.

[0008] In a preferred embodiment, the annular support structure is partially removed to form a vent. This vent facilitates rapid airflow between the Fabry-Perot cavity and the outside air, thereby increasing the instantaneous response speed of the movable mirror within the Fabry-Perot cavity during movement.

[0009] In a preferred embodiment, the movable mirror is fabricated using an SOI wafer, wherein the glass is filled into the SOI wafer by etching the silicon layer of the SOI wafer. The variety of fabrication methods for the movable mirror allows for the selection of a suitable fabrication method based on actual needs.

[0010] In a preferred embodiment, the other mirror also comprises a silicon film embedded with glass. This variety of alternative mirror options allows for selection of a suitable mirror based on specific needs, increasing design flexibility.

[0011] In a preferred embodiment, the other mirror surface includes a fixed mirror surface, which comprises a glass substrate and a mirror material disposed on the glass substrate. The diverse selection of the other mirror surface allows for the selection of a suitable mirror surface according to actual needs, increasing design flexibility.

[0012] In a preferred embodiment, another movable mirror is also bonded to the other surface of the fixed mirror opposite to the movable mirror, and this other movable mirror and the other surface of the fixed mirror form another Fabry-Perot cavity. The diverse selection of the other mirror allows for the selection of a suitable mirror according to actual needs, increasing design flexibility.

[0013] In a preferred embodiment, the thickness of the glass-embedded silicon thin film is between 10 and 200 micrometers. The thickness of the embedded thin film is much smaller than that of conventional glass substrates (over 300 micrometers), making the device more compact.

[0014] In a preferred embodiment, the optical mirror is made of silicon, silicon oxide, or a combination thereof, or silver. The variety of mirror materials allows for the selection of a suitable material based on actual needs.

[0015] In a preferred embodiment, the bonding method includes eutectic bonding, polymer bonding, or anodic bonding. This bonding method allows for tight structural bonding, ensuring the stability of the tunable optical filter device.

[0016] In a preferred embodiment, a driving device is provided on the movable mirror surface for controlling the relative displacement of the movable mirror surface. The driving device causes relative displacement between the movable mirror surface and another mirror surface, thereby adjusting the gap between the cavities and achieving an adjustable optical filtering function.

[0017] In a preferred embodiment, the driving device includes a capacitor drive and an actuator drive with a piezoelectric thin film structure. The relative displacement of the movable mirror is controlled by the capacitor drive or the actuator drive with a piezoelectric thin film structure, thereby achieving an adjustable optical filtering effect.

[0018] In a preferred embodiment, the driving device includes a first electrode and a second electrode disposed on the periphery of the movable mirror and the surface opposite to the mirror, and in the embedded silicon layer region. A capacitive structure formed between the first and second electrodes allows for displacement of the movable mirror to adjust the cavity gap.

[0019] In a preferred embodiment, the driving device includes a piezoelectric thin film structure disposed on the periphery of the movable mirror and the surface opposite to the mirror. The piezoelectric thin film structure disposed on the movable mirror can deform the movable mirror, thereby causing displacement of the movable mirror.

[0020] In a preferred embodiment, the piezoelectric thin film is deposited on the movable mirror surface by sputtering or sol-gel.

[0021] In a preferred embodiment, the piezoelectric thin film structure includes a lead zirconate titanate film, an aluminum nitride film, or a zinc oxide film. The variety of materials used in the piezoelectric thin film structure allows for the selection of appropriate materials based on specific needs.

[0022] A method for manufacturing an adjustable Fabry-Perot cavity device with a movable mirror, characterized by comprising the following steps:

[0023] S1: Provide a substrate and etch a pattern of a certain depth onto the substrate;

[0024] S2: Melt the glass and fill it onto the etched substrate;

[0025] S3: Grind the surface of the substrate after the glass is filled to form a substrate inlaid with glass;

[0026] S4: Deposit optical mirror material onto the surface of a substrate inlaid with glass to form an optical mirror;

[0027] S5: Grinding or etching removes excess substrate to form a movable mirror or Fabry-Perot cavity with a thin-film structure inlaid with glass.

[0028] In a preferred embodiment, S5 further includes the following step:

[0029] S51: Two glass-embedded substrates with optical mirrors are bonded together to form a Fabry-Perot cavity between the mirrors;

[0030] S52: Grinding or etching to remove excess substrate to form a Fabry-Perot cavity with a thin-film structure inlaid with glass.

[0031] In a preferred embodiment, the substrate provided in S1 is a silicon substrate or an SOI substrate.

[0032] In a preferred embodiment, S1 includes the following steps:

[0033] S11: Provide an SOI substrate and etch the silicon layer on the SOI substrate to form a pattern of a certain depth;

[0034] S12: Provides a glass substrate and bonds the glass substrate to the SOI substrate.

[0035] The adjustable Fabry-Perot cavity device of the present invention has a movable mirror formed by glass and silicon inlay. Since the Young's hardness of silicon is much higher than that of glass, the movable mirror inlaid with glass and silicon can have good mechanical strength and a stable elastic coefficient, and is not affected by stress. This makes the movable mirror have good controllability and stability. Furthermore, the inlay combination of glass and silicon can increase the flexibility of device design. By adjusting the design of the inlay structure, the same device structure can be applied to devices of different sizes. In addition, the addition of silicon material adjusts its conductivity, so the movable mirror can also form an electrode structure for the electrodes of the external leads of the adjustable Fabry-Perot cavity device. Attached Figure Description

[0036] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. Other embodiments and many anticipated advantages of the embodiments will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0037] Figure 1 This is a cross-sectional view of an adjustable optical filter device according to an embodiment of the present invention;

[0038] Figure 2 This is a top view of an adjustable optical filter device according to an embodiment of the present invention;

[0039] Figure 3 This is a diagram illustrating a method of forming a movable mirror according to an embodiment of the present invention;

[0040] Figure 4 This is a cross-sectional view of an adjustable optical filter device according to a second embodiment of the present invention;

[0041] Figure 5 This is a cross-sectional view of an adjustable optical filter device according to a third embodiment of the present invention;

[0042] Figure 6 This is a cross-sectional view of an adjustable optical filter device according to a fourth embodiment of the present invention;

[0043] Figure 7 This is a cross-sectional view of an adjustable optical filter device according to a fifth embodiment of the present invention. Detailed Implementation

[0044] In the following detailed description, reference is made to the accompanying drawings, which form part of the detailed description and are illustrated by specific illustrative embodiments in which the invention may be practiced. In this regard, directional terms such as “top,” “bottom,” “left,” “right,” “up,” “down,” etc., are used with reference to the orientation of the described figures. Because components of the embodiments can be positioned in several different orientations, directional terms are used for illustrative purposes and are by no means limiting. It should be understood that other embodiments may be utilized or logical changes may be made without departing from the scope of the invention. Therefore, the following detailed description should not be taken in a limiting sense, and the scope of the invention is defined by the appended claims.

[0045] Figure 1 This is a cross-sectional view of an adjustable optical filter device according to an embodiment of the present invention. Figure 1 As shown, an adjustable Fabry-Perot cavity device with a movable mirror includes a movable mirror, which is a thin film formed by embedding a glass 12 and a silicon layer 11. Specifically, it can be a silicon thin film 10 including embedded glass. The central region of the silicon thin film 10 is embedded with glass 12 to form a light-transmitting region. A mirror material is deposited on the silicon thin film 10 to form an optical mirror 30. The movable mirror is disposed opposite to another mirror. The movable mirror and the other mirror are bonded to each other at their periphery by a bonding agent 60 to form a Fabry-Perot cavity between the mirrors. The transition region between the bonded peripheral region and the central region of the silicon thin film is embedded with glass to form an elastic structure. In this embodiment, the other mirror is also a silicon thin film 10 including embedded glass.

[0046] In a specific embodiment, the movable mirror is a silicon thin film 10 embedded with glass, with a thickness between 10 and 200 micrometers, which is thinner than that of ordinary glass substrates (greater than 300 micrometers), allowing for device miniaturization. The silicon layer 11 remaining between the transition region and the central region of the silicon thin film 10 forms a ring-shaped support structure, which can be referenced... Figure 2 The annular support structure can enhance the mechanical flatness of the movable mirror. It should be recognized that the shape of the annular support structure is not limited to a circle; it can also be an ellipse, rectangle, or other regular or irregular shapes. The appropriate etching method should be selected to etch the required shape depending on the specific application scenario. Furthermore, the shape and position of the silicon layer 11 can be designed in different patterns as needed, and the bonding compound 60 can also be arranged in different positions as required.

[0047] In a specific embodiment, a mirror material is deposited on the silicon thin film 10 to form an optical mirror 30. The material of the optical mirror includes silicon, silicon oxide, or a combination thereof, or silver. When the optical mirror 30 uses a conductive material such as silver, since the conductivity of the silicon material can be adjusted by doping or other methods, the electrode 40 can be placed on the surface of the silicon layer 11. The silicon layer with good conductivity forms a driving conductive path with the optical mirror 30 on the other side through the silicon thin film 10. Furthermore, the electrode 40, which is made of the same material as the optical mirror 30, can be formed by the same layer process in microfabrication to form a driving device for controlling the relative displacement of the movable mirror, such as a capacitor drive.

[0048] In specific embodiments, the bonding method between the movable mirror and another mirror can be eutectic bonding, polymer bonding, or anodic bonding. Eutectic bonding uses a metal as a transition layer to achieve silicon-to-silicon bonding, has low surface requirements, low bonding temperature, and high bonding strength. Anodic bonding has advantages such as low bonding temperature, good compatibility with other processes, and high bonding strength and stability, and can be used for bonding between silicon / silicon substrates, non-silicon materials and silicon materials, and between glass, metal, semiconductors, and ceramics. The appropriate bonding method can be selected based on the actual surface process and materials used in the bonding to achieve bonding between two glass films.

[0049] In a specific embodiment, the embedded movable mirror can be fabricated through the following steps: S1: providing a silicon substrate and etching a pattern of a certain depth on the silicon substrate; S2: melting glass and filling it onto the etched silicon substrate; S3: grinding the surface of the silicon substrate after the glass is filled to form a silicon substrate with embedded glass; S4: depositing optical mirror material on the surface of the silicon substrate with embedded glass to form an optical mirror; S5: grinding or etching away excess silicon substrate to form a movable mirror with a silicon thin film structure with embedded glass. Since silicon has a much higher Young's modulus than glass, the silicon layer can be fabricated as a whole silicon thin film while maintaining its flatness. Furthermore, since silicon is opaque in the visible to near-far-infrared range, the silicon layer 11 can also block or reflect light.

[0050] In a specific embodiment, another step S5 can also be used, which can be: S51: bonding two glass-embedded substrates with optical mirrors together to form a Fabry-Perot cavity between the mirrors; S52: grinding or etching to remove excess substrates to form a Fabry-Perot cavity with a thin film structure embedded with glass.

[0051] In a specific embodiment, the movable mirror is fabricated using SOI wafer 13, such as... Figure 3As shown, the main difference between its fabrication steps and those of the above embodiment lies in S1, specifically: S11: Providing an SOI substrate 13 and etching a silicon layer on the SOI substrate to form a pattern of a certain depth; S12: Providing a glass substrate 14 and bonding the glass substrate to the SOI substrate; S2: Melting the glass and filling it onto the etched silicon substrate; S3: Grinding the surface of the silicon substrate after the glass is filled to form a silicon substrate with embedded glass; S4: Depositing optical mirror material onto the surface of the silicon substrate with embedded glass to form an optical mirror; S5: Grinding or etching to remove excess silicon substrate to form a movable mirror with a silicon thin film structure with embedded glass.

[0052] In a specific embodiment, a driving device for controlling the relative displacement of the movable mirror is provided on the movable mirror surface. Specifically, this device includes a first electrode 40 and a second electrode 40 on the periphery of the movable mirror surface opposite to the mirror surface, and in the region of the embedded silicon layer 11. The movable mirror surface can be driven to move by the capacitor structure formed between the first and second electrodes to adjust the gap of the cavity.

[0053] Figure 4 A cross-sectional view of an adjustable optical filter device according to a second embodiment of the present invention. Figure 4 As shown, the main difference from the above embodiment is that the other mirror is a fixed mirror 21, which includes a glass substrate and a mirror material disposed on the glass substrate. The diverse selection of the other mirror allows for the selection of a suitable mirror according to actual needs, increasing design flexibility.

[0054] Figure 5 A cross-sectional view of an adjustable optical filter device according to a third embodiment of the present invention. Figure 5 As shown, based on the above embodiment, the annular support structure portion in the silicon layer 11 is removed to form a venting via 15. The removal of silicon can be accomplished by dry or wet etching. The venting via facilitates rapid airflow between the Fabry-Perot cavity and the outside air, thereby increasing the instantaneous response speed when the movable mirror of the Fabry-Perot cavity moves.

[0055] Figure 6 A cross-sectional view of an adjustable optical filter device according to a fourth embodiment of the present invention. Figure 6 As shown, an adjustable Fabry-Perot cavity device with movable mirrors includes two movable mirrors with embedded glass silicon thin films 10 and a fixed mirror 21. The fixed mirror 21 is made of a glass substrate and optical mirrors 30 are deposited on both the top and bottom. The two movable mirrors are bonded to the fixed mirror 21 to form two Fabry-Perot cavities. The mirror materials of the two Fabry-Perot cavities can be the same or different. By adjusting the light transmission characteristics of the two Fabry-Perot cavities, a light filtering function that cannot be achieved by a single Fabry-Perot cavity can be realized.

[0056] Figure 7 The diagram shows a cross-sectional view of the tunable optical filter device according to the fifth embodiment of the present invention. Figure 7 As shown, the actuator is driven by a piezoelectric thin film structure. Specifically, the driving device includes a piezoelectric thin film structure 50 disposed on the periphery of the movable mirror and the surface opposite to the mirror. The piezoelectric thin film is deposited on the movable mirror surface by sputtering or sol-gel deposition. The piezoelectric thin film structure includes lead zirconate titanate film, aluminum nitride film, or zinc oxide film, which can be selected according to the actual application.

[0057] This invention utilizes a movable mirror formed by inlaying glass and silicon. Since silicon has a much higher Young's hardness than glass, the movable mirror inlaid with glass and silicon can possess good mechanical strength and a stable elastic coefficient, and is unaffected by stress. This results in good controllability and stability for the movable mirror. Furthermore, the inlaying of glass and silicon increases the flexibility of device design. By adjusting the design of the inlay structure, the same device structure can be applied to devices of different sizes. Moreover, the addition of silicon material adjusts its conductivity, so the movable mirror can also form an electrode structure for the electrodes of the external leads of adjustable Fabry-Perot cavity devices.

[0058] It is evident that those skilled in the art can make various modifications and alterations to the embodiments of the present invention without departing from the spirit and scope of the invention. In this way, the invention is also intended to cover such modifications and alterations if they fall within the scope of the claims and their equivalents. The word "comprising" does not exclude the presence of other elements or steps not listed in the claims. The simple fact that certain measures are described in mutually different dependent claims does not indicate that a combination of these measures cannot be used for profit. Any reference numerals in the claims should not be considered as limiting the scope.

Claims

1. An adjustable Fabry-Perot cavity device with a movable mirror, characterized in that, The movable mirror is disposed opposite to another mirror, and the movable mirror and the other mirror are bonded to each other on the periphery to form a Fabry-Perot cavity between the mirrors. The movable mirror is characterized in that the movable mirror includes a silicon thin film embedded with glass, formed by etching a region in a layer containing a silicon substrate filled with glass. The central region of the silicon thin film is embedded with glass to form a light-transmitting region, and a mirror material is formed on the surface of the light-transmitting region facing the cavity. The transition region between the bonded peripheral region and the central region of the silicon thin film is embedded with glass to form an elastic structure.

2. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 1, characterized in that, The silicon layer remaining between the transition region and the central region of the silicon thin film forms a ring-shaped support structure.

3. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 2, characterized in that, The annular support structure was partially removed to form a ventilation hole.

4. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 1, characterized in that, The movable mirror is made using an SOI wafer, wherein the glass is filled into the SOI wafer by etching the silicon layer of the SOI wafer.

5. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 1, characterized in that, The other mirror also includes a silicon film embedded with glass.

6. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 1, characterized in that, The other mirror includes a fixed mirror, which includes a glass substrate and a mirror material disposed on the glass substrate.

7. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 6, characterized in that, Another movable mirror is also bonded to the other surface of the fixed mirror that is opposite to the movable mirror, and the other movable mirror and the other surface of the fixed mirror form another Fabry cavity.

8. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 1, characterized in that, The thickness of the glass-embedded silicon film is between 10 and 200 micrometers.

9. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 1, characterized in that, The mirror material includes silicon, silicon oxide, or a combination thereof, or silver.

10. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 1, characterized in that, The bonding methods include eutectic bonding, polymer bonding, or anodic bonding.

11. An adjustable Fabry-Perot cavity device with a movable mirror according to claim 1, characterized in that, The movable mirror is provided with a driving device for controlling the relative displacement of the movable mirror.

12. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 11, characterized in that, The driving device includes capacitor driving and actuator driving with a piezoelectric thin film structure.

13. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 11, characterized in that, The driving device includes a first electrode and a second electrode disposed on the periphery of the movable mirror and the surface opposite to the mirror, and in the embedded silicon layer region.

14. The adjustable Fabry-Perot cavity device with a movable mirror according to claim 11, characterized in that, The driving device includes a piezoelectric thin film structure disposed on the periphery of the movable mirror and the surface opposite to the mirror.

15. An adjustable Fabry-Perot cavity device with a movable mirror according to claim 14, characterized in that, The piezoelectric thin film is deposited on the movable mirror surface by sputtering or sol-gel.

16. An adjustable Fabry-Perot cavity device with a movable mirror according to claim 14, characterized in that, The piezoelectric thin film structure includes lead zirconate titanate film, aluminum nitride film, or zinc oxide film.

17. A method for manufacturing an adjustable Fabry-Perot cavity device with a movable mirror according to any one of claims 1-16, characterized in that, Includes the following steps: S1: Provide a substrate and etch a pattern of a certain depth onto the substrate; S2: Melt the glass and fill it onto the etched substrate; S3: Grind the surface of the substrate after the glass is filled to form a substrate inlaid with glass; S4: Deposit optical mirror material onto the surface of a substrate inlaid with glass to form an optical mirror; S5: Grinding or etching removes excess substrate to form a movable mirror or Fabry-Perot cavity with a thin-film structure inlaid with glass.

18. A method for manufacturing an adjustable Fabry-Perot cavity device with a movable mirror according to claim 17, characterized in that, S5 also includes the following steps: S51: Two glass-embedded substrates with optical mirrors are bonded together to form a Fabry-Perot cavity between the mirrors; S52: Grinding or etching to remove excess substrate to form a Fabry-Perot cavity with a thin-film structure inlaid with glass.

19. A method for manufacturing an adjustable Fabry-Perot cavity device with a movable mirror according to claim 17, characterized in that, The substrate provided in S1 is a silicon substrate or an SOI substrate.

20. A method for manufacturing an adjustable Fabry-Perot cavity device with a movable mirror according to claim 17, characterized in that, S1 includes the following steps: S11: Provide an SOI substrate and etch the silicon layer on the SOI substrate to form a pattern of a certain depth; S12: Provides a glass substrate and bonds the glass substrate to the SOI substrate.

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