MEMS micromirror with light source and forming method thereof
By directly integrating the light source with the MEMS micromirror through the bonding process, the problems of large size, complex packaging and high cost during the integration process are solved, and a more efficient and compact optical system solution is achieved.
Patent Information
- Application Number
- CN202411414141.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-11
- Publication Date
- 2025-02-25
AI Technical Summary
During the integration process, existing MEMS micromirrors have problems such as large components, high packaging complexity and high cost, which limits their application potential.
By providing a MEMS micromirror with its own light source, its light source is directly integrated with the MEMS micromirror using a bonding process to form a synchronous movement of the whole, simplifying the assembly process and reducing equipment volume and manufacturing costs.
A more efficient and compact optical system solution is achieved, suitable for demanding application environments, reducing manufacturing difficulty and cost.
Smart Images
Figure CN119503721A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present application relate to the field of semiconductor technology, and in particular to a MEMS micromirror with its own light source and a method for forming the same. Background Art
[0002] MEMS micromirror (Micro-Electro-Mechanical Systems Mirror) is a miniature drivable mirror manufactured based on micro-electromechanical system technology. The basic principle of MEMS micromirror is that the laser emitted by a laser or other light source is projected onto a rotatable MEMS micromirror, which then rotates and reflects the laser to a specific target area. MEMS micromirrors can precisely control the direction of reflected light and are widely used in optical and electronic devices, such as lidar, projectors, and fiber-optic communication systems. Although MEMS micromirrors have been widely used in many technical fields, existing integration methods have problems such as large component size, high packaging complexity, and high cost, which not only increases the difficulty of manufacturing, but also limits the application potential of MEMS micromirrors. Summary of the invention
[0003] The technical problem solved by the embodiments of the present application is to provide a MEMS micromirror with its own light source and a method for forming the same, so as to improve the performance of the MEMS micromirror.
[0004] To solve the above problems, an embodiment of the present application provides, on the one hand, a method for forming a MEMS micromirror with its own light source, comprising the following steps: providing a first substrate, the first substrate forming a movable structure to be released and a metal layer covering the top of the movable structure to be released; providing a second substrate, the second substrate forming a light source, the light source comprising a bottom surface and a top surface opposite to the bottom surface, wherein a light emitting surface is located on the top surface; and bonding the metal layer to the bottom surface by a bonding process to form an integrated structure.
[0005] Optionally, in the step of providing a first substrate, the method for forming the first substrate includes: providing a first silicon wafer, the first silicon wafer including a first silicon layer, a second silicon layer, and a first buried oxide layer buried between the first silicon layer and the second silicon layer; patterning the second silicon layer to form a movable structure to be released; and sequentially forming an oxide layer and the metal layer on top of the movable structure to be released.
[0006] Optionally, in the step of providing a second substrate, the method for forming the second substrate includes: providing a second silicon wafer, the second silicon wafer including a third silicon layer, an initial VCSEL material layer, and a second buried oxide layer located between the third silicon layer and the initial VCSEL material layer; and patterning the initial VCSEL material layer to form a VCSEL material layer.
[0007] Optionally, before the step of bonding the metal layer to the bottom surface by a bonding process to form an integrated structure, the step further includes: cleaning the metal layer and the bottom surface, and / or activating the metal layer and the bottom surface.
[0008] Optionally, in the step of providing a first substrate, the first substrate further includes: a first silicon layer and a first buried oxide layer, wherein the first buried oxide layer is located between the first silicon layer and the movable structure to be released; after the step of bonding the metal layer to the bottom surface using a bonding process to form an integrated structure, it also includes: removing at least part of the first silicon layer and the first buried oxide layer so that the bottom of the movable structure to be released is suspended to form a suspended movable structure.
[0009] Optionally, in the step of providing a second substrate, the light source is a vertical cavity surface emitting laser, and the second substrate further includes: a third silicon layer, a second buried oxide layer, and a VCSEL material layer, wherein the second buried oxide layer is located between the third silicon layer and the VCSEL material layer.
[0010] Optionally, after the step of bonding the metal layer to the bottom surface by a bonding process to form an integrated structure, the method further includes: removing the third silicon layer and the second buried oxide layer.
[0011] Optionally, in the step of bonding the metal layer to the bottom surface by using a bonding process to form an integrated structure, the bonding process is a thermocompression bonding process or a eutectic bonding process.
[0012] On the other hand, an embodiment of the present application provides a MEMS micromirror with its own light source, comprising: a light source for providing a light signal, comprising a bottom surface and a top surface opposite to the bottom surface, wherein a light emitting surface is located on the top surface; a MEMS micromirror, comprising a suspended movable structure and an oxide layer and a metal layer formed in sequence and located on the top surface of the suspended movable structure, wherein the bottom surface of the light source is fixedly connected to the metal layer of the MEMS micromirror through a bonding process, and the light source moves synchronously driven by the MEMS micromirror.
[0013] Optionally, the light source is a vertical cavity surface emitting laser or an edge emitting laser; the MEMS micromirror is an electrostatically driven MEMS micromirror, an electromagnetically driven MEMS micromirror, a piezoelectrically driven MEMS micromirror or a thermally driven MEMS micromirror.
[0014] Compared with the prior art, the technical solution of the embodiment of the present application has the following advantages:
[0015] The MEMS micromirror with its own light source and the method for forming the same provided in this embodiment directly integrate the light source and the MEMS micromirror using bonding technology, which not only simplifies the assembly process, but also significantly reduces the size of the equipment and manufacturing costs, and can provide a more efficient and compact optical system solution suitable for demanding application environments. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.
[0017] Figure 1 It is a schematic diagram of the structure of an existing MEMS micromirror and light source.
[0018] Figure 2-Figure 9 This is a schematic structural diagram corresponding to each step in an embodiment of a method for forming a MEMS micromirror with its own light source provided by the present invention. DETAILED DESCRIPTION
[0019] As can be seen from the background technology, the existing MEMS micromirrors have problems such as large size, high packaging complexity and high cost.
[0020] Specifically, refer to Figure 1 In the prior art, light sources (such as lasers) and MEMS micromirrors are usually processed separately as independent components and then integrated and packaged. The existing process of separate processing and subsequent packaging leads to many problems: first, since the light source and MEMS micromirror need to be processed independently, the volume of the entire system is relatively large, which limits its use in space-constrained environments; second, each independently processed component subsequently requires complex packaging technology to ensure optical accuracy and stability, which not only increases the difficulty of production, but also increases the manufacturing cost.
[0021] In order to solve the above technical problems, an embodiment of the present invention provides a MEMS micromirror with a built-in light source, comprising:
[0022] A light source, for providing a light signal, comprising a bottom surface and a top surface opposite to the bottom surface, wherein a light emitting surface is located on the top surface;
[0023] The MEMS micromirror comprises a suspended movable structure and an oxide layer and a metal layer formed in sequence on the top surface of the suspended movable structure, wherein the bottom surface of the light source is fixedly connected to the metal layer of the MEMS micromirror through a bonding process, and the light source moves synchronously driven by the MEMS micromirror.
[0024] In order to solve the above technical problems, an embodiment of the present invention further provides a method for forming a MEMS micromirror with its own light source, comprising the following steps:
[0025] Providing a first substrate, wherein the first substrate is formed with a movable structure to be released and a metal layer covering the top of the movable structure to be released;
[0026] Providing a second substrate, wherein the second substrate is formed with a light source, the light source comprising a bottom surface and a top surface opposite to the bottom surface, wherein a light emitting surface is located on the top surface;
[0027] The metal layer is bonded to the bottom surface by a bonding process to form an integrated structure.
[0028] The MEMS micromirror with its own light source provided in this embodiment integrates the light source onto the surface of the MEMS micromirror by means of a bonding process, and the MEMS micromirror and the light source form a whole that can move synchronously, and the MEMS micromirror acts as a rotatable bracket to drive the light source fixed thereon to rotate, thereby achieving precise control of light. The MEMS micromirror with its own light source provided in this embodiment can reduce the volume of the optical system while improving the accuracy of the optical system.
[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.
[0030] Figures 2 to 9 It is a structural schematic diagram corresponding to each step in an embodiment of a method for forming a MEMS micromirror with its own light source provided by the present invention.
[0031] refer to Figure 4 , providing a first substrate 100 , wherein the first substrate 100 is formed with a movable structure 131 to be released, an oxide layer 140 covering the top of the movable structure 131 to be released, and a metal layer 150 covering the oxide layer 140 .
[0032] In this step, the first substrate 100 has been pre-formed with a movable structure 131 to be released. The movable structure (or also referred to as a suspended movable structure) is an important component of the MEMS micromirror. The movable structure can be physically moved under external or internal stimulation, thereby achieving precise optical path control. The movable structure 131 to be released in this step is a movable structure that has not yet been released, and the bottom of the movable structure 131 to be released is not suspended, but is in contact with the buried oxide layer 120. In subsequent steps, the buried oxide layer 120 and the first silicon layer 110 at the bottom of the movable structure 131 to be released will be removed. With the removal of the bottom buried oxide layer 120 and the first silicon layer 110, the movable structure 131 to be released will be in a truly suspended state, forming a suspended movable structure.
[0033] In this embodiment, the material of the movable structure 131 to be released is silicon. In some other embodiments, the movable structure 131 to be released may also be a silicon compound, a metal, etc.
[0034] The movable structure can physically move under the drive of external or internal signals to achieve precise optical path control. According to the different driving forms, MEMS micromirrors can be further divided into electrostatic drive, electromagnetic drive, piezoelectric drive, thermal drive, etc. Among them, electrostatic drive uses electrostatic force to drive the movement of the micromirror, electromagnetic drive drives the micromirror structure through the interaction between magnetic field and current, piezoelectric drive uses the characteristic of piezoelectric materials to produce displacement under the action of electric field to drive the micromirror structure, and thermal drive causes material deformation through local heating, thereby achieving the movement of the micromirror structure. The appropriate drive technology can be selected according to the specific application requirements to achieve efficient optical control.
[0035] The metal layer 150 is located above the movable structure 131 to be released, and can completely cover the top of the movable structure 131 to be released. In this embodiment, an oxide layer 140 is also formed between the metal layer 150 and the movable structure 131 to be released, and the material of the oxide layer 140 is silicon dioxide. The metal layer 150 will subsequently serve as a coupling surface connected to the light source, and the metal layer 150 can provide leads for the light source circuit. For example, VCSEL circuit leads can be pre-formed on the metal layer 150, and the VCSEL circuit is subsequently connected to the corresponding VCSEL light source through a bonding process. The material of the metal layer 150 can be metal materials such as aluminum, gold, and silver.
[0036] As a specific example, Figures 2 to 4 An alternative method of forming the first substrate 100 is shown.
[0037] refer to Figure 2 , providing a first silicon wafer 101, wherein the first silicon wafer 101 includes a first silicon layer 110, a second silicon layer 130 and a first buried oxide layer 120 buried between the first silicon layer 110 and the second silicon layer 130.
[0038] refer to Figure 3 , patterning the second silicon layer 130 to form a movable structure 131 to be released.
[0039] In this step, an etching process may be used to remove part of the second silicon layer 130 to form a movable structure 131 to be released. During the etching process, the buried oxide layer 120 may be used as an etching stop layer.
[0040] refer to Figure 4 , forming a metal layer 150 covering the top of the movable structure 131 to be released.
[0041] In this step, the metal layer 150 may be formed by thin film deposition technology. Specifically, the metal material may be evaporated or sputtered onto the surface of the oxide layer 140 or the movable structure 131 to be released by physical vapor deposition (PVD) to form a uniform metal film; or the metal film may be deposited on the top of the oxide layer 140 or the movable structure 131 to be released by chemical vapor deposition (CVD).
[0042] refer to Figure 6 , providing a second substrate 200, wherein the second substrate 200 is formed with a light source, the light source comprising a bottom surface 2311 and a top surface 2312 opposite to the bottom surface 2311, wherein a light emitting surface is located on the top surface 2312;
[0043] In this step, the second substrate 200 has been pre-formed with a light source, which can be a laser light source. In this embodiment, the light source is a vertical cavity surface emitting laser (Vertical-Cavity Surface-Emitting Laser, VCSEL), which is a semiconductor laser, usually composed of multiple layers of semiconductor materials, and the light beam is emitted perpendicular to the surface of the semiconductor chip. Specifically in this embodiment, a VCSEL material layer 231 is formed on the second substrate 200, and the light emitting surface 2312 is located on the top surface of the VCSEL material layer 231.
[0044] It is understood that the light source is not limited to VCSEL, and in some other embodiments, the light source may also be an edge emitting laser (Edge Emitting Laser, ELL). ELL is a semiconductor laser. In EEL, the laser beam is emitted from the edge of the device along the plane of the semiconductor material, and the light emitting surface is located at the edge of the ELL.
[0045] As a specific example, Figure 5 and Figure 6 An alternative method of forming the second substrate 200 is shown.
[0046] refer to Figure 5 , providing a second silicon wafer 201 , wherein the second silicon wafer 201 includes a third silicon layer 210 , an initial VCSEL material layer 230 , and a second buried oxide layer 220 located between the third silicon layer 210 and the initial VCSEL material layer 230 .
[0047] refer to Figure 6 , patterning the initial VCSEL material layer 230 to form a VCSEL material layer 231, Figure 6 This is the structure of a silicon wafer after being flipped upside down.
[0048] refer to Figure 7, the metal layer 150 is bonded to the bottom surface 2311 by a bonding process to form an integrated structure.
[0049] In this step, the light source is integrated into the surface of the MEMS micromirror by a bonding process, so that the MEMS micromirror and the light source form a whole that can move synchronously. Specifically, when the movable structure of the MEMS micromirror moves, the light source bonded to the surface of the micromirror can also move synchronously. After bonding, the light beam emitted by the light source is emitted from the light emitting surface located on the top surface 2312. By controlling the movable structure in the MEMS micromirror, precise control of the light path can be achieved.
[0050] The bonding process can be thermocompression bonding, eutectic bonding, etc. Thermocompression bonding achieves surface bonding by applying pressure and temperature at the same time. During the bonding process, the two surfaces to be bonded are heated to a certain temperature (usually higher than room temperature but lower than the melting point of the material) and pressure is applied to promote diffusion and bonding between materials. Thermocompression bonding is particularly suitable for bonding between metals. Eutectic bonding can be used for bonding between heterogeneous materials, such as bonding between metal and silicon. In practical applications, the bonding process can be selected according to the specific material of the bottom surface 2311 of the light source.
[0051] In order to ensure the bonding quality, the surface to be bonded is pre-treated before the bonding step. Specifically, the metal layer 150 and the bottom surface 2311 can be thoroughly cleaned in advance to remove oil, dust and other impurities; and the metal layer 150 and the bottom surface 2311 can be surface activated in advance, and the surface to be bonded can be micro-etched or plasma treated to increase the surface energy and improve the bonding strength.
[0052] After bonding to form an integrated structure, the excess material can be further removed and the device can be packaged.
[0053] refer to Figure 8 , remove the third silicon layer 210 and the second buried oxide layer 220.
[0054] refer to Fig. 9 , at least a portion of the first silicon layer 110 and the first buried oxide layer 120 is removed, so that the bottom of the movable structure 131 to be released is suspended in the air, thereby forming a suspended movable structure 132.
[0055] Correspondingly, the present application also provides a MEMS micromirror with its own light source, referring to Fig. 9The MEMS micromirror with its own light source includes: a light source for providing a light signal, including a bottom surface 2311 and a top surface 2312 opposite to the bottom surface 2311, wherein a light emitting surface is located on the top surface 2312; a MEMS micromirror, including a suspended movable structure 132 and an oxide layer 140 and a metal layer 150 formed in sequence and located on the top surface of the suspended movable structure 132, wherein the bottom surface 2311 of the light source is fixedly connected to the metal layer 150 of the MEMS micromirror through a bonding process, and the light source moves synchronously driven by the MEMS micromirror.
[0056] The light source may be a laser light source. In the present embodiment, the light source is a vertical cavity surface emitting laser (VCSEL). VCSEL is a semiconductor laser, usually composed of multiple layers of semiconductor materials, and the light beam is emitted perpendicular to the surface of the semiconductor chip. It can be understood that the light source is not limited to VCSEL. In some other embodiments, the light source may also be an edge emitting laser (ELL). ELL is a semiconductor laser. In EEL, the laser beam is emitted from the edge of the device along the plane of the semiconductor material.
[0057] The suspended movable structure 132 is an important component of the MEMS micromirror. The movable structure can physically move under external or internal stimulation, thereby achieving precise light path control. In this embodiment, the material of the suspended movable structure 132 is silicon. In some other embodiments, the suspended movable structure 132 can also be a silicon compound, metal, etc.
[0058] The suspended movable structure 132 can be physically moved under the drive of external or internal signals to achieve precise optical path control. According to the different driving forms, MEMS micromirrors can be further divided into electrostatic drive, electromagnetic drive, piezoelectric drive, thermal drive, etc. Among them, electrostatic drive uses electrostatic force to drive the movement of the micromirror, electromagnetic drive drives the micromirror structure through the interaction between magnetic field and current, piezoelectric drive uses the characteristic of piezoelectric material to generate displacement under the action of electric field to drive the micromirror structure, and thermal drive causes material deformation through local heating, thereby realizing the movement of the micromirror structure. Appropriate driving technology can be selected according to specific application requirements to achieve efficient optical control.
[0059] The metal layer 150 is located above the suspended movable structure 132 and can completely cover the top of the suspended movable structure 132. In this embodiment, an oxide layer 140 is also formed between the metal layer 150 and the suspended movable structure 132, and the material of the oxide layer 140 is silicon dioxide. The metal layer 150 will serve as a coupling surface connected to the light source, and the metal layer 150 can provide leads for the light source circuit. For example, VCSEL circuit leads can be pre-formed on the metal layer 150, and the VCSEL circuit is subsequently connected to the corresponding VCSEL light source through a bonding process. The material of the metal layer 150 can be metal materials such as aluminum, gold, and silver.
[0060] The bonding process can be thermocompression bonding, eutectic bonding, etc. Thermocompression bonding realizes surface bonding by applying pressure and temperature at the same time. During the bonding process, two surfaces to be bonded are heated to a certain temperature (usually higher than room temperature but lower than the melting point of the material) and pressure is applied to promote diffusion and bonding between materials. Thermocompression bonding is particularly suitable for bonding between metals. Eutectic bonding can be used for bonding between heterogeneous materials, such as bonding between metal and silicon. In practical applications, the bonding process can be selected according to the specific material of the bottom surface 2311 of the light source. It can be seen that the MEMS micromirror with a self-contained light source and the method for forming the same provided in the embodiment of the present application directly integrate the light source and the MEMS micromirror through bonding technology, which not only simplifies the assembly process, but also significantly reduces the equipment volume and manufacturing cost, thereby providing a more efficient and compact optical system solution, which is suitable for demanding application environments.
[0061] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.
[0062] Although the embodiments of the present application are disclosed above, the present application is not limited thereto. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be subject to the scope defined by the claims.
Claims
1. A method for forming a MEMS micromirror with its own light source, characterized in that: The following steps are involved: Providing a first substrate, wherein the first substrate is formed with a movable structure to be released and a metal layer covering the top of the movable structure to be released; Providing a second substrate, wherein the second substrate is formed with a light source, the light source comprising a bottom surface and a top surface opposite to the bottom surface, wherein a light emitting surface is located on the top surface; The metal layer is bonded to the bottom surface by a bonding process to form an integrated structure.
2. The method for forming a MEMS micromirror with its own light source as claimed in claim 1, characterized in that: In the step of providing a first substrate, the method for forming the first substrate includes: Providing a first silicon wafer, wherein the first silicon wafer comprises a first silicon layer, a second silicon layer, and a first buried oxide layer buried between the first silicon layer and the second silicon layer; patterning the second silicon layer to form a movable structure to be released; An oxide layer and the metal layer are sequentially formed on the top of the movable structure to be released.
3. The method for forming a MEMS micromirror with its own light source as claimed in claim 1, characterized in that: In the step of providing a second substrate, the method for forming the second substrate includes: Providing a second silicon wafer, wherein the second silicon wafer comprises a third silicon layer, an initial VCSEL material layer, and a second buried oxide layer located between the third silicon layer and the initial VCSEL material layer; The initial VCSEL material layer is patterned to form a VCSEL material layer.
4. The method for forming a MEMS micromirror with its own light source as claimed in claim 1, characterized in that: Before the step of bonding the metal layer to the bottom surface by a bonding process to form an integrated structure, the method further includes: The metal layer and the bottom surface are cleaned and / or activated.
5. The method for forming a MEMS micromirror with its own light source as claimed in claim 1, characterized in that: In the step of providing a first substrate, the first substrate further comprises: a first silicon layer and a first buried oxide layer, wherein the first buried oxide layer is located between the first silicon layer and the movable structure to be released; After the step of bonding the metal layer to the bottom surface using a bonding process to form an integrated structure, the method further includes: removing at least a portion of the first silicon layer and the first buried oxide layer to allow the bottom of the movable structure to be released to be suspended in the air to form a suspended movable structure.
6. The method for forming a MEMS micromirror with its own light source as claimed in claim 1 or 5, characterized in that: In the step of providing the second substrate, the light source is a vertical cavity surface emitting laser, and the second substrate further includes: a third silicon layer, a second buried oxide layer, and a VCSEL material layer, wherein the second buried oxide layer is located between the third silicon layer and the VCSEL material layer.
7. The method for forming a MEMS micromirror with its own light source as claimed in claim 6, characterized in that: After the step of bonding the metal layer to the bottom surface by a bonding process to form an integrated structure, the method further includes: The third silicon layer and the second buried oxide layer are removed.
8. The method for forming a MEMS micromirror with its own light source as claimed in claim 1, characterized in that: In the step of bonding the metal layer to the bottom surface by using a bonding process to form an integrated structure, the bonding process is a thermal compression bonding process or a eutectic bonding process.
9. A MEMS micromirror with its own light source, characterized in that: include: A light source, for providing a light signal, comprising a bottom surface and a top surface opposite to the bottom surface, wherein a light emitting surface is located on the top surface; The MEMS micromirror comprises a suspended movable structure and an oxide layer and a metal layer formed in sequence on the top surface of the suspended movable structure, wherein the bottom surface of the light source is fixedly connected to the metal layer of the MEMS micromirror through a bonding process, and the light source moves synchronously driven by the MEMS micromirror.
10. The MEMS micromirror with its own light source as claimed in claim 9, characterized in that: The light source is a vertical cavity surface emitting laser or an edge emitting laser; the MEMS micromirror is an electrostatically driven MEMS micromirror, an electromagnetically driven MEMS micromirror, a piezoelectrically driven MEMS micromirror or a thermally driven MEMS micromirror.