Sensor package

Abstract

A sensor package is provided, which includes a fixed frame, a movable platform, an elastic reset member and a sensor chip. The movable platform is movable relative to the fixed frame and is used to carry the sensor chip. The elastic reset member is connected between the fixed frame and the movable platform and is used to return the movable platform to an original position. The sensor chip is arranged on the elastic reset member to transmit detection data through the elastic reset member.

Description

[0001] This application is a divisional application of Chinese invention patent application No. 201810994009.7, filed on August 29, 2018, entitled "Sensor Package and Manufacturing Method Thereof". Technical Field

[0002] This invention relates to a sensor package, and more particularly to a package having a movable sensor that mounts a sensor on a movable platform of a microelectromechanical system actuator, and a method thereof for manufacturing the same. Background Technology

[0003] Microelectromechanical systems (MEMS) are micromechanical structures formed by etching silicon wafers. They can be used as MEMS actuators to convert electrical signals into mechanical motion, and are used to control extremely subtle movements.

[0004] In image acquisition devices that include autofocus (AF) or optical stabilization (OIS) functions, microelectromechanical systems (MEMS) actuators can be used to achieve precise adjustment of focal length and sampling position. Summary of the Invention

[0005] The present invention provides a package with a movable sensor and a method for manufacturing the same, which has a sensing chip disposed on an elastic structure, the elastic structure having both reset and signal transmission functions.

[0006] This invention provides a sensor package comprising a microelectromechanical system (MEMS) actuator, at least one resilient reset element, and a sensor chip. The fixed frame comprises silicon layers bonded together without an oxide insulating layer between them. The MEMS actuator includes the fixed frame and a movable platform for movement relative to the fixed frame in at least one direction. The at least one resilient reset element is connected between the fixed frame and the movable platform for returning the moved movable platform to its original position. The sensor chip is disposed on the movable platform and transmits detection data through the at least one resilient reset element.

[0007] To make the above and other objects, features and advantages of the present invention more apparent, a detailed description will be provided below with reference to the accompanying drawings. Furthermore, in the description of the present invention, the same components are denoted by the same reference numerals, which will be stated herein as well. Attached Figure Description

[0008] Figure 1 This is a top view of the sensor package according to an embodiment of the present invention;

[0009] Figure 2 This is a top view of a sensor package according to another embodiment of the present invention;

[0010] Figure 3 This is a top view of a sensor package according to another embodiment of the present invention;

[0011] Figure 4 This is a side view of a sensor package according to another embodiment of the present invention;

[0012] Figures 5a-5f This is a schematic diagram illustrating the fabrication of the sensor package according to the first embodiment of the present invention;

[0013] Figures 6a-6h This is a schematic diagram illustrating the fabrication of the sensor package according to the second embodiment of the present invention;

[0014] Figure 7 This is a flowchart of a method for manufacturing a sensor package according to the first embodiment of the present invention;

[0015] Figure 8 This is a flowchart of a method for manufacturing a sensor package according to a second embodiment of the present invention; and

[0016] Figure 9 This is a top view of a sensor package according to another embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures

[0018] 10 Sensor Package

[0019] 11 Fixed frame

[0020] 111 First comb-shaped electrode

[0021] 13 Movable Platforms

[0022] 131 Second comb electrode

[0023] 15. Elastic reset component

[0024] 17 Sensor Chips Detailed Implementation

[0025] Please refer to Figure 1 The image shown is a top view of a sensor package 10 according to an embodiment of the present invention. The sensor package 10 is, for example, an image sensor package. The sensor package 10 includes a microelectromechanical system (MEMS) actuator for changing the one-dimensional or two-dimensional position of the mounted optoelectronic component. The optoelectronic component is a separately manufactured component independent of the MEMS actuator, and after the MEMS actuator is manufactured, it is mounted on the MEMS actuator via a resilient reset member, and the resilient reset member transmits detection signals.

[0026] The microelectromechanical system (MEMS) actuator includes a fixed frame 11 and a movable platform 13, which are MEMS structures formed by processing a silicon wafer (illustrated below) using photolithography or etching processes. In the processed silicon wafer, the fixed frame 11 and the movable platform 13 are separated (connected only by an elastic restoring element as described below), so the movable platform 13 can move relative to the fixed frame 11.

[0027] The fixed frame 11 has a plurality of first comb-shaped electrodes 111 (only a few are shown), and the movable platform 13 has a plurality of second comb-shaped electrodes 131 (only a few are shown). Figure 1 As shown, the first comb-shaped electrode 111 and the second comb-shaped electrode 131 are respectively disposed on two opposite sides of the inner side of the fixed frame 11 and two opposite edges of the movable platform 13. The first comb-shaped electrode 111 and the second comb-shaped electrode 131 are used to generate electrostatic force so that the movable platform 13 moves relative to the fixed frame 11 in at least one direction. Figure 1 As shown, each of the first comb electrodes 111 is located between the two second comb electrodes 131, and each of the second comb electrodes 131 (except the outermost one) is located between the two first comb electrodes 111. By applying a voltage to the first comb electrodes 111 and the second comb electrodes 131, an attractive or repulsive force (determined by the polarity of the applied voltage) can be generated to move the movable platform 13.

[0028] The resilient reset element 15 is a patterned metal layer, such as a conductive metal like aluminum, nickel, or gold, or a combination thereof, which is a structure separately formed on the silicon wafer (e.g., by deposition process), rather than formed by etching the silicon wafer. The resilient reset element 15 is connected between the fixed frame 11 and the movable platform 13 to return the moved movable platform 13 to its original position.

[0029] For example Figure 1 In the diagram, the movable platform 13 is shown as a rectangle, and the elastic reset member 15 is formed between the two opposite sides of the rectangle (shown as the left and right sides) and the fixed frame 11. For example, one end of the elastic reset member 15 is disposed on the surface of the fixed frame 11 and the other end is disposed on the surface of the movable platform 13. When an electrostatic force is formed between the first comb electrode 111 and the second comb electrode 131 in the vertical direction, the movable platform 13 moves in the vertical direction, and the elastic reset member 15 forms a restoring force in the opposite direction to the electrostatic force.

[0030] The sensor chip 17, such as a CMOS image sensor chip or a CCD image sensor chip, is disposed on the movable platform 13 and transmits detection data, such as image data or detection data from other optoelectronic components, through the resilient reset member 15. For electrical connection, the sensor chip 17 includes solder balls or contact pads; for example, the bottom surface of the sensor chip 17 has multiple solder balls or contact pads as electrical connection points. The sensor chip 17 is electrically connected to the resilient reset member 15 through the solder balls or contact pads.

[0031] Figure 2 , 3 This is a top view of a sensor package according to another embodiment of the present invention. The sensor packages 10' and 10" also include a fixed frame 11, a movable platform 13, an elastic reset member 15, and a sensing chip 17. Figure 1 The difference is Figure 2 , 3 The fixed frame 11 and the movable platform 13 are connected by an elastic reset member 15 configured in another way, so that the movable platform 13 can move relative to the fixed frame 11 in a one-dimensional or two-dimensional direction.

[0032] For example Figure 2 In this design, a relatively large number of elastic reset members 15 are formed on the left and right sides of the rectangular movable platform 13, resulting in a large restoring force. It is understood that the magnitude of the restoring force depends not only on the number of elastic reset members 15, but also on the size and thickness of the elastic reset members 15. During manufacturing, the size, thickness, and / or number of the elastic reset members 15 can be configured according to the magnitude of the electrostatic force generated by the first comb electrode 111 and the second comb electrode 131. The magnitude of the electrostatic force is determined, for example, by the number, size, spacing, and applied voltage of the first comb electrode 111 and the second comb electrode 131.

[0033] For example Figure 3 In this structure, elastic reset members 15 are formed between the four corners of the rectangular movable platform 13 and the fixed frame 13 to generate restoring forces in two directions (e.g., up and down and left and right). Simultaneously, to generate electrostatic forces in two dimensions, the first comb electrode 111 and the second comb electrode 131 are also disposed on opposite sides in the left and right directions.

[0034] In this invention, there is no specific limitation on the number and position of the comb-shaped electrode groups 111 and 131 and the elastic reset member 15. It is determined according to the actual application, as long as the restoring force generated by the elastic reset member 15 can balance the electrostatic force generated by the comb-shaped electrode groups 111 and 131.

[0035] It is understood that the resilient reset member 15 is configured relative to the electrical contacts (e.g., solder balls or contact pads) of the sensing chip 17, so that the sensing chip 17 can be directly mounted on the movable platform 13 and electrically connected to the resilient reset member 15 through the electrical contacts. Furthermore, since the resilient reset member 15 is also used to transmit detection data, and the fixed frame 11 and the movable platform 13 are used to be subjected to voltage to generate electrostatic force, in order to avoid affecting signal quality, an electrical insulating layer 16 is also provided between the movable platform 13 and the resilient reset member 15, and between the fixed frame 11 and the resilient reset member 15, such as... Figure 4 As shown.

[0036] Figure 4 This is a side view of a sensor package according to another embodiment of the present invention, wherein the sensor chip 17 can transmit electrical signals (e.g., control signals and / or detection data of the sensor chip 17) not only through the resilient reset member 15, but also through at least one bonding wire 19 connected between the sensor chip 17 and the mounting frame 11. For example, the mounting frame 11 also has at least one electrical contact pad, and at least one bonding wire is connected between the solder balls 18 of the sensor chip 17 and at least one electrical contact pad of the mounting frame 11 by a wire bonding process. Figure 4 In the middle, the fixed frame 11 includes a first silicon layer 111, a second silicon layer 13, and an oxide insulating layer 12 between the first silicon layer 111 and the second silicon layer 13.

[0037] Reference Figures 5a-5f and Figure 7 Next, a method for fabricating a sensor package according to the first embodiment of the present invention will be described, comprising the following steps: providing a silicon-on-insulator wafer having a first silicon layer, an insulating oxide layer, and a second silicon layer (step S71); forming a patterned metal layer on the first silicon layer (step S72); etching the first silicon layer to form a platform region, a fixing frame, and a trench between the platform region and the fixing frame (step S73); etching the second silicon layer to form an exposed region relative to the platform region and the trench (step S74); etching the insulating oxide layer of the exposed region to release the platform region and form a movable platform (step S75); and disposing a sensor chip on the patterned metal layer (step S76).

[0038] Step S71: The silicon-on-insulator (SOI) wafer has a first silicon layer 51, a second silicon layer 53, and an oxide insulating layer 52 sandwiched therebetween, such as Figure 5aAs shown. The silicon-on-insulator wafer can be a commercially available off-the-shelf wafer or a self-made wafer, without specific limitations. For example, the first silicon layer 51 is a silicon wafer with a thickness of 10-20 micrometers as a device layer, while the second silicon layer 53 is a silicon wafer with a thickness of 300-400 micrometers as a handle layer. The oxide insulating layer 52 serves as an etch stop layer.

[0039] Step S72: Next, a patterned metal layer 55 with a preset pattern is formed on the first silicon layer 51, such as... Figure 5b As shown, this serves as a resilient restoring element for the microelectromechanical system (MEMS) actuator. The preset pattern is based on the position of the solder balls 58 or contact pads of the sensor chip 57 to be subsequently installed (e.g., referring to...). Figure 5f The patterned metal layer 55 is pre-configured, for example, using a photolithography process.

[0040] Furthermore, to improve signal quality, an electrically insulating layer 16 can be formed on the first silicon layer 51 before depositing the metal layer (e.g., ...). Figure 4 As shown), the first silicon layer 51 is electrically isolated from the patterned metal layer 55.

[0041] Step S73: Next, the first silicon layer 51 is etched by vapor phase etching or wet etching to form a platform region 513, a fixing frame 511, and a trench 515 between the platform region 513 and the fixing frame 511, as shown below. Figure 5c As shown. The etched configuration is, for example, as follows. Figure 1-3 Either of these, depending on the actual implementation. Due to the presence of the oxide insulating layer 52, etching of the first silicon layer 51 stops at the oxide insulating layer 52. After this etching step is completed, the patterned metal layer 55 is connected across the trench 515 between the platform region 513 and the fixing frame 511 as a resilient restoring element. The platform region 513 is connected to the fixing frame 511 via the oxide insulating layer 52.

[0042] Step S74: To release the platform region 513 in subsequent steps, the second silicon layer 53 is etched (either dry or wet etching) relative to the platform region 513 and the trench 515 to form an exposed region 531, exposing a portion of the oxide insulating layer 52. Etching stops when the oxide insulating layer 52 is reached. Figure 5d As shown.

[0043] It is understood that the etching process of the first silicon layer 51 and the second silicon layer 53 can form a protective layer to etch the first silicon layer 51 and the second silicon layer 53 into a predetermined structure. The first silicon layer 51 and the second silicon layer 53 can be etched using the etching process used in the fabrication of microelectromechanical systems, so it will not be described in detail here.

[0044] Furthermore, step S73 is not limited to being performed before step S74. Alternatively, the first silicon layer 51 can be etched after the second silicon layer 53 has been etched, as long as the exposed oxide insulating layer 52 is aligned with the platform region 513 and the trench 515.

[0045] Step S75: Next, the oxide insulating layer 52 within the exposed area 531 is etched to release the platform area 513, forming a movable platform, as shown. Figure 5e As shown. Depending on the etch selectivity, the etching of the oxide insulating layer 52 will not etch the first silicon layer 51 and the second silicon layer 53, and vice versa. After this step is completed, the platform region 513 is only connected to the fixing frame 511 through the patterned metal layer 55, while the other parts are completely separated from the fixing frame 511.

[0046] Step S76: Finally, the preset sensor chip 57 is placed on the patterned metal layer 55. The sensor chip 57, for example, has pre-configured solder balls 58 at its bottom. After the solder balls 58 are bonded to the patterned metal layer 55 using a high-temperature process, the sensor package of the present invention is completed. Figure 5f As shown. The high temperature used is determined by the material of the solder ball 58 and the temperature tolerance of the sensor chip 57.

[0047] Furthermore, if additional bonding lines are required outside the patterned metal layer 55, a wire bonding process can be performed after step S76 or before releasing the movable platform 513 in step S75 to form at least one bonding line 19 between the sensing chip 57 and the fixing frame 511, such as... Figure 4 As shown. For example, at least one electrical contact pad is formed on the mounting frame 511 and the platform area 513 for connecting the bonding wire. Thereby, a portion of the solder balls 58 of the sensing chip 57 are disposed on the patterned metal 55, and another portion of the solder balls 58 are disposed on the electrical contact pad of the platform area 513 for electrical connection with the bonding wire.

[0048] by Figures 5a-5f The completed sensor package includes a mounting frame 11 comprising a first silicon layer 511, a second silicon layer 53, and an oxide insulating layer 52 between the first silicon layer 511 and the second silicon layer 53.

[0049] Reference Figures 6a-6h and Figure 8Next, a method for fabricating a sensor package according to a second embodiment of the present invention will be described, comprising the following steps: providing a first silicon layer having a first surface and a second surface (step S81); forming a patterned metal layer on the first surface of the first silicon layer (step S82); bonding a second silicon layer on the first surface of the first silicon layer (step S83); thinning the first silicon layer (step S84); etching the thinned first silicon layer to form a movable platform and a fixing frame (step S85); bonding a third silicon layer on the thinned surface of the first silicon layer (step S686); removing the second silicon layer to expose the movable platform and the patterned metal layer (step S87); and disposing a sensor chip on the patterned metal layer (step S88).

[0050] Step S81: In this embodiment, instead of using a silicon-on-insulator wafer, the fabrication begins directly from the first silicon layer 61. The first silicon layer 61 includes a first surface 61S1 and a second surface 61S2 that are opposite to each other.

[0051] Step S82: First, deposit a metal layer on the first surface 61S1 of the first silicon layer 61, such as... Figure 6a As shown. The metal layer is, for example, a conductive metal such as aluminum, nickel, or gold, or a combination thereof. Next, a patterned metal layer 65 is formed using a photolithography process, such as... Figure 6b As shown. As previously mentioned, the pattern of the patterned metal layer 65 is predetermined based on the configuration of the solder balls or contact pads of the sensor chip used.

[0052] Furthermore, to ensure good insulation between the patterned metal layer 65 and the first silicon layer 61, an electrically insulating layer 16 can be formed on the first surface 61S1 of the first silicon layer 61 before forming the patterned metal layer 65, such as... Figure 4 As shown, the first silicon layer 61 and the patterned metal layer 65 are electrically isolated.

[0053] Step S83: Next, a second silicon layer 63 with a receiving space is bonded to the first surface 61S1 of the first silicon layer 61 (in the portion where the metal layer has been removed, if there is an electrically insulating layer 16, it is also removed), and the patterned metal layer 65 is positioned within the receiving space. For example, Figure 6c The second silicon layer 63 is bonded to the first surface 61S1 of the first silicon layer 61 only at its edge region, but is not limited to the edge region of the bond, and can be determined according to the setting position of the subsequent movable platform. For example, the second silicon layer 63 has sidewalls extending upward from its edge, such that the middle region is lower than the edge region. The bonding of the first silicon layer 61 and the second silicon layer 63 can use known wafer bonding processes and is not specifically limited.

[0054] Step S84: Next, the first silicon layer 61 is thinned to form a thinned first silicon layer 61' with a thickness of approximately 10-20 micrometers, as shown below. Figure 6d As shown. For example, thinning is performed by grinding or etching the second surface 61S2. In some embodiments, the thinning step may be omitted if the first silicon layer 61 is already thin enough.

[0055] Step S85: Next, the thinned first silicon layer 61' is etched to form the movable platform 613 and the fixing frame 611, as shown. Figure 6e As shown. The configuration of the etched movable platform 613 and fixed frame 611 can be selected as follows: Figure 1-3 One of them.

[0056] After etching in this step is completed, the patterned metal layer 65 is connected between the movable platform 613 and the fixed frame 611 to serve as an elastic recovery element.

[0057] Step S86: Next, a third silicon layer 64 having an accommodating space is bonded to the thinned surface 61S2' of the first silicon layer 61, wherein the accommodating space is such that the third silicon layer 64 does not contact the movable platform 613 to maintain the degree of freedom of movement of the movable platform 613. Therefore, as Figure 6f The third silicon layer 64 shown is bonded to the thinned surface 61S2' only at its edge region (e.g., the region relative to the fixing frame 611). For example, the third silicon layer 64 has sidewalls extending upward from its edges such that the middle region is lower than the edge region. The bonding of the thinned surface 61S2' of the first silicon layer 61 to the third silicon layer 64 can also be achieved using known wafer bonding processes.

[0058] Step S87: Next, the second silicon layer 63 is removed to expose the movable platform 613 and the patterned metal layer 65, as shown. Figure 6g As shown. For example, the second silicon layer 63 can be removed by grinding or etching, and the second silicon layer 63 can be completely removed or a portion of the second silicon layer 63' that is bonded to the fixing frame 611 can be left, depending on the structure of the microelectromechanical system actuator and the etching process.

[0059] Step S88: Finally, the sensor chip 67 to be mounted is disposed on the patterned metal layer 65 to complete the sensor package of this embodiment. The sensor chip 67 has, for example, solder balls 68 or contact pads on its bottom. The solder balls 68 can be bonded to the patterned metal layer 65 and have good electrical connection through a high-temperature process.

[0060] Furthermore, if additional signal transmission paths are required besides the patterned metal layer 65, at least one bonding line 19 can be formed between the sensor chip 67 and the mounting frame 611 using a wire bonding process, such as... Figure 4 As shown. Similarly, before forming the bonding line 19, an electrical contact pad can be formed on the movable platform 613 and the fixed frame 611 to electrically connect with the bonding line 19.

[0061] by Figures 6a-6h The completed sensor package includes a mounting frame 11 comprising interlocking silicon layers (e.g., a first silicon layer 61, a second silicon layer 63, and a third silicon layer 64) but excluding an oxide insulating layer therebetween. The second silicon layer 63 and the third silicon layer 64 are respectively disposed on two different sides of the first silicon layer 61.

[0062] In embodiments of the present invention, the microelectromechanical system actuator is electrically connected to a circuit board (not shown) via solder, for example, to be electrically connected to other components within the system (e.g., a mobile electronic device) via electrical traces on the circuit board to transmit signals.

[0063] It should be noted that although the above embodiments are described using linear movement in one or two dimensions, the present invention is not limited thereto. In other embodiments, the microelectromechanical system actuator can activate movement or rotation in multiple dimensions through the configuration of other resilient reset elements.

[0064] It must be noted that although the above embodiments are illustrated by the example of a fixed frame 11 continuously surrounding a movable platform 13, the present invention is not limited thereto. In other embodiments, the fixed frame 11 may be formed only on two or three edges of the movable platform 13, or may surround the movable platform 13 in a discontinuous manner, without any specific restrictions, as long as the movable platform 13 can move relative to the fixed frame 11.

[0065] It must be noted that although the above embodiments are described using a single sensor package, the present invention is not limited thereto. In mass production, multiple sensor packages according to embodiments of the present invention can be fabricated simultaneously on a wafer, and then dicing can be used to separate multiple individual sensor packages. The dicing process is well known to those skilled in the art, and therefore will not be described in detail here.

[0066] It must be noted that although the movable platform in the above embodiments is positioned at the center of the microelectromechanical system actuator, this is not intended to limit the invention. In other embodiments, the movable platform may be positioned elsewhere. Furthermore, more than one optoelectronic component may be simultaneously mounted on the movable platform, depending on the application.

[0067] While the above embodiments show that the sensor package 10 includes multiple resilient reset elements 15, the present invention is not limited thereto. In a non-limiting embodiment, the sensor package 10 includes a single resilient reset element 15, such as... Figure 9 As shown. That is, in this invention, the sensor package 10 has at least one elastic reset member 15 for providing restoring force and a path for transmitting electrical signals.

[0068] In summary, known microelectromechanical systems (MEMS) can be used as actuators to adjust precise positions. Therefore, this invention provides a sensor package with a movable sensor (…). Figure 1-4 ) and its production method ( Figure 7 , 8 This device integrates a sensor chip onto an elastic restoring element, enabling the element to simultaneously transmit signals and provide restoring force.

[0069] While the present invention has been disclosed through the foregoing examples, it is not intended to limit the invention. Anyone skilled in the art to which this invention pertains can make various modifications and alterations without departing from the spirit and scope of the invention. Therefore, the scope of protection of this invention shall be determined by the appended claims.

Claims

1. A sensor package comprising: Microelectromechanical system (MEMS) actuator, the MEMS actuator comprising: Movable platform; and A fixed frame comprises a first silicon layer and a second silicon layer directly bonded together without an oxide insulating layer between them. The first silicon layer has a first surface and a second surface. The edge region of the second silicon layer includes sidewalls higher than the middle region to form an accommodating space, and it is directly bonded to the second surface of the first silicon layer only through the sidewalls. The accommodating space prevents the second silicon layer from contacting the movable platform to maintain the degree of freedom of movement of the movable platform. in, The movable platform is used to move relative to the fixed frame in at least one direction; At least one elastic reset element is connected between the first surface of the first silicon layer of the fixed frame and the movable platform for returning the moved movable platform to its original position; as well as A sensing chip is disposed on the movable platform and is used to transmit detection data through the at least one elastic reset element.

2. The sensor package according to claim 1, wherein the at least one resilient reset element is a patterned metal layer.

3. The sensor package of claim 1, wherein the sensing chip includes solder balls electrically connected to the at least one resilient reset member.

4. The sensor package according to claim 1, wherein the movable platform is rectangular, and the at least one elastic reset member is formed between two opposite sides of the rectangle and the fixed frame.

5. The sensor package according to claim 1, wherein the movable platform is rectangular, and the at least one elastic reset member is formed between the four corners of the rectangle and the fixed frame.

6. The sensor package according to claim 1, wherein... The fixed frame has multiple first comb-shaped electrodes and the movable platform has multiple second comb-shaped electrodes. The plurality of first comb electrodes and the plurality of second comb electrodes are used to generate electrostatic force to move the movable platform.

7. The sensor package of claim 1 further comprises an electrically insulating layer between the movable platform and the at least one elastic reset member, and between the fixed frame and the at least one elastic reset member.

8. The sensor package according to claim 1 further includes at least one bonding line connected between the sensing chip and the fixing frame for transmitting control signals and / or detection data of the sensing chip.

9. The sensor package of claim 1, further comprising an etched silicon layer on the first surface of the first silicon layer of the retaining frame and located around the resilient reset member.

10. The sensor package of claim 1, wherein the movable platform is connected to the fixed frame only through the at least one resilient reset member.

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