Micro-mirror package structure with diaphragm deflection angle feedback structure and packaging process thereof

Abstract

The present application relates to a micro-mirror package structure with a vibrating diaphragm deflection angle feedback structure and a packaging process thereof, comprising a micro-mirror, the micro-mirror having opposite front and back surfaces, the front surface having a vibrating diaphragm, and the back surface having a back cavity; a substrate, the back surface of the micro-mirror being fixedly connected to the substrate; a first detection electrode, the first detection electrode being attached to a plane of the vibrating diaphragm close to the substrate; a second detection electrode, the second detection electrode being fixed to a surface of the substrate; and a shielding mechanism, the shielding mechanism comprising a shielding electrode, the shielding electrode being attached to the plane of the vibrating diaphragm close to the substrate, and the shielding electrode being sleeved outside the first detection electrode; the present application can infer the distance between the vibrating diaphragm and the detection electrode by detecting the capacitance between the vibrating diaphragm and the detection electrode, and further infer the deflection angle of the vibrating diaphragm, so as to feedback the deflection state of the vibrating diaphragm, so as to compensate the vibrating diaphragm in time when the vibrating diaphragm is abnormally deflected, and thus more quickly eliminate the influence of the abnormal vibrating diaphragm; the shielding electrode surrounds the first detection electrode, which can effectively eliminate the stray signals in the capacitance detection process and improve the detection precision.

Description

Technical Field

[0001] This specification relates to the field of micromirror detection technology, and more particularly to a micromirror packaging structure with a diaphragm deflection angle feedback structure and its packaging process. Background Technology

[0002] Currently, micromirrors are a type of micro / nano chip that can effectively control optical paths and are widely used in projection, imaging, laser navigation, and other fields. The most commonly used micromirrors include electrostatic, electromagnetic, piezoelectric, and electrothermal types. Most currently used micromirrors employ capacitive sensing for angle feedback. However, a drawback is that the sensing electrodes generate a large amount of stray signals during the sensing process, affecting the accuracy of the capacitive sensing and leading to delayed feedback.

[0003] In summary, this application proposes a micromirror packaging structure with diaphragm deflection angle feedback and its packaging process to solve the aforementioned problems. Summary of the Invention

[0004] The present invention aims to solve the problems mentioned in the background art. The purpose of one or more embodiments of this specification is to propose a micromirror packaging structure with a diaphragm deflection angle feedback structure and its packaging process, to eliminate stray signals, improve detection accuracy, and provide good conditions for subsequent compensation.

[0005] Based on the above objectives, one or more embodiments of this specification provide a micromirror packaging structure with a diaphragm deflection angle feedback structure, comprising: a micromirror having a front side and a back side, the front side having a diaphragm and the back side having a back cavity; a substrate, the back side of the micromirror being fixedly connected to the substrate; a first detection electrode, the first detection electrode being attached to a plane of the diaphragm near the substrate; a second detection electrode, the second detection electrode being fixed to the surface of the substrate; wherein the first detection electrode and the second detection electrode are both located inside the back cavity of the back side of the micromirror; and a shielding mechanism, the shielding mechanism comprising: a shielding electrode, the shielding electrode being attached to a plane of the diaphragm near the substrate, the shielding electrode being sleeved outside the first detection electrode; wherein the first detection electrode, the shielding electrode, and the second detection electrode are all electrically connected to the substrate.

[0006] The micromirror packaging structure with diaphragm deflection angle feedback structure proposed in this embodiment of the invention forms a capacitor between the detection electrode and the diaphragm. According to the capacitance formula, the capacitance C = ε·A / d (where ε is the dielectric constant, A is the area of ​​the capacitor, and d is the distance between the detection electrode and the diaphragm). When the diaphragm vibrates and deflects at an angle, the distance between the diaphragm and the detection electrode can be estimated by detecting the capacitance between the diaphragm and the detection electrode, and thus the deflection angle of the diaphragm can be estimated. This feedback provides feedback on the deflection state of the diaphragm, enabling timely compensation of the diaphragm when abnormal deflection occurs, thereby more quickly eliminating the influence of diaphragm abnormalities. The shielding electrode surrounding the first detection electrode can effectively eliminate stray signals during the capacitance detection process and improve detection accuracy.

[0007] The micromirror packaging structure with diaphragm deflection angle feedback structure proposed in the embodiments of the present invention further includes: a support member disposed on the surface of a substrate, and the second detection electrode disposed on the support member.

[0008] According to the micromirror packaging structure with diaphragm deflection angle feedback structure proposed in the embodiments of the present invention, the support member is a low-resistivity silicon pillar.

[0009] According to the micromirror packaging structure with diaphragm deflection angle feedback structure proposed in the embodiments of the present invention, the shielding mechanism further includes: a metal frame, the metal frame being sleeved on the outer side wall of the substrate and electrically connected to the substrate; a metal shielding shell, the metal shielding shell having a front and a back facing each other, the back facing having a receiving cavity, the back facing of the metal shielding shell being fixedly connected to the metal frame, and the micromirror being located inside the receiving cavity.

[0010] According to an embodiment of the present invention, a packaging process is provided for forming the micromirror packaging structure described above. The packaging process includes: cutting a micromirror from a wafer, the micromirror having a front side and a back side, the front side having a diaphragm, and the back side having a back cavity; forming a first solder joint and a second solder joint on the surface of the diaphragm of the micromirror away from the back cavity; bonding and fixing a first detection electrode on the surface of the diaphragm of the micromirror near the back cavity, wherein the first detection electrode corresponds to the position of the first solder joint; and forming a through-hole on the diaphragm of the micromirror corresponding to the positions of the first detection electrode and the first solder joint. A first through-hole; a first wire passes through the first through-hole and is electrically connected to the first detection electrode and the first solder joint, respectively; a second through-hole is formed on the diaphragm of the micromirror, corresponding to the positions of the second detection electrode and the second solder joint; a second wire passes through the second through-hole and is electrically connected to the second detection electrode and the second solder joint, respectively; a substrate is provided and bonded to the back of the micromirror; a second detection electrode is bonded to the surface of the substrate; a first solder pad and a second solder pad are formed on the surface of the substrate, the first solder pad being electrically connected to the first solder joint, and the second solder pad being electrically connected to the second solder joint.

[0011] According to an embodiment of the present invention, a packaging process includes: bonding and fixing a support member composed of low-resistivity silicon pillars on the surface of the substrate, and bonding and fixing a second detection electrode on the support member.

[0012] According to an embodiment of the present invention, a packaging process includes: setting a metal frame that is fixedly connected to the outer wall of a substrate; forming a third pad on the surface of the substrate, wherein the metal frame is electrically connected to the third pad; setting a metal shielding shell that is bonded and fixed to the metal frame, wherein the metal shielding shell has a front side and a back side, the back side having a receiving cavity, and the micromirror being located inside the receiving cavity.

[0013] The beneficial effects of the present invention will be described in detail below with reference to embodiments and accompanying drawings. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in one or more embodiments of this specification or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one or more embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the external structure of the micromirror and the substrate in an embodiment of the present invention;

[0016] Figure 2 for Figure 1 A sectional view;

[0017] Figure 3 for Figure 1 Exploded view of the structure;

[0018] Figure 4 for Figure 1 A cross-sectional view of another embodiment;

[0019] Figure 5 for Figure 4 Structural explosion;

[0020] Figure 6 This is a schematic diagram of the external structure of the metal shielding shell and the metal frame in an embodiment of the present invention;

[0021] Figure 7 for Figure 6 A sectional view;

[0022] Figure 8 for Figure 6 Exploded view of the structure.

[0023] In the attached figures, the following are the reference numerals: 1. Micromirror; 11a. First through-hole; 11b. Second through-hole; 12a. First solder joint; 12b. Second solder joint; 13a. First wire; 13b. Second wire; 14. Diaphragm; 2. Substrate; 21a. First pad; 21b. Second pad; 21c. Third pad; 3a. First detection electrode; 3b. Second detection electrode; 4. Metal shielding shell; 5. Metal frame; 6. Shielding electrode; 7. Support. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments.

[0025] The following is based on Figures 1-8 The specific structure of the micromirror packaging structure in the embodiments of the present invention will be described.

[0026] Example 1

[0027] The micromirror packaging structure with diaphragm deflection angle feedback structure according to an embodiment of the present invention includes a micromirror 1, a substrate 2, a first detection electrode 3a, a second detection electrode 3b, and a shielding mechanism.

[0028] The micromirror 1 has a front and a back side, with a diaphragm 14 on the front side and a back cavity on the back side. The surface of the substrate 2 is bonded to the back side of the micromirror 1. A first detection electrode 3a is attached to the surface of the diaphragm 14 near the substrate 2 and is electrically connected to the substrate 2. A second detection electrode 3b is bonded to the surface of the substrate 2 and corresponds to the position of the first detection electrode 3a, such as... Figure 1-3As shown. The first detection electrode 3a and the second detection electrode 3b form a capacitor. During the vibration of the diaphragm 14, according to the capacitance formula, the capacitance C = ε·A / d, where ε is the dielectric constant, A is the area of ​​the capacitor, and d is the distance between the detection electrode and the diaphragm 14. The distance d changes continuously, so the capacitance C changes continuously. By monitoring the capacitance C, the distance d can be estimated, and then the deflection angle of the micromirror diaphragm 14 can be estimated, determining whether the deflection of the diaphragm 14 is abnormal, thus providing conditions for subsequent compensation. The shielding mechanism includes a shielding electrode 6, which is attached and fixed to the surface of the diaphragm 14 near the substrate 2. The shielding electrode 6 is sleeved outside the first detection electrode 3a and surrounds the first detection electrode 3a. This shields the detection capacitor of the first detection electrode 3a and the second detection electrode 3b from stray signals, improving the detection accuracy of the capacitance. Optionally, the micromirror packaging structure also includes a support member 7, which is bonded to the substrate 2. The second detection electrode 3b is disposed on the support member 7, shortening the distance between the first detection electrode 3a and the second detection electrode 3b, thereby improving the sensitivity of capacitance detection. Optionally, the support member 7 is a low-resistivity silicon pillar, and the second detection electrode 3b is bonded to the substrate 2. The second detection electrode 3b does not require separate wiring for electrical connection with the substrate 2, simplifying the packaging process. Figure 4-5 As shown. Optionally, the shielding mechanism further includes a metal frame 5 and a metal shielding shell 4. The metal frame 5 is sleeved on the outer wall of the substrate 2 and is electrically connected to the substrate 2. The metal shielding shell 4 has a front and a back facing each other, with a receiving cavity on the back. The back of the metal shielding shell 4 is fixedly connected to the metal frame 5, and the micromirror 1 is located inside the receiving cavity, as shown. Figure 6-8 As shown, the metal shielding shell 4 and the metal frame 5 form an outer shielding layer, which further eliminates stray signals during the capacitance detection process and improves the detection accuracy.

[0029] Example 2

[0030] The packaging process according to an embodiment of the present invention includes the following steps:

[0031] S1, Micromirror 1 is cut off from the wafer. Micromirror 1 has a front side and a back side with opposite sides. The front side has a diaphragm 14 and the back side has a back cavity.

[0032] S2, a first solder joint 12a and a second solder joint 12b are formed on the surface of the diaphragm 14 of the micromirror 1 away from the back cavity.

[0033] S3, the first detection electrode 3a is bonded and fixed on the surface of the diaphragm 14 of the micromirror 1 near the back cavity, and the first detection electrode 3a corresponds to the position of the first solder joint 12a.

[0034] S4, a first through hole 11a is formed on the diaphragm 14 of the micromirror 1, corresponding to the position of the first detection electrode 3a and the first solder joint 12a.

[0035] S5, the first wire 13a passes through the first through hole 11a and is electrically connected to the first detection electrode 3a and the first solder joint 12a respectively.

[0036] S6, a second through hole 11b is formed on the diaphragm 14 of the micromirror 1, corresponding to the positions of the second detection electrode 3b and the second solder joint 12b.

[0037] S7, the second wire 13b passes through the second through hole 11b and is electrically connected to the second detection electrode 3b and the second solder joint 12b respectively.

[0038] S8, a substrate 2 is bonded and fixed to the back of the micromirror 1.

[0039] S9, the second detection electrode 3b is bonded and fixed on the surface of the substrate 2.

[0040] S10, a first pad 21a and a second pad 21b are formed on the surface of the substrate 2. The first pad 21a is electrically connected to the first solder joint 12a, and the second pad 21b is electrically connected to the second solder joint 12b.

[0041] Optional, including:

[0042] Step S11: Set up a metal frame 5 that is fixedly connected to the outer wall of the substrate 2.

[0043] Step S12: A third pad 21c is formed on the surface of substrate 2, and the metal frame 5 is electrically connected to the third pad 21c.

[0044] Step S13: Set a metal shielding shell 4 that is bonded and fixed to the metal frame 5. The metal shielding shell 4 has a front and a back facing each other. The back has a receiving cavity, and the micromirror 1 is located inside the receiving cavity.

[0045] Example 3

[0046] The packaging process proposed in this embodiment of the invention differs from that in Embodiment 2 in that it includes the following steps:

[0047] S9, a support member 7 composed of low-resistivity silicon pillars is bonded and fixed on the surface of substrate 2, a second detection electrode 3b is bonded and fixed on the support member 7, and the second detection electrode 3b is bonded and fixed on the surface of substrate 2.

[0048] One or more embodiments of this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of this specification should be included within the scope of protection of this disclosure.

Claims

1. A micromirror packaging structure with a diaphragm deflection angle feedback structure, characterized in that, include: Micromirror (1), the micromirror (1) having a front side and a back side, the front side having a diaphragm (14) and the back side having a back cavity; Substrate (2), the back side of the micromirror (1) is fixedly connected to the substrate (2); The first detection electrode (3a) is attached to the plane of the diaphragm (14) near the substrate (2); The second detection electrode (3b) is fixed on the surface of the substrate (2); The first detection electrode (3a) and the second detection electrode (3b) are both located inside the back cavity on the back of the micromirror (1); The shielding mechanism includes: A shielding electrode (6) is attached to the plane of the diaphragm (14) near the substrate (2), and the shielding electrode (6) is sleeved outside the first detection electrode (3a); A support member (7) is disposed on the surface of a substrate (2), and the second detection electrode (3b) is disposed on the support member (7) on the side close to the micromirror (1). The first detection electrode (3a), the shielding electrode (6) and the second detection electrode (3b) are all electrically connected to the substrate (2).

2. The micromirror packaging structure with diaphragm deflection angle feedback structure according to claim 1, characterized in that, The support member (7) is a low-resistivity silicon pillar.

3. The micromirror packaging structure with diaphragm deflection angle feedback structure according to claim 1, characterized in that, The shielding mechanism also includes: A metal frame (5) is fitted onto the outer side wall of the substrate (2) and is electrically connected to the substrate (2). The metal shielding shell (4) has a front and a back side, the back side has a receiving cavity, the back side of the metal shielding shell (4) is fixedly connected to the metal frame (5), and the micromirror (1) is located inside the receiving cavity.

4. A packaging process for forming the micromirror packaging structure according to any one of claims 1-3, characterized in that... The packaging process includes: A micromirror (1) is cut off from a wafer. The micromirror (1) has a front side and a back side, the front side has a diaphragm (14), and the back side has a back cavity. A first solder joint (12a) and a second solder joint (12b) are formed on the surface of the diaphragm (14) of the micromirror (1) away from the back cavity; A first detection electrode (3a) is bonded and fixed to the surface of the diaphragm (14) of the micromirror (1) near the back cavity, and the first detection electrode (3a) corresponds to the position of the first solder joint (12a); A first through hole (11a) is formed on the diaphragm (14) of the micromirror (1) at the position corresponding to the first detection electrode (3a) and the first solder joint (12a). A first wire (13a) is passed through the first through hole (11a) and electrically connected to the first detection electrode (3a) and the first solder joint (12a) respectively; A second through hole (11b) is formed through the diaphragm (14) of the micromirror (1) at the position corresponding to the second detection electrode (3b) and the second solder joint (12b). A second wire (13b) is passed through the second through hole (11b) and electrically connected to the second detection electrode (3b) and the second solder joint (12b), respectively; A substrate (2) is provided and bonded to the back of the micromirror (1); A second detection electrode (3b) is bonded and fixed on the surface of the substrate (2); A first pad (21a) and a second pad (21b) are formed on the surface of the substrate (2). The first pad (21a) is electrically connected to a first solder joint (12a), and the second pad (21b) is electrically connected to a second solder joint (12b).

5. The packaging process according to claim 4, characterized in that, include: A support member (7) made of low-resistivity silicon pillars is bonded and fixed on the surface of the substrate (2), and a second detection electrode (3b) is bonded and fixed on the support member (7).

6. The packaging process according to claim 4, characterized in that, include: A metal frame (5) is provided and fixedly connected to the outer wall of the substrate (2); A third pad (21c) is formed on the surface of the substrate (2), and the metal frame (5) is electrically connected to the third pad (21c); A metal shielding shell (4) is provided and bonded to the metal frame (5). The metal shielding shell (4) has a front and a back facing each other. The back facing has a receiving cavity, and the micromirror (1) is located inside the receiving cavity.

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