CN102879903A - Device integrated with micro-electromechanical system (MEMS) micro-mirror with controllable inclined angle - Google Patents

Abstract

The invention discloses a device integrating a tilt-controllable MEMS micromirror, comprising a MEMS micromirror, a substrate, and an electric lead, the electric lead is arranged on the substrate, and a connection is made between the MEMS micromirror and the substrate. The drive arm, the bottom of the MEMS micromirror is suspended without support, and a feedback circuit is integrated on the drive arm to feed back the deflection angle of the MEMS micromirror in real time. The MEMS micromirror of the device is inclined at a certain angle with the incident light source, no additional base is needed, and its inclination angle can be freely controlled; the single-chip MEMS micromirror is integrated, and the electrical connection of the MEMS micromirror is set on the substrate, which is convenient for operation.

Description

A device integrating tilt-controllable MEMS micromirror

technical field

The invention relates to a device integrating an MEMS micromirror with controllable inclination angle, which belongs to the field of microelectromechanical systems.

Background technique

MEMS (Micro-electro-mechanical systems), that is, micro-electro-mechanical systems, are various micro-devices or systems manufactured by micro-processing technology, mainly including micro-structures, micro-sensors, micro-actuators and corresponding processing circuits. It is a high-tech cutting-edge discipline developed on the basis of integrating various micro-processing technologies and applying the latest achievements of modern information technology, and the MEMS micro-mirror system is a typical application of this technology. MEMS micromirrors are mainly used to control the deflection direction of light, and are widely used as typical products of MEMS devices. With the miniaturization of devices, MEMS micromirrors are widely used in micro-projectors, optical switches, optical variable attenuators, micro-spectrometers, micro-optical probes, etc.; angle, as shown in Figure 1.

In order to tilt the MEMS micromirror at a certain angle, the existing method is generally to attach the MEMS micromirror to a base with a fixed angle (Huikai Xie etc., 3D In Vivo optical coherencetomography based on a low-voltage, large- scan-range 2D MEMS mirror), or insert the MEMS micromirror into the groove at a certain angle with the base (Xiaojing Mu etc, MEMSmicromirror integrated endoscopic probe for optical coherence tomographybioimaging).

Due to the need to add additional pedestals or grooves with specific angles in the existing methods, the device is bulky, and additional electrical connections are required to connect the pads of the MEMS micromirror to the pedestal or additional other component circuits, so , the overall performance of the device is not stable enough, and the angle of the MEMS micromirror cannot be freely controlled, resulting in a single function of the device; in addition, a large amount of assembly work is required, and the yield is low.

Contents of the invention

The object of the present invention is to propose a device with an integrated inclination controllable MEMS micromirror, the MEMS micromirror of the device is inclined at a certain angle with the incident light source, no additional base is needed, and its inclination angle can be freely controlled; the monolithic MEMS micromirror Integrated, the electrical connection of the MEMS micromirror is set on the substrate for easy operation.

For reaching this purpose, the present invention adopts following technical scheme:

A device that integrates a tilt-controllable MEMS micromirror, including a MEMS micromirror, a substrate, and an electrical lead, the electrical lead is arranged on the substrate, and a driving arm is connected between the MEMS micromirror and the substrate, so The bottom of the MEMS micromirror is suspended without support.

Further, the MEMS micromirror includes a frame, a mirror surface and a mirror body driving arm, and the mirror body driving arm is connected between the frame and the mirror surface.

Further, the driving method of the driving arm is electrothermal driving, piezoelectric driving or thermal expansion polymer.

Further, the driving arm includes at least two sections of double-layer structure, the first section and the second section of the double-layer structure include a first material layer and a second material layer, and the first material layer of the first section is set Above the second material layer, the first material layer of the second section is arranged below the second material layer; the first section and the second section are sequentially connected and arranged.

Further, the driving arm includes at least two sections of multilayer structure, the first section and the second section of the multilayer structure include a first material layer and a second material layer, and the first material layer of the first section is set Above the second material layer, the first material layer of the second section is arranged below the second material layer; the first section and the second section also include the first material layer and the second material layer One or more layers of material structure, the first segment and the second segment are sequentially connected.

Further, the driving arm at least includes an upper material layer and a lower material layer, and the upper material layer and the lower material layer have different material thermal expansion coefficients.

Furthermore, one or more material layers are arranged on the upper surface of the upper material layer, the lower surface of the lower material layer, or between the upper material layer and the lower material layer.

Further, at least one layer of the driving arm is a conductor layer.

Further, a pad is provided on the base, the electrical lead is electrically connected to the pad on the base, and the other end of the electrical lead is electrically connected to the conductor of the driving arm.

Further, the inclination angle of the mirror body itself of the MEMS micromirror is fixed, or the inclination angle of the mirror body itself is adjustable through the mirror body driving arm around it.

Further, the mirror body driving arm includes at least two sections of double-layer structure, the first section and the second section of the double-layer structure include a first material layer and a second material layer, and the first material of the first section The layer is arranged above the second material layer, and the first material layer of the second section is arranged below the second material layer; the first section and the second section are arranged sequentially.

Further, the mirror body driving arm includes at least two sections of double-layer structure, the first section and the second section of the double-layer structure include a first material layer and a second material layer, and the first material of the first section layer is arranged above the second material layer, and the first material layer of the second section is arranged below the second material layer; the first section and the second section also include the first material layer and the second One or more layers of structure other than the material layer, the first segment and the second segment are connected in sequence.

Further, the mirror body driving arm includes at least an upper material layer and a lower material layer, and the upper material layer and the lower material layer have different material thermal expansion coefficients.

Further, at least one side of the mirror body is connected with a mirror body driving arm.

Further, the initial deflection angle of the MEMS micromirror is controlled by the length of the driving arm, material thickness and process parameters.

Further, a feedback circuit is integrated on the driving arm to feed back the deflection angle of the MEMS micromirror in real time.

The beneficial effects of the present invention are: the present invention improves the electrical connection between the MEMS micromirror and the substrate into a double-layer or multi-layer structure composed of two materials with different expansion coefficients, and uses electrothermal driving to freely control the inclination angle of the micromirror; The feedback circuit is integrated on the driving arm, the feedback signal is timely, and the tilt angle is precisely controlled. The installation process does not need to align the tilt angle in advance, which is more convenient; the MEMS micromirror is directly connected to the substrate through the driving arm without support, which greatly reduces the overall volume of the system. MEMS micromirrors can reduce the area of the frame to increase the fill rate of the mirror.

Description of drawings

Fig. 1 is the schematic diagram that prior art MEMS micromirror forms a certain angle with incident light;

Fig. 2 is the schematic diagram that the MEMS micromirror provided by the present invention forms a certain angle with incident light;

Fig. 3 is a schematic diagram of the device structure of an integrated inclination controllable MEMS micromirror of the present invention;

Fig. 4 is a kind of connection mode of MEMS micromirror and substrate among Fig. 3;

Fig. 5 is another connection mode of MEMS micromirror and substrate among Fig. 3;

Fig. 6 is a schematic diagram of the MEMS micromirror structure in Fig. 3;

FIG. 7 is a schematic diagram of an embodiment of the MEMS device in FIG. 3 .

in:

1. MEMS micromirror; 2. Driving arm; 3. Incident light; 4. Feedback circuit; 11. MEMS micromirror platform; 12. Mirror body driving arm; 13. Mirror body; 21. Upper material layer; 22. Lower layer material 23, the middle layer; 24, the first material layer; 25, the second material layer; 26, the first segment; 27, the second segment; 31, the electric lead.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

As shown in Fig. 2 to Fig. 6, a kind of device of integrated inclination controllable MEMS micromirror, comprises MEMS micromirror 1, substrate 3, electric lead 31, and described electric lead 31 is arranged on described substrate 3, and described MEMS A driving arm 2 is connected between the micromirror 1 and the base 3 , and the bottom of the MEMS micromirror 1 is suspended without support. At the same time, the substrate 3 is provided with pads, and the electric leads 31 and the pads on the substrate 3 are electrically connected through conductive glue or wires. One end of the electric leads 31 is electrically connected to one end of the driving arm 2, and the other end is electrically connected to the external circuit. connect. Compared with the prior art, the present invention saves the existing fixed base for placing the MEMS micromirror and has a certain inclination angle, and the connecting wires for the electrical connection between the MEMS micromirror and the electrical leads of the substrate 3, The size of the whole device is reduced, and the installation is simple and convenient. In addition, a feedback circuit 4 is integrated on the driving arm 2 to feed back the deflection angle of the MEMS micromirror in real time.

Wherein, the driving method of the driving arm 2 is electrothermal driving, piezoelectric driving or thermal expansion polymer.

As a preferred mode of the present invention, as shown in FIG. 5 , the driving arm 2 includes at least two sections of double-layer structure, and the first section 26 and the second section 27 of the double-layer structure include a first material layer 24 and a The second material layer 25, the first material layer 24 of the first section 26 is arranged above the second material layer 25, and the first material layer 24 of the second section 27 is arranged below the second material layer 25; The first section 26 and the second section 27 are connected in sequence. Wherein, the thermal expansion coefficients of the first material layer 24 and the second material layer 25 of the first section 26 and the second section 27 are different, and at least one layer in the double-layer structure is a conductor layer. Preferably, in this manner, the driving arm 2 is wrapped with a layer of Al by a flexible polymer film as the first material layer, and the second material layer is filled with a polymer with a large thermal expansion coefficient, such as SiO ₂ . The driving arm 2 of this double-layer structure is connected between the MEMS micromirror 1 and the substrate 3, and the electrical connection between the substrate 3 and the electric lead 31, when the external circuit transmits the electric signal to the electric lead 31 until the driving arm 2, Because the material expansion coefficients of the double-layer structure of the driving arm 2 are different, after power is applied, the conductor layer in the double-layer structure is heated, and the materials of the first material layer and the second material layer are heated to make them move toward the one with the smaller expansion coefficient. Side deflection, so as to realize the deflection control of the tilt angle, and can achieve different deflection results according to different electrical signals, so the tilt angle of the MEMS micromirror can be freely controlled.

As another preferred mode of the present invention, the driving arm 2 includes at least two sections of multilayer structure, and the first section 26 and the second section 27 of the multilayer structure include a first material layer 24 and a second material layer 25 , the first material layer 24 of the first section 26 is arranged above the second material layer 25, and the first material layer 24 of the second section 27 is arranged below the second material layer 25; the first section 26 and the second section 27 also include one or more layers of material structures other than the first material layer 25 and the second material layer 25, and the first section 26 and the second section 27 are sequentially connected. Wherein, the thermal expansion coefficients of the first material layer 24 and the second material layer 25 of the first section 26 and the second section 27 are different, and at least one layer in the multilayer structure is a conductor layer. The driving arm 2 of this multilayer structure is connected between the MEMS micromirror 1 and the substrate 3, and the electrical connection between the substrate 3 and the electric lead 31, when the external circuit transmits the electrical signal to the electric lead 31 until the driving arm 2, Since the material expansion coefficients of the multi-layer structure of the driving arm 2 are different, after power is applied, the conductor layer in the multi-layer structure is heated, and the materials of the first material layer and the second material layer are heated to make them move toward the one with the smaller expansion coefficient. Side deflection, so as to realize the deflection control of the tilt angle, and can achieve different deflection results according to different electrical signals, so the tilt angle of the MEMS micromirror can be freely controlled.

As another preferred mode of the present invention, as shown in FIG. 4, the driving arm 2 at least includes an upper material layer 21 and a lower material layer 22, and the upper material layer 21 and the lower material layer 22 have different thermal expansion coefficients; One or more material layers are arranged on the upper surface of the upper material layer 21 , the lower surface of the lower material layer 22 or between the upper material layer 21 and the lower material layer 22 . Wherein, at least one layer of the structural material layers of the driving arm 2 is a conductor layer. Preferably, in this embodiment, the driving arm 2 uses a flexible polymer film to wrap a layer of Al as the upper material layer, and the lower material layer is filled with a polymer with a large thermal expansion coefficient, such as SiO ₂ , between the upper material layer and the lower material layer An intermediate material layer is arranged between them, and the intermediate material layer is used as a conductor layer, and its material is Pt. The driving arm 2 of this structure is connected between the MEMS micromirror 1 and the substrate 3, and the electrical connection between the substrate 3 and the electric lead 31, when the external circuit transmits the electric signal to the electric lead 31 until the driving arm 2, due to the driving The material expansion coefficients of the upper material layer and the lower material layer of the arm 2 are different. After electrification, the middle material layer Pt is energized and heated, and starts to heat the materials of the upper and lower material layers, so that it deflects to the side with a smaller expansion coefficient, thereby realizing tilting Angle deflection control, and can achieve different deflection results according to different electrical signals, so the tilt angle of the MEMS micromirror can be freely controlled.

As shown in FIG. 6 , the MEMS micromirror 1 includes a MEMS micromirror platform 11 , a mirror body 13 and a mirror body driving arm 12 connected between the mirror body 13 and the MEMS micromirror platform 11 . Further, at least one side of the mirror body 13 is connected with a mirror body driving arm 12 . Preferably, in this embodiment, there are four mirror body driving arms 12 , which are respectively arranged in the direction of four corners of the mirror body 13 , so as to flexibly control the inclination angle of the mirror body 13 . Wherein, the inclination angle of the mirror body 13 of the MEMS micromirror 1 is fixed, or the inclination angle of the mirror body 13 itself can also be adjusted and changed by the mirror body driving arm 12 around it. Preferably, in this embodiment, the inclination angle of the mirror body 13 is also adjustable. Specifically, the material layer structure of the mirror body driving arm 12 is the same as any one of the above three structures of the driving arm 2. Preferably, the mirror body driving arm 12 is a double-layer material layer structure with different expansion coefficients. Heating the structural layer; when the external electrical signal passes through the electric lead 31, passes through the driving arm 2, and finally reaches the mirror body driving arm 12, the heating structure embedded in the middle of the mirror body driving arm 12 is energized and heated, and the upper and lower layers are heated, so that the mirror body When the driving arm 12 deflects, the angle of the mirror body 13 changes accordingly, so that the angle of the mirror body can be adjusted.

Further, when the driving arm 2 and the mirror body driving arm 12 are manufactured, an initial inclination angle will be formed due to heat and cooling, and this angle can be determined by the length of the driving arm 2 and the mirror body driving arm 12 and the thickness of the material layer. The parameters are determined. Therefore, during the entire system assembly process, there is no need to pre-align the inclination angle of the MEMS micromirror, and then adjust it according to the need during use, which makes the installation process easier.

At the same time, since the driving arm 2 can not only control the inclination angle of the MEMS micromirror 1, but also play a supporting role, the MEMS micromirror 1 does not need an additional support structure in the entire MEMS device system, which not only reduces the overall volume of the system , so that the MEMS micromirror 1 can reduce the frame area of the micromirror platform 11 and improve the filling rate of the mirror surface.

In the present invention, the structure of the driving arm 2 of the MEMS micromirror and the structure of the mirror body driving arm 12 of the mirror body 13 can adopt the same or different structural forms. However, for the convenience of design and processing, the same structural form is generally adopted, and the specific processing process is shown in Figure 7:

(a) SOI preparation;

(b) PECVD _SiO2 and patterning;

(c) Pt graphics;

(d) PECVD _SiO2 and patterning;

(e) Al graphics;

(f) PECVD _SiO2 and patterning;

(g) Make the backside DRIE mask;

(h) Backside DRIE Si, RIE SiO ₂ ;

(i) DRIE Si on the front side, and side drilling to remove the silicon under the driving structure;

(j) The structure is fully released.

In the above manner, no other process steps need to be added, which saves costs. However, different structural forms can also be used, which only increases the complexity of the process.

The above describes the technical principles of the present invention in conjunction with specific embodiments. These descriptions are only for explaining the principles of the present invention, and cannot be construed as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can think of other specific implementation modes of the present invention without creative efforts, and these modes will all fall within the protection scope of the present invention.

Claims (16)

1. the device of the controlled MEMS micro mirror in integrated inclination angle, comprise MEMS micro mirror (1), substrate (3), electrical lead (31), described electrical lead (31) is arranged in the described substrate (3), it is characterized in that: be connected with actuating arm (2) between described MEMS micro mirror (1) and the described substrate (3), described MEMS micro mirror (1) bottom is without supporting the unsettled setting in ground.

2. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 1, it is characterized in that: described MEMS micro mirror (1) comprises frame (11), minute surface (13) and mirror body actuating arm (12), and described mirror body actuating arm (12) is connected between frame (11) and the minute surface (13).

3. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 1, it is characterized in that: the type of drive of described actuating arm (2) is electrothermal drive, Piezoelectric Driving or thermal expansion polymer.

4. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 1, it is characterized in that: described actuating arm (2) comprises at least two sections double-deckers, described double-deck first paragraph (26) comprises the first material layer (24) and the second material layer (25) with second segment (27), first material layer (24) of described first paragraph (26) is arranged on the top of the second material layer (25), and first material layer (24) of described second segment (27) is arranged on the below of the second material layer (25); Described first paragraph (26) is connected setting successively with second segment (27).

5. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 1, it is characterized in that: described actuating arm (2) comprises at least two sections sandwich constructions, the first paragraph of described sandwich construction (26) comprises the first material layer (24) and the second material layer (25) with second segment (27), first material layer (24) of described first paragraph (26) is arranged on the top of the second material layer (25), and first material layer (24) of described second segment (27) is arranged on the below of the second material layer (25); Described first paragraph (26) and described second segment (27) also comprise one or more layers material structure except the first material layer (24) and the second material layer (25), and described first paragraph (26) is connected setting successively with second segment (27).

6. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 1, it is characterized in that: described actuating arm (2) comprises upper layer of material layer (21) and subsurface material layer (22) at least, and described upper layer of material layer (21) is different from the material thermal expansion coefficient of subsurface material layer (22).

7. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 6 is characterized in that: be provided with one or more layers material layer between the lower surface of the upper surface of described upper layer of material layer (21), subsurface material layer (22) or upper layer of material layer (21) and the subsurface material layer (22).

8. according to claim 4 to the device of 6 each controlled MEMS micro mirrors in described a kind of integrated inclination angle, it is characterized in that: having one deck in the described actuating arm (2) at least is conductor layer.

9. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 1, it is characterized in that: described substrate (3) is provided with pad, pad conduction in described electrical lead (31) and the described substrate (3) is connected, and the other end of described electrical lead (31) is electrically connected with the conductor of actuating arm (2).

10. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 1, it is characterized in that: the mirror body (13) of described MEMS micro mirror self angle of inclination is fixed, and perhaps mirror body (13) self pitch angle is adjustable by the mirror body actuating arm (12) around it.

11. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 10, it is characterized in that: described mirror body actuating arm (12) comprises at least two sections double-deckers, described double-deck first paragraph (26) comprises the first material layer (24) and the second material layer (25) with second segment (27), first material layer (24) of described first paragraph (26) is arranged on the top of the second material layer (25), and first material layer (24) of described second segment (27) is arranged on the below of the second material layer (25); Described first paragraph (26) is connected setting successively with second segment (27).

12. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 10, it is characterized in that: described mirror body actuating arm (12) comprises at least two sections sandwich constructions, the first paragraph of described sandwich construction (26) comprises the first material layer (24) and the second material layer (25) with second segment (27), first material layer (24) of described first paragraph (26) is arranged on the top of the second material layer (25), and first material layer (24) of described second segment (27) is arranged on the below of the second material layer (25); Described first paragraph (26) and described second segment (27) also comprise one or more layers material structure except the first material layer (24) and the second material layer (25), and described first paragraph (26) is connected setting successively with second segment (27).

13. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 10, it is characterized in that: described mirror body actuating arm (12) comprises upper layer of material layer (21) and subsurface material layer (22) at least, and described upper layer of material layer (21) is different from the material thermal expansion coefficient of subsurface material layer (22).

14. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 10 is characterized in that: described mirror body (13) is Yi Bian be connected with at least mirror body actuating arm (12).

15. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 1, it is characterized in that: the initial deflection angle of described MEMS micro mirror (1) is by length, material thickness and the process parameter control of actuating arm (2).

16. the device of the controlled MEMS micro mirror in a kind of integrated inclination angle according to claim 1 is characterized in that: the upper integrated feedback circuit (4) that is provided with of described actuating arm (2), with the deflection angle of Real-time Feedback MEMS micro mirror.

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