MEMS micro-displacement platform and position detection method thereof

Abstract

The invention discloses an MEMS micro-displacement platform and a position detection method thereof, and belongs to the field of MEMS device detection.The MEMS micro-displacement platform is mainly characterized in that a position sensing component is placed near an MEMS micro-mirror, the sensing component is integrated into the MEMS micro-mirror, when the mirror surface of the MEMS micro-mirror deflects to be close to the sensing component, the sensing component can generate a corresponding electric signal, and after the sensing component is placed, the MEMS micro-displacement platform can be used for detecting the position of the MEMS micro-displacement platform. Signals are transmitted to the drive control circuit through TSV or TGV and other technologies, and therefore the position of the mirror surface is obtained in real time. According to the invention, the device detection is combined with the TSV or TGV process, the integration level of the existing detection device is greatly improved, and the device can be produced in a large-scale and low-cost manner, and has a relatively high market prospect.

Description

Technical Field

[0001] The present invention relates to the field of MEMS device detection, and in particular to a MEMS micro-displacement platform and a position detection method thereof. Background Art

[0002] Micro-electro-mechanical system (MEMS), also known as micro-electro-mechanical system, microsystem, micro-machine, etc., its internal structure is generally in the micron or even nanometer level, and it is an independent intelligent system. MEMS is developed on the basis of microelectronics technology (semiconductor manufacturing technology), and is a high-tech electronic mechanical device made by integrating lithography, corrosion, thin film, LIGA (MEMS processing technology based on X-ray lithography technology), silicon micromachining, non-silicon micromachining and precision machining. In order to improve the stability of the MEMS micro-displacement platform during operation, a position detection functional unit is generally integrated on the MEMS micro-displacement platform (on or near the platform support structure) to obtain the position, angle and other information of the platform movement, and then the real-time feedback control of the micro-motion platform movement is realized through the drive circuit. Among them, for electrostatic, electrothermal, electromagnetic, piezoelectric and other MEMS devices with mirrors, they all work by deflecting their mirrors and reflecting light for scanning, so it is very important to know the position of the mirror.

[0003] The position detection of MEMS micro-displacement platform is a difficult problem that bothers everyone. The position detection methods of MEMS micro-displacement platform mainly include the following:

[0004] 1. The piezoresistive measurement method is used, that is, a pressure-sensitive component is attached to the driving structure, or the pressure-sensitive component is independently connected to the mirror surface. It is generally used in structures such as optical scanning. The piezoresistive measurement method currently has good accuracy, but there is no quantitative analysis yet, and there are disadvantages such as poor temperature characteristics and complex processes. In addition, the piezoresistive measurement method is only applicable to MEMS micro-displacement platforms whose driving arms are made of single-crystal silicon, and cannot be applied to different types of micro-mirror structures.

[0005] 2. Use photosensitive devices for detection. The principle is that when the micromirror module is in use, a beam of light hits the surface of the micromirror. When the micromirror moves, the reflected light directly hits the photosensitive device, or when the window glass is transparent, part of the light is reflected to the position sensitive detector (PSD). Its advantages are high optical judgment accuracy and wide application range. Its disadvantages are that the position sensitive detector PSD is expensive and not easy to integrate, which increases the difficulty of packaging and packaging and testing costs.

[0006] 3. The solution of calculating the displacement position through an algorithm, for example: the voltage supplied to the chip driver is a sine curve, and the torsion trajectory of the mirror displacement position is also a sine curve. Then, by setting two high-speed photodiodes in the scanning optical path, the torsion phase and amplitude of the MEMS micromirror are obtained according to the position relationship of the two photodiodes and the time when the scanning light beam passes through the two photodiodes, and the torsion angle of the MEMS micromirror at any time is estimated according to the angle / time trajectory of the sine curve. This algorithm requires that the quality of the chip mirror is completely symmetrical on the left and right and is not subject to external interference. There is a certain probability of calculation errors, and the accuracy of the test cannot be guaranteed. Summary of the invention

[0007] The purpose of the present invention is to overcome the technical problems existing in the prior art and provide a MEMS micro-displacement platform and a position detection method thereof, which is mainly aimed at judging the position of MEMS micro-displacement platforms with mirrors such as electrostatic, electrothermal, electromagnetic, and piezoelectric, so as to achieve low-cost, easy integration, and high-precision batch use.

[0008] The objective of the present invention is achieved through the following technical solutions:

[0009] In a first aspect, a MEMS micro-displacement platform is provided, in which a sensing component for detecting a change in a mirror position is integrated, and the sensing component is connected to a drive control circuit via a conducting structure.

[0010] In some embodiments, the MEMS micro-displacement platform is an electrostatic micro-mirror, an electrothermal micro-mirror, an electromagnetic micro-mirror or a piezoelectric micro-mirror.

[0011] In some embodiments, the sensing element is a capacitor, an inductor, a position sensor or a photodiode.

[0012] In some embodiments, the conductive structure is a through silicon via structure or a through glass via structure.

[0013] In some embodiments, the conductive structure is vertically conductive.

[0014] In some embodiments, the conductive structure is stacked in multiple layers.

[0015] In some embodiments, a sensing component carrier is also included, and the sensing component carrier is used to support and place the sensing component.

[0016] In some embodiments, the sensing component carrier is a silicon wafer and / or a glass wafer.

[0017] In some embodiments, the conductive structure is connected to the driving control circuit via an external solder ball.

[0018] In a second aspect, a position detection method of a MEMS micro-displacement platform is provided, which is used for the MEMS micro-displacement platform, comprising:

[0019] The position change of the mirror is detected by the sensing element to generate a corresponding electrical signal; the electrical signal is transmitted to the drive control circuit through the conduction structure, and the position information of the mirror is read in real time by the drive control circuit.

[0020] It should be further explained that the technical features corresponding to the above options can be combined or replaced with each other to form a new technical solution if there is no conflict.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention mainly integrates sensing components near the MEMS micromirror. When the mirror surface of the MEMS micromirror deflects and approaches the sensing components, the sensing components will generate corresponding electrical signals, and then transmit the signals to the drive control circuit through conduction processes such as TSV or TGV, so as to obtain the position of the mirror surface in real time, accurately determine the position of the displacement platform and provide real-time feedback. The structural design is simple and applicable to different types of micromirror structures. At the same time, the present invention combines the position detection of the micro-displacement platform with the TSV or TGV process, greatly improving the integration of existing detection devices, and can be mass-produced in large quantities at low cost, with a high market prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A typical TSV structure shown in an embodiment of the present invention;

[0024] Figure 2 A typical structure of a TGV shown in an embodiment of the present invention;

[0025] Figure 3 The existing MEMS electrostatic micromirror structure shown in the embodiment of the present invention;

[0026] Figure 4 The MEMS electrostatic micromirror platform structure after the integrated sensing components are shown in the embodiment of the present invention;

[0027] Figure 5 The MEMS electrothermal micromirror platform structure after integrating sensing components is shown in an embodiment of the present invention;

[0028] Figure 6 The MEMS electromagnetic micromirror platform structure after integrating sensing components is shown in an embodiment of the present invention;

[0029] Figure 7 The MEMS piezoelectric micromirror platform structure after integrating sensing components is shown in an embodiment of the present invention.

[0030] In the figure: 1-positive electrode of MEMS mirror, 2-negative electrode of MEMS mirror, 3-mirror, 4-comb teeth, 5-torsion beam, 6-silicon wafer (glass wafer), 7-sensing components, 8-wiring of TGV (TSV) process, 9-solder ball, 10-driving arm, 11-integrated coil. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various configurations. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] It should be noted that the defects existing in the solutions in the above-mentioned prior art are the results obtained by the inventor after practice and careful research. Therefore, the discovery process of the above-mentioned problems and the solutions proposed in the embodiments of the present application for the above-mentioned problems below should all be the contributions made by the inventor to the present application in the process of invention and creation, and should not be understood as technical contents known to technical personnel in this field.

[0033] Before describing the embodiments of the present application, an introduction to TSV and TGV processes is given as follows:

[0034] TSV, the abbreviation of "Through-Silicon Via", is a vertical electrical interconnection through a silicon substrate (wafer or chip). A simple description is a through-silicon via. It is an advanced packaging technology that allows a conductive channel to be formed vertically on a silicon chip or wafer, thereby achieving electrical interconnection between different layers or different chips. TSV mainly completes the vertical electrical interconnection of through-silicon vias by filling with conductive materials such as copper, reducing signal delays, reducing capacitance and inductance, achieving low power consumption and high-speed communication of chips, increasing bandwidth and realizing miniaturization requirements of device integration. TSV is a key process in wafer-level multi-layer stacking technology that effectively improves system integration and performance. Figure 1 The figure shows the typical structure of TSV, which is a through hole in the silicon substrate, electroplated with metal, such as copper, to achieve vertical electrical interconnection inside the silicon wafer. Then, solder balls are implanted at the bottom of the silicon wafer to achieve conduction between the top electrode and the bottom solder balls.

[0035] TGV, the abbreviation of "Through-Glass Via", is a vertical electrical interconnection through the glass substrate. Simply put, it is a through-glass hole. Through-glass hole technology is made by sandblasting, photosensitive glass method, focused power generation method, plasma etching method, laser ablation method, electrochemical discharge machining method, laser induced etching method and other technologies. Figure 2 The typical structure of TGV is shown in the figure. It is a through hole on a glass substrate. The substrate can be high-quality borosilicate glass or quartz glass. Then it is also filled with electroplated metal to achieve vertical electrical interconnection, so as to reduce the distance of signal transmission. The direction is not limited to the vertical direction, and the wiring can be arranged in different depths and directions.

[0036] Figure 3 A MEMS electrostatic micromirror platform structure is provided. Specifically, in the figure, reference numeral 1 is the positive electrode of the MEMS mirror (specifically the positive electrode of the comb tooth driver in the structure), reference numeral 2 is the negative electrode of the MEMS mirror (specifically the negative electrode of the comb tooth driver in the structure), a voltage of a certain waveform is applied to the MEMS comb tooth driver, and a capacitance effect is vertically formed between the comb teeth 4. When the electric field of the two rows of comb teeth structure changes, the electric field between the comb teeth changes to generate a force to deflect the mirror surface 3. The electrostatic force generated by the electric field drives the comb teeth 4 to move vertically, and the vertical movement force drives the mirror surface 3 at the micro-displacement platform position to twist through the torsion beam 5, and the mirror surface 3 deflects at a certain angle.

[0037] Furthermore, if Figure 4 As shown, the MEMS electrostatic micromirror is bonded to a silicon wafer 6 (glass wafer). After the mirror 3 at the position of the micro-displacement platform is deflected, the sensing component 7 located below the mirror 3 senses the position change of the mirror 3, generates a corresponding electrical signal, and transmits the signal to the external solder ball (Pad) 9 through the wiring 8 of the TGV (TSV) process, thereby realizing the communication between the sensing component 7 and the external drive control circuit board, so as to obtain the position of the mirror 3 in real time. Among them, the silicon wafer 6 is used as the sensing component carrier. In other examples, the sensing component carrier can also be an electrical interconnection structure realized by the silicon wafer and the glass wafer through the process, and then connected to the PCB board or the ceramic substrate.

[0038] In some examples, the conductive structure can be a through-hole structure on silicon, or a wiring structure on the back, or by bonding with a silicon wafer (glass wafer), combining device testing with TSV (TGV) technology. The conductive structure can be a vertical conductive structure or a multi-layer stack.

[0039] Figure 5 A MEMS electrothermal micromirror platform structure is presented. The driving force of the electrothermal driven micromirror comes from the difference in thermal conductivity and thermodynamic properties of different materials. After the driving arm is powered on and heated, thermal expansion occurs to generate driving force. The micromirror uses a double-layer driving structure, such as a bimorph driven micromirror made of Al / SiO2 material. The electrothermal bimorph driver is a double-layer driving structure with different thermal expansion coefficients (CTE). The thermal expansion difference caused by power heating will cause the structure to deform, thereby driving the scanning mirror to deflect.

[0040] like Figure 5As shown in the figure, label 1 is the positive electrode of the MEMS mirror, label 2 is the negative electrode of the MEMS mirror, and a voltage of a certain waveform is applied to the MEMS micromirror. After the driving arm 10 is powered on and heated, thermal expansion occurs to generate a driving force, which drives the micromirror surface 3 to deflect. The sensing component 7 located below the micromirror surface 3 senses the position change of the mirror surface 3 and generates a corresponding electrical signal. The signal is transmitted to the external solder ball (Pad) 9 through the wiring of the TGV (TSV) process, thereby realizing the communication between the sensing component 7 and the external circuit board.

[0041] Figure 6 A MEMS electromagnetic micromirror platform structure is given. Electromagnetic drive uses current to generate Lorentz force through a magnetic field. The torsion of the micromirror is controlled by controlling the amplitude and direction of the current. Electromagnetic drive micromirrors are often driven by an external magnetic field, which is generally generated by Permalloy or a powered coil. Electromagnetic drive scanning mirrors use Lorentz force to achieve drive. Since the Lorentz force is proportional to the size, the larger the size, the greater the driving force. Electromagnetic drive is current driven, with low driving voltage and no need for a boost chip. To build in a strong magnetic field or a strong magnet, a coil is integrated on the MEMS electromagnetic micromirror. The coil is placed in a magnetic field. The magnetic field interacts with the coil with current flowing through it to generate Lorentz force, driving the MEMS mirror to deflect.

[0042] like Figure 6 As shown in the figure, label 1 is the positive electrode of the MEMS mirror, label 2 is the negative electrode of the MEMS mirror, and a current of a certain amplitude is applied to the MEMS micromirror. After the integrated coil 11 is energized, it interacts with the magnetic field to generate a Lorentz force, driving the micromirror surface 3 to deflect. The sensing component 7 located next to the micromirror surface 3 senses the position change of the mirror surface 3 and generates a corresponding electrical signal. The signal is transmitted to the external circuit board through the TSV structure at the bottom to achieve communication connection.

[0043] Figure 7 A MEMS piezoelectric micromirror platform structure is given. The driver of the MEMS piezoelectric micromirror uses the positive and negative piezoelectric effects of piezoelectric materials to convert electrical signals into mechanical force to drive the micromirror to deflect. The driver is usually composed of a PZT piezoelectric film. By applying an additional electric field at both ends of the PZT piezoelectric film, the positive and negative charges inside the PZT piezoelectric film are relatively displaced to form an electric polarization phenomenon. Under the influence of the electric polarization phenomenon, the length of the PZT piezoelectric film changes, generating a force to drive the micromirror to deflect. Four multilayer torsion beam supports containing PZT materials can achieve two-dimensional deflection.

[0044] like Figure 7As shown in the figure, label 1 is the positive electrode of the MEMS mirror, label 2 is the negative electrode of the MEMS mirror, and an additional electric field is applied to both ends of the MEMS micromirror, and the positive and negative charges inside the piezoelectric film are relatively displaced. The displacement generates a force to drive the micromirror surface 3 to deflect, and the sensing component 7 located below the micromirror surface 3 senses the position change of the mirror surface 3 and generates a corresponding electrical signal. The signal is transmitted to the external solder ball (Pad) 9 through the TGV process structure at the bottom, and the communication between the sensing component 7 and the external circuit board is realized by gold wire bonding.

[0045] Compared with the existing technology, the manufacturing integration of the present invention is high, mass production can be achieved through the process, the precision and accuracy are high, and the mirror position can be fed back in real time. When faced with device cost pressure, time pressure, high precision requirements, etc., this solution has low cost and high efficiency. In addition, the market currently has mature TSV (TGV) technology. Long-term testing experience has shown that this solution does have high reliability and a broad market.

[0046] It should be noted that the above solutions can be combined by themselves and are not limited to the above categories. Any deformation structure formed based on the concept of the present invention and the corresponding detection method are within the protection scope of this application.

[0047] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A MEMS micro-displacement platform, characterized in that: A sensing component for detecting the change in mirror position is integrated in the MEMS micro-displacement platform, and the sensing component is connected to a drive control circuit through a conducting structure.

2. A MEMS micro-displacement platform according to claim 1, characterized in that: The MEMS micro-displacement platform is an electrostatic micro-mirror, an electrothermal micro-mirror, an electromagnetic micro-mirror or a piezoelectric micro-mirror.

3. A MEMS micro-displacement platform according to claim 1, characterized in that: The sensing element is a capacitor, an inductor, a position sensor or a photodiode.

4. The MEMS micro-displacement platform according to claim 1, characterized in that: The conductive structure is a through silicon via structure or a through glass via structure.

5. The MEMS micro-displacement platform according to claim 1, characterized in that: The conductive structure is longitudinally conductive.

6. The MEMS micro-displacement platform according to claim 1, characterized in that: The conductive structure is stacked in multiple layers.

7. The MEMS micro-displacement platform according to claim 1, characterized in that: It also includes a sensing component carrier, which is used to support and place the sensing component.

8. The MEMS micro-displacement platform according to claim 7, characterized in that: The sensing element carrier is a silicon wafer and / or a glass wafer.

9. The MEMS micro-displacement platform according to claim 1, characterized in that: The conduction structure is connected to the drive control circuit via an external solder ball.

10. A method for detecting the position of a MEMS micro-displacement platform, used for the MEMS micro-displacement platform according to any one of claims 1 to 9, characterized in that: include: The position change of the mirror is detected by the sensing element to generate a corresponding electrical signal; The electrical signal is transmitted to the drive control circuit through the conduction structure, and the position information of the mirror is read in real time through the drive control circuit.

Images