A heterogeneously integrated chip-level spectral tuning microsystem

Abstract

The present invention relates to a heterogeneously integrated chip-level spectral tuning microsystem, comprising: a fixed filter structure layer, a driving electrode (13), a driving detection electrode (12), a lower support column (14), and a signal input terminal (18) are manufactured on the top silicon of an SOI silicon wafer, and a conductive bonding layer (16) is provided on the signal input terminal; a movable filter structure layer is photoetched with a movable structure (22) and an upper support column (23), and the upper support column and the lower support column are bonded and connected, and a Fabry-Perot interference cavity is formed by the above-mentioned fixed filter structure and movable filter structure; a cap layer (30) is provided with a vertical conductive column (31), a conductive metal (35) and a PAD point (33); and a drive circuit chip (40) is connected to the PAD point (41). The present invention has the beneficial effects of combining an electrostatic drive electrode with a composite optical film structure, improving the optical duty cycle, increasing the driving force, and improving the operating accuracy and stability of the filter system.

Description

Technical Field

[0001] The present invention belongs to the field of micro-opto-electromechanical systems (MOEMS), and specifically is a heterogeneously integrated chip-level spectral tuning microsystem. Background Art

[0002] Micro-opto-electromechanical system (MOEMS) is a new and dynamic new technology system developed in micro-electromechanical system (MEMS) in recent years. It is a new type of micro-optical structure system produced by the combination of micro-optics, micro-electronics and micro-mechanics. MOEMS is a controllable micro-optical system. The micro-optical elements in the system can control the convergence, diffraction, reflection and filtering of light beams under the action of micro-electronics and micro-mechanical structures.

[0003] As optoelectronic detection systems develop towards intelligence, miniaturization and integration, the application of imaging spectroscopy technology is becoming more and more extensive, and has extended from military aspects such as aerospace detection and target anti-camouflage to civilian applications.

[0004] Advanced infrared imaging systems require increasingly higher spectral resolution and will undergo the development process of multi-spectral, hyper-spectral and hyper-spectral. At present, the traditional spectroscopic method usually uses prisms, gratings, etc. on the infrared optical system to split the infrared radiation to achieve infrared multi-spectral and hyper-spectral imaging. The use of this spectroscopic method will result in a large photoelectric detection system, complex optical path, high power consumption, and cannot meet the requirements of micro-platform use.

[0005] The spectral tuning microsystem based on the Fabry-Perot interference principle provides input voltage to the pixel-level MOEMS filter array structure through the ASIC chip to control the wavelength band of the incident infrared radiation on each pixel. This chip-level spectral tuning microsystem can effectively simplify the optical system of spectral imaging, greatly reduce the volume and power consumption of the whole system, and its high spectral selection flexibility and spectral accuracy promote the in-depth development of spectral imaging technology. Summary of the invention

[0006] The purpose of the present invention is to provide a heterogeneously integrated chip-level spectral tuning microsystem, which involves micro-optics, microelectronics, and micromechanics, and has the advantages of drive signal feedback, large driving force, controllable damping, high duty cycle, and easy subsequent integration with detectors.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] A heterogeneous integrated chip-level spectrum tuning microsystem, characterized in that it is composed of: a fixed filter structure layer, a movable filter structure layer, a cap layer and an ASIC driving circuit from bottom to top.

[0009] The fixed filter structure layer is prepared by SOI silicon wafer, and patterned driving electrodes, driving detection electrodes, lower support pillars, signal input terminals to buried oxide layers are photolithographically produced on the top silicon of the SOI silicon wafer, and highly reflective composite films are prepared on the driving electrodes and driving detection electrodes, and a conductive bonding layer is provided on the signal input terminal, and the driving electrodes and driving detection electrodes are respectively connected to the corresponding signal input terminals through top silicon interconnection lines;

[0010] The movable filter structure layer is prepared by SOI silicon wafer, including a patterned movable structure corresponding to the driving electrode and the driving detection electrode and an upper support column corresponding to the lower support column made by photolithography process, a high-reflection composite film is prepared under the movable filter structure, the upper support column and the lower support column are bonded and connected correspondingly by wafer-level bonding, the driving electrode and the upper high-reflection composite film form a fixed filter structure of the Fabry-Perot cavity, the movable structure and the lower high-reflection composite film form a movable filter structure of the Fabry-Perot cavity, and the fixed filter structure and the movable filter structure together constitute a Fabry-Perot interference cavity;

[0011] The cap layer is made of double-polished silicon wafer, a cavity is provided on the back of the middle part of the cap layer to match the movable filter structure layer, a vertical conductive column corresponding to the signal input end is provided around the cap layer, an insulating dielectric isolation layer is provided on the outer periphery of the vertical conductive column, a conductive metal is provided at the inner end of the vertical conductive column, and a PAD point is provided at the outer end, and an anti-reflection composite film is formed on the bottom surface of the cavity of the cap layer and the outer surface corresponding to the bottom surface;

[0012] Bonding the prepared cap layer on the movable filter structure layer through wafer-level alignment, wherein the vertical conductive pillars are electrically connected to the conductive bonding layer of the fixed filter structure layer through conductive metal;

[0013] The driving circuit chip is prepared by using a standard integrated circuit process, including a PAD point for a flip-chip process, and the flip-chip process is used to align and bond the PAD point of the driving circuit chip with the PAD point of the cap.

[0014] The movable filter structure layer and the fixed filter structure layer of the present invention form a Fabry-Perot interference cavity, which can be a unit type or an array type. An ASIC driving circuit is used to apply a driving voltage between the movable filter structure layer and the fixed filter structure layer to adjust the interference cavity length and control the light transmission spectrum, thereby achieving the purpose of spectrum tuning.

[0015] The beneficial effects of the present invention are:

[0016] The spectral tuning microsystem combines an electrostatically driven electrode with a composite optical thin film structure, which improves the optical duty cycle and increases the driving force. It adopts wafer-level vacuum damping adjustable packaging to achieve controllable damping of the movable filter structure and improve the stability of spectral tuning. The driver chip adopts TSV heterogeneous integration to reduce the chip-level spectral tuning microsystem area. The electrostatic drive and electrostatic drive detection are integrated together to improve the operating accuracy and stability of the filter system. It is easy to integrate the detector chip, thereby effectively reducing the volume of the photoelectric detection system and simplifying the structure of the photoelectric detection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0018] Figure 1 It is a schematic diagram of the structure of the present invention;

[0019] Figure 2 It is a top view of the fixed filter structure layer of the present invention.

[0020] Specific implementation method

[0021] Combination Figure 1 As shown, the present invention provides a heterogeneously integrated chip-level spectral tuning microsystem with a total of four layers, which are, from top to bottom: an ASIC driving circuit, a cap layer, a movable filter structure layer, and a fixed filter structure layer.

[0022] The fixed filter structure layer is made of SOI silicon wafer, including substrate silicon 17a, buried oxide layer 17 and top silicon 17b. The patterned driving electrode 13, driving detection electrode 12, lower support column 14, signal input terminal 18 to buried oxide layer 17 are photolithographically made on the top silicon 17 of the SOI silicon wafer. A high-reflection composite film 15 is prepared on both the driving electrode 13 and the driving detection electrode 12, which can be made of evaporated silicon and silicon dioxide or other materials. A conductive bonding layer 16 is provided on the signal input terminal 18. The driving electrode 13 and the driving detection electrode 12 are respectively connected to the corresponding signal input terminal 18 through the top silicon interconnection line;

[0023] like Figure 2 As shown, the fixed filter structure layer is shown in the schematic diagram Figure 2 The The array structure is for reference only and can be adjusted according to design requirements to form An array, wherein the driving electrodes 13 and the driving detection electrodes 12 are connected to the corresponding signal input terminals 18 through top-layer silicon interconnection lines 12a and 13a, respectively.

[0024] As shown in Figure 1, the movable filter structure layer is made of SOI silicon wafer, including a movable structure 22 and a bonding support column 23. A high-reflection composite film 21 is prepared under the movable filter structure, and the bonding support column 23 is connected to the fixed filter structure layer support column 14 through wafer-level bonding. The driving electrode 13 and the high-reflection composite film 15 above form a fixed filter structure of the Fabry-Perot cavity, and the movable structure 22 and the high-reflection composite film 21 below form a movable filter structure of the Fabry-Perot cavity. The fixed filter structure and the movable filter structure together constitute a Fabry-Perot interference cavity. In the present invention, the fixed filter structure can be used as both a driving electrode plate and an optical channel. Compared with the generally used driving plate and optical channel separation structure, the optical duty cycle and electrostatic driving force are improved under the same chip area.

[0025] The cap layer 30 is made of double-polished silicon wafer, and a cavity 34 cooperating with the movable filter structure layer is provided on the back of the middle part of the cap layer, and a vertical conductive column 31 corresponding to the signal input terminal 18 is provided around the cap layer, and an insulating dielectric isolation layer 32 is provided on the outer periphery of the vertical conductive column, and a conductive metal 35 is provided at the inner end of the vertical conductive column, and a PAD point 33 of the Flip-Chip process is provided at the outer end, and an anti-reflection composite film 36 is respectively formed on the bottom surface of the cap layer cavity 34 and the outer surface corresponding to the bottom surface;

[0026] The prepared cap is bonded on the movable filter structure layer through wafer-level alignment, wherein the vertical conductive pillar 31 is electrically connected to the bonding layer 16 of the fixed filter structure layer through the conductive metal 35 .

[0027] The driving circuit chip 40 is prepared by a standard integrated circuit process and includes a PAD point 41 for a flip-chip process. The PAD point 41 of the driving circuit chip is aligned and bonded with the PAD point 33 of the cap 3 by a flip-chip process to form a good electrical connection. The driving voltage signal is transmitted to the fixed filter structure layer driving electrode 13 and the movable filter structure 22 through the vertical conductive column 31 of the cap, so that the movable filter structure 22 can be translated up and down, thereby adjusting the gap (cavity length) 19 formed by the movable filter structure 22 and the driving electrode 13, so as to achieve the purpose of tuning the transmission spectrum.

Claims

1. A heterogeneously integrated chip-level spectrum tuning microsystem, characterized in that: From bottom to top, it is composed of: fixed filter structure layer, movable filter structure layer, cap layer and ASIC drive circuit. The fixed filter structure layer is prepared using an SOI silicon wafer, and patterned drive electrodes (13), drive detection electrodes (12), lower support pillars (14), signal input terminals (18) to a buried oxide layer (17) are photolithographically produced on the top silicon layer of the SOI silicon wafer, a high-reflection composite film (15) is prepared on both the drive electrode (13) and the drive detection electrode (12), a conductive bonding layer (16) is provided on the signal input terminal (18), and the drive electrode (13) and the drive detection electrode (12) are respectively connected to the corresponding signal input terminal (18) via top silicon interconnect lines; The movable filter structure layer is prepared using an SOI silicon wafer, and comprises a patterned movable structure (22) corresponding to the driving electrode (13) and the driving detection electrode (12) and an upper support column (23) corresponding to the lower support column (14) produced by a photolithography process; a high-reflection composite film (21) is prepared below the movable filter structure; the upper support column (23) and the lower support column (14) are bonded and connected correspondingly via wafer-level bonding; the driving electrode (13) and the upper high-reflection composite film (15) form a fixed filter structure of the Fabry-Perot cavity; the movable structure (22) and the lower high-reflection composite film (21) form a movable filter structure of the Fabry-Perot cavity; the fixed filter structure and the movable filter structure together form a Fabry-Perot interference cavity; The cap layer (30) is made of a double-polished silicon wafer, a cavity (34) cooperating with the movable filter structure layer is provided on the back of the middle part of the cap layer, a vertical conductive column (31) corresponding to the signal input end (18) is provided around the cap layer, an insulating dielectric isolation layer (32) is provided around the vertical conductive column, a conductive metal (35) is provided at the inner end of the vertical conductive column, and a PAD point (33) is provided at the outer end, and an anti-reflection composite film (36) is formed on the bottom surface of the cavity (34) of the cap layer and on the outer surface corresponding to the bottom surface; Bonding the prepared cap layer on top of the movable filter structure layer through wafer-level alignment, wherein the vertical conductive column (31) is electrically connected to the conductive bonding layer (16) of the fixed filter structure layer through the conductive metal (35); The driving circuit chip (40) is prepared using a standard integrated circuit process and includes a PAD point (41) for a flip-chip process. The flip-chip process is used to align and bond the PAD point (41) of the driving circuit chip with the PAD point (33) of the cap (3).

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