A method for preparing a micro-optical electromechanical system

Abstract

The invention relates to a preparation method of micro-opto-mechanical system, comprising the following steps: forming a patterned high-reflection film, a top silicon electrode and a detection electrode on the top silicon of a first SOI silicon wafer; the patterned top silicon of a second SOI silicon wafer and the high-reflection film together form a movable filter structure, and the bottom of the patterned metal support column is connected to the top silicon; aligning and bonding the movable filter structure layer wafer prepared by S3 to the top of the fixed filter structure layer wafer prepared by S2, and bonding the metal support column in the movable filter structure to the metal support column in the fixed filter structure to form a support column; taking a standard wafer after polishing on both sides as a cap layer, and preparing a metal Pad point on the front of the cap to connect with a vertical conductive lead; the beneficial effects of the invention are: the preparation method is compatible with optical and MEMS preparation processes, can be mass-produced, and the micro-opto-mechanical system prepared by the method has the advantages of high integration, large optical duty cycle, large electrostatic driving force, easy integration with detectors, etc.

Description

Technical Field

[0001] The invention belongs to the field of micro-opto-electro-mechanical systems (MOEMS), and in particular relates to a method for preparing a micro-opto-electro-mechanical system. 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] Based on the principle of Fabry-Perot interference, the micro-opto-electromechanical system 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 micro-opto-electromechanical system can effectively simplify the optical system of spectral imaging, greatly reducing the volume and power consumption of the entire system. Its high spectral selection flexibility and spectral accuracy have promoted the in-depth development of spectral imaging technology. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a micro-opto-electromechanical system. The micro-opto-electromechanical system prepared by the method has the advantages of high integration, large optical duty cycle, large electrostatic driving force, easy integration with detectors, etc., and the processing technology is simple, the consistency is good, and batch production can be achieved.

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

[0008] A method for preparing a micro-opto-electromechanical device, characterized by comprising the following steps:

[0009] S1, taking a first SOI silicon wafer, including a top silicon layer, a buried oxide layer and a substrate silicon, as a fixed filter structure layer;

[0010] S2, forming a Bragg high reflective film on the top silicon of the first SOI silicon wafer by photolithography, evaporating silicon and silicon dioxide or other materials, and forming a patterned Bragg high reflective film by a stripping process or an etching process;

[0011] Use photolithography, sputtering, and stripping to prepare patterned metal support pillars and bonding metal layers;

[0012] The top silicon layer is etched to the buried oxide layer by photolithography and etching process to form a patterned high-reflection film and a patterned top silicon electrode and a detection electrode. The top silicon electrode and the high-reflection film are combined to form independent driving electrodes, forming a driving and optical channel integrated structure.

[0013] S3, taking a second SOI silicon wafer as a movable filter structure layer, including a substrate, a buried oxide layer and a top silicon layer, forming a high reflectivity film on the top silicon layer through evaporation film formation, photolithography and etching processes, the high reflectivity film material and the preparation process are consistent with the high reflectivity film material and the fixed filter structure, the patterned top silicon layer of the second SOI silicon wafer and the high reflectivity film located on the top silicon layer of the second SOI silicon wafer together form a movable filter structure,

[0014] The manufacturing process of the metal support column is the same as that of the patterned metal support column in the fixed filter structure, and the bottom of the patterned metal support column is connected to the top silicon layer;

[0015] S4, aligning and bonding the movable filter structure layer wafer prepared in S3 to the fixed filter structure layer wafer prepared in S2, wherein the metal support pillars in the movable filter structure are bonded together with the metal support pillars in the fixed filter structure to form support pillars, and then dry etching to remove the second SOI wafer substrate and buried oxide layer;

[0016] S5. Take a standard wafer after polishing on both sides as a cap layer, make a cavity on the back of the cap layer through photolithography and etching processes, make electrode holes around the cap layer, and fill the conductive holes with an electrical insulating layer. Fill the electrical insulating layer with metal materials to form vertical conductive leads. Use photolithography and etching processes to make an optical composite film for increasing transmission on the front of the cap layer and the bottom of the cavity. The optical composite film is made of silicon and silicon dioxide, or other suitable anti-reflection materials made by evaporation process; use film formation, photolithography and etching processes to make a conductive metal block on the back of the cap and connect it to the vertical conductive lead, and prepare a metal Pad point on the front of the cap to connect it to the vertical conductive lead 31;

[0017] S6, aligning and bonding the cap wafer prepared in S5 to the fixed filter structure wafer prepared in S4, so that the conductive metal block is bonded to the corresponding bonding metal layer;

[0018] S7, align and bond the electrodes of the driving circuit chip with the metal pad points on the wafer surface prepared in S6, and complete the preparation of the heterogeneous integrated micro-opto-electromechanical system.

[0019] The beneficial effects of the present invention are as follows: the preparation method is compatible with optical and MEMS preparation processes and can be mass-produced; the micro-opto-electromechanical system prepared by the method has the advantages of high integration, large optical duty cycle, large electrostatic driving force, and easy integration with detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0021] Figure 1 is a schematic diagram of step S1 of the present invention;

[0022] Figure 2 is a schematic diagram of step S2 of the present invention;

[0023] Figure 3 is a schematic diagram of step S3 of the present invention;

[0024] Figure 4 is a schematic diagram of step S4 of the present invention;

[0025] Figure 5 is a schematic diagram of step S5 of the present invention;

[0026] Figure 6 is a schematic diagram of step S6 of the present invention;

[0027] Figure 7 is a schematic diagram of step S7 of the present invention;

[0028] Figure 8 It is a top view of the fixed filter structure layer of the present invention.

[0029] Specific implementation method

[0030] The present invention provides a method for preparing a micro-opto-electromechanical device, comprising the following steps:

[0031] S1. Combination Figure 1 As shown, a first SOI silicon wafer, including a top silicon layer 17b, a buried oxide layer 17 and a substrate silicon 17a, is taken as a fixed filter structure layer;

[0032] S2. Combination Figure 2 As shown, a Bragg high reflective film is formed on the top silicon 17b by photolithography, evaporation of silicon and silicon dioxide or other materials, and a patterned Bragg high reflective film 15 is formed by a stripping process or an etching process;

[0033] The patterned metal support column 14 and the bonding metal layer 16 are prepared by photolithography, sputtering, and stripping. The metal can be selected from materials suitable for bonding, such as gold, aluminum, copper, etc. The corresponding bonding process is a mature process and will not be described in detail here.

[0034] By photolithography and etching the top silicon 17b to the buried oxide layer 17, a patterned high-reflective film 15 and a patterned top silicon electrode 13 and a detection electrode 12 are formed. The top silicon electrode 13 and the high-reflective film 15 are combined to form a mutually independent driving electrode 19, forming a driving and optical channel integrated structure;

[0035] S3. Combination Figure 3 As shown, a second SOI silicon wafer is taken as a movable filter structure layer, including a substrate 25, a buried oxide layer 24 and a top silicon layer 22. A high reflectivity film 21 is formed on the top silicon layer 22 through evaporation film formation, photolithography and etching processes. The high reflective film material and the preparation process are consistent with the high reflective film material and the preparation process of the fixed filter structure. The patterned top silicon layer 22 of the second SOI silicon wafer and the high reflective film 21 located on the top silicon layer 22 of the second SOI silicon wafer jointly form a movable filter structure 26.

[0036] The manufacturing process of the metal support column 23 is the same as that of the patterned metal support column 14 in the fixed filter structure. The bottom of the patterned metal support column 23 is connected to the top silicon 22. The material of the metal support column can be gold, aluminum, copper, etc., which are suitable for wafer bonding;

[0037] S4. Combination Figure 4 As shown, the movable filter structure layer wafer prepared in S3 is aligned and bonded to the fixed filter structure layer wafer prepared in S2, wherein the metal support column 23 in the movable filter structure is bonded to the metal support column 14 in the fixed filter structure to form a support column, and then the second SOI wafer substrate 25 and the buried oxide layer 24 are removed by dry etching;

[0038] S5. Combination Figure 5As shown, a standard wafer after polishing on both sides is taken as the cap layer 30, and the side with the cavity is defined as the back side, and the other side is the front side. A cavity 34 is made on the back side of the cap layer through photolithography and etching processes, electrode holes are made around the cap layer, and an electrical insulation layer 32 is filled in the conductive hole. Metal materials are filled in the electrical insulation layer to form a vertical conductive lead 31. An optical composite film 36 for increasing transmission is made on the front side of the cap layer and the bottom side of the cavity through photolithography and etching processes. The optical composite film 36 can be composed of silicon and silicon dioxide made by evaporation process, or other suitable anti-reflection materials; a conductive metal block 35 is made on the back side of the cap 30 through film forming, photolithography and etching processes to connect to the vertical conductive lead 31 and keep it electrically insulated from other places of the double-polished silicon wafer. A metal pad point 33 is prepared on the front side of the cap 30 to connect to the vertical conductive lead 31. The metal pad point 33 is used for subsequent bonding with the driver chip;

[0039] S6. Combination Figure 6 As shown, the cap wafer prepared in S5 is aligned and bonded to the fixed filter structure wafer prepared in S4, so that the conductive metal block 35 is bonded to the corresponding bonding metal layer 16. This process can control the damping of the movable filter structure by controlling the wafer-level bonding vacuum degree to meet the damping design requirements of the movable filter structure.

[0040] S7, Combination Figure 7 As shown, the electrode 41 of the driving circuit chip 40 prepared by the foundry is aligned and bonded with the metal pad point 33 on the wafer surface prepared in S6 to complete the preparation of the heterogeneous integrated micro-opto-electromechanical system.

[0041] S8. Combination Figure 8 As shown, the fixed filter structure is described, the driving detection electrodes 12 and the driving electrodes 13 are arranged in parallel, and the electrical signals of the driving detection electrodes 12 and the driving electrodes 13 are transmitted by the electrode leads 10.

[0042] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form; any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a micro-opto-electromechanical device, characterized in that The following steps are involved: S1, taking a first SOI silicon wafer, including a top silicon layer (17b), a buried oxide layer (17) and a substrate silicon (17a), as a fixed filter structure layer; S2, forming a Bragg high reflective film on the top silicon (17b) of the first SOI silicon wafer by photolithography, evaporation of silicon and silicon dioxide or other materials, and forming a patterned Bragg high reflective film (15) by a stripping process or an etching process; Using photolithography, sputtering, and stripping to prepare a patterned metal support column (14) and a bonding metal layer (16); The top silicon layer (17b) is etched to the buried oxide layer (17) by photolithography and etching processes to form a patterned high-reflection film (15) and a patterned top silicon electrode (13) and a detection electrode (12); the top silicon electrode (13) and the high-reflection film (15) are combined to form a mutually independent driving electrode (19), forming a driving and optical channel integrated structure; S3, taking a second SOI silicon wafer as a movable filter structure layer, including a substrate (25), a buried oxide layer (24) and a top silicon layer (22), forming a high reflectivity film (21) on the top silicon layer (22) through evaporation film formation, photolithography and etching processes, wherein the high reflectivity film material and preparation process are consistent with the high reflectivity film material of the fixed filter structure, and the patterned top silicon layer (22) of the second SOI silicon wafer and the high reflectivity film (21) located on the top silicon layer (22) of the second SOI silicon wafer together form a movable filter structure (26), The manufacturing process of the metal support column (23) is the same as that of the patterned metal support column (14) in the fixed filter structure, and the bottom of the patterned metal support column (23) is connected to the top silicon layer (22); S4, aligning and bonding the movable filter structure layer wafer prepared in S3 to the fixed filter structure layer wafer prepared in S2, wherein the metal support pillars (23) in the movable filter structure are bonded to the metal support pillars (14) in the fixed filter structure to form support pillars, and then dry etching to remove the second SOI wafer substrate (25) and the buried oxide layer (24); S5, take a standard wafer after polishing on both sides as a cap layer (30), make a cavity (34) on the back of the cap layer through photolithography and etching processes, make electrode holes around the cap layer, and fill the conductive holes with an electrical insulating layer (32), fill the electrical insulating layer with metal material to form a vertical conductive lead (31), use photolithography and etching processes to make an optical composite film (36) for increasing transmission on the front of the cap layer and the bottom of the cavity, the optical composite film (36) is made of silicon and silicon dioxide, or other suitable anti-reflection materials made by evaporation process; use film formation, photolithography and etching processes to make a conductive metal block (35) on the back of the cap (30) and connect it to the vertical conductive lead (31), and prepare a metal pad point (33) on the front of the cap (30) and connect it to the vertical conductive lead (31); S6, aligning and bonding the cap wafer prepared in S5 to the fixed filter structure wafer prepared in S4, so that the conductive metal block (35) is bonded to the corresponding bonding metal layer (16); S7, performing die-to-wafer alignment and bonding of the electrode (41) of the driving circuit chip (40) and the metal pad point (33) on the surface of the wafer prepared in S6, thereby completing the preparation of the heterogeneously integrated micro-opto-electromechanical system.

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