Research On Key Technologies Of Miniaturized Integrated Scanning Grating Micromirror With High Performance And Low Cost

Miniaturized integrated scanning grating micromirror is a new generation of light dispersion device.The grating is integrated on the mirror plate of a scanning micromirror,thus possessing both functions of light dispersion and spectral components scanning.Due to the advantages of small volume,low power consumption,low cost and high integration level,it has been a crucial common component of numerous spectroscopy equipments.Aiming at the urgent demand of light dispersion device for low-cost NIR(Near Infrared)micro-spectrometers,it is very promising and highly desired to carry out the key technology research on the miniaturized integrated scanning grating micromirror with low cost and high performance.Aiming to overcome the existing shortcomings of current scanning grating micromirrors(e.g.low diffraction efficiency,small mirror plate,high power consumption,poor performance of the corresponding angle sensor,etc.),a novel Al N film based piezoelectric integrated scanning grating micromirror integrated with blazed grating and piezoelectric differential angle sensor is developed in this thesis.Owing to Al N film's excellent MEMS(micro-electro-mechanical systems)process compatibility,the high-efficiency blazed grating,large-aperture mirror plate,low-power piezoelectric micro-actuators and piezoelectric differential angle sensor are integrated on the same tilted(111)single-crystal silicon substrate.The corresponding key technologies of integrated design and compatible fabrication process are broken through.The prototype is successfully fabricated through a 7-mask MEMS process and tested through the corresponding test setup.Test results show that the diffraction efficiency is above 40%at the wavelength range of 800 nm-1800 nm,the resonant frequency is860.4 Hz,the maximum mechanical scan angle can reach±5.9°at the driving voltage of±40 V_pp,the integrated piezoelectric differential angle sensor possesses the sensitivity of 788.7 m V_pp/°,the linearity of 0.9997,the SNR(signal to noise ratio)of69.7 d B and the resolution of 0.02°,the power consumption of the device is only 90.16?W when the mechanical scan angle is±4°,the shock and vibration reliability are better than 500 g and 15 g(20 Hz-2000 Hz)respectively.Furthermore,a new generation of FR4(flame retardant 4)based electromagnetic scanning grating micromirror with high shock and vibration resistance and lower cost is presented to meet the need of some special application environments.The prototype of FR4 based electromagnetic scanning grating micromirror is fabricated,assembled and tested.Test results show that the resonant frequency is 270.6 Hz,the maximum mechanical scan angle can reach±6.2°at the driving current of 75 m A_rms,the integrated electromagnetic differential angle sensor possesses the sensitivity of 916.0m V_pp/°,the linearity of 0.99993,the SNR of 80.5 d B and the resolution of 0.007°,the power consumption of the device is only 7.58 m W when the mechanical scan angle is±4°,the shock and vibration reliability are 2000 g and 20 g(20 Hz-2000 Hz)respectively.Finally,based on the NIR micro-spectrometer platform developed by our group(Microsystem research center of Chongqing University),the application verification experiments of the two prototypes are carried out.The experimental results indicate the both prototypes'good feasibility for the low-cost and high-performance NIR micro-spectrometer application.The main works of the thesis are listed as follows:(1)The research status,development tendency and major existing scientific and key technological issues of the miniaturized scanning grating micromirror are analyzed.Aiming to meet the requirement of NIR micro-spectrometers application,research objectives and contents of this thesis are determined.(2)A novel Al N film based piezoelectric integrated scanning grating micromirror is proposed.Based on the grating theory and PCGrate software,optimization design of the integrated blazed grating are completed.The piezoelectric micro-actuator is investigated and discussed to determine the optimized thicknesses of the silicon substrate and Al N piezoelectric film.Also,dynamics analysis of the Al N film based piezoelectric integrated scanning grating micromirror is performed.Furthermore,based on the finite element analysis software ANSYS,a finite element model is established to perform the optimization design and performance simulation of the device.(3)The key processes of integrating blazed grating,Al N film preparation and 3D microstructure fabrication are investigated.The microfabrication process flow and layout of the Al N film based piezoelectric integrated scanning grating micromirror are designed.Then,the prototype is fabricated and the corresponding test platform is built.The main performance parameters of the prototype are tested and analyzed.(4)A new generation of FR4 based electromagnetic scanning grating micromirror is presented.The corresponding theoretical models of the device and integrated electromagnetic differential angle sensor are established to optimize the structure parameters.The performance simulation of the device is carried out using finite element analysis software ANSYS and Ansoft Maxwell.(5)The process flow of silicon blazed grating element,the PCB layout of FR4micromirror,the package structure and the device assembly process are designed.Then,the prototype of the FR4 based electromagnetic scanning grating micromirror is fabricated,assembled and tested.(6)The performances of both prototypes are compared and analyzed.After that,the both prototypes'feasibility for NIR micro-spectrometers application is experimentally validated.The results indicate that the both prototypes can meet the application requirement of the NIR micro-spectrometer with the spectral range of 800nm-1800 nm.