Preparation and Performance of Integration Device between Si Microlens Array and Infrared Focal Plane Array(Invited)
Integration device between silicon(Si)microlens array and Infrared Focal Plane Array(IRFPA)has been a hot research topic domestically and internationally.IRFPA nowadays serves military and commercial equipment fields,such as defense weapons,infrared remote sensing and meteorological environment because of its high sensitivity and strong anti-interference.Si microlens array can be integrated with IRFPA to solve the problems caused by the low filling factor and chip cracking of IRFPA,thereby improving the performance of IRFPA.In this paper,in order to improve the performance of IRFPA,Si diffractive microlens array is designed.The Si diffractive microlens array and InSb IRFPA are prepared and integrated together.And the performance of integration device is given and discussed.Firstly,design parameters and preparation method of Si microlens array for IRFPA are given in detail.The Si diffractive microlens array is comprised of eight zones within one pixel.The radius of each zone is 6.2 μm,8.8 μm,10.8 μm,12.45 μm,13.95 μm,15.3 μm,16.5 μm,17.7 μm.The minimum zone width is 1.2 μm.Each etch depth is different.The etching depths are 0.868 μm,0.434 μm,0.217 μm.Plasma etching is used in Si diffractive microlens array preparation.The Si diffractive microlens array is prepared by three photolithographic and etching processing steps.The SI500E type equipment is used as reactive ion etching.The etching conditions are the gas flow of CHF3∶O2 of 24 mL∶6 mL,the ICP source power of 400 W,the Radio Frequency(RF)source power of 150 W,and the pressure of reaction room of 0.5 Pa.Secondly,the InSb IRFPA is made using the prepared InSb array and Si Readout Circuit(ROIC).An n-type InSb substrate is used and a P-type layer is obtained through the diffusion Cd.A surface with mesa is obtained by photolithography and etching.After passivation of the mesa,a chrome gold layer is evaporated and then electrodes are obtained through photolithography and corrosion processes.After the chip is prepared,the developed InSb array and the readout circuit array are photolithographed with indium column windows and evaporated with indium film at the same time.The indium column arrays are obtained through stripping process,and then connected through flip-chip bonding.The flip-chip bonding device is assembled and encapsulated after bottom filling,thinning polishing,and vapor deposition of anti-reflection film.Thirdly,the prepared Si diffractive microlens array and InSb IRFPA are integrated together by using the glue without bubbles.Each element of the Si diffraction microlens array and the InSb IRFPA is aligned according to the prepared alignment.The Si diffractive microlens array is thinned and polished to focus on a point.Finally,they are tested by optical system and IRFPA test-bench.Results show that the diffraction efficiency of the Si diffractive microlens array with the double-sided anti-reflecting is 83.6%.The image of response voltage test shows no chip cracking on the integration device.The working band of integrated device is 3.7 μm to 4.8 μm.At this time,the average blackbody responsivity and detectivity of integration device is 4.85×107 V/W and 7.12×109 cm·Hz1/2·W-1,respectively.The working temperature is 77 K.The performance of integration device is superior to the performance of the existing infrared focal plane array.The results indicate that Si microlens array not only increases the filling factor of IRFPA,but also optimizes the stress matching of IRFPA to solve the problem of chip cracking.The results are of reference significance for improving the performance of IRFPA to meet the system application requirements.
万方数据
维普
