Research On Key Technology Of Terahertz Lens Antenna Based On DRIE Process

This paper focuses on the front end of heterodyne receiver with high integration,miniaturization and high gain.Aiming at the requirements of low loss,high compactness and micron tolerance for antenna feed in terahertz band,this paper studies the micro-lens antenna feed in terahertz band and Bosch process in deep silicon etching.The main research contents and results of this paper are as follows:1.Two dual polarization micro-lens antennas are studied.Based on the geometric relationship of the extended hemispherical lens,the micro-lens are designed.The aperture of the micro-lens is electrically small.With the iris structure and half wavelength air cavity,a high directional antenna is realized.The gain of the 320 GHz lens antenna is 20.6d Bi and the-15 d B impedance bandwidth is 298-345 GHz while the gain of 640 GHz lens antenna is25.5d Bi with a 17.9% bandwidth.In addition,the sidelobe level is better than-15 d B.The two antennas have good rotational symmetry,high gain and small overall size.Using silicon-based technology,they can be stacked longitudinally to improve the integration with subsequent circuits.They are suitable for use as focal plane array units of reflector antennas.They are suitable for use as focal plane array units of reflector antennas.In addition,the process implementation methods of each part of the lens antenna are studied.By establishing the Bosch process model in the process simulation software SILVACO,and simulating each process flow,the feasibility of the process implementation method is verified.The perpendicularity of the side wall of the square waveguide is 89.1°-90.5° and the electromagnetic simulation performance is good.The operating frequency band moves slightly to low frequency.The bandwidth,gain and sidelobe level performance are basically consistent with the ideal model.2.Two Orthomode Transducers with stepped transition structure are studied.The operating frequencies are 320 GHz and 640 GHz respectively.The Orthomode Transducer is composed of three parts.The T-junction is used as the polarization separation junction.The transition section is designed according to the principle of binomial matching converter.Finally,the return loss in the simulation frequency band(280-360 GHz and 580-700GHz)is better than 20 d B with better than 0.15 d B insertion loss and 75 d B isolation.At the same time,the polarization separation performance is good,and the cross-polarization is better than75 d B.It is suitable for combination with the dual polarization antenna unit fed by waveguide,realizing polarization separation function.In addition,the process implementation of Orthomode Transducer is introduced.In view of the multi-depth structure of the device,in order to improve its fabrication accuracy,the stepped silicon oxide is used as the device mask,and the high selection ratio in the DRIE process is used for processing.The process simulation is carried out in SILVACO.The electromagnetic simulation performance under the process structure shows that the insertion loss in the simulation frequency band is better than 0.6d B.The return loss is better than 10 dB,and the port isolation and polarization isolation are better than 65 d B.3.The joint simulation and optimization of lens antenna unit and Orthomode Transducer are carried out.Finally,the gain of 320 GHz dual polarization focal plane array unit reaches 20.9d Bi with better than 85 d B isolation and-20 d B sidelobe level,and the cross-polarization level is lower than-30 d B;The unit gain of 640 GHz dual polarization focal plane array reaches 20.8d Bi with better than 70 d B isolation in the whole frequency band and-15 d B sidelobe level,and the cross-polarization level is lower than-40 d B.The E-plane and H-plane of the two antennas are in good agreement.At the same time,because the Bosch process flow is passivation and etching alternately,the classical corrugated structure will be generated on the side wall of the structure.In order to understand the impact of the real device morphology on the overall performance of the structure,the joint simulation of the process simulation software and electromagnetic simulation software is carried out,and the dimensional parameters of the device are further optimized,so as to improve the processing efficiency and the performance of the physical structure.Under the non-ideal surface,the performance of the two antennas is better than 20 d Bi after optimization,and the bandwidth is in good agreement with the simulation results of the optimized ideal model.