Research On Period And Direction Adjustment Technology Of Interference Pattern In Scanning Beams Interference Lithography

Large-size and high-precision holographic plane gratings are a prerequisite for the use of equipment such as high-end immersion lithography machines,inertial confinement nuclear fusion device and large-scale astronomical telescopes.Scanning beams interference lithography is the most potential technology for manufacturing such devices.However,the current interference lithography exposure system is limited by the spatial alignment of the beam,which makes it difficult to achieve rapid adjustment of the optical path,and the period and the direction of the interference pattern cannot be adjusted quickly.Facing the grating manufacturing requirements of different periods,the lithography machine cannot complete the rapid conversion of the interference pattern period.When the scanning motion direction of the exposed substrate and the interference pattern direction have an angular deviation,the grating manufacturing accuracy will be affected.In order to solve the above problems,this paper provides an interference pattern variable period and direction adjustment scanning beams interference lithography method,which can realize the rapid adjustment of the exposure system under different interference states,and lock the phase of the interference pattern in different interference states.The specific research work is as follows:First,expounding the principle of scanning beams interference lithography,the principle of adjusting the period and direction of the interference pattern is deduced,and the phase distortion distribution and period distribution of the interference pattern interfering with the light beam in different spatial states are analyzed.A scheme for adjusting the period and direction of the interference pattern is proposed,and its working principle is explained.After that,the principle of beam pose adjustment based on the gimbal mirror is deduced in detail,the transformation of Gaussian beam in the optical path and lens is analyzed,a heterodyne phase measurement interferometer suitable for the moving beam in this scheme is designed,and the interference pattern is analyzed.The principle of phase locking is explained in detail.Then,based on the experimental equipment parameters,I calculated the ability of adjusting the interference pattern period and direction,and established the ZEMAX and MATLAB co-simulation model of the scanning beams interference lithography principle prototype.The model verified the feasibility of the interference pattern variable period and direction adjustment.The simulation verified the high-precision measurement method of the interference pattern period.On the basis of this method,the high-precision adjustment mode of the interference pattern based on the universal mirror is simulated,and then the adjustment error of the gimbal mirror was analyzed.The lens aberration analysis was carried out,the effect of aspheric lens aberration on the deviation of the lens light angle and the position of the interference spot was deduced,the optimal position of the device installation was discussed,the lens aberration test experiment was carried out.The influences of the optical path difference,the radial separation of the interference beam and the included angle on the contrast of the interference signal are respectively analyzed,and it is verified by simulation and experiment.Finally,an experiment prototype was built to verify the principle of the interferometric pattern changing period and direction,and the interferometric pattern phase locking control experiment was carried out,experiment show that the residual error of phase lock control is ±0.0693rad(3?).Carried out the interference pattern period repeatability measurement experiment,the repeated measurement error is ±0.5nm(3?).The interference pattern period adjustment experiment and the direction adjustment experiment were carried out,and the experimental results showed that the interference pattern period can be adjusted at the picometer level.Under the state of small interference angle,the direction of the interference pattern can be adjusted at the sub-milliradians level.