Automatic Beam Alignment System Designed For Scanning Beam Interference Lithography

Scanning beam interference lithography technology is a modern mainstream technology of manufacturing large-scale and high-precision grating. It combines innovation with efficiency. Both manufacturing precision and manufacturing efficiency are at the forefront of the grating fabrication technology. Automatic beam alignment system is a subsystem of scanning beam interference lithography. By ensuring that the spots of interferential light beams coincide on the plane of the substrate, and the angle between the interferential beam and the normal is the same, to reduce the non-linear of the interference fringes. In this paper, the research is about the automatic beam alignment system. The research are around automatic alignment system designing, each module design of automatic alignment system, automatic alignment system control algorithms and precision alignment of automatic alignment system and so on.First, based on the research of beam alignment domestic and foreign, an automatic beam alignment program that short optical path is suitable for scanning interference lithography system is proposed. The program mentioned herein uses a transmission grating as a spectroscopic devices cleverly, its 0 order and +1 order diffracted light as the measuring beam, position sensitive detector(PSD) as a measuring device, electric mirror mount as the implementation of the device, and designs the new automatic alignment system of short optical path, small geometry,and easy integration.Secondly, according to the system design, design each module by analyzing their performance requirements. Analyze the needs of a transmission grating, compare simulation of theoretical diffraction efficiency to the and actual experimental results. Analysis and experiment of PSD performance parameters include the PSD work area size, position resolution, absolute accuracy, digital noise of PSD, working temperature and the impact of vibration on the PSD samples. Analyze the performance requirements of the light source. The performance of electric mirror mount which is the system implementation device is tested. The innovation of this part is to propose the testing program and calibration program which is applicable for PSD resolution and measurement accuracy.Then, according to the basis of the foregoing design and system module design, the alignment scheme that is suitable for the new automatic beam alignment is proposed. The paper follows the traditional iterative alignment algorithm, proposing that using the measured value of the last completed adjustment as the initial value of the next iteration, improving the iterative alignment accuracy of the automatic alignment system, and reducing the error caused by regulating and coupling x-direction and y-direction.Finally, develop protocols according to the earlier research on automatic beam alignment system plan, the system module design, automatic alignment algorithm, and verify that the automatic alignment system(alignment accuracy for position and angle) mentioned in this article can satisfy the alignment requirements of scanning interference lithography for automatic alignment subsystem.