The wafer pre-aligner is a crucial component in the lithography process to correct the wafer center and notch orientation. To improve the precision and the efficiency of pre-alignment, a new method to calibrate the center and the orientation of a wafer based on the weighted Fourier series fitting of circles (WFC) method and the least squares fitting of circles (LSC) method, respectively, is proposed. The WFC method effectively suppressed the influence of the outliers and had high stability compared with the LSC method when fitted to the center of the circle. While the weight matrix degenerated to the identity matrix, the WFC method degenerated into the Fourier series fitting of circles (FC) method. The fitting efficiency of the FC method is 28% higher than that of the LSC method, and the fitting accuracy of the center of the FC method is the same as that of the LSC method. In addition, the WFC method and the FC method perform better than the LSC method in radius fitting. The pre-alignment simulation results showed that the absolute position accuracy of the wafer was ±2 µm, the absolute direction accuracy was 0.01°, and the total calculation time was less than 3.3 s in our platform.

By inserting a modulator in the imaging system and scanning in different positions, ptychographic modulation imaging can achieve higher quality reconstruction for smooth or weakly scattered objects compared to conventional ptychography imaging. However, its imaging resolution is still limited by the pixel size of the detector. In this paper, divergent illumination is introduced to enhance imaging resolution. Compared with the original planar illumination scheme, our proposed method can achieve two-fold resolution improvement with only the use of thirty diffraction patterns for ten iterations. The quantitative phase imaging capability of the proposed method is also demonstrated by testing the binary phase sample. In the reconstruction, the divergent illumination geometry is converted to planar illumination model. The equivalent sampling intervals and diffraction distances of the modulator, object, and detector planes are analyzed in detail. In addition, a new high-accuracy distance calibration method for point light sources is proposed and verified in experiments.

Due to the extreme accuracy requirements of the lithography machine and the high sensitivity of the components to thermal fluctuations, the stability of the temperature is a key factor affecting the performance of the various subsystems in the lithography machine. The temperature regulation mechanism of the lithography machine shows significant characteristics of large inertia and large time delay, and is vulnerable to a variety of disturbances. Therefore, achieving fast response, high accuracy, and stable temperature control remains a key challenge. This study proposes an advanced control strategy that enhances temperature regulation performance while ensuring fast adjustment speed. By combining Smith predictor with variable universe fuzzy Proportional Integral Derivative (VUFPID) controller, a new Smith predictor–variable universe fuzzy PID (Smith-VUFPID) controller algorithm is proposed. The fuzzy PID controller, variable universe fuzzy PID controller and Smith-VUFPID controller are simulated in MATLAB under complex conditions such as target temperature changes and different external disturbances. The simulation results show that the steady-state error of the proposed method can be maintained below 0.01 °C, and the stability is significantly better than the other two algorithms. In addition, considering the complex conditions such as heat sources in the wafer stage and mask stage when the lithography machine is working, Multi-channel comparative simulations were conducted and transfer function change comparison simulation experiments for Smith-VUFPID algorithm. The results show that the algorithm can still maintain the stability of the system in the face of multiple interference superposition or transfer function change. The steady-state error can still be kept below 0.01 °C, and it has strong anti-interference and robustness. These findings suggest that the Smith-VUFPID algorithm offers promising potential for high-performance temperature control in advanced lithography machines.