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双光栅叠栅条纹对准方法具有精度高、可靠性强等特点,适用于接近接触式光刻。为了实现高精度测量,实际应用中要求掩模光栅标记与硅片光栅标记高度平行。掩模光栅标记在CCD中成像通常存在一定的倾斜角。由此,在已提出的相位斜率倾斜条纹标定方法上,提出了一种改进方法。该方法充分利用掩模光栅45°和135°两个方向的相位信息标定CCD的成像位置,以实现掩模光栅条纹的标定。对比两种方法分析表明,改进后的方法具有倾角测量范围大、抗噪性强、精度高等优点,理论极限精度优于0.001°量级。
Double grating moire alignment method with high precision, reliability, etc., suitable for near-contact lithography. In order to achieve high-precision measurement, the actual application requires that the mask grating mark and the silicon grating mark height parallel. Mask grating marks in the CCD imaging there is usually a certain tilt angle. As a result, an improved method has been proposed for the method of calibrating the tilt of a phase slope. The method makes full use of the phase information of 45 ° and 135 ° of the mask grating to calibrate the imaging position of the CCD so as to realize the calibration of the mask grating stripes. The comparison between the two methods shows that the improved method has the advantages of large measuring range, strong anti-noise and high precision, and the theoretical limit precision is better than 0.001 °.