With the development of science and technology, the industry has an increasing demand for high-precision optical detection, such as wave aberration detection of the lithography objective lens, the core component of the lithography machine . System errors inevitably exist in the process of optical detection. Because the random averaging method has the characteristics of simple operation, this paper studies the system error calibration of the measuring device based on the random sphere method. Rotate the direction of the ball lens with a certain accuracy at random in the optical path, eliminate the random error in the measurement system and the uneven error of the spherical lens surface on average, and then subtract the inherent spherical aberration of the ball lens from the average measurement data to realize the measurement. Self-calibration of device systematic errors. The experimental platform for the verification of this method includes: a 632.8 nm light source, a 10 μm pinhole, a common lens, a spherical lens with a refractive index of 1.52 and a diameter of 40 mm, and a SID4 camera. After experimental verification, the method can realize the purpose of calibrating the system error of the measuring device with high precision and low cost by using a low-precision ball lens.
This article introduces an image quality compensation method based on tolerance sensitivity matrix analysis. First, use the optical software CODE V to establish an optical system model, and add tolerances to a set of i-line projection objectives with a numerical aperture of 0.33. Then the singular value decomposition (SVD) is performed on the sensitivity matrix composed of the structural parameters of the system's sensitive components to select the image quality compensator. The image quality is compensated by coupling the determined three compensators to each other. Comparing the performance of the compensated lithography objective lens with the tolerance lithography objective lens, the system wave aberration is converged from 33.5nmRMS to 23.9nmRMS, the wave aberration PV value is reduced from 0.07λ to 0.02λ for the tolerance objective lens, and the distortion is reduced from 491nm to 48.6nm. The rate is reduced from 0.03ppm to 0.01ppm. This study uses fewer compensators to restore the system wave aberration, distortion and magnification to close to the design level, effectively reducing the manufacturing difficulty and cost of the projection lithography objective lens, and verifying the effectiveness of the compensation method and model.
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