Model-based Optical Proximity Correction (OPC) is widely used in advanced lithography processes. The OPC model
contains an empirical part, which is calibrated by fitting the model with data from test patterns. Therefore, the success of
the OPC model strongly relies on a test pattern sampling method.
This paper presents a new automatic sampling method for OPC model calibration, using centroid-based clustering in a
hybrid space: the direct sum of geometrical sensitivity space and image parameter space. This approach is applied to an
example system in order to investigate the minimum size of a sampling set, so that the resulting calibrated model has the
error comparable to that of the model built with a larger sampling set.
The proposed sampling algorithm is verified for the case of a contact layer of the most recent logic device.
Particularly, test patterns with both 1D and 2D geometries are automatically sampled from the layer and then measured
at the wafer level. The subsequent model built using this set of test patterns provides high prediction accuracy.
A receiver structure referred to as piecewise maximum likelihood (PML) is proposed in order to reduce the complexity of the PRML receiver. A channel response of optical disk is used for the performance evaluation. The channel distortion such as tangential tilt effect of optical disk also considered. The hardware implementation complexity between the PML and adaptive PRML is compared.
The wavelength selectivity of the hologram using the reference beams with random phase codes and multiple wavelengths is calculated and compared with experimental results. If the angle between signal and reference beams goes to 180 degrees, the effect of random phase code does not significantly affect the wavelength selectivity. Cross-talk noise analysis is Fourier holographic memory using random phase codes and multiple wavelengths is performed, and the signal-to-noise ratio is shown to depend on the angle between signal and reference beams as well as the wavelength difference.
Jin-Ki Hong, Yun Chul Chung, In-Jae Kim, Dong-Yun Shin, Eun-Sung Kim, Il-Soo Choi, Ki-Hyun Kim, Young-Taek Song, Jeong-Chil Shim, Young Hun Kim, Ki-Nam Oh, Suk-Kyoung Hong, Sun-Ung Kim, Mann-Jang Park, S. Jeon
In order to investigate the surface states of electron which can tunnel through the sufficiently thin insulator, the electron tunneling spectroscopy is used to measure the tunneling current in function of the bias voltage, and directly to get the subbands of accumulation layer. The tunneling current through ZnS barrier in the Hg1-xCdxTe-ZnS-In junction structure is measured by various applied bias at 77 K and 4.2 K. From the measurement at 77 K, the subband energy levels in the electron accumulation layer at the surface of n-type Hg1-xCdxTe are found to be located at -59 meV for the ground state and -13 meV for the first excited state relative to the Fermi level of Hg1-xCdxTe. At low temperature when the applied bias is larger than the difference between the work function of In and the electron affinity of ZnS, a negative differential resistance is measured. On the calculation using transfer matrix method it is understood that this negative conductance is attributed to Fowler-Nordheim tunneling which is caused by the variation of ZnS barrier according to the various applied bias.
Optical fiber and fiber taper are used for reference waves in writing and reading volume holograms. The object wave interferes with the speckle pattern reference wave coming from fiber tip in the holographic medium to make a volume hologram. The spatial selectivity of the volume hologram is improved by the proposed scheme. Both experimental results and theoretical analysis are discussed.
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