A new chrome etch system was acquired and implemented to manufacture 65 nm node critical level masks. The etch performance of FEP 171, ZEP 7000, NEB 22, and REAP 200 resist systems in this new chrome etch system was evaluated. The critical dimension (CD) uniformity, etch bias, and etch linearity of this new etch system relative to the older generation etch system is presented. Implementation of the new etch system resulted in a 40-60 nm reduction in etch bias with no degrade in CD uniformity performance. In addition, it was found that the etch contribution to CD linearity was reduced by 50%. Detailed characterization of both macroloading and microloading etch effects was performed and showed substantial improvement relative to the previous generation etch system. The change in chrome etch rate as a function of etch area was reduced by 50%, improving mean to target CD performance on new designs. Implementation of the new etch system has enabled achievement of CD and defect density performance requirements for 65 nm node mask manufacturing. The results presented in this paper were collected during the process development phase and are not necessarily representative of the final optimized process.
We present the results of a study of the sensitivity of the human visual system (HVS) to spatially varying color stimuli. Sinusoidal grating patterns of different spatial frequencies were presented to six observers and the contrast required to just distinguish the pattern from the surrounding uniform field was determined. Tables and curves of contrast (measured in ΔE<sub>Lab</sub>) as a function of frequency were generated at different values of; the orientation (horizontal, vertical and diagonal) of the pattern, the average luminance, the x and y chromaticity co-ordinates, and the direction of the variation of the stimulus in color space (luminance, red-green, and blue-yellow). The results show that the HVS is more sensitive to sinusoidal gratings oriented horizontally and vertically regardless of the type of variation. Furthermore, the HVS is more sensitive to luminance variations than it is to chromatic variations. Tables and curves of the data are presented.