Simulation parameter effects on critical dimension and sensitivity of 193 nm Chemically Amplified Resist
It is helpful in lithography process and developing resist to know the relationship between the critical dimension variation and simulation parameters such as aerial image parameters, the Dill exposure parameters, PEB (Post Exposure Bake) parameters, and development parameters. In this paper the profiles of a 193 nm CAR (Chemically Amplified Resist) were simulated with those various parameter, and those results were analyzed by the response surface methodology (RSM) approach to know the influence of independent factors on a dependent response and to optimize each process. Both the parameter effects of each process and the simulation process effects of the whole process were described about critical dimension and side wall angle so that the sensitivity of lithography process could be assumed. The development parameters were modified with those of flood exposure experiment according to the pattern density and pattern size for more accurate lithography simulation. Also those effects on critical dimension and side wall angle were analyzed. For the validity of our results the quantitative comparison between our results and those of a commercial tool was shown.
Effective exposure-dose measurement in optical microlithography
An accurate measurement technique for effective exposure dose in optical microlithography has been developed. The effective exposure dose can be obtained by a dose monitor mark in a photomask named effective dose-meter, consisting of plural segments including grating patterns with a pitch below the resolution limit and different duty ratios gradually. Since the effective dose-meter does not resolve on a wafer but it makes flood exposure with the dose as a function of the duty ratio, residual thickness of the photoresist after development changes according to the duty ratio. Therefore, the effective exposure dose can be obtained by grasping the duty ratio of the grating patterns in the effective dose-meter corresponding to the position that the photoresist had cleared completely. A calibration technique utilizing an aerial image measurement system also has been proposed to avoid the influence of intra- wafer process variation. The advantages of this method are (1) completely focus-free, (2) the effective dose-meter is small enough to ignore the influence of the intra-wafer process variation on the accuracy, and (3) highly dose resolution of less than 0.5%. It was found that this technique function effectively. The variation of the effective exposure dose in a wafer in the current krypton-fluoride-excimer-laser lithography process was measured as a demonstration of this technology.
Influence of electric fields on friction electrification between metals and borosilicate glass
Abstract In a cylindrical geometry, electric fields were applied through the entire contact area between the sliding metal and the glass surface. The maximum electric charges developed on the metal were measured and plotted against the applied voltage producing the field. The metals were high-purity nickel and gold. The borosilicate glass was Pyrex, brand 7740. The experiments with nickel, which has a work function greater than that of the glass, were performed in 10 −7 mm Hg vacuum. The experiments with gold, with a work function smaller than that of glass, were carried out in air at atmospheric pressure. The results show that: 1. 1) There is both asymmetry and a reversed slope portion in the charge vs. voltage plot. 2. 2) For a certain range of reversing fields, the electric charge developed on the nickel is always negative and the charge on gold is always positive.