PREVAIL: Operation of the electron optics proof-of-concept system

A proof-of-concept (POC) system was built to prove the electron optics conc ept of PREVAIL as a viable technology for next generation lithography (NGL) , and is described elsewhere (H. C. Pfeiffer et al., J. Vac. Sci. Technolog y B, these proceedings; W. Stickel et al. ibid., these proceedings). The pr imary objective of the PREVAIL POC system is the embodiment of the curvilin ear variable-axis lens (CVAL) optics which provides superior performance in terms of minimum geometric aberrations over unusually large deflection dis tances off the system axis (see Stickel et al.). Another major benefit of t he CVAL is the minimization of the Coulomb interaction blur, since this app roach permits the reduction of the column length to the smallest practical dimensions. The implementation of the PREVAIL CVAL requires a much higher d egree of complexity than that of probe-forming systems, even of those which incorporate variable-axis immersion lenses [M. A. Sturans et al., J. Vac. Sci. Technol. B 8, 1682 (1990)] in the projection optics. The procedure use d to establish the proper curvilinear variable-axis trajectory has required the development of hardware and software tools and is semiautomated. In th is article we describe the means employed to properly establish the imaging conditions and the curvilinear trajectory of the deflected beam. Proper ad justment of the components is verified by comparison with the theoretically predicted excitation values for the deflection and axis-shifting yokes. Pe rformance results presented by Pfeiffer et al. in terms of image blur and s ubfield distortion provide the proof of concept for the CVAL imaging condit ions. (C) 1999 American Vacuum Society. [S0734-211X(99)05906-5].