Guenther O. Langner

PREVAIL - Evolution and properties of large area reduction projection electron optics

The large area reduction projection optics with beam scanning of the PREVAIL proof-of-concept system is described as the result of an evolution of a variable axis lens doublet system from one with a straight to one with a curvilinear axis, driven by the need to contain image blur caused by Coulomb interactions, and to maintain symmetry of the resulting optics.

Telecentric beam positioning for advanced e-beam lithography

Abstract Telecentric e-beam positioning systems are evaluated by computer simulation. Compared to post-lens double deflection and and deflection through the lens front focal point, the variable axis immersion lens (VAIL) concept is superior for applciation to lithography of pattern dimensions smaller than 0.5 um in fields larger than 4 mm. The simulations suggest that resolving power and telecentricity are conjugated in VAIL: Meeting the VAL condition is favorable for resolution, but not for perpendicular beam landing.

Electron optical performance of electron beam lithography columns predicted by a simple model

A simple model is presented which predicts the maximum attainable current density and associated optimum brightness and semi‐angle in a variable shaped spot (VSS) and a Gaussian spot (GS) electron beam lithography system for a given resolution (edge width). For a GS the optimum source demagnification factor is also predicted. The contribution of the forward scattering in the resist is taken into consideration. The model allows the assessment of the sensitivity of the attainable current density to various design and operation parameters. The model is based on the quadratic sum of uncorrelated and uncorrectable aberrations and solves the expression for the sum for the current density using the reduced brightness as variable. VSS systems are characterized by an optimum brightness and a high sensitivity to stochastic trajectory displacement due to electron–electron interaction. The acceleration potential has a paramount effect on the attainable current density, still enhanced when forward scattering due to th...