The electron-beam column for a high-dose and high-voltage electron-beam exposure system EX-7

Abstract

The electron optical column is designed for the electron‐beam (EB) exposure system EX‐7 employing a vector scanned variably shaped beam (VSB) on a continuously moving stage. The column, which utilizes a high current density of 200 A/cm2 and a high voltage of 50 kV, has been designed for a 0.25 μm patterning. Generation of triangular shapes in addition to rectangular shapes reduces shot numbers to enhance throughput. An octapole deflector with small deflection distortion, has been developed for beam shaping. The ray tracing method using an analytical expression for the electric and magnetic field was used to design the objective focusing and deflection system, which is composed of a magnetic lens and dual channel electrostatic octapole deflectors. Beam edge resolution including the electron‐beam interaction effect is about 0.12 μm and distortion is <0.01 μm at the final beam convergence semiangle of 8 mrad and field size of 600 μm square. As a result, a 0.25 μm resist pattern has been obtained over 600 μm field. Main deflection field stitching error was <±0.04 μm (3σ) without deflection distortion correction.