Computer - Aided - Design Of Focused Ion Beam For a Lithography System

        A complete computer aided design (CAD) by using optimization methods for the ion optical systems have been developed, by mixing the dynamic programming procedure and artificial intelligence technique. The relative spherical and chromatic aberrations coefficients were obtained according to figure of merit for the following optimized optical systems:

1. Single-lens design (electrostatic and magnetic).
2. Two-lens system consists of two electrostatic lenses.
3. Three-lens system consists of three electrostatic lenses.
4. Multi-lens system (electrostatic and magnetic).

Four types of electrostatic lenses and a magnetic lens model were designed as small as possible of optical properties (i.e. the first and third optical properties), and reconstructions of electrodes and pole pieces were plotted in two and three dimensions graphics by using SIMION 7.0 simulator depending on the stored database (i.e. knowledge base).These lenses are as follows:

• Unipotential lens 1 (operated in deceleration mode).

• Unipotential lens 2 (operated in acceleration mode).

• Immersion lens.

• Diaphragm lens.

• Magnetic lens.
•      Present software has been designed and written in Java expert system shell (JESS) and Visual Basic 6 (VB6) for optimizing and analyzing full calculation processes, it has called CADION package.   The optimized axial potential distributions for both electrostatic and magnetic fields according to the constraints have been used in the optical column setup, which are two-lens system, three-lens system and multi-lens system. Spot size measurements were calculated in nano scales, which have values closed to (3.0) nm applicable in nano technology applications used in lithographic systems.    Also, the present work has been suggested definitions and abbreviations in charged particle optics to be consider some of the results, as a verification of the uncertainty principle relationship like.