Fundamental Principles of Optical Lithography

1.3. Mask Illumination Purpose: The purpose of this section is to describe how masks are illuminated in lithographic imaging systems and how this illumination affects image formation. Objectives: Upon completion of this section, you will be able to:  Describe the effect of illumination angle on the diffraction pattern  Define partial coherence  Describe the impact of illumination on resolution  Define Kohler illumination