In EUV masks, what is the phenomenon called in which the absorber pattern's thickness is not negligible compared with the wavelength, so obliquely incident light casts shadows and otherwise affects the image?

Answer: B. Mask 3D effects

EUV masks are reflective, and light arrives tilted by about 6°. Because the absorber is tens of nanometers thick, more than the 13.5 nm wavelength, its sidewalls cast shadows and alter the phase, shifting dimensions and positions depending on pattern orientation. These are called mask 3D effects and are addressed by developing thinner absorber materials and by OPC corrections.

• A. Blooming is charge overflow in image sensors.
• B. Correct. They are effects of the mask's three-dimensional structure.
• C. The loading effect is a change in process rate with processed area.