Lithography
What is the purpose of a phase-shift mask?
- ATo change the phase of light passing through adjacent openings and use interference to improve resolution and contrast
- BTo make the mask lighter
- CTo double the exposure light
Show answer and explanation
Answer: A. To change the phase of light passing through adjacent openings and use interference to improve resolution and contrast
A phase-shift mask shifts the phase of light passing through parts of the mask by 180°, so light from adjacent features cancels and contrast at pattern edges increases. It is one of the resolution enhancement techniques for resolving finer patterns at the same wavelength.