What is Depth of focus (DOF)?
The range of focus over which a pattern prints with acceptable quality. Raising the numerical aperture improves resolution but reduces DOF, which makes wafer planarity important.
Field: Lithography
Depth of focus (DOF) in the explanations
Depth of focus is DOF = k2·λ/NA², inversely proportional to NA squared, so raising NA shrinks it rapidly—to around 100 nm in leading-edge lithography.
How does the depth of focus (DOF) generally change when the…Finer patterns mean shallower depth of focus—around 100 nm in leading-edge lithography—so even slight unevenness blurs the image.
What is the main reason silicon wafers must be very flat?Depth of focus shrinks, and because reduction differs by direction, the exposure field is halved.
Which correctly describes 'High-NA EUV', developed as the n…
Questions that mention Depth of focus (DOF) (5)
- How does the depth of focus (DOF) generally change when the numerical aperture (NA) of an exposure tool is increased?
- What is the main reason silicon wafers must be very flat?
- Which correctly describes 'High-NA EUV', developed as the next-generation EUV exposure tool?
- Compared with planarization by thermal reflow or etch-back, what is an advantage of CMP?
- In processes such as multilevel wiring, what is the main reason the wafer surface must be planarized by CMP?
Related terms
CMP Numerical aperture (NA) High-NA EUV ArF excimer laser Bottom anti-reflective coating (BARC) Chemically amplified resist EUV lithography Immersion lithography Line edge roughness (LER) Multiple patterning