Light in the deep-ultraviolet range used in semiconductor lithography. DUV lithography generally refers to exposure using KrF excimer lasers (248 nm) and ArF excimer lasers (193 nm) as light sources.
Japanese name: DUV(深紫外線)
DUV (deep ultraviolet) appears in 1 practice question across 1 topic, including Silicon photonics.
Field: Lithography
Lithography light sources moved from the g-line (436 nm) and i-line (365 nm) of mercury lamps to shorter-wavelength deep ultraviolet (DUV). DUV lithography uses excimer lasers: KrF, using krypton and fluorine, emits at 248 nm, and ArF, using argon and fluorine, at 193 nm. KrF came into full use from the 0.25 µm generation in the late 1990s and spread together with chemically amplified resists. A 157 nm F2 laser with an even shorter wavelength was also developed, but problems with lens materials and other issues, together with the arrival of ArF immersion lithography, kept it out of volume production.
The resolvable feature size is approximated by the Rayleigh equation R = k1·λ/NA: the shorter the wavelength λ and the larger the numerical aperture NA, the finer the patterns. In dry ArF, with air between lens and wafer, NA tops out at about 0.93, but ArF immersion lithography fills that gap with water and uses its refractive index at 193 nm (about 1.44) to raise NA to 1.35. With NA 1.35 and k1 0.27, for example, R ≈ 39 nm (half-pitch); finer patterns are made by combining multiple patterning such as SADP.
EUV lithography uses extreme ultraviolet light at 13.5 nm, roughly one-fourteenth of DUV's 193 nm, and can print finer patterns in a single exposure. EUV light is strongly absorbed even by air and glass, however, so it requires a vacuum, multilayer mirrors and reflective masks. DUV uses lenses of fused silica and calcium fluoride with transmissive masks and does not need a vacuum. EUV tools are far more expensive, while DUV is a mature technology with advantages in cost and productivity. EUV uses NA 0.33, and High-NA EUV with NA 0.55 began to be introduced in the mid-2020s.
Even in leading-edge logic and DRAM manufacturing, EUV is used only for the layers that need the finest patterns, while many other layers are exposed with ArF immersion, dry ArF or KrF. Layers that need less precision and implant patterns also use KrF or i-line. Mature-node logic, power semiconductors, analog, MEMS and silicon photonics are made mainly with DUV lithography. DUV scanners, excimer lasers and resists therefore remain essential technologies in semiconductor manufacturing even as EUV spreads.
Answer: A. It can use the same silicon materials as CMOS, along with large-diameter wafers and equipment and processes such as lithography and etching
In silicon photonics, waveguides are formed on SOI wafers by lithography and dry etching, modulator pn junctions by ion implantation, and Ge photodetectors by selective epitaxial growth, with electrodes connected by metal interconnects. All of these use materials and processes established in CMOS fabs, enabling mass production with high precision and reproducibility on 200 mm and 300 mm wafers. Waveguide widths are a few hundred nm, so leading-edge logic scaling is unnecessary and DUV lithography is sufficient. On the other hand, compound semiconductors such as InP raise contamination concerns and are generally handled separately from CMOS fabs.
DUV uses KrF (248 nm) or ArF (193 nm) excimer lasers and exposes through lenses and transmissive masks. EUV uses 13.5 nm light, so it requires a vacuum, mirrors and reflective masks. EUV can print finer patterns in one exposure, but the tools are expensive.
Yes. ArF immersion lithography is DUV lithography with an ArF excimer laser (193 nm) in which water fills the space between lens and wafer to raise the numerical aperture to 1.35.
It is not usually counted as DUV. The i-line is 365 nm light from a mercury lamp, and DUV lithography normally refers to exposure with KrF or ArF excimer lasers.
Waveguide widths are a few hundred nm, so leading-edge logic scaling is unnecessary and DUV lithography is sufficient.
What is the main reason silicon photonics is said to be wel…As an Amazon Associate I earn from qualifying purchases.
Silicon photonics Dry etching Ion implantation Selective epitaxial growth CMOS Waveguide InP (indium phosphide) ArF excimer laser Bottom anti-reflective coating (BARC) Chemically amplified resist