Ultra Violet Lithography

Lithography & Patterning Installation 1
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Optical lithography is a fast patterning technique as all patterns are transferred to the photoresist through the mask in parallel. This requires that the relevant photomasks are already available or that they also need to be fabricated usually by electron beam lithography (in the case of non-standard patterns). Standard photomasks are made of fused quartz coated with a layer of chromium. During mask fabrication Cr is etched away where the geometric patterns need to be. This way UV light has a clear path through the mask, so as to expose the photosensitive resist and transfer the patterns, while Cr acts as a light-stop layer to prevent the illumination of the rest of the photoresist. The most common UV light wavelengths used in standard photolithography are the 436 nm ("g-line"), the 405 nm ("h-line") and the 365 nm ("i-line"), all being spectral lines of an Hg lamp. The achievable resolutions at these wavelengths go down to below 1 μm. There are different modes one can perform standard photolithography either with the mask being in contact with the resist-coated sample (contact lithography) or leaving a small gap (proximity lithography) each one having its own advantages and disadvantages.


WARNING: Access to CNRS temporarily not available

          provided at NFFA-Europe laboratories by:

Mask aligner MJB4 (soft UV)  (316)

Contact optical lithography

Soft UV source

365 nm

Resolution: about 1 µm

Samples are typically small pieces and 1, 2, 3 and 4 inch

Mask sizes 3.5", 4" and 5"



Mask Aligners MA6/MA8/MJB3

Optical lithography

UV light

365 and 405 nm 

MA6/MA8: max 0.6 μm

MJB3: >1 μm

MA6/MA8: alignment accuracy ~1 μm

MJB3: alignment accuracy few microns

MA6: 4" and 6" wafers only

MA8: 6" and 8" wafers only

MJB3: chips and wafers up to 3"

Contact modes:

MA6: Hard/soft/vacuum/proximity

MA8: Hard/soft/vacuum

MJB3: soft

Spin-coater, wet-bench, developers, hot-plates, microscopes, etc


Mask Aligners MJB3 and MA25

Ultra Violet Lithography

350W HBO lamps

Primary exposure wavelength 365nm

 Achievable resolutions: 2.0 µm in soft contact mode, 1.0 µm in hard contact mode

MJB3: high-precision alignment stage accurate to 0.5 µm and a brightfield microscope equipped with 5X, 10X and 25X objectives

MA25:  simultaneous double  side exposure and manual operation of wafers and small samples, alignment accuracy between upper and lower side of the wafer of <2 microns, and alignment table rotation of <2 degrees



MJB3: substrates of various sizes up to 3 inches in diameter and 3mm in thickness, and masks up to 4 inches

MA25: maximum wafer diameter of 4" and maximum mask size of 5" x 5"


A large set of general purpose masks (gratings dots etc) available


Mask aligner Süss MA6 and MA/BA6

Contact/proximity optical lithography in single/double side

Soft UV source

365nm (i-line) or 405nm (g-line)

Constant intensity of light: 11 mwatt/cm2 (MA6) or 7,5 mwatt/cm2 (MA/BA6)

Better than 1.5 microns

Manual positioning and alignment

Double side exposition/alignment capability  

Typically 100mm or 150mm wafers, with or without CMOS contaminant metals

Active area, field of exposition: masks of 5”x 5” or 7”x 7”

Optical microscope

Ambient (class 100 clean room)

(MA/BA6) - alignment and clamping fixture for bonding of wafers

Automatic resist coater/developer Süss Gama 80

Manual spinners and hot-plates