Ultra Violet Lithography

Nano to Micro/Macro (Micro-fabrication)

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.

i
@
          provided at NFFA-Europe laboratories by:
CNR-IOM (TS)
Italy
C2N-CNRS
France
CSIC-CNM
Spain
CSIC-ICMAB
Spain
ICN2
Spain
LUND + MAX IV
Sweden
PSI
Switzerland
EURONANOLAB
France
INESC-MN
Portugal
CNR-IOM (TS)
Italy
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
LUND + MAX IV
Sweden
Mask aligner MJB4 (soft UV) (316)
Contact optical lithography Exposure type: Soft contact, hard contact, Vacuum contact, flood exposure.
Soft UV source
365 nm (i-line), 405 nm (h-line), 436 nm (g-line) Intensity approx 15mW/cm2 - 30mW/cm2
Resolution: Approx. 1µm Alignment accuracy: Approx. 1µm
Small samples: 3mm up to approx. 10mm Wafers:1, 2, 3 and 4" wafers. Max sample thickness: 4mm Can accomodate mask sizes: 4" and 5".
Ellipsometry to measure resist thickness. Pattern inspection: Optical microscopy, or scanning electron microscopy.
ISO 5
Sample preparation: Spin coating, pre- and post-exposure baking, pattern development.
No
PSI
Switzerland
Mask Aligners MA6/MA8/MJB3
Optical lithography
UV light
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"
Spin-coater, wet-bench, developers, hot-plates, microscopes, etc
365 and 405 nm
Contact modes: MA6: Hard/soft/vacuum/proximity MA8: Hard/soft/vacuum MJB3: soft
ICN2
Spain
Dilase 250, Kloe instruments
UV Laser lithography
1um spot size, 365nm wavelenght LED UV laser
30mW
1um lateral resolution
substrates up to 4" wafers, exposure area up to 100x100mm
No
ICN2
Spain
KUB3, Kloe Instruments
Mask aligner UV lithography
365nm LED UV lamp
2um lateral resolution
substrates up to 4" wafers, masks up to 5x5"
No