written 5.6 years ago by | • modified 5.5 years ago |
Types of lithography :
Electron beam lithography
Ion beam lithography
Ion track lithography
x-ray lithography
Nanoimprint lithography
Extreme ultraviolet lithography
x-ray lithography :
x-ray lithography is a process used in electronic industry to selectively remove parts of a thin film.
It uses x-rays to transfer a geometric pattern from a mask to a light sensitive chemical photoresist or simply "resist" on the substrate.
A series of chemical treatments then engraves the produced pattern into the material underneath the photoresist.
The x-ray lithography is almost identical to photolithography and extreme ultraviolet lithography but uses a mask in made from an x-ray transparent material with a pattern of high z material either etched or deposited on it.
Exposure of the substrate resist is done using a parallel beam of x-rays.
The x-rays source begins with an electron beam than is converted to an x-ray beam in a synchrotron.
Exposure source : x-ray (synchrotron)
resist :
PMMA
Mask : SIC
membrane covered by high 2 - metal [fabricated by e-beam writer]
Advantages :
Fast process
high resolution of $\backsim$ 5 $\mu$ m
not affected by organic defects in mask
reduction in diffraction, reflection and scattering effects
solves depth of focus problem
high aspect ratio.
Disadvantages :
shadow printing
lateral magnification error
brighter x-ray sources needed
more sensitive resists needed
difficult fabrication of x-ray mask
Applications :
- Most commonly used in computer chips and other semiconductor related devices.