The team — led by physicist Andrew Turberfield and chemist Bob Denning, both of the University of Oxford, United Kingdom — started by building
photoresist films thick enough to carve a 3D matrix out of.
But there's one component of the chip - making process in need of an overhaul if Moore's law is to continue: the chemical mixture
called photoresist.
And importantly, they have done so by characterizing the chemistry
of photoresist, crucial to further improve performance in a systematic way.
This is a microscope image of glass coated first with aluminum and then
with photoresist, a light - sensitive material used to form a patterned coating on a surface.
Fujifilm Corporation and nano - electronics research institute imec have demonstrated full - color organic light - emitting diodes (OLED) by using their jointly -
developed photoresist technology for organic semiconductors, a technology...
Now scientists have discovered a way to bulk
up photoresists to make them thick enough to serve as photonic materials.
The
new photoresist not only had to be exquisitely sensitive to short wavelength light, but it also had to be stable at high temperatures, resistant to contamination, and reliably adhere to semiconductor substrates.
The light - particle interaction generates an angular light distribution as governed by Mie scattering, which can be compounded by multiple illuminations to sculpt novel 3D structures in the
underlying photoresist.
The new technique builds on a different method: creating flat structures with light - wave - scale subdivisions by hardening special resins,
called photoresists, with light.
A silicon wafer, about a foot in diameter, is cleaned and coated with a layer
of photoresist.
Suzanne McClelland, Runners Up (detail), 2014 — 16, ninety - nine pieces of sandblasted, fused glass
with photoresist.
The darker patches are places where
the photoresist has been exposed by a laser and will eventually lead to holes in the aluminum.
Where the light passed through, it hit an underlying organic film called
a photoresist and caused the material to polymerize.
Because
this photoresist was largely transparent, UV photons penetrated deep within the film, forming tall polymer pillars.
The team pointed four laser beams at
the photoresist film.
Laser beams harden the desired microstructure in
a photoresist.
First, a film of photosensitive material, or
photoresist, is applied onto a silicon wafer.
Exposure to a pattern of intense light causes
the photoresist to harden into a protective mask.
Direct laser writing means that a computer - controlled, focused laser beam generates the structure in
a photoresist similar to a pen.
Similar to film used in photography,
photoresist, also just called resist, is used to lay down the patterns of ever - shrinking lines and features on a chip.
Finding a new kind of
photoresist is «one of the largest challenges facing the semiconductor industry in the materials space,» says Patrick Naulleau, director of the Center for X-ray Optics (CXRO) at Berkeley Lab.
Unfortunately, today's
photoresist isn't yet ready for high volume manufacturing.
Using the Nanofabrication and Imaging and Manipulation facilities at the Molecular Foundry to analyze the patterns, the researchers saw improvements in the smoothness of lines created by
the photoresist, even as they shrunk the width.
Furthermore, researchers were able to tune and increase the amount of X-rays the photopolymer resists could absorb, improving attenuation by more than 10 times over
the photoresists commonly used for the technique.
The technique bypasses the usual diffraction limit of other methods because
the photoresist material that cures and hardens to create structures — previously a trade secret — simultaneously absorbs two photons instead of one.
Because the laser light refracts as it passes through
the photoresist material, the linchpin to solving the puzzle, the researchers said, was «index matching» — discovering how to match the refractive index of the resist material to the immersion medium of the lens so the laser could pass through unimpeded.