Sharpening the focus in quantum photolithography

December 17, 2013

Photolithography uses light beams to design thin geometric patterns on the substrates of semiconductors used in microelectronic devices. This is achieved using a chemical reaction on a light-sensitive chemical, called photoresist. The trouble is that the phenomenon of light diffraction does not permit highly accurate patterns. Often, the edges of stripes have low contrast, and the distances between the stripes and the stripes' width are limited by what is referred to as Rayleigh's diffraction limit. Now, a scientist from Russia has developed a quantum lithography protocol designed to improve the resolution of this technology. The findings of George Miroshnichenko, a physicist at Saint Petersburg National Research University of Information Technologies, Mechanics and Optics, have just been published in EPJ D.

Until now, quantum lithograph protocols have been based on multi-photon absorption. This means that the frequency of the incoming light needed to be several times smaller than the frequency required for the absorption of a single photon, to trigger the absorption of multiple photons by the photoresist. As a result, this approach requires a higher wavelength, and produces lower resolution.

Instead, Miroshnichenko establishes the formula for the probability of a single - and no longer multiple - photon transition from a bound state of a quantum system to a state of continuous spectrum, using the so-called Markov approximation. This makes it possible to select the exposure time and the beam's intensity to obtain a narrow stripe in the photoresist on the substrate.

Thus, in negative photoresist, this protocol can be used to create a stripe with a width equal to half the wavelength and high-contrast edges. For positive photoresist, thin stripes can be formed on the substrate with a width that is substantially smaller than the wavelength, but the distance between these stripes is equal to half the wavelength.
-end-
Reference:

G. P. Miroshnichenko (2013), Quantum lithography on bound-free transitions, European Physical Journal D, DOI 10.1140/epjd/e2013-40586-2

For more information visit: http://www.epj.org

The full-text article is available to journalists on request.

Springer

Related Chemical Reaction Articles from Brightsurf:

New multicomponent reaction frontiers
The synthesis of complex molecules such as drugs, requires a process that sometimes involves several phases that increase its cost and harden the access to the product.

Allergic reaction: How the immune system identifies nickel
The metal nickel is one of the most common triggers of allergic contact dermatitis in humans.

Electrochemical reaction powers new drug discoveries
A Cornell-led collaboration is flipping the switch on traditional synthetic chemistry by using electricity to drive a new chemical reaction that previously stumped chemists who rely on conventional methods.

Al2Pt for oxygen evolution reaction in water splitting
Looking for rational design of new types of OER electrocatalysts and addressing fundamental questions about the key reactions in energy conversion, the inter-institutional MPG-consortium MAXNET Energy integrated the scientists from different institutions in Germany and abroad.

Researchers shed light on new enzymatic reaction
Researchers have discovered that repurposed enzymes and light are key to producing chemical compounds in an environmentally friendly fashion.

A small twist leads to a big reaction
In proteins, amino acids are held together by amide bonds.

Is the simplest chemical reaction really that simple?
New research by scientists at the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has shown, surprisingly, in the simplest, well-studied reaction, there is still uncovered mechanism.

First direct look at how light excites electrons to kick off a chemical reaction
The first step in many light-driven chemical reactions, like the ones that power photosynthesis and human vision, is a shift in the arrangement of a molecule's electrons as they absorb the light's energy.

Predicting reaction results: Machines learn chemistry
In the production of chemical compounds, the success of each individual reaction depends on numerous parameters.

Chemists glimpse the fleeting 'transition state' of a reaction
Chemists at MIT, Argonne National Laboratory, and several other institutions have devised a technique that allows them to determine the structure of the transition state of a reaction by observing the products that result from the reaction.

Read More: Chemical Reaction News and Chemical Reaction Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.