Lithography
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What Is Electron Beam Lithography, And How Does Electron Beam Lithography Work?

Invented in the 17th century, electron lithography refers to a simple and cost-effective approach to printing and publishing theatrical works. Therefore, electron beam lithography (EBL) refers to the practice of scanning the focused beam of electrons to write custom shapes on an electron-sensitive resist film. The electron beam changes the solubility of the resist ensuring a selective removal through immersing the exposed or the unexposed areas of the resist in the solvent.

While the concept of lithography was first initiated in the 17th century, electron beam lithography, as reported in the 1960s and to date, has been used for patterning nano-to micron-scale features for cell studies. The Electron Beam Lithography allows for patterning minimal features, often with sub-micrometer dimensions covering the surface’s selected areas.

How Does Electron Beam Lithography Work?

As illustrated above, electron beam lithography is derived from the first scanning of electron microscopes. Therefore, the technique involves scanning a beam of electrons across a surface covered with a resist film sensitive to the electrons. Thus, the effect is depositing energy in the desired pattern on the resist film.

The electron beam resists feature the recording and transfers media for the E-Beam lithography. The usual resists are usually polymers that are dissolved in the liquid solvent. Eventually, the liquid resist is dropped on a substrate that spins at 1000 to 6000 revolutions per minute, forming a coating. Finally, after baking out the casting solvent, the electron exposure modifies the resist.

Positive Tone Resists And Negative Tone Resists

The positive and negative tone resists are the two forms of Electron Beam Resists. The positive tone resists, develops away at the exposed regions while the negative resist features the developed area that remains after development. Polymethyl Methacrylate (PMMA) is the standard positive electron beam resist. It is usually available in two high molecular weights in the casting solvent like Chrolobenzene or anisole. Through the exposure of the electron beam, the polymer breaks into fragments dissolving in a 1:1 ratio.

What Are The Components Of The Electron Beam Lithography System?

Electron Beam Lithography

The universal electron lithography systems consist of the scan generator electron, representing the hardware component, and the PC-based operating system representing the software. The electron beam lithography system comes with the control in three major areas of scanning Electron Microscopes, the Beam Blanker Control, Scan and Signal control, and the stage control. The mode4rn EBL systems feature windows based environment while the functionality comprises a modular design. Through the use of GDSII internal editor, editing and pattern techniques are simplified. This allows the users to build a hierarchy pattern on the different levels and designs with any dose level. Therefore, a simple CAD program can be used for generating pattern data.

Where Is Electron Beam Lithography Useful?

e-Beam Lithography can be used in a wide range of application areas. The wide range of application areas includes Cryo-Electric Devices, Opto-Electronic Devices, Quantum Structures, and semiconductor/superconductor interfaces in transportation studies. Other application areas include microsystem techniques and optical devices.

Conclusion

Lithography is subdivided into different types. Electron beam lithography is just one form of lithography. With electron beam lithography, a focused beam is scanned across the wafer, and the scan is done line by line.

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