Electron Beam Lithography in a nutshell

Electron Beam Lithography (EBL) is used to create the remarkably tiny patterns the current electronics industry needs for integrated circuits. This is understandable because electrons have petite spot sizes, while optical lithography’s resolution is limited by the wavelength of light applied for exposure. The wavelength of the electron beam is so short that diffraction no longer dictates the lithographic resolution.

The electron beam lithography device scans an intense beam of electrons to create unique forms on surfaces coated with electron-sensitive resist. Electron beam lithography (EBL) continues to be a general method in applications requiring the creation of micro-and nanostructures on a broad range of materials. Specific standard applications include national labs, research universities, and other businesses. It is worth noting that modern EBL machines can write nanometer-sized patterns on surfaces as big as mm2.

There are several maskless lithography technologies, the most common of which being electron beam lithography (EBL), interference lithography, and direct laser writing. Other methods, like dip pen lithography and focus ion beam lithography, are gaining popularity. Electron lithography is widely employed in several research fields dealing with nanotechnology, creating patterns with really high resolution down to only several nanometers. EBL is not diffraction-limited under usual working circumstances since the wavelength of the electrons is in the picometer range or less. A narrowly intense stream of electrons exposes a resistance developed during the EBL writing process. The resist pattern can then be treated in a variety of ways to produce the ultimate structure. The resistance and subsequent processing processes are significant constraints to attaining high resolution in an EBL system. Positive resist poly(methyl methacrylate) (PMMA) is one of the most commonly used resists, owing to its extremely high resolution (linewidths as small as 10 nm).

The majority of the patterning time in EBL is spent on three things: electron beam settling, resist exposure, and stage movement (for structures more significant than a single write-field). The settling time is a lag that is generally built into the EBL software to guarantee that the beam remains steady at each new position. The highest attainable beam current is physically limited due to space charge effects.

What is the process of Electron Beam Lithography?

The working principle of electron beam lithography is explained in this section.

If this is your first time hearing about electron lithography, we hope to expand on the subject and explain how electron beam lithography, also known as EBL, works. This article attempts to provide readers with the technical foundation they need to understand how electron lithography works.

An overview of the EBL operating concept

The electron beam lithography system, in theory, operates on a basic idea. The EBL operating concept is comparable to that of photolithography in several ways. As a result, an electron-focused beam is scanned across the substrate coated by an electron-sensitive substance known as the resist. The resist’s solubility characteristics alter in response to the energy deposited by the electron beam. Developing will eliminate the regions that have been exposed or have not been subjected to the tone of the resist.

Modern EBL systems have a razor-sharp depth of focus that can reach several hundred nanometers. These systems use cutting-edge technology to compensate for large-scale wafer height fluctuations. As a result, current electron lithography can deal with the rugged topology of ordinary GaN exceptionally effectively.

Another advantage of utilizing contemporary EBL is that it enables numerous designs on a single wafer manufacturing.

How does Electron Beam Lithography differ from other methods?

Electron beam lithography is an expensive and time-consuming method. EBL patterning is slower than stamping, photolithography, or self-assembly techniques. Remember that the substrate charging plus proximity error effects must be considered to ensure suitable quality devices. As a result, Electron Beam Lithography necessitates the use of cleanroom facilities. The EBL is better suited for generating unusually high-resolution patterns or unique products for which photomask production is time-consuming or inefficient.

In general, electron lithography has a higher patterning resolution than lithography. The high patterning precision is often due to the shorter wavelength of the 10-50 keV electrons used.

Electron Beam Lithography system components

The EBL system is made up of several components. The components are as follows:

• The computer system manages the other parts.
• The wafer handling system automatically feeds wafers into the machine and unloads the wafers after processing.
• The automated platform is used to position the wafer in front of the electron beam.
• An electron column is a device that forms and directs an electron beam.
• The electron cannon or electron source that provides electrons

Electron lithography, like optical lithography, employs positive and negative resists, also recognized as electron beam resists. E-beam resists are beam-sensitive compounds that are used to cover wafers in a specific pattern.

Industrial applications of Electron Beam Lithography

Electron beam lithography is used in a variety of applications. These are some examples:

• Pyroelectric devices 
• Devices for optoelectronics
• Structures of quantum physics
• Investigations into transport mechanisms
• Interfaces between semiconductors and superconductors
• Techniques for Microsystems
• Optical instruments

Conclusion

Electron beam lithography techniques evolved from scanning electron microscopes. The beam shape and beam deflection system are used to categorize the systems.