The electron beam lithography system is used to scan a focused beam of electrons and draw custom shapes on surfaces covered with electron-sensitive resist. The electron beam lithography (EBL) remains a tool of choice in application areas involving the writing of micro-and nanostructures on the wide variety of materials. Some of the everyday use cases include in national laboratories, the research universities, and various industries. Note that the modern EBL machines write nanometer-sized structures on areas of up to mm2
So, how does the electron beam lithography work? In this post, we cover the electron beam lithography working principle.
If it is your first time learning about the electron lithography, we seek to expound on the topic and explain how the electron beam lithography, commonly abbreviated EBL, works. This article aims to cover the technical background for the readers to understand how the electron lithography works.
An Overview Of EBL Working Principle
Ideally, the electron beam lithography system works through a relatively simple concept. The EBL working principle is somehow similar to photolithography. Therefore, a focused beam of an electron is scanned across the substrate covered by an electron sensitive material, referred to as resist. The resist changes its solubility properties per the energy that is deposited by the electron beam. The areas exposed, or not exposed to the tone of the resist, will be removed through developing.
The modern EBL systems feature a razor-sharp depth of focus, up to several hundred nanometers. These systems feature advanced technology and can correct for large-scale height variations of the wafer. Therefore, the modern electron lithography can cope very well with the rough topology of the typical GaN.
Another advantage of using modern EBL is allowing the fabrication of multiple designs to be fabricated together on a typical wafer.
How Does Electron Beam Lithography Work Compared To Other Methods?
Electron beam lithography represents a slow and expensive process. EBL is slower than photolithography, stamping, or the use of self-assembly methods for patterning. Bear in mind that the substrate charging and proximity error effects have to be taken into account to ensure suitable quality devices. Therefore, Electron Beam Lithography requires cleanroom facilities. The EBL is more suited for creating extremely high-resolution patterns or creating super unique items for which the creation of photomask is time-consuming or wasteful.
Overall, electron lithography offers a high patterning resolution compared to the lithography. The high patterning resolution is often because of the shorter wavelength possessed by the 10-50 ke V electrons that it employs.
Parts of the Electron Beam Lithography System.
- The EBL system comprises of various parts. The parts include:
- The electron gun or the electron source supplying electrons
- An electron column that shapes and focuses the electron beam
- The mechanical stage used for positioning the wafer under the electron beam
- The wafer handling system for feeding wafers to the system automatically and unloading the wafers after processing
- Computer system that controls the other components
Similar to the optical lithography, the electron lithography uses the positive and the negative resists often referred to as the electron beam resists. The E-beam resists are beam sensitive materials used for covering the wafers as per the defined pattern.
Electron Beam Lithography Industrial Applications
The electron beam lithography is used in a wide range of areas. These include:·
- Cryo-electric devices
- Opto-electronic devices
- Quantum structures
- Transport mechanism studies
- Semiconductor/superconductor interfaces
- Microsystem techniques
- Optical devices
The electron beam lithography systems are derived from the early scanning electron microscopes. The systems are classified according to the beam shape and the beam deflection strategy.