Do you know that there are different forms of lithography? Of the various forms, the E-beam technology and optical fiber lithography are the most popular. This article seeks to explain all that you need to know when it comes to Electron Beam Lithography Resolution. Further, the article looks at the key terms when it comes to EBL systems. Keep reading to understand the difference.
Optical Fiber Lithography
As the name depicts, Optical Fiber Lithography refers to the patterned photomask, commonly referred to as reticles, with partial opaque and partial translucent areas. Therefore, the exposure with the ultra-violet radiation or the gas lasers is done at a scale of 1:1.
The optical fiber is integrated as the transmission medium for the UV exposure light source. The optical fiber end serves as the lithography pattern and realizes the high precision pattern transfer of the optical fiber end face shape.
The optical fiber is well suited for sensing the applications due to its intrinsic advantages associated with its use. The optical fiber presents remote operation capability, low intrusiveness, and stability in harsh environments. Therefore, periodic patterns of the nanoscale structures operate as miniaturized optical components implementing the optical transduction mechanism on the tiny spatial scale.
Ebeam lithography draws custom patterning on the surface of materials that are coated with a layer of resist. Therefore, resist is exposed to electronics leading to the material becoming highly soluble and allowing its removal through immersion in a solvent or cross-links, making the material resistant to the solvent. The surrounding resist is removed.
The E-beam technology is highly reliable owing to its accuracy levels. However, it is slower technology compared to optical fiber lithography. Besides, E-beam technology is expensive and requires usage in a cleanroom facility. Therefore, the EBL lithography is more suited for creating extremely high-resolution patterns or for the unique items where the creation of the photomask feels time-consuming or wasteful.
Now that we have explained the two lithography techniques let us look at the other methods used today.
Contact Exposure is one of the oldest lithography methods. As the name suggests, the photomask is placed in direct contact with the resist layer, while the structures are transferred on a scale of 1:1. Therefore, the disruptive scattering effects will only appear at the edges of the facilities.
Contact exposure lithography allows moderate feature sizes. Since all the chips are exposed simultaneously, the wafer throughput is usually higher compared to other methods. Ideally, the construction of the lithographic unit is generally straightforward. For the contact exposure method, the photomask is contaminated since of its contact to the resist. Moreover, it can be stretched, while the resist layer can be damaged. Moreover, if there are particles between the mask and the resist, then the optical imaging will be degraded.
With proximity exposure, there will not be direct contact with the photomask and the resist. Therefore, only the shadow image is usually projected onto the wafer, resulting in a much worse resolution of the structures while the contact issues will; be prevented.
The x-ray lithography features a resolution of about 40 nm. The imaging is done through a step-and-repeat technique and at a scale of 1:1 in atmospheric pressure or at low pressure in the helium atmosphere. Therefore, the x-ray source can be a synchrotron or plasma.
ION beam Technology
The other lithography method is the use of the IOM Beam Technology. The technology is a variation of the electron beam lithography resolution.
The ion beam lithography is typical in various nanofabrication processes. They include milling, etching, ion implantation, and resist exposure. Compared to EBL lithography, ion beam technology requires about 1-10% of the particle dose to expose the resist. The resist could be the ordinary polymethyl methacrylate resist that can absorb most ions during the exposure.
We have looked at the comparison of optical fiber lithography and E-beam lithography. Besides, we have analyzed the different forms of lithography available today. Note that electron beam lithography is the most expensive compared to the other forms of lithography.