For several purposes, EBL may be utilized to generate photolithography masks. EBL takes longer since it requires you to write the pattern in a specific sequence. To cut down on writing time, a variety of approaches are employed. In industrial environments, EBL devices often employ extremely high acceleration voltages (50 kV).

Let’s look at the most crucial tips which make Electron Beam Lithography Easy!

• The Electron beam lithography businesses, on the other hand, employ more cost-effective devices in many research contexts. They are, however, sluggish and built for high-resolution writing. They aren’t considered suitable for producing large-scale structures with a high pattern density, even for low-resolution applications. Using the Raith e LiNE EBL, the authors show that altering the writing parameters can save writing time by more than 40 times when compared to standard instrument settings.
• The authors’ optimization method resulted in extremely accurate photolithography masks. According to the instrument software, the most often used settings took 14 days to create. Our pattern definition outperforms currently available chrome masks.
• There are numerous options for printing without a mask. The most common techniques are electron lithography, direct laser writing 1,2, and interference lithography. Alternative lithography techniques, including beam lithography and dip-pen lithography, are becoming increasingly popular in recent years.
• By lighting a resistor with a tightly focused electron beam, electron beam lithography systems (EBL) reveal it. To create the final structure, the resist pattern can be handled in a variety of ways. EBL is not diffraction-limited under normal working conditions since electrons have wavelengths in the picometer range or less. Because of the resists and subsequent processing operations, high resolution in an EBL system is challenging. Because of its ability to write patterns with remarkable accuracy down to a few nanometers, EBL is frequently used in numerous nanotechnology-related research fields.
• The majority of patterning time in electron lithography is spent on resist exposure, stage movement (for structures larger than a single write-field), and electron beam settling. You may use EBL software to ensure that the beam is stable at every new location. The settling term is already included in this situation. Due to space charge effects, the maximum beam current that may be obtained has a physical limit. When just one beam is utilized for serial exposure, this value restricts the patterning time. Because the total beam current is higher when utilizing shaped beams and multi-beam exposure techniques, they may be used faster.
• Both the exposure time and the idle time must be decreased to improve the write speed of any EBL device. When exposed to a 50 kV electron beam, newer resists, such as the negative tone resist SU-8, have been found to be as sensitive as 3.6 C/cm2.

Take a look at these under-the-radar ways for lithography businesses to improve their electron beam lithography systems:

How Do you Figure out How Fast You’re Going?

The dose required to overcome resistance increases as the acceleration voltage increases. Why? Because forward-scattered electrons transmit energy to the resistor more efficiently at lower acceleration voltages (10 kV), clearance dose requirements are decreased, but at the expense of a larger incident beam spot and rougher line surfaces.

Furthermore, depending on the developer type and development process, the amount of clearance necessary varies considerably.

Aperture Size Selection for Collimation

To collimate and current-limit an electron beam, you can utilize a beamline with interchangeable apertures. A collimating aperture with a diameter of 120 microns was used to increase the beam current. More electrons from the filament were able to reach the sample as a result of this. In an electron microscope, a collimating aperture in the electron column is a typical feature. It’s essentially a way to change the numerical aperture of a beam. Lower apertures result in a smaller numerical aperture, resulting in a larger depth of focus.

The High Current Mode Must be Turned On.

Raith offers a “high current” option that modifies the condenser lens’ focusing properties on generating a narrower, more parallel beam. The beam current is nearly doubled at this level. Due to the effects of space charge, the ultimate resolution will be slightly reduced, but the depth of focus will be improved because of the narrower, parallel beam. Using a collimating aperture with a 120-meter diameter and a 10 kV acceleration voltage, we measured a beam current of 6.8 nA.

Set the Size of the Field.

A standard writing field is 100 m by 100 m in size. Because we used such a large write field, we were able to replicate the pattern even with a 100-fold reduction in the number of write fields (the maximum is 2000 m 2000 m). As a result of the sample stage moving and settling being faster, the sample stage moving and settling time will be decreased by 100. There are some disadvantages to using bigger write fields. Because the pattern generator’s digital-to-analog converter (DAC) has a limited addressable resolution, it’s important to reduce the minimum step size. The addressable step size of the EBL is still rather small for write fields of 1000 m 1000 m.

In a write field, there are two methods for moving the beam around: raster scan and vector scan. Although it is the most basic method, it takes the longest to finish. As the beam passes overexposed areas, it begins to unblank. The vector scan is more technically challenging since it leads the beam to each region that has to be exposed and only scans over the components that need to be exposed. While utilizing a vector scan might save time, it is very dependent on the pattern being created, so bear that in mind while using it.

The E – LiNE design program employs the GDSII Raith lithography module. For integrated circuits, the GDSII format is extensively used. Bitmaps and other pattern file formats, as well as other file kinds, can be imported. You may import a bitmap using the “bitmap as reference” function of the e LiNE program. You can use the “bitmap as reference” format while using the line or meander modes. As the laser scans the whole write field, un- and exposure blanking will occur.