Electron column for electron beam lithography and imaging 

Electron beam lithography (EBL) is a unique process technology for advanced patterning of micro- to nanometer-scale structures. Unlike optical lithography, exposure of a lithographic resist is performed by electrons rather than photons. While aberration-free optics in combination with advanced mask technology plays a key role in mainstream optical lithography, Gaussian electron beam lithography is maskless.

As a consequence, high-performance electron columns are based on low-error electron optics along with high-precision electron deflection systems to provide small spot beams with excellent beam placement and pattern fidelity.

In EBL, the exposure process itself is realized by scanning the electron beam across the entire exposure field with varying electron doses per image pixel. This way, a digital image is transferred into the e-beam-sensitive photo resist. At the same time, the photo resist exposure process itself strongly depends on resist chemistry and the electron energy. Exposure occurs not only by exposure through electron-resist interaction of the primary electron beam, but also by secondary electron generation from the beam-substrate interaction.

As a consequence, final resist profiles depend on many factors, including

  • beam spot size,
  • beam energy,
  • substrate and resist properties,
  • and many more.

In order to maintain full control over the patterning results, an understanding of the complexity of EBL and access to the right EBL system performance and control feature are crucial for success.

At Raith, we offer a variety of electron columns to meet customers’ needs for a large variety of applications. In addition, we design our systems in a way to account for the complexity of EBL structuring. This includes advanced calibration features, sophisticated beam control over the whole exposure field, and high-precision beam placement functionality incorporated into our hardware and software architecture. In addition, individual system components are well balanced to achieve uncompromised patterning results for our EBL systems with electron columns from 30 kV to 100 kV. In more than 45 years of experience in electron beam lithography, we found this range of electron columns best suited for high-throughput EBL.

Each Raith EBL product is tailored toward specific performance features and applications. Raith offers dedicated patterning machines which focus on precision and best throughput at 100 kV and 50 kV, as well as 30 kV EBL systems with advanced detector configurations for complementary high-resolution SEM imaging. The products are grouped into product families based on electron columns and elevated system platforms.

Questions?

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100 kV columns  EBPG technology

The EBPG electron optical column is the culmination of more than 45 years of experience in electron beam lithography. Offering excellent engineering with evolutionary introduction of innovations and targeting stability and maximum performance, the EBPG is in a class of its own.

The 100 kV thermal field emission electron column with its ultrafast double-stage deflection system has been specifically designed for maximum throughput at highest pattern placement accuracy. Sophisticated fully automatic system calibration strategies guarantee best patterning performance and long unattended patterning jobs. As a consequence, excellent pattern placement accuracies can be achieved with perfect round and focussed beam shape over the entire write field, including the write field corners. Furthermore, focus, astigmatism, and distortion corrections are applied at every subfield within the entire maximum write field of max. 1 mm² (@100 kV).

A specific high-speed conjugate beam blanker eliminates leak currents and instantaneously blanks the beam, thus avoiding beam traces and associated undesired exposures on the sample when switching off the beam. As a result, sub-5 nm patterning is achieved and a maximum of 350 nA of beam current supports high-speed large-area patterning. With features including automated sample handling and benchmark-setting software, our 100 kV electron column systems are reliable and productive. That’s why EPBG systems are not only installed in nanofabrication research centers and centers of excellence worldwide, but also industrial production environments.

50 kV columns – eWrite technology

The eWrite technology built into VOYAGER is the key to highest-performance EBL in terms of writing speed and resolution at 50 kV. The innovative 50 kV electron optics design is combined with a 50 MHz pattern generator and state-of-the-art data handling. VOYAGER offers an environmental enclosure for high-resolution, high-precision patterning even in difficult environments and therefore qualifies for various applications in industry and academia.

Although VOYAGER is a dedicated high-speed EBL system, additional advanced imaging options are available for integrated process control, incorporating secondary and backscattered electron detectors (SE and BSE). Patterning results can be controlled for pattern fidelity in order to increase device yield or to retrieve valuable information from a designed experiment.

This makes the VOYAGER a versatile, yet uncompromised 50 kV EBL system with an attractive price/performance ratio.

30 kV columns – Gemini technology

The 30 kV Gemini electron optics technology offers state-of-the-art lithography performance below 10 nm linewidth. The unique Gemini lens with its in-lens detector provides highest-quality SEM imaging for both, SE and BSE detection. This makes Raith 30 kV products not only suitable for dedicated high performance EBL patterning, but is also attractive for implementation in multi user facilities with high-end SEM imaging requirements.

Unlike regular SEM imaging systems, Raith 30 kV products combines proven 30 kV electron column technology with advanced pattern generator capabilities, high-precision laser stage navigation, and Raith’s best-in-class Raith patterning software.

The large install base of 30 kV Gemini EBL technology worldwide comes with a well-established user community with years of applications experience for best practice sharing. Users are well connected and Raith is committed to taking user input on board to advance 30 kV electron column EBL systems still further.