Researcher in the Spotlight: Rik Peelen
The main goal is to achieve high levels of cleanliness in high-end equipment, with a specific focus on electron microscopes
My name is Rik Peelen and I work in the Elementary Processes in Gas Discharges research group of the Department of Applied Physics. For my PhD, I focus on how we can clean surfaces in electron microscopes by using the electron beam of the microscope and creating a plasma with it.
Contamination control
The project is part of the ACCESS-2 program, an acronym for Active Contamination Control for Equipment and SubstrateS. The main goal is to achieve high levels of cleanliness in high-end equipment, with a specific focus on electron microscopes in my case. Unlike light-based microscopes, electron microscopes employ a high-energy electron beam (e-beam) to illuminate the target of interest. However, this process leads to the deposition of hydrocarbons on the sample, induced by electron bombardment, resulting in substantial measurement errors.
Cleaning
Although the e-beam partly contributes to the contamination, it can also be used to clean the microscope. The idea is to use the high-energy electrons to ionize a gas to form a plasma. In this way, we hope to achieve fast, in-situ cleaning of the microscope. The energy of the electrons within the e-beam can be precisely controlled to directly ionize the gas, providing control over critical parameters like electron temperature. The plasma that is created contains highly reactive species that can be used to clean the surfaces. This control over electron temperature enables surface cleaning with minimal impact on the surrounding environment.
Diagnostics
To characterize the electron beam, we need to employ diagnostic techniques, and one promising technique is microwave cavity resonance spectroscopy (MCRS). This technique has been developed within our research group over the past few years, so it would be interesting to apply it to an e-beam. Using MCRS allows us to obtain the current of the e-beam with high spatial and temporal resolution. As a bonus, it can also be used to measure the electron density of the plasma that is created by the e-beam. This would make it possible to characterize the whole system with high precision, which will hopefully lead to new insights into e-beam generated plasmas that can be used for substrate cleaning in electron microscopes.
This project is sponsored by the Nationaal Groeifonds program NXTGEN Hightech and by VDL ETG.