A new beam-assisted process for removing silicon from a surface in the nanometer scale in a conventional scanning electron microscope is presented. This approach is based on focused electron beam induced etching with pure chlorine gas being used as the precursor. In contrast to the established etching process using a focused ion beam (with or without the addition of a precursor), no amorphization and gallium implanting of the substrate takes place. The observed low etch rates facilitate removal with sub-nanometer precision. No spontaneous etching of silicon as in the case of xenon difluoride was observed. Etch rates of up to 4 nm min( - 1) could be achieved as well as a minimum feature size of below 80 nm. The effect of etching parameters like electron beam energy, electron beam accelerating voltage or pixel spacing were systematically examined. Finally, the underlying etching mechanism in terms of secondary electron interactions and precursor replenishment is discussed.

A novel method for cleaning a high vacuum chamber is presented. This method is based on concurrent in situ high-energetic UV light activation of contaminants located in the residual gas and at the vacuum chamber surfaces as well as the in situ generation of highly reactive ozone. Ozone oxidizes the contaminants to volatile species. Investigations by energy-dispersive x-ray analysis of residual gas depositions and mass-spectroscopy measurements of the residual gas in the vacuum chamber identify the contaminant species as hydrocarbons. After a cleaning period of 8 h, a decrease in measured chamber contamination by about 90% could be achieved according to atomic force microscope analysis. Mass spectroscopy measurements using a residual gas analyzer indicate the creation of volatile, carbonaceous species during the cleaning process.

For the first time focused electron beam induced etching of silicon using molecular chlorine has been developed as reliable and reproducible process. Around the etched pits the etching process was found to be accompanied by carbonaceous deposition from hydrocarbon contamination of the residual gas typically present in a scanning electron microscope (SEM). This work will focus on the effect of residual gas deposition on this silicon etch process using chlorine. The process mechanisms for residual gas deposition (in the absence of chlorine) as well as the silicon etch process in the presence of chlorine are discussed in terms of precursor replenishment of the sample surface and precursor delivery to the processed area. The formation of carbonaceous deposits from undesired contaminants can block the surface from an etch process. Especially for low beam currents this problem was encountered. Results suggest that the presence of chlorine when processed with a high electron beam current dominates over residual gas deposition. On the other hand, the etch-inhibiting effect of an increased level of SEM chamber contamination (resulting in increased residual gas deposition rates) is shown.