Raith 150 Specifications and Capabilities
Key Specifications of the Raith 150
- 150x150mm stage for direct writing over 6” wafers
- Automatic airlock for sample loading
- Schottky thermal field-emission filament
- 200V-30kV beam acceleration
- 2pA-10nA beam current
- 2nm beam resolution at 20kV
- Laser interferometer for stage positioning with ~30nm precision
Although the beam size of the Raith 150 is of the order of 2nm, the actual patterning resolution of the system is considerably larger and is limited mainly by the resist and pattern transfer techniques used. The figure below shows a set of gold wires that were patterned with PMMA and metal lift-off. They are approximately 25nm wide and represent the smallest features that can be routinely fabricated with our EBL system.
For patterning on scales smaller than ~25nm, PMMA resist is no longer viable since the film must be so thin that it no longer serves as a useful mask for subsequent processing steps. The Raith 150 system has recently been shown to be capable of patterning features of <10nm elsewhere with HSQ (hydrogen silsequioxane) based resists, so efforts are now underway here in Sheffield to achieve similar resolutions.