When large size 300mm wafers are transported, 9KHz field noise are inevitably generated by the robot transporters. The ambient field in the surrounding can change the electron beam of the scanning electron microscope (SEM) / transmission electron microscopes (TEM) so much so that the resolution of images will be greatly distorted. The SC26 system is specially designed to neutralize the field and most applicable to CD SEM application.
The SC26 has inputs for two 200 kHz AC field sensors (blue) that it can mix to optimise the electron beam tool performance. These provide useful cancelling down to 10 Hz.Cancelling can be extended down to DC by adding a “Sensor SC24/DC+AC” and a sensor combiner for each input channel used. The SC26 is an enhanced replacement for the SC20Fast system, which has an installed base of over 200 units in wafer fabs world wide. The principle of operation of the SC26 is similar to our other field cancelling systems. The field cancelling method is wide-band analogue negative feedback. An embedded microcomputer controls the system and digitises the fields for measurement but is not within the feedback loop.
- Real time, wideband cancelling from DC to > 9 kHz fields
- Adapts to field amplitude and frequency changes within 10 µs
- Neutralize ambient magnetic field for electron beam tools in 300 mm wafer Fab
- Touch screen intelligent user interface with automatic setup and DC reset
- Simultaneous AC & DC field display with choice of Tesla or Gauss unit
- Mixes dual sensors to create virtual sensor “inside” the EM column
- Built-in test field generator
- Ethernet and USB ports for remote operation and monitoring