SC22 Magnetic Field Cancelling System
Today's high performance electron beam tools are very sensitive to changing ambient magnetic fields. The fields move the beam causing loss of resolution and measurement accuracy. The SC22 system reduces the ambient AC field and restores the resolution and accuracy.
Manufacturer
Spicer Consulting
Spicer Consulting has built a world-wide reputation in magnetic field cancelling for electron microscopes and similar instruments. Today, working with equipment manufacturers and users alike, the company is recognised as an industry expert in maximising the performance of electron microscopes, electron beam lithography systems, CD-SEM and focused ion beam tools. Spicer Consulting magnetic field cancelling systems protect sensitive equipment in the world's leading laboratories, universities and semiconductor manufacturing plants, as well as in the test facilities of electron and ion beam equipment manufacturers. Its magnetic field, vibration and acoustic analysis systems have been adopted as standard equipment for the conduct of site surveys by leading equipment manufacturers.
Key Features
- Protects your investment in electron beam technology by stabilising the magnetic field environment
- Cancels and monitors the AC field
- Low cost, high performance system
- Intelligent user interface
- Automated set up
- Cancels AC fields from 2.5 Hz to 5 kHz 50 x field improvement at 60Hz
- Full 3 axis (X, Y, Z) system
- Up to 60 mG (6.0 μT) pk-pk range
- Adapts to field changes within 100 μs
- Supports dual sensors for TEMs and high gradient fields
- USB monitoring port
Overview
Today's high performance electron beam tools are very sensitive to changing ambient magnetic fields. The fields move the beam causing loss of resolution and measurement accuracy. The SC22 system reduces the ambient AC field and restores the resolution and accuracy. The SC22 system comprises a Magnetic Field Control Unit, an AC Magnetic Field Sensor and three multicore cables, which are installed in the room where the field is to be cancelled.
Each power amplifier in the control unit drives a current through its cable to create a field of the opposite sign to the change in ambient field. The magnetic field sensor measures the resulting field and real time negative feedback reduces the ambient field by the loop gain of the system. The system is dynamic, automatically responding to field changes within 100 μs. AC Line fields (50/60 Hz) are reduced by 50 x.
The SC22 does not cancel DC field changes from sources such as elevators, trains and traffic. The larger SC24 system is available to cancel both AC and DC fields.
Product range
SC22 Magnetic Field Cancelling System
SC24 Magnetic Field Cancelling System
SC26 Magnetic Field Cancelling System
Installation Options
The Monitor SC22
The Monitor SC22 is a program for Microsoft Windows® PCs that can remotely monitor and control the state of the SC22 via a USB cable. The software shows the front panel is it appears on the SC22 and allows you to operate the front panel buttons remotely. It can also chart the SC22 meter readings, log the readings to a text file and send email alerts when the SC22 indicates certain conditions.
Mixer
When two sensors are used their outputs are combined by a mixer. The mixer creates a “virtual sensor” which can appear to be located inside the column. The mixer controls enable the apparent position of the sensor to be adjusted separately for the X, Y, and Z axes to tune the cancelling system for optimum improvement in the tool imaging. The mixer is most effective when optimum double loop cancelling cables are used that create a very uniform cancelling field.
Cancelling Cables
The SC22 field cancelling cables are made with a loop and a tail. The loop creates the field and the tail (which makes no field) connects the loop to the control unit. The loop parts are shown in red, green and blue. SC22 room cables have X and Y loops 16 metres long and a Z loop 20 metres long. Longer cables are available to special order. The installation shown is suitable for most SEM applications where the electron beam column is typically 1.5 metres from the room walls. The maximum field which can be cancelled (the dynamic range) depends on the size and position of the cable loops relative to the electron beam column. With 5m x 3m X and Y loops and the column 1.5m from the walls the dynamic range is about 25 mG (2.5 μT) pk-pk.
Reference Room Cables
To specify the SC22 performance more rigorously, we use a reference room cable installation. The electron beam column is centred in the 3m x 5m X and Y loops (which cross over above and below the column) and the 5m x 5m Z loop. For leading edge TEM installations, double loop room sized helmholtz cables are available. These are recommended for TEM’s fitted with Gatan Imaging filters (GIF’s). Customers are advised to consult us for design and installation of these special field cables. For leading edge TEM installations, double loop room sized helmholtz cables are available. These are recommended for TEM’s fitted with Gatan Imaging filters (GIF’s).
Frame
When the room is large or in clean rooms where there are no local walls, a frame around the electron beam tool can be used to mount double loop frame cables. A frame limits access to the tool so should only be used where room cable installation is not possible. The cancelling performance with a frame may be inferior to a room cable installation.
Sensor Options
The SC22 system uses the SC24/AC field sensor.
Sensor Mount
The optional sensor mount is for attaching the sensor to an electron beam column.
Work Chamber
A typical installation on an SEM where the sensor is standing on the work chamber at the bottom of the column. This is the most common configuration with one sensor.
Two Sensors
For some applications, there are advantages in using two sensors.Downloads
If you would like to learn more about Magnetic Field Cancelling Systems, contact our experienced technical team today. We would be happy to help you find the right solution for your needs. Contact us today!