SOP for Hitachi S-2150 Scanning Electron Microscope For review purposes only Version 1.0 Prepared by D. Turnbull February 21, 2007. Please submit any omissions to the Author Note: This SEM is a recent donation to Niagara College from Luxcell. It is still in need of some TLC and the state of the electrical wiring is not fully known. Extra caution should be taken at rear of the instrument for electrical hazards until instrument is fully commissioned. This SOP is intended as a starting point for qualified individuals who are familiar with this type of equipment and the associated hazards. This SOP has been prepared primarily for faculty who have been trained and are familiar with the instrument. The operator is referred to the, Model S-2150 Scanning Electron Microscope Manual for more complete instructions.
Startup / Shutdown / Power failure Report any issues immediately to one of the department Technologists. See the attached document from Hitachi. Note: as set-up in V13A we do not have a main switch the isolation transformer is unplugged at the wall. Note: Please review and be familiar with the procedure, measure against power failure so that you can quickly perform this in the event of a power failure.
Start-up notes: 1. Open water valve ~ ¼ open. This will provide adequate cooling water (1-1.5 L/min). This is interlocked and an alarm will sound if flow is too low. 2. It will take about 20 minutes for the high vacuum light to come on. At this point, the ready lamp will start flickering do not press ACC voltage on until this lamp stays on steady. Failing to do so will greatly shorten the filament lifetime. Shut down notes: Turn the accelerating voltage and magnification down to the lowest setting, turn off the ACC voltage, complete the log book, and turn off as described above. Note: there is a twenty-minute cool down time before the water is turned off. Note: there is no main switch at this step unplug isolation transformer from the wall. Sample installation: Note: On the front of the sample compartment there are default settings for the x, y, z and tilt setting. These must be set before opening the compartment. Failing to do so could cause serious damage to the instrument, particularly the tilt setting. The Z- axis default is 15 mm. If this is set greater than 15 mm, i.e. 20mm, it is because a thicker sample is currently installed. It is suggest the sample compartment be opened without resetting to 15mm when a greater than 15 mm Z setting is set).
i.e. in the above table, cannot rotate past 40 tilt if Z=7.5mm or less (note: care should be taken as we do not have the height adjust tool and do not absolutely know the correct height).
In images below is the specimen stage showing the X, Y, Z, tilt, and rotation (located in center of X control) stage controls and shows the stage opened. Note that specimen stage should slide easily along the rails to open. It should not be forced open (i.e. opened before it reaches atmospheric pressure). Sample installation: 1. Make sure ACC voltage is off (turn down and then off) 2. Press air switch wait for chamber to reach atmospheric pressure. Then slide open. 3. Loosen Allen screw and install specimen stub with sample mounted or mount onto specimen stub that is present. A good electrical connection is important. This is still currently under development. However, for microchips (even on a ceramic base) and metal coated glass slides, aluminum tape to mount the sample and as a grounding strap, attaching the sample to the specimen stub seems to work. Bonding with super glue then a bonding strap also works. Metallic coatings and conductive pastes and epoxies are being investigated at the time of writing. Sample should fit onto the specimen stub. Sample height is important to set so that damage to the objective lens does not occur. Unfortunately, the SEM was received without the height gauge. Typically a flat sample should not be of any concern. Use 15 mm Z setting. If sample is thicker the Z setting should be increased approximately the sample diameter (i.e. Higher numbers 15 to 20 moves the specimen away from the objective lens). Refer to the manual for more information on sample installation and movable range and tilt limitations based on the sample size (copy included above).
Image Observation: The following is just an overview with some suggestions for a trained user. The user is referred to the manual for more details. Appended to this SOP are manual pages 2-25, 2-26,2-27 that are a set of tables with some guidelines for obtaining clear image quality. 1. High Vacuum light is on and ACC voltage ready lamp is on and not flickering, press ACC voltage ON/OFF switch. Press the up arrow to increase. a. For microchip sample tested an image can be seen at as low as 1.5 kv. However, 5-10 kv seem to be a good starting point. Emission current should be seen on the readout. 2. CRT screen will start in a raster mode. Press to switch to TV mode. 3. If instrument was left in working order. Pressing the auto then ABC buttons a few times should bring the image into view. Switching to manual and adjusting the brightness and contrast seems to work better than auto. 4. As above, auto focus coarse and fine and auto Stigmator followed by fine manual adjustment should bring a fairly clear image into view. 5. At this point one can increase the magnification adjusting the above at each step. 6. At some point the accelerating voltage may have to be increased, the aperture adjusted, and C. Lens adjusted to obtain a clear image that does not wander on the CRT too much. a. Note: The operator should be trained in these adjustments and refer to the manual for further details. Reducing the condenser lens current excessively with the post HV = on (as in normal operation) can cause too much secondary electron emission which may damage the scintillator. (p.2-27) 7. Tables 2-2 to 2-5 are appended to this document and provide some guidelines for settings.
Example #1 effect of working distance on image AMD chip ACC=10kV Aperture = 3 Mag = 1000X C lens = 9:30 Tilt = 45 WD = 25 mm, 17 mm in pictures 1 and 2 Picture 1 Picture 2
Example #2 effect of tilt on image AMD chip ACC=10kV Aperture = 3 Mag = 1000X C lens = 10:00 Z=17mm Tilt = 0, 45, 60 - pictures 3, 4, 5, respectively Picture 3 Picture 4
Picture 5
Example #3 effect of accelerating voltage on image AMD chip ACC=10kV and 20 kv pictures 6 and 7, respectively Aperture = 3 Mag = 1000X C lens = 10:00 Z=17mm Tilt = 60 Picture 6 Picture 7
Example #3 effect of magnification on image AMD chip ACC=20 kv picture 8 and 25 kv pictures 9-11 Aperture = 4 Mag = 2K, 8K, 20K, and 30K, respectively C lens = 10:00 to 10:30 Z= 17 mm Tilt = 60 Picture 8 Picture 9
Picture 10 Picture 11